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Diagnosis of urinary tract infections: quick reference tools for primary care

Published 8 May 2024

Applies to England

© Crown copyright 2024

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This publication is available at https://www.gov.uk/government/consultations/urinary-tract-infection-diagnostic-tools-for-primary-care/diagnosis-of-urinary-tract-infections-quick-reference-tools-for-primary-care

Background

The quick reference guide was first published in 2007. In 2018, the tool underwent a full review and update, which included a literature review, iterative modifications, and stakeholder consultations to ensure alignment with other national guidance for urinary tract infection (UTI) management in England.

In 2022, UK Health Security Agency (UKHSA) conducted a partial review to identify and examine any relevant literature and guidance published over the previous 5 years, and to explore accessibility, usability and application of the guidance tool to clinical practice. The tool was then updated accordingly, in collaboration with expert stakeholders and a multidisciplinary steering group, and will undergo further public consultation, expected to be in May 2024.

Main changes to the tool include:

  • updated algorithm design with the addition of text summaries of the recommendations
  • removal of the diagnostic decision tool for children under 16 years (as covered by the updated UTI in under 16s : diagnosis and management from National Institute for Health and Care Excellence (NICE)
  • separating the previous decision tool for adults over the age of 65 years and those with suspected catheter-associated urinary tract infections (CAUTI) into 2 separate algorithms

Aims and implications

This quick reference tool aims to provide a simple, effective, economical and empirical approach to the diagnosis of UTIs, and minimise the risk of treatment failure and the emergence of antibiotic resistance, thus improving safe care.

The quick reference tool should lead to improved diagnosis of UTI and more appropriate antibiotic use. The tool should reduce inappropriate urine dipstick and culture tests, leading to financial and time savings for laboratories and primary care commissioners and primary care staff.

Because the incidence of asymptomatic bacteriuria (ASB) is greater in care homes than in the community and increases with age, the choice of quick reference tool may depend on the setting of the patient rather than their age. For example, the flow chart for women under 65 years may be more appropriate in some women over 65 years who are in good health and not in care homes, while the flow chart for older patients may be more suitable for some younger patients in care homes or with complex co-morbidities.

Audience and target group

This quick reference tool is for:

  • primary care prescribers in general practice and out-of-hours settings, including doctors, nurses, pharmacists and care home staff
  • those giving first point of contact for UTIs, covering acute uncomplicated infections in adults, older patients with urinary symptoms and children

Because NICE offer guidance on UTI diagnosis and management in children and young people, this group is not covered here.

Production and review process

The quick reference tool has been produced in consultation with general practitioners, nurses, specialists and patient representatives. The tool is in agreement with other guidelines published by NICE and NICE Clinical Knowledge Summaries (CKS).

This tool was produced and reviewed in collaboration with NHS England (NHSE).

The quick reference tool includes its grading method, rationale and a list of references.

The reference tool is not all-encompassing – it is meant to be used as a ‘quick reference’. Clinicians should rely on their clinical judgement and use it alongside other recommended resources. If more detail is required, we suggest referral to the websites and references cited.

A review of the literature is conducted every 5 years to assess the need to update recommendations based on new evidence or changes in best practice. Updates based on new developments or user feedback are raised to the steering group and a change note made if an update is indicated.

This decision tool was developed for application in England. We would discourage major changes to the quick reference tool, but the format allows minor changes to suit local service delivery and sampling protocols.

To create ownership agreement on the quick reference tool locally, dissemination should be agreed and planned at the local level between primary care clinicians, laboratories and secondary care providers.

While every care has been taken in the preparation of this quick reference tool, UKHSA and the partner organisations shall, to the greatest extent possible under any applicable law, exclude liability for all losses, costs, claims, damages or expenses arising out of or connected with the use of this quick reference tool or any information contained within it.

If alterations are made by an end user to this quick reference tool for local use, it must be made clear within the amended document where the alterations have been made and by whom. It should also be acknowledged that UKHSA and the partner organisations shall bear no liability for such alterations.

The evidence base and expert consensus recommendations are as complete as possible at the date of issue. Any omissions and new material will be considered at the next review.

This guidance is Crown copyright, which should be acknowledged where appropriate.

Diagnostic decision tool for women (under 65 years) with suspected UTI

This version of the flowchart is a static image for illustration purposes. You can download a version with active hyperlinks from the landing page.

Text summary of diagnostic decision tool for women (under 65 years) with suspected UTI

This tool is for women under the age of 65 with suspected uncomplicated UTI. It excludes those with a recurrent UTI (defined as 2 episodes in the last 6 months or 3 episodes in the last 12 months; see the rationale) and excludes those who have a urinary catheter. See NICE guidance for management of recurrent UTI [NG112] and CAUTI [NG113].

It will be suitable for some women aged over 65 years in the community setting (refer to Audience and target group above).

Use symptoms and dipsticks to help diagnose UTIs

Do not treat asymptomatic bacteriuria (ASB) in non-pregnant women as it does not reduce mortality or morbidity and may cause harm (see rationale).

No individual or combination of symptoms or signs is completely reliable in diagnosing a UTI, therefore severity of symptoms and safety-netting are important in all patients.

Step 1

Exclude other genitourinary causes of urinary symptoms (see rationale).

Consider:

  • 75% to 80% of individuals with vaginal discharge will not have a UTI
  • sexual history for sexually transmitted infections (STIs) in those who are sexually active, for example chlamydia and gonorrhoea
  • urethritis; urinary symptoms may be due to urethral inflammation post sexual intercourse, irritants or STIs
  • genitourinary symptoms of menopause, atrophic vaginitis or vaginal atrophy

Step 2

In all patients with urinary symptoms, check for new symptoms or signs of pyelonephritis, systemic infection or risk of suspected sepsis.

Think sepsis. Check for symptoms or signs using local or national tools such as NICE guideline NG51 or NEWS2 (see rationale).

Check for any new symptoms or signs of pyelonephritis including:

  • kidney pain or tenderness in back under ribs
  • flu-like illness
  • shaking chills (rigors) or temperature of 37.9°C or above
  • nausea or vomiting

See rationale.

Step 3

If suspected urinary sepsis or pyelonephritis:

  • obtain urine specimen before antibiotics are taken and send for culture but do not delay treatment
  • send urine culture before antibiotics are taken to inform definitive treatment
  • immediately start antibiotic treatment, using NICE guideline on pyelonephritis: antimicrobial prescribing or local or national guidelines for sepsis
  • refer, according to the recommendations in the local or national guidelines, if symptoms or signs suggest further investigation or hospitalisation is required

See rationale.

Step 4

In women under 65 years of age, use symptoms or signs of dysuria, new nocturia or cloudy urine to guide treatment:

  • 2 or more of these 3 symptoms or signs in general practice are likely to indicate a UTI (see Table 1):
    • outcome: UTI likely (see Step 6a)
  • one symptom or sign suggests a UTI is possible, as 68% of women will have a culture-confirmed UTI (>106 colony forming units per litre (cfu/L)):
    • use urine dipstick to increase diagnostic certainty (see Step 5)
  • where there are none of these 3 symptoms, a UTI is less likely:
    • use urine dipstick if other urinary symptoms (frequency, urgency, haematuria, suprapubic tenderness) (see Step 5)

See rationale.

Table 1. Prevalence of women with a positive urine culture if symptom present

Dysuria, new nocturia or cloudy urine present Percentage of GP patients with suspected UTI presenting with these symptoms or signs Percentage with these symptoms or signs who have culture confirmed UTI (at least 106 cfu/L) Suggested management
All 3 29% 82% Consider immediate antibiotic (if pregnant always immediate) OR back-up if mild symptoms and not pregnant
Two or more 71% 74% Consider immediate antibiotic (if pregnant always immediate) OR back-up if mild symptoms and not pregnant
One 25% 68% (if one or more symptom) Use urine dipstick to increase diagnostic certainty
None 4% not specified Use urine dipstick if other urinary symptoms

For antibiotic choice use NICE guideline on lower UTI: antimicrobial prescribing. Check history to determine resistance risk.

The study used as the data source for Table 1 is in the references section.

Step 5

To increase the diagnostic certainty and reduce unnecessary antibiotics, use a urine dipstick in women with only one of the following symptoms or signs:

  • dysuria
  • cloudy urine
  • new nocturia

Alternatively, use a urine dipstick in women presenting with any combination of other symptoms including:

  • frequency
  • visible haematuria
  • urgency
  • suprapubic tenderness

Follow the guidance of the manufacturer for accurate use of urine dipsticks tests, including test timing.

Dipstick results:

Positive nitrite, or both positive leukocyte and blood.
Outcome: UTI likely (see Step 6a).

Leukocyte positive but nitrite negative.
Outcome: UTI equally likely to other diagnosis (see Step 6b).

All nitrite, leukocyte and blood negative.
Outcome: UTI less likely (see Step 6c).

Consider assessment or referral for other diagnoses for women with urinary tract symptoms and dipstick with haematuria alone (without nitrites or leukocytes). See NICE guideline on suspected cancer for recognition and referral criteria.

Step 6

Management (see rationale):

For all: involve patients in decisions about management options using TARGET UTI leaflets or UTI combined leaflet.

Step 6a

If a UTI is likely:

  • send urine specimen for culture if risk of antibiotic resistance or pregnant
  • if not pregnant and mild symptoms, consider watch and wait with back-up antibiotic

or:

Step 6b

If a UTI is equally likely to other diagnosis:

  • review time of specimen (morning is more reliable as some bacteria require 4 hours or more to convert nitrate to nitrite levels that are detectable in the urine)
  • send urine for culture to confirm diagnosis
  • consider immediate or back-up antibiotic (if not pregnant) depending on symptom severity using NICE guideline on lower UTI: antimicrobial prescribing

Step 6c

If a UTI is less likely:

  • no urine culture unless the patient is pregnant
  • reassure patient that UTI is less likely
  • consider other diagnosis

For antibiotic choice, use NICE guideline on lower UTI: antimicrobial prescribing and check history to determine resistance risk.

If pregnant and dipstick and/or urine culture indicates any bacteriuria:

Step 7

For all patients, share self-care and safety-netting advice using TARGET UTI leaflets or UTI combined leaflet and involve patients in decisions about management options (see rationale).

Discuss safety-netting to seek advice if:

  • worsening symptoms
  • symptoms or signs of pyelonephritis
  • symptoms or signs of sepsis
  • no improvement after 48 hours

Discuss self-care advice to:

  • take paracetamol for pain or, if preferred and suitable, ibuprofen
  • drink enough fluid to avoid dehydration

If no clinical improvement, review antibiotic choices and start or change antibiotic as appropriate (use susceptibility results if available). Refer to appropriate services if symptoms or signs of serious illness or condition suggest further investigation or if hospitalisation is required.

Refer to NICE guidance on:

Diagnostic points for men under 65 years

Asymptomatic bacteriuria (ASB) is rare in men under 65 years (see rationale).

Consider other genitourinary causes of urinary symptoms (see rationale) and:

  • check sexual history for STIs (in sexually active men), for example, chlamydia and gonorrhoea
  • urethritis due to urethral inflammation post sexual intercourse, irritants, or STIs

Check for pyelonephritis, prostatitis, systemic infection or suspected sepsis using local policy (see rationale) and remember that:

  • urinary symptoms with fever or systemic symptoms in men are strongly suggestive of prostatic involvement or pyelonephritis
  • acute prostatitis may present with feverish illness of sudden onset, symptoms of prostatitis (low back, suprapubic, perineal or sometimes rectal pain), symptoms of UTI (dysuria, frequency, urgency or retention), or exquisitely tender prostate on rectal examination
  • recurrence or relapsing UTI in men should prompt referral to urology for investigation

Additional diagnostics points in men

Refer to the rationale for more information.

To confirm diagnosis, always send a mid-stream urine sample for culture, collected before antibiotics are given.

Do not use dipsticks to rule out infection as they are unreliable for this (see rationale).

A urine dipstick test with positive nitrates makes UTI more likely in men (PPV 96%). Negative for both nitrite and leucocyte make UTI less likely, especially if symptoms are mild.

If UTI suspected, offer immediate treatment according to NICE guidelines on lower UTI: antimicrobial prescribing and review choice of antibiotic with pre-treatment culture results.

For all patients, please refer to the information and reference tables in NICE guidance:

Diagnostic decision tool for adults over 65 years with suspected uncomplicated UTI

This version of the flowchart is a static image for illustration purposes. You can download a version with active hyperlinks from the landing page.

Text summary of diagnostic decision tool for adults over 65 years with suspected UTI

This tool is for adults over the age of 65 with suspected uncomplicated UTI. It excludes those with a recurrent UTI (defined as 2 episodes in the last 6 months or 3 episodes in the last 12 months; see rationale) and excludes those who have a urinary catheter.

Some women over the age of 65 years in the community setting can be managed using the decision tool for women under 65 years (refer to Aims and implications).  

Use symptoms and signs to determine the most appropriate management

Men and women over 65 years may present with:

  • localised symptoms or signs of a UTI (including new onset dysuria, incontinence or urgency)
  • temperature (38°C or above, 36°C or below, 1.5°C above normal twice in the last 12 hours)
  • non-specific signs of infection, for example, delirium, loss of diabetic control

See rationale.

Urine dipsticks

Do not perform urine dipsticks (see rationale). Urine dipsticks are more unreliable with increasing age over 65 years. By 80 years about half of older adults in care will have bacteria present in the urine without infection. ASB is not harmful and, although it can cause a positive urine dipstick, treatment with antibiotics is not beneficial and may cause harm.

Consider genitourinary syndrome of menopause (vulvovaginal atrophy) as a potential cause of symptoms as this can present with dysuria (see rationale). Also consider risk of urethritis, prostatitis or STI.

Step 1

First consider potential for sepsis and check for signs using local or national tool such as NICE, RESTORE2 or NEWS2 (see rationale).

Check for any new symptoms or signs of pyelonephritis including:

  • kidney pain or tenderness in back, under ribs
  • new or different myalgia, or flu-like symptoms
  • nausea or vomiting
  • shaking chills (rigors) or temperature over 37.9°C or 36°C or below

See rationale.

Step 2

If there are signs of sepsis or pyelonephritis (see rationale (if not kidney pain, rule out other localised infection see symptoms of other infection below (see Step 5 below)):

  • send urine culture before antibiotics are taken to inform definitive treatment
  • assess antibiotic resistance risk and immediately start antibiotic for upper UTI or sepsis using NICE guideline on pyelonephritis: antimicrobial ­­­­­prescribing or local or national guidelines for sepsis
  • refer according to the recommendations in the local or national guidelines if symptoms or signs suggest further investigation or hospitalisation is required

Step 3

If pyelonephritis or sepsis is ruled out, check all for new urinary symptoms, including:

  • new onset dysuria alone

Or 2 or more of the following symptoms or signs:

  • temperature: 1.5°C above normal twice in the last 12 hours
  • new frequency or urgency
  • new incontinence
  • new or worsening delirium or functional decline
  • new suprapubic pain
  • visible haematuria

See rationale.

If fever and delirium or functional decline only, exclude other infections before treating for UTI.

Step 4

If urinary symptoms suggest UTI see Step 3 above, and follow the following management points:

See rationale.

Step 5

If delirium present and symptoms do not suggest a UTI, check for other causes and manage as needed (see rationale).

Using ‘PINCH ME’ can help identify other potential underlying causes of delirium superimposed on dementia. It can be used in different clinical settings.

PINCH ME is an acronym for:

  • pain
  • (other) infection
  • (poor) nutrition
  • constipation
  • (poor) hydration
  • (other) medication
  • environment (change)

Consider other local or national delirium management resources.

Step 6

Check for symptoms and signs suggesting other infection:

  • respiratory tract infection – shortness of breath, cough or sputum production, new pleuritic chest pain
  • gastrointestinal tract infection – nausea or vomiting, new abdominal pain, new onset diarrhoea
  • skin and soft tissue infection – new redness, warmth

Follow relevant local diagnostic and treatment guidance if other infection suspected.

If no evidence for other cause of symptoms, advise watchful waiting or active monitoring, with further investigation, if needed.

Step 7

For all patients, share self-care and safety-netting advice using TARGET UTI leaflet for older adults or UTI combined leaflet and involve patients in decisions about management options (see rationale).

Discuss safety-netting to seek advice if:

  • worsening symptoms
  • signs of pyelonephritis
  • signs or symptoms of sepsis
  • no improvement after 48 hours

Discuss self-care advice to:

  • take paracetamol for pain or, if preferred and suitable, ibuprofen
  • drink enough fluid to avoid dehydration

Step 8

If no clinical improvement, review antibiotic choices and start or change antibiotic as appropriate (use susceptibility results if available). Refer if symptoms or signs of serious illness or condition suggest further investigation or if hospitalisation is required. Refer to NICE guidance on:

Diagnostic decision tool for adults who have a suspected catheter-associated UTI (CAUTI)

This version of the flowchart is a static image for illustration purposes. You can download a version with active hyperlinks from the landing page.

Text summary of diagnostic decision tool for adults who have a suspected CAUTI

CAUTI is defined as the presence of symptoms or signs compatible with a UTI in people with a catheter with no other identified source of infection plus significant levels of bacteria in a catheter specimen taken from the sample port (or a midstream urine specimen when the catheter has been removed within the previous 48 hours) (see rationale).

Men and women with CAUTI may present with:

  • temperature – 38°C or above; 36°C or below; 1.5°C above normal twice in the last 12 hours
  • localised symptoms or signs of a UTI if a catheter has been recently removed, including:
    • new onset dysuria; incontinence; urgency
    • non-specific signs of infection – for example, delirium; loss of diabetic control

See rationale.

Urine dipsticks

Do not perform urine dipsticks

Most adults with urinary catheter in place for more than one month will have bacteria present in the bladder and/or urine without infection. Asymptomatic bacteriuria (ASB) is not harmful and, although it causes a positive urine dipstick, treatment with antibiotics is not beneficial and may cause harm.

Consider genitourinary syndrome of menopause (vulvovaginal atrophy) as a potential cause of symptoms as this can present with dysuria. Also consider risk of urethritis, prostatitis or STI (see rationale).

Use symptoms and signs to determine most appropriate management

Step 1

First, consider potential for sepsis and check for signs using local or national tools, such as NICE, RESTORE2, or NEWS2 (see rationale).

Exclude pyelonephritis by checking for any one sign:

  • kidney pain or tenderness in back, under ribs
  • new or different myalgia, or flu-like symptoms
  • nausea or vomiting
  • shaking chills (rigors) or temperature over 37.9°C or 36°C or below

See rationale.

Step 2

If there are signs of sepsis or pyelonephritis (if no other urinary symptoms or kidney pain or tenderness in back, rule out other localised infection (see Step 5)) (see rationale).

If urinary catheter for more than 7 days, consider changing (if possible, remove) as soon as possible but do not allow catheter change or removal to delay antibiotics.

Obtain urine specimen before antibiotics are taken and send for culture to inform definitive treatment. If catheter is changed, obtain sample from new catheter, or obtain mid-stream urine sample, if it is removed. Label sample correctly with appropriate clinical information including catheter use.

Assess antibiotic resistance risk and immediately start antibiotic for upper UTI or sepsis using NICE guideline on pyelonephritis: antimicrobial prescribing or local or national guidelines for sepsis.

Refer, according to the recommendations in the local or national guidelines, if symptoms or signs suggest further investigation or hospitalisation is required.

Step 3

If pyelonephritis or sepsis is ruled out, check all for new urinary symptoms, including:

  • temperature: 1.5°C above normal twice in the last 12 hours
  • new or worsening delirium or functional decline
  • new suprapubic pain
  • visible haematuria

See rationale.

If fever and delirium or functional decline only, exclude other infections before treating for UTI (see Step 5).

See age-specific UTI diagnostic decision tool for additional symptoms to consider if patient does not currently have an indwelling urinary catheter but had a urinary catheter that was removed in the previous 48 hours.

Step 4

If urinary symptoms suggest CAUTI (see Step3), follow these management points:

  • share self-care and safety-netting advice using TARGET UTI leaflets  and involve patients in decisions about management options
  • if indwelling urinary catheter for over 7 days: consider changing (if possible remove) catheter as soon as possible but do not delay antibiotics
  • obtain urine specimen before antibiotics are taken and send for culture to inform definitive treatment. If catheter is changed – obtain sample from new catheter, or obtain mid-stream urine sample, if it is removed. Label sample correctly with appropriate clinical information including catheter use
  • offer immediate antibiotics using NICE guideline on catheter-associated UTI: antimicrobial prescribing or local prescribing guidelines
  • consider antibiotic resistance risk using patient history
  • review the choice of antibiotic and change the antibiotic according to susceptibility results if the bacteria are resistant, using narrow-spectrum antibiotics wherever possible

See rationale.

Urinary catheter management considerations include:

  • checking for catheter blockage and consider catheter removal if indwelling urinary catheter for over 7 days
  • offering antibiotic treatment if symptoms or signs UTI due to leaking or blocked long-term indwelling catheters
  • check bag positioning, constipation, see guidance for other causes of symptoms/signs
  • consider time-limited antibiotic prophylaxis for people with a history of symptomatic UTI after catheter change or an experience of trauma (frank haematuria after catheterisation or 2 or more attempts of catheterisation)

See rationale.

Step 5

If delirium is present and symptoms do not suggest a UTI, check for other causes and manage as needed (see rationale).

Using ‘PINCH ME’ can help identify other potential underlying causes of delirium superimposed on dementia. It can be used in different clinical settings.

PINCH ME is an acronym for:

  • pain
  • (other) infection
  • (poor) nutrition
  • constipation
  • (poor) hydration
  • (other) medication
  • environment (change)

Consider other local or national delirium management resources.

Step 6

Check for symptoms and signs suggesting other infection:

  • respiratory tract infection – shortness of breath; cough or sputum production; new pleuritic chest pain
  • gastrointestinal tract infection – nausea or vomiting; new abdominal pain; new onset diarrhoea
  • skin and soft tissue infection – new redness; warmth

Follow relevant local diagnostic and treatment guidance if other infection suspected.

If no evidence for other cause of symptoms, advise watchful waiting or active monitoring, with further investigation if needed.

Step 7

For all patients, share self-care and safety-netting advice using TARGET UTI leaflet for older adults or those with a urinary catheter or UTI combined leaflet and involve patients in decisions about management options (see rationale).

Discuss safety-netting to seek advice if:

  • worsening symptoms
  • signs of pyelonephritis
  • symptoms or signs of sepsis
  • no improvement after 48 hours

Discuss self-care advice to:

  • take paracetamol for pain or, if preferred and suitable, ibuprofen
  • drink enough fluid to avoid dehydration

Step 8

If no clinical improvement, review antibiotic choices and start or change antibiotic as appropriate (use susceptibility results if available). Refer if symptoms or signs of serious illness or condition suggest further investigation or if hospitalisation is required.

Refer to the information in NICE guideline on catheter-associated UTI: antimicrobial prescribing.

Sending urine for culture and interpreting results in all adults

Review the need for culture when considering treatment (see rationale).

Send urine specimen for culture when situation involves:

  • patient aged over 65 years if symptomatic and antibiotic indicated
  • pregnancy: for routine antenatal tests, or if symptomatic
  • suspected pyelonephritis or sepsis
  • suspected UTI in men
  • failed antibiotic treatment or persistent symptoms
  • recurrent UTI (2 episodes in 6 months or 3 in 12 months)
  • if prescribing antibiotic in someone with a urinary catheter
  • as advised by local microbiologist

Consider risk factors for resistance and send urine specimen for culture if:

  • antibiotic exposure within previous 6 months
  • abnormalities of genitourinary tract
  • renal impairment
  • care home resident
  • hospitalisation for less 7 days in last 6 months
  • recent travel to a country with increased resistance
  • previous UTI resistant

See rationale.

If prescribing an antibiotic, review choice when culture and antibiotic susceptibility results are available and contact patient if pathogen resistant to prescribed treatment.

Urine sampling in different groups

The sections below cover urine sampling in different groups (see rationale).

Women

Collecting a mid-stream urine (see NHS Choices) and holding the labia apart may help reduce contamination but if not done, sample can still be sent for culture. Do not cleanse with antiseptic before collection, as bacterial growth may be inhibited.

Older adults with functional decline

Only take urine sample if symptomatic and able to collect a clean catch sample. If incontinent, clean catch in disinfected container and condom catheters for men may be viable options but there is little evidence to support.

Men

Advise on how to take a mid-stream specimen (see NHS choices).

People with urinary catheters

It is best to collect a urine sample from a newly placed catheter if possible using aseptic technique. If not possible to collect from newly placed catheter, drain a few mL of residual urine from tubing before using sampling port, then collect a fresh sample from catheter sampling port.

For all (see rationale)

Culture urine within 4 hours of specimen collection and refrigerate or use boric acid preservative between specimen collection and incubation. Boric acid could cause false negative culture if urine not filled to correct mark on specimen bottle. Boric acid may be inhibitory to some organisms and may inhibit tests for leucocyte esterase, so you should not use with urine dipsticks.

Interpreting a urine culture result if a UTI is suspected

The sections below cover interpreting a urine culture if a UTI is suspected. Culture should be interpreted in parallel to severity of symptoms or signs (see rationale). False negatives or positives can occur. Do not treat ASB unless pregnant as it does not reduce mortality or morbidity.

Urine culture results in patients with urinary symptoms that usually indicate UTI (see rationale)

Many labs use growth of 107 to 108 cfu/L (104 to 105 cfu/mL) to indicate UTI.

Lower counts can also indicate UTI if patient symptomatic:

  • strongly symptomatic women: single isolate >105 cfu/L (>102 cfu/mL) in voided urine
  • in men counts as low as 106 cfu/L (103 cfu/mL) of a pure or predominant organism
  • any single organism >107 cfu/L (>104 cfu/mL)
  • Escherichia coli (E.coli) or Staphylococcus saprophyticus >106 cfu/L (>103 cfu/mL)
  • greater than 108 cfu/L (>105 cfu/mL) mixed growth with one dominant organism

Epithelial cells or mixed growth (see rationale)

The presence of epithelial cells is not necessarily an indicator of perineal contamination, culture result should be interpreted with symptoms and repeated if significance is uncertain.

Mixed growth may indicate perineal contamination. However, a small proportion of UTIs may be due to genuine mixed infection. Consider a re-test if symptomatic.

Red cells may be present in UTI (see rationale)

Chemical tests (such as urine dipsticks) may be more sensitive than microscopy because of the detection of haemoglobin released by haemolysis.

Refer patients with persistent haematuria post-UTI to urology.

White blood cells (WBC) or leucocytes (see rationale)

White cells >1010 WBC/L (>104 WBC/mL) are considered to represent inflammation in the urinary tract, including the urethra.

White cells can be present in older people with ASB, as the immune system does not differentiate colonisation from infection.

Sterile pyuria (see rationale)

Sterile pyuria is present when there is no bacterial growth on routine culture media and the persistent presence of white blood cells in the urine.

In sterile pyuria, consider Chlamydia trachomatis (especially if 16 to 24 years), other vaginal infections and other non-culturable organisms including TB or renal pathology.

If recurrent pyuria with UTI symptoms, discuss with local microbiologist as lower counts, down to 105 cfu/L (102 cfu/mL), may be significant. Higher volume of urine may need to be cultured, including for fastidious organisms.

Follow-up (see rationale)

Do not send follow-up urine unless pregnant or advised by the laboratory.

If UTI is recurrent, refer or seek specialist advice on further investigation or management for:

People with unexplained persistent haematuria or suspected cancer, please see NICE guideline on suspected cancer for recognition and referral for other referral criteria and considerations.

For all patients

Consider antibiotic susceptibility results and resistance when deciding on management and reviewing antibiotic treatment. Refer to NICE guidance on:

Grading method

The reference and rationale section of the quick reference tool rates the evidence cited using the Oxford Centre for Evidence-Based Medicine: Levels of Evidence and subsequent grade ratings.

These are represented as a number or letter in square brackets, after the citation (in round brackets) and a grade given after the statement.

Each strength rating form addresses several priority factors, namely, the overall quality of the evidence that exists for the recommendation.

The main factors assessed include:

  • the magnitude of the effect (individual or combined effects)
  • the certainty of the results (precision, consistency, heterogeneity and other statistical or study related factors)
  • the balance between desirable and undesirable outcomes
  • the impact of patient values and preferences on the intervention and the certainty of those patient values and preferences

The guidance adds a minus-sign (-) to denote an inconclusive answer, because of either a single result with a wide confidence interval (CI) or a systematic review (SR) with troublesome heterogeneity.

Grade A

Studies include consistent level 1 studies.

Strength rating:

  • 1a: SR (with homogeneity) of randomised control trials (RCTs)
  • 1b: individual RCT (with narrow CI)

Grade B

Studies include consistent level 2 or 3 studies, or extrapolations from level 1 studies.

Strength rating:

  • 2a: SR (with homogeneity) of cohort studies
  • 2b: individual cohort study (including low-quality RCT, for example, <80% follow-up)
  • 3a: SR (with homogeneity) of case-control studies
  • 3b: individual case-control study

Grade C

Studies include level 4 studies, or extrapolations from level 2 or 3 studies.

A strength rating of 4 denotes a case-series (and poor-quality cohort and case-control studies).

Grade D

Studies include level 5 evidence or troublingly inconsistent, or inconclusive studies of any level.

A strength rating of 5 denotes an expert opinion without explicit critical appraisal, or based on physiology, bench research or ‘first principles’.

Grade E

This denotes a finding where evidence is lacking during the review expert consensus and consultation was draw upon to inform recommendations.

Grade N or Grade Nat

This denotes a recommendation that is already covered under other national guidance (cited in the rationale).

Rationale for women (under 65 years) with suspected UTI diagnostic tool

Target groups

The flowchart for women (under 65 years) with suspected UTI excludes women with recurrent UTI. A recurrent UTI is defined as at least 2 episodes in last 6 months or at least 3 in last 12 months. (1) [Grade Nat].

Asymptomatic bacteriuria (ASB)

Based on national guidance and evidence, it is not beneficial to screen and treat for asymptomatic bacteriuria (ASB) in non-pregnant women, as this does not reduce morbidity or mortality (2 to 4) [Grade A] and it may cause harm (5, 6) [Grade B].

A systematic review published in 2019 by Henderson and others assessed the benefits and harms of ASB screening and treatment in adults, aiming to inform a preventative services taskforce in the USA (2) [1a].

The review included studies that assessed adults and pregnant women of any age who were asymptomatic for, and not in specialty care for, conditions of the urinary tract. Studies among community-dwelling adults, including those living in independent or assisted living facilities, were included, but studies conducted in hospital or institutional settings were not included.

Studies included randomized clinical trials (RCTs) and observational studies that explored the benefits and harms of screening for ASB and RCTs on benefits and harms of ASB treatment. In total, 19 studies (1 good quality, 18 fair quality; n = 8,443) were included. Of these 14 were conducted with pregnant women. Five trials examined the effectiveness and harms of ASB treatment among non-pregnant adults, primarily women and older adults. For general non-pregnant adult populations, no evidence identified health benefits associated with screening or treatment of screen detected ASB. This is consistent with findings in other reviews, including the Infectious Diseases Society of America (4), [N].

Concerns about potential overuse of antimicrobial treatment and the development of resistance to treatment are therefore highlighted in discussions regarding clinical practice for asymptomatic people, including older adults and those with diabetes. Few studies of ASB screening or treatment in pregnant populations have been conducted in the past 40 years; historical evidence established ASB screening and treatment as standard obstetric practice in the United States. The most consistent finding from the available trials indicates that treatment of ASB in pregnancy was associated with a lower risk of pyelonephritis, even when the studies at highest risk of bias were excluded in sensitivity analysis.

A systematic review was conducted by Zalmanovici and others in 2015 and included 9 studies that looked at RCT assessing the antimicrobial management of asymptomatic bacteriuria in various populations (5) [1a]. They found no difference in symptomatic UTI, complications, death, and kidney function, between treatment and non-treatment arms of the studies. However, they did find that the treatment arms showed more adverse effects from antibiotics.

Cia and others published a study in 2012 where they looked at 673 women with recurrent UTI who presented in an STI clinic with ASB (6) [2b]. They were split into 2 groups, one received antibiotics for the ASB and one did not. The findings showed that women in the treatment group were more likely to have UTI recurrence than the no treatment group, indicating that for young women with recurrent UTI, ASB may protect against recurrence.

NICE publish national guidance on the management of lower urinary tract infection (3) [N]. They recommend that pregnant women who have ASB should be offered an immediate antibiotic as they are at risk for pyelonephritis and premature delivery, taking into account urine culture/susceptibility results and previous use of antibiotics.

Genitourinary causes of urinary symptoms

Exclude other genitourinary causes of urinary symptoms: Vaginal discharge, check sexual history, urethritis, genitourinary syndrome of menopause (GSM) (Grade B).

Previous studies have shown patients with vaginal discharge or vaginal irritation are less likely to have a UTI. (7, 8) [2a-, 2a-]. Giesen and others conducted a systematic review to determine the diagnostic accuracy of symptoms and signs in women presenting with suspected UTI (7) [2a-]. The findings from the review showed that in women presenting with UTI symptoms, the presence of vaginal discharge decreases the probability of a positive urine culture [+LR 0.65 (95% CI: 0.51-0.83) with positive urine culture defined as ≥102 cfu/mL]. Bent and others conducted a systematic review of diagnostic studies in 2002, aiming to review the accuracy and precision of history taking and physical examination for the diagnosis of UTI in women (8) [2a-]. Results showed that the presence of vaginal discharge or vaginal irritation reduced the probability of UTI to around 20%. Highlighting that vaginal infections and sexually transmitted diseases such as Chlamydia and Gonorrhoea can mimic the symptoms of a UTI but should be considered separately.

A review of evidence-based approaches for the evaluation of adult patients with dysuria by Michaels and Sands found that, though cystitis was the main cause, other infectious causes can include urethritis, sexually transmitted infections, and vaginitis (9) [4]. Non-infectious inflammatory causes include a foreign body in the urinary tract and dermatologic conditions. Non-inflammatory causes of dysuria include medication use, urethral anatomic abnormalities, local trauma, and interstitial cystitis/bladder pain syndrome. Women with vulvovaginal symptoms should be evaluated for vaginitis.

The term GSM comes from a 2012 consensus report published by the Board of Directors of the International Society for the Study of Women’s Sexual Health (ISSWSH) and the Board of Trustees of the North American Menopause Society (NAMS) as a more medically accurate, all-encompassing, and more publicly acceptable term than vulvovaginal atrophy (10) [5].

The syndrome may include but is not limited to:

  • genital symptoms of dryness, burning, and irritation
  • sexual symptoms of lack of lubrication, discomfort or pain, and impaired function
  • urinary symptoms of urgency, dysuria and recurrent urinary tract infections

Women may present with some or all of the symptoms and signs.

Palma and others conducted a multi-centric study in Italy which aimed to provide nationwide data on prevalence and management of GSM (11) [2b]. This included 913 women, 59.3 ± 7.4 years old recruited from those asking for a routine gynaecological examination. There were 722/913 (79.1%) women diagnosed with GSM with a prevalence ranging from 64.7% to 84.2%, starting from one to 6 years after menopause. Recent vaginal infection was more likely in women with GSM (OR 2.48, 95% CI: 1.33 to 4.62; p = 0.0041). Symptoms reported by women with GSM were:

  • vaginal dryness (100%)
  • dyspareunia (77.6%)
  • burning (56.9%)
  • itching (56.6%)
  • dysuria (36.1%)

Signs detected by gynaecologists were:

  • mucosal dryness (99%)
  • thinning of vaginal rugae (92.1%)
  • pallor of the mucosa (90.7%)
  • mucosal fragility (71.9%)
  • petechiae (46.7%)

Only 274 (30%) of women had had a previous diagnosis of vaginal atrophy or GSM.

Sepsis

Check for sepsis using local or national guidance or resources [Grade Nat]

This review highlights 3 tools for assessing for sepsis used in the UK, but users should defer to tools specific to their treatment group endorsed within their local governance structure.

The Royal College of General Practitioners’ sepsis toolkit provides a collection of tools, knowledge, and current guidance to support the identification and appropriate management of patients with sepsis according to NICE Sepsis Guidance CG51. The toolkit highlights the work of the UK Sepsis Trust) which develops resources to screen for sepsis in multiple settings including general practice. The toolkit is aimed at GPs and healthcare professionals assessing people in the community with acute infection (12) [5].

NICE produce clinical guidance (CG51) that covers sepsis recognition, diagnosis and early management (13) [N]. The guidance states that sepsis may have non-specific, non-localised presentations, such as feeling unwell without a high temperature of over 38°C. Where high temperature is recognised as a cause for concern, this guideline also lists a tympanic temperature of less than 36°C as a moderate to high-risk criteria for sepsis. The document also provides guidance on considerations for treatment.

The Royal College of Physicians (RCP) has led the development of a new National Early Warning Score (NEWS2) (14) [5]. The tool looks to standardise the use of a sepsis scoring system across the NHS to drive the ‘step change’ required in the assessment and response to acute illness. The NEWS2 is based on a simple aggregate scoring system in which a score is allocated to physiological measurements (respiratory rate, temperature, blood pressure etc.), already recorded in routine practice. Whilst the tool has not been validated in primary care, many authorities do use it to assess, communicate and refer patients across providers in multiple settings.

Checking for new symptoms or signs of pyelonephritis

Check for any new symptom or sign of pyelonephritis (kidney pain or tenderness in back under ribs; new or different myalgia, flu-like illness; shaking chills (rigors) or temperature 37.9°C or above; nausea or vomiting) (Grade B).

A review of the evidence for diagnosis and treatment of acute pyelonephritis in women was conducted by Colgan and others in 2011 (15) [4]. Authors state that history and physical examination are the most useful tools for diagnosis.

Most patients have fever, although it may be absent early in the illness. Flank pain is nearly universal, and its absence should raise suspicion of an alternative diagnosis. The authors also list tachycardia, hypotension, possible abdominal or suprapubic tenderness, constitutional symptoms (for example, fever, chills, malaise) and gastrointestinal symptoms (for example, nausea, vomiting, anorexia, abdominal pain) as potential symptoms/signs.

A positive urinalysis confirms the diagnosis in patients with a compatible history and physical examination. Urine specimen for culture should be obtained in all patients to guide antibiotic therapy if the patient does not respond to initial empirical antibiotic regimens. Outpatient treatment is appropriate for most patients. Inpatient therapy is recommended for patients who have severe illness or in whom a complication is suspected.

A systematic review of diagnostic studies conducted by Bent and others identifies fever and back pain/costovertebral angle tenderness as symptoms of potential pyelonephritis within the review and highlights nausea and vomiting as 2 others that could be linked to the condition (8) [2a-]. These key symptoms align with other existing clinical guidance (1, 16) [N, N].

Managing pyelonephritis

Send urine for culture and manage according to national guidance [Grade Nat].

NICE sets out an antimicrobial prescribing strategy for acute pyelonephritis (upper urinary tract infection) in NG111 (17) [N]. This guidance clearly states which antibiotics should be used to manage pyelonephritis in tables and visual summaries that accompany the guidelines. The recommendations state that advice should be given on self-care to all those with suspected pyelonephritis. Mid-stream urine specimens should be sent, and advice should be given on antibiotic choice and administration.

The guidance states to reassess if symptoms worsen rapidly or significantly at any time, or do not start to improve within 48 hours of taking the antibiotic, taking account of:

  • other possible diagnoses
  • any symptoms or signs suggesting a more serious illness or condition, (such as sepsis)
  • previous antibiotic use, which may have led to resistant bacteria

Admission should be considered in those aged 16 years and over with acute pyelonephritis if they are significantly dehydrated or unable to take oral fluids and medicines, or are pregnant, or have a higher risk of developing complications (see NG111) [N]. Self-care advice includes the use of paracetamol for pain relief and drinking enough fluids to avoid dehydration.

Diagnosis using a combination of urinary symptoms and signs and urine dipstick

Use a combination of urinary symptoms and signs and urine dipstick to diagnose a UTI (see grades below).

A UTI is likely if the patient has:

  • 2 or 3 of dysuria, nocturia or cloudy urine (Grade B)

or:

  • one of dysuria, nocturia, cloudy urine or a combination of other symptoms (urgency, frequency, visible haematuria [Grade B] or suprapubic tenderness [Grade D])
    with:
  • a dipstick positive for nitrites or both RBC and leukocytes [Grade B]

A UTI is equally likely if the patient has:

  • one of dysuria, nocturia, cloudy urine

or:

  • a combination of other symptoms (urgency, frequency, visible haematuria) [Grade B]

or:

  • suprapubic tenderness [Grade D] with:

Any of the points above must be accompanied by a dipstick negative for nitrites but positive for both RBC and leukocytes [Grade B].

A UTI is less likely if the patient has:

  • one of dysuria, nocturia, cloudy urine

or:

  • a combination of other symptoms

Any of the points above must be accompanied by a dipstick negative for all 3 of nitrites, RBC and leukocytes [Grade B].

Diagnostic studies

Systematic reviews and cohort studies were considered to determine recommendations around symptoms and signs that are predictive of a UTI, which was determined by the presentation of symptoms or signs and a positive urine culture. Key studies used to inform the diagnostic algorithm for women under 65 years are highlighted in this section.

Giesen and others conducted a systematic review and meta-analysis to determine the diagnostic accuracy of symptoms and signs in women presenting with suspected UTI in 2010 (7) [2a-]. The review also examined the diagnostic value of individual symptoms and signs combined with dipstick test results in terms of clinical decision making and stratified results according to urine culture results.

In the review, 16 studies incorporating 3,711 patients were included. Subgroup analysis showed improved diagnostic accuracy using lower reference standards ≥102 cfu/mL and ≥ 103 cfu/mL. Likelihood ratios (LRs) and post-test probably (PTP) were calculated.

Six symptoms were identified as useful diagnostic symptoms when a threshold of ≥102 cfu/mL was used as the reference standard. The presence of the following all increased the probability of UTI:

  • dysuria (+LR 1.30 95% CI: 1.20 to 1.41) (PTP 71%, 95% CI: 70.0 to 71.0)
  • frequency (+LR 1.10 95% CI 1.04 to 1.16) (PTP 67.8, 95%CI: 67.0 to 68.5)
  • haematuria (+LR 1.72 95%CI 1.30 to 2.27) (PTP 75.8, 95% CI: 70.9 to 80.1)
  • nocturia (+LR 1.30 95% CI 1.08 to 1.56) (PTP 69.4, 95% CI: 67.3 to 71.3)
  • urgency (+LR 1.22 95% CI 1.11 to 1.34) (PTP 69.8, 95% CI: 68.5 to 71.1)

The presence of vaginal discharge decreased the probability of a UTI (+LR 0.65, 95% CI: 0.51 to 0.83). Back pain, fever, flank pain, and lower abdominal pain were not identified as predictive of a UTI.

The authors conclude that individual symptoms and signs only have a modest ability to raise the pre-test risk of UTI, but diagnostic accuracy improved considerably when combined with dipstick tests, particularly tests for nitrites. The presence of a positive nitrite test increased the PTP to >90.0 for all 5 symptoms.

The reviewers noted important limitations that affected the application of findings from this study. Because the use of the meta-analysis necessitated representation in 4 studies, some symptoms were excluded. The authors were unable to look at symptom combinations and noted a high amount of variability in the diagnostic estimates across studies (heterogeneity), which could have been because age was not restricted in the analysis or because the definition of symptoms varied significantly across some studies. Finally, the analysis of the contribution of urine dipsticks drew on data from another meta-analysis conducted by Deville and others in 2004, which included studies conducted in other groups including men and pregnant women (19) [3a-]. Because of this, this study has been used to support the inclusion of diagnostic signs, symptoms, and urine dipstick results within the decision tool, but not to exclude those that did not show statistical significance or that were not assessed.

In 2011, Medina-Bombardoa and others published a systematic review and meta-analysis including 11 studies from 1973 to 2003 (20) [2a-]. The review excluded any study that did not use ≥105 cfu/mL as the standard for the presence of UTI.

Pooled diagnostic odds ratios (DOR) found that individual symptoms of the following were weak diagnostic indicators of UTI:

  • dysuria (DOR 1.4 95%CI: 1.13 to 1.73)
  • urgency (DOR 1.61 95%CI: 1.15 to 2.27)
  • nocturia (DOR 1.79 95%CI: 1.17 to 2.69)
  • the simultaneous presence of urgency and dysuria (DOR 3.47 95%CI: 1.04 to 11.62)

The authors also found a strong predictive value if a urine dipstick was positive for nitrites (DOR 11.3, 95%CI: 6.95 to 18.35). Vaginal discharge and suprapubic pain were weak predictors of the absence of infection (DOR 0.50, 95% CI: 0.36 to 0.70 and DOR 0.66, 95% CI: 0.56 to 0.79 respectively). They did not find that frequency, back pain or fever were predictive of a UTI.

Low study numbers limited the authors’ ability to explore how heterogeneity influenced some variables. The authors discussed the limitations around interpreting the results as there were variations in how symptoms were defined across multiple studies and moderate to high levels of heterogeneity for some symptoms and signs. Because of these reasons, and because this study excluded studies with a lower urine culture threshold, it has been used to support the inclusion of diagnostic signs, symptoms, and urine dipstick results within the decision tool, but not to exclude those that did not show statistical significance or were not assessed.

Little and others conducted a body of research using an English cohort of primary care patients to determine the value of using urinary symptoms, signs and dipsticks to identify symptomatic women with a positive urine culture (21, 22) [2b, 2b]. The team published a study in 2006 that included 427 non-pregnant women under 70 years presenting in GP surgeries with UTI symptoms (without vaginal discharge). Urine dipstick results with nitrites and both leukocytes, plus red blood cells, were found to be predictive of a UTI. The findings identified cloudy urine, smelly urine, dysuria, and nocturia as predictive of a UTI (haematuria, urgency, and frequency were not found to be predictive of a UTI).

Because earlier work was used to derive a diagnostic algorithm that can lead to artificially inflated predictive values, in 2010, Little and others published a validation study to determine the value of using urinary symptoms, signs and urine dipsticks for diagnosis of confirmed UTI (22) [2b].

The study employed the same inclusion and exclusion criteria as the previous study and included 434 women with at least 2 urinary symptoms of UTI and no vaginal discharge from across 62 different practices in England (66% of women had a confirmed UTI using laboratory cultures of ≥103 cfu/mL).

The study confirmed that the following were predictive of a UTI:

  • cloudy urine (AOR 2.5, 95% CI: 1.6 to 3.9)
  • moderate or severe dysuria (AOR 2.00, 95% CI: 1.3 to 3.0)
  • any nocturia (AOR 1.6, 95% CI: 1.0 to 2.6)

However, smelly urine was not identified as predictive (AOR 1.2, 95% CI: 0.7 to 2.1). Nitrites (AOR 5.6, 95% CI: 2.7 to 11.7), leukocytes (AOR 3.5, 95% CI: 2.1 to 5.8), and blood (AOR 2.1, 95% CI: 1.3 to 3.4) were also shown to predict UTI.

Positive predictive values (PPV) and negative predictive values (NPV) for dipsticks were improved by varying the cut-off point. NPV was 76% for all 3 dipstick results being negative. PPV was 92% for having nitrite and either blood or leucocyte esterase (with a NPV of 42%). When clinical variables were examined, the PPV was 82% for women with all 3 of cloudy urine, dysuria of any degree, and new nocturia to any degree, 74% for 2 of these, and 68% for 1 of these. The NPV was 67% for none of these 3 features.

The authors concluded that although dipsticks can moderately improve diagnostic precision, they are poor at ruling out infection. Clinical strategies need to take into account poor NPV. No symptoms, signs, or combination was able to confirm UTI with absolute certainty and this needs to be reflected in management strategies. The authors acknowledge the possibility of type 1 errors (false positive results) because they used multiple variables in the models. However, because the results are similar to the previous study published in 2006 and the results show strong significance, this is less likely.

Because of the findings from this cohort study, the 2017 UTI diagnostic review group discussed and agreed that a strategy of using a combination of clinical score and urine dipstick will optimise correct use of antibiotics. As at least 74% of patients with 2 symptoms from dysuria, cloudy urine or nocturia will have a proven UTI, it is reasonable to prescribe empirically in these patients. In patients with no or only one of dysuria, cloudy urine or nocturia, but with presence of other urinary symptoms, a urine dipstick will help determine who should be given empirical antibiotics:

  • if nitrite is positive or both WBC and RBC are positive, UTI is likely
  • if nitrite is negative and WBC positive, only half will have UTI, if all dipstick results are negative, UTI is much less likely

Depending on the likelihood of UTI and severity of symptoms, then an immediate or back-up or no antibiotic strategy can be discussed with the patient.

Because of the limitations of studies assessing the diagnostic accuracy of symptoms, other symptoms of urgency, frequency, visible haematuria, and abdominal pain are included in the diagnostic algorithm. Urgency, frequency and visible haematuria were identified as predictive of a UTI in the systematic reviews previously discussed (7, 20) [2a-, 2a-]. A recent systematic review by Kaußner and others also highlights the usefulness of haematuria as a means to understand the severity of UTI (23) [1a].

Types of lower abdominal pain or pressure have been found to be predictive of UTI in some cohort studies (23) [2b] and not predictive in other studies (7, 8) [2a-, 2a-]. In one recent cohort study and a systematic review, abdominal pain had a negative correlation with bacteriuria, but it is unclear if that is because women with vaginal discharge were not excluded from the studies or cohorts of women (20, 24) [2a-, 2b].

In 2023, Fanshawe and others published a diagnostic accuracy study comparing the 2 main diagnostic algorithms for lower UTI in the UK (26) [2b]. The study was a secondary analysis of data from 1,103 women who participated in a primary care-based RCT of 3 urine sampling devices. Women were asked about urinary symptoms and urine dipstick results were recorded. Of urine cultures, 53.7% were positive (104 to 105 or over 105cfu/mL of a pure or predominant organism), 27.7% were mixed growth, and 18.6% were negative. Findings from 509 women under 65 years showed that when presenting with 2 or more key symptoms or other combinations of symptoms self-reported as ‘severe’, with positive nitrites on a dipstick, 61.1% (95% CI: 56.7% to 65.3%) had a urine culture that was positive,  26.3% (95% CI:  22.6% to 30.4%) had mixed growth, and 12.6% (95% CI:  9.9 to 15.8%) had no significant growth. Using urine dipstick results for all members in this group did not significantly improve diagnostic accuracy. The team found that not using severity classifications for symptoms improved diagnostic performance in the ‘UTI less likely’ subgroups. This aligns with another study which showed that symptom groupings were found to be more accurate at detecting a positive culture when key symptoms of any severity were included (22) [2b]. Because of this, caveats around symptom severity are no longer included in the diagnostic algorithm. The authors also highlight that because of the limited ability of symptom and dipstick combinations to successfully rule out UTI in women, stringent safety-netting measures need to be in place when managing care. 

Sampling and UTI management

Send urine specimen for culture if risk of antibiotic resistance, pregnant, or if UTI equally likely [Grade Nat].

Consider immediate or back-up antibiotic (if not pregnant) depending on symptom severity using NICE/PHE guideline for lower UTI: antimicrobial prescribing [Grade Nat].

If not pregnant and mild symptoms, watch and wait with back-up antibiotic, or consider immediate antibiotic (if pregnant always immediate) using NICE/PHE guideline on lower UTI: antimicrobial prescribing [Grade Nat].

Urine culture results

In research and clinical practice, the ‘gold standard’ for UTI diagnosis is traditionally identified by bacteria in the urine culture of a symptomatic individual.

For UTI diagnosis in the UK, the Standards for Microbiology Investigation: investigation of urine, recommend a single growth isolate of 106 cfu/L to 107 cfu/L (103 to 104 cfu/mL) in symptomatic women (18) [N]. The guidance does acknowledge that in acutely symptomatic women, UTI may be associated with counts of a single isolate as low as 105 cfu/L (102 cfu/mL) in voided urine. NICE guidelines on suspected cancer for recognition and referral are highlighted in order to highlight cancer risk if a woman has only red blood cells on a urine dipstick.

National guidance on UTI management

NICE guidance on Urinary tract infection (lower): antimicrobial prescribing, produced by the NICE public health and social care guidelines team, sets out an antimicrobial prescribing strategy for lower urinary tract infection [Grade Nat]. It aims to optimise antibiotic use and reduce antibiotic resistance. It clearly states which antibiotics should be used for infections in tables within the guidelines and these tables are also included in the visual summaries that accompany the guidelines.

The recommendations state that advice should be given on self-care to all those with suspected lower UTI. This includes paracetamol for pain and adequate intake of fluids. No evidence was found on cranberry products to treat a lower UTI. Guidance states to obtain a mid-stream urine sample before prescribing antibiotics for pregnant women and men with lower UTI and send for culture and susceptibility testing. This should happen before antibiotics are taken. Consider a back-up antibiotic prescription or an immediate antibiotic prescription for women with lower UTI who are not pregnant.

Take account of:

  • the severity of symptoms
  • the risk of developing complications
  • previous urine culture and susceptibility results
  • previous antibiotic use which may have led to resistant bacteria
  • preferences of the woman for antibiotic use

If a urine sample has been sent for culture and susceptibility testing and an antibiotic prescription has been given, review the choice of antibiotic when microbiological results are available. Change the antibiotic according to susceptibility results if bacteria are resistant and symptoms are not already improving, using a narrow spectrum antibiotic wherever possible.

Reliability of urine specimen

Urine specimen more reliable after 4 hours [Grade D].

A review published by Wilson and others in 2004 highlights that a limitation to using urine dipstick test for nitrites is that it requires testing a specimen of the first urine produced in the morning, as 4 or more hours are required for bacteria to convert nitrate to nitrite at levels that are reliably detectable (25) [5].

Rationale for diagnostic points for men (under 65 years) with suspected UTI

ASB is rare in men aged under 65 years [Grade C].

A previously summarised, a systematic review published in 2019 by Henderson and others assessed the benefits and harms of ASB screening and treatment in adults, aiming to inform and update a preventative services taskforce in the USA (2) [1a]. This review found that for general non-pregnant adult populations, there was no evidence for health benefits associated with screening or treatment of screen-detected ASB.

A review of the literature conducted by Nicolle and others found that for young healthy adult men, ASB is uncommon (Lipsky 1989) (26) [4]. The author cites a study that found no evidence for ASB in Japanese men under the age of 50 (Freedman 1965). One study reported a prevalence of 1.5% in 405 men aged 20 to 70 years attending a genitourinary outpatient clinic in London. On careful questioning, however, all men with bacteriuria had symptoms of dysuria (Wilson 1986). The author concludes that asymptomatic bacteriuria is not a relevant clinical issue in young healthy men, and screening for ASB is not appropriate.

Consider other genitourinary causes of urinary symptoms [Grade C].

Other genitourinary causes of urinary symptoms should be considered, for example STIs in sexually active men such as Neisseria gonorrhoeae and Chlamydia trachomatis (9, 27) [4, 4]. Michaels and Sands published a review in 2015 of evidence-based approaches for the evaluation of adult patients with dysuria (9) [4]. Dysuria is usually caused by infection (UTI) but can also be caused by urethritis and STIs. Non-infectious inflammatory causes include a foreign body in the urinary tract and dermatologic conditions. Non-inflammatory causes of dysuria include medication use, urethral anatomic abnormalities, local trauma, and interstitial cystitis or bladder pain syndrome.

An initial targeted history includes features of a local cause (for example, urethral irritation), risk factors for a complicated UTI, and symptoms of pyelonephritis. In men, urethral inflammation and discharge is typically present. In patients with suspected urethritis, a urethral, vaginal, endocervical, or urine nucleic acid amplification test for Neisseria gonorrhoeae and Chlamydia trachomatis is indicated. Any complicating features or recurrent symptoms warrant a history, physical examination, urinalysis, and urine culture.

Coker and Dierfeldt published a review in 2016 to highlight advances in research on UTI and bacterial prostatitis in men (27) [5]. Patients often present with acute onset of irritative or obstructive voiding symptoms. Suprapubic, rectal, or perineal pain, painful ejaculation, and hematospermia. Painful defecation may be present as well. In sexually active men, Neisseria gonorrhoeae and Chlamydia trachomatis should be considered. Diagnosis is usually made based on history and physical examination but may be aided by urinalysis. Other infectious causes include urethritis, STIs and vaginitis. Urethritis should be suspected in younger, sexually active patients with dysuria and pyuria without bacteriuria; in men, urethral inflammation and discharge is typically present. In patients with suspected urethritis, test for Neisseria gonorrhoeae and Chlamydia trachomatis.

Check for pyelonephritis, prostatitis, systemic infection, or suspected sepsis using local policy [Grade C].

Check for pyelonephritis, prostatitis, systemic infection, or suspected sepsis using local policy. Various toolkits have been designed by the Royal College of General Practitioners (RCGP), NICE and the RCP, which have been summarised previously.

Current evidence shows that most men with a febrile UTI without pyelonephritis symptoms show involvement of the prostate (28) [5]. A prospective study of 70 men with febrile UTI detected prostatic involvement as measured by transient increases in serum prostate-specific antigen and/ or the prostate volume in more than 90% of the patients (29) [3].

A review to highlight advances in research on UTI and bacterial prostatitis in men (27) [5]. Systemic symptoms, such as fever, chills, nausea, emesis, and malaise, commonly occur and should indicate the need to consider sepsis. The physical examination should include abdominal, genital, and digital rectal examination to assess for a tender, enlarged, or boggy prostate. Diagnosis is predominantly made based on history and physical examination but may be aided by urinalysis.

Ulleryd and others conducted a prospective study to investigate the prevalence and clinical importance of urological abnormalities in men with community-acquired febrile UTI (30) [2b]. The authors assessed 85 men (median age 63 years, range 18 to 86) for one year after an episode of febrile UTI. They were investigated by excretory urography, cysto-urethroscopy, uroflowmetry, digital rectal examination and measurement of post-void residual urine volume by abdominal ultrasonography.

The lower urinary tract investigation disclosed 46 findings in 35 men. In all, surgically correctable disorders were found in 20 patients, of whom 15 had previously unrecognised abnormalities. All patients who required surgery were identified either by a history of voiding difficulties, acute urinary retention at the time of infection, the presence of microscopic haematuria at follow-up after one month, or early recurrent symptomatic UTI. Routine imaging studies of the upper urinary tract seem dispensable in men with febrile UTI.

To reveal abnormalities of clinical importance, any urological evaluation should primarily be focused on the lower urinary tract. This provides evidence that men should be referred for urological investigation if they fail to respond to appropriate antibiotics or have recurrent UTI.

Other diagnostic points in men

The NICE guidance on lower UTI: antimicrobial prescribing states a midstream urine sample should always be sent for culture to confirm UTI diagnosis in men (3) [Grade Nat]. This guidance also provides recommendations for the management of men with suspected UTI, including antibiotic choice.

Urine dipsticks and UTI diagnosis in men [Grade B]

Koeijers and others conducted a study of 422 male patients with symptoms indicative of a UTI (31) [2b]. Urine dipstick results were compared with the results of urine culture analysis. The mean age was 57 years. A total of 236 men (56%) had a positive urine culture result. The study was limited by the fact that, for 45 patients (12%), no nitrite and/or leucocyte test results could be obtained, possibly because, according to the general practitioner guidelines in the Netherlands, the leucocyte test should not be performed when results of the nitrite test are positive.

Findings indicated that for all patients for whom both the nitrite test and the leucocyte test were performed, the sensitivity of the nitrite test was 47%, and the specificity was 98%. The sensitivity of the leucocyte test was 78%, and the specificity was 59%. When these parameters were calculated for all patients who underwent either test, the values changed only marginally. The positive predictive value of a positive nitrite test result was 96%. In the instance of a negative nitrite test result, the probability of disease was 41%; the addition of a negative leucocyte test result decreased this probability to 27%, and a positive result increased it to 55%.

The authors concluded that for this group, a positive nitrite test result should be considered indicative of a UTI, and the patient should be treated empirically, pending culture results. However, when the nitrite test yields negative results, a UTI cannot be excluded, and urine samples should be further investigated by culture, without start of empirical therapy.

Rationale for decision tool for suspected UTI in catheterised adults and those aged over 65 years

Target groups

The flowchart for adults over 65 years with suspected UTI and the flowchart for those with a urinary catheter with suspected CAUTI excludes people with recurrent UTI. A recurrent UTI is defined as at least 2 episodes in last 6 months or at least 3 in last 12 months (1) [ Grade Nat].

CAUTI definition

CAUTI is defined by NICE as the presence of symptoms or signs compatible with a UTI in people with a catheter with no other identified source of infection plus significant levels of bacteria in a catheter specimen taken from the sample port (or a midstream urine specimen when the catheter has been removed within the previous 48 hours) (34) [Grade Nat].

Use of urine dipsticks and management of  asymptomatic bacteriuria

Do not perform urine dipsticks to identify older adult or catheterised patients with bacteriuria (older adult in care home or patient with a urinary catheter Grade A; adult over the age of 65 Grade D) and do not treat asymptomatic bacteriuria [Grade A].

Due to the prevalence of ASB and pyuria, evidence continues to support unreliability of dipsticks or urinalysis for diagnosis in older adults, especially those residing care homes, or those with a urinary catheter and recommends the use of urine culture to guide antibiotic choice for symptomatic patients (2, 4, 33 to 38) [1a, 5, 1b, 1b, 2b, 5, 4, 2b].

While the evidence indicates that levels of ASB in the community increase with age, the age cut-off and risk factors are not clear. Because research frequently uses the age cut-off of 65 years to define the older adult population, this tool continues to recommend using the cut-off of 65 years and older to provide an indicator for this population with a caveat to highlight the concerns about lack of data to inform the cut-off age. This is explained in the aims and target audience section. Further research is being undertaken to clarify the recommendation for this aspect of the guidance.

The NICE quality standards for urinary tract infection in older adults highlight that men and non-pregnant women should not be prescribed antibiotics to treat ASB, and that adults with indwelling urinary catheters should not have dipstick testing to diagnose UTIs (41) [N]. NICE guidelines for urinary tract infection (catheter-associated) also state that the longer a catheter is in place, the more likely bacteria will be found in the urine. After a catheter is in place for one month nearly all people have bacteriuria and antibiotic treatment is not routinely needed for ASB in people with a catheter (34) [N].

Although levels of ASB increase with age, residential status and catheter use, rates remain variable across cohorts. The updated Scottish Intercollegiate Guidelines Network (SIGN) guidance for 2020 conducted a review of studies looking at ASB in various age groups of women in a community and care home setting (40) [5]. They found an ASB prevalence:

  • of 1.0 to 4.8% in studies assessing community rates in pre-menopausal women (13 studies with age ranges from 15 to 50 years)
  • of 2.8 to 16% (with an outlier of 50%) in post-menopause women in the community (17 studies with ages ranges starting from over 50 years)
  • ranging from 23% to 70% for studies focusing on post-menopausal women in long-term care facilities (7 studies with age ranges unknown or starting from over 65 years)

A 2003 review of cohort studies (from multiple countries), conducted by Nicolle and others, found that prevalence of ASB is common in older populations living in the community settings (36) [5]. The prevalence of ASB in studies conducted with adults living in the community ranged from 8% to 10% in women aged from 70 to 80 years and increasing with age regardless of sexual activity. Prevalence was 4% to 7% in men over 70 living in the community. For older adults in long-term care facilities, levels of ASB were higher, at 25% to 50% of women and 15% to 40% of men, correlating with impaired functional status, including incontinence of urine or bowel, and dementia.

Another evidence review in 2019 found levels of ASB in the community to be 2.8 to 8.6% for post-menopausal women, 10.8 to 16% for women over 70 years in the community and 25% to 50% for women living in care homes (4) [5].

Screening and treatment for ASB is not currently recommended in older adults, with no clear benefits for morbidity and mortality (2, 33, 34) [1a, 1b, 1b]. Additionally, antimicrobial therapy has been associated with an increased incidence of re-infection and adverse antimicrobial drug effects as well as isolation of increasingly resistant organisms in recurrent infection when compared with no therapy (34) [1b].

Tambyah and others conducted a prospective study of 761 newly catheterised patients in a university hospital (41) [2b]. These patients had their urine sampled daily from day of admission onwards. They were also assessed for symptoms of UTI and records were checked for other indications of infection such as fever or elevated white blood cell count. Urine samples were cultured immediately after collection every data in the hospital laboratory.

Out of those sampled, 82 (10.8%) developed nosocomial CAUTI (> 103 colony-forming units per mL). Mean duration of catheterisation was significantly higher (p=0.001) in those who developed a UTI (5.2 days) and those who did not (3.2 days). Pyuria was most strongly associated with CAUTI caused by gram-negative bacilli. Pyuria had a specificity of 90% for predicting CAUTI with greater than 103 colony-forming units per millilitre but a sensitivity of only 37%. In patients with short-term indwelling urinary catheters, pyuria is less strongly correlated with CAUTI than in non-catheterised patients with UTI. Pyuria is common in catheterised patients, and it has poor predictive value in this population.

A recent systematic review by Henderson and others (2019) (see summary in rationale) considered evidence of screening for asymptomatic bacteria in adults. It concluded that for non-pregnant adult populations, there was no evidence of health benefits associated with screening or treatment of screen-detected ASB (2) [1a]. This review considered data from 5 trials (n=777) and addressed benefits of treating screen detected ASB in general adult populations focused on women and older adults, with 4 studies conducted only in women, and the fifth trial primarily older adult women (84%). Treatment was variable, ranging from a single dose to 3 months of daily antibiotics, however no study identified a difference in mortality, mobility, or rates of symptomatic infections between treated and untreated individuals.

A systematic review of near patient tests to improve diagnosis of UTI in older adults included 26 studies describing 35 diagnostic tests, and concluded that overall, no one marker came out as sufficiently sensitive and specific, with robust likelihood ratios to differentiate between genuine UTI and asymptomatic bacteria (38) [2b].

Findings also supported that urine dipsticks were not suitable for the diagnosis of UTI in older people, and do not overcome the issue of asymptomatic bacteria.

Use of microbiological investigations to guide diagnosis was recently explored by international Delphi consensus (37) [4]. Due to high prevalence of ASB and pyuria in the frail older adult population, the expert panel emphasised not using urinalysis outside the presence of symptoms and signs consistent with infection. Additionally, urine culture should not be used to rule in a UTI diagnosis, as positive culture results often indicate ASB in frail older patients without localising symptoms or signs. Instead, the value of a urine culture is recommended as a guide to the choice of antibiotic therapy in cases where treatment is indicated based on the clinical presentation.

A systematic literature review covering quantitative primary studies that assess the urine dipstick as a tool in diagnosing urinary tract infection in older adults was conducted by Eriksen and Bing-Jonsson and published in 2015 (42) [2a-]. The review summarised 6 studies that looked at urine dipstick use, and the correlation to positive urine culture. The authors found there was a PPV of leukocytes and nitrites on a urine dipstick ranging from 31% to 93% and an NPV ranging from 49% to 100%. The authors conclude that dipsticks are more useful for ruling out a positive urine culture (than in) but summarise a number of limitations that clinicians need to be aware of and highlight reasons why dipsticks may give a false positive or negative in this group.

An observational study conducted by Ducharme and others in 2007, looked at the use of urine dipsticks to identify patients with a positive urine culture in 2 cohorts (43) [2b]. Each cohort included 100 patients aged 65 years presenting in an emergency department with no UTI symptoms (non-infectious/systemic complaints) or non-specific UTI symptoms (acute confusion, weakness or fever without focal symptoms). Patients with common UTI symptoms were excluded. A positive dipstick was determined by any leukocyte-esterase or nitrite or both and a positive culture; any single organism count greater than 105 cfu/mL in midstream specimens and greater than 102 cfu/mL in specimens collected by catheterization. The non-infectious and non-specific infection groups had similar PPVs (31% and 37% respectively) and NPVs (93% and 92% respectively). Because dipstick results were negative and there were no localizing urinary symptoms, 5 patients presenting in the ED with positive cultures and non-specific signs of infection had a UTI excluded from diagnosis. The authors highlight that though dipsticks performed better at ruling out a positive culture, they were not completely dependable.

Although urine dipsticks seem to be better at ruling out a positive urine culture than ruling one in for older adults, there is a wide variation in estimates across studies and potential risk if a positive culture (or a UTI) is ruled out incorrectly for vulnerable patients with non-specific signs of infection. For this reason, this quick reference tool does not recommend their use to rule in a UTI or to rule out a UTI in older adult groups.

Excluding other genitourinary causes of urinary symptoms

Consider GSM and other genitourinary causes of urinary symptoms including urethritis, sexually transmitted infection and prostatitis [Grade B].

Previous studies have shown patients with vaginal discharge or vaginal irritation are less likely to have a UTI (7, 8) [2a-, 2a-]. Giesen and others conducted a systematic review to determine the diagnostic accuracy of symptoms and signs in women presenting with suspected UTI (7) [2a-]. The findings from the review showed that in women presenting with UTI symptoms, the presence of vaginal discharge decreases the probability of a positive urine culture [+LR 0.65 (95% CI: 0.51 to 0.83) with urine culture of ≥102 cfu/mL]. Bent and others conducted a systematic review of diagnostic studies in 2002, aiming to review the accuracy and precision of history taking and physical examination for the diagnosis of UTI in women (8) [2a-]. Results showed that the presence of vaginal discharge or vaginal irritation reduced the probability of UTI to around 20%. This highlighted that vaginal infections and STIs such as chlamydia and gonorrhoea can mimic the symptoms of a UTI but should be considered separately.

A review of evidence-based approaches for the evaluation of adult patients with dysuria by Michaels and Sands, found that, though cystitis was the main cause, other infectious causes include urethritis, STIs, and vaginitis (9) [4]. Non-infectious inflammatory causes include a foreign body in the urinary tract and dermatologic conditions. Non-inflammatory causes of dysuria include medication use, urethral anatomic abnormalities, local trauma, and interstitial cystitis or bladder pain syndrome. Prostatitis can present with dysuria. Women with vulvovaginal symptoms should be evaluated for vaginitis.

The term GSM comes from a 2012 consensus report published by the Board of Directors of the International Society for the Study of Women’s Sexual Health (ISSWSH) and the Board of Trustees of the North American Menopause Society (NAMS) as a more medically accurate, all-encompassing, and more publicly acceptable term than vulvovaginal atrophy (10) [5].

The syndrome may include but is not limited to:

  • genital symptoms of dryness, burning, and irritation
  • sexual symptoms of lack of lubrication, discomfort or pain, and impaired function
  • urinary symptoms of urgency, dysuria and recurrent urinary tract infections

Women may present with some or all of the symptoms and signs.

Palma and others conducted a multi-centric study in Italy which aimed to provide nationwide data on prevalence and management of GSM (11) [2b]. This included 913 women, 59.3 ± 7.4 years old recruited from those asking for a routine gynaecological examination. There were 722 out of 913 (79.1%) women diagnosed with GSM with a prevalence ranging from 64.7% to 84.2%, starting from one to 6 years after menopause.

Recent vaginal infection was more likely in women with GSM (OR 2.48, 95% CI: 1.33 to4.62; p = 0.0041). Symptoms reported by women with GSM were:

  • vaginal dryness (100%)
  • dyspareunia (77.6%)
  • burning (56.9%)
  • itching (56.6%)
  • dysuria (36.1%)

Signs detected by gynaecologists were:

  • mucosal dryness (99%)
  • thinning of vaginal rugae (92.1%)
  • pallor of the mucosa (90.7%)
  • mucosal fragility (71.9%)
  • petechiae (46.7%)

Only 274 (30%) of women had had a previous diagnosis of vaginal atrophy or GSM.

Sepsis

Check for sepsis using local or national guidance or resources [Grade Nat].

If sepsis suspected, send urine for culture and manage according to national guidance [N].

First, check for signs of sepsis using local or national tools such as RCGP, NICE or NEWS2. These toolkits are designed to aid healthcare professionals in assessment and response to acute infection and sepsis (12 to 14) [N].

This review highlights 3 tools for assessing for sepsis used in the UK, but users should defer to tools specific to their treatment group endorsed within their local governance structure.

The Royal College of General Practitioners’ sepsis toolkit provides a collection of tools, knowledge, and current guidance to support the identifying and appropriate management of patients with sepsis according to NICE Sepsis Guidance CG51. The toolkit highlights the work of the UK Sepsis Trust which develops resources to screen for sepsis in multiple settings including general practice. The toolkit is aimed at GPs and healthcare professionals assessing people in the community with acute infection (12) [5].

NICE produce clinical guidance (CG51) that covers sepsis recognition, diagnosis and early management (13) [N]. The guidance states that sepsis may have non-specific, non-localised presentations, such as feeling unwell without a high temperature of over 38°C. Where high temperature is recognised as a cause for concern, this guideline also lists a tympanic temperature of less than 36°C as a moderate to high-risk criteria for sepsis. The document also provides guidance on considerations for treatment.

The RCP has led the development of a new National Early Warning Score (NEWS2) (14) [5]. The tool looks to standardise the use of a sepsis scoring system across the NHS to drive the ‘step change’ required in the assessment and response to acute illness. The NEWS2 is based on a simple aggregate scoring system in which a score is allocated to physiological measurements (respiratory rate, temperature, blood pressure and so on), already recorded in routine practice. Whilst the tool has not been validated in primary care, many authorities do use it to assess, communicate and refer patients across providers in multiple settings.

RESTORE2 is a physical deterioration and escalation package that is designed specifically for residential/nursing homes and domiciliary care (44) [5]. It is used to detect early soft sign deterioration. The tool and resources support staff to calculate NEWS2 scores and communicate concerns with the clinical services.

Pyelonephritis

Check for any new symptom or sign of pyelonephritis:

  • kidney pain or tenderness in back or under ribs
  • flu-like illness
  • nausea or vomiting
  • shaking chills (rigors)
  • temperature over 37.9°C [Grade B]
  • temperature 36°C or below [Grade E]

If pyelonephritis suspected, send urine for culture and manage according to national guidance [Grade Nat].

Pyelonephritis should be excluded by checking for any one sign of kidney pain or tenderness in back, under ribs, or flu-like symptoms, nausea or vomiting; shaking chills (rigors) or temperature over 37.9°C or 36°C or below.

A systematic review of diagnostic studies reviewed accuracy of history taking and physical examination for the diagnosis of UTI in women of all ages (8) [2a-]. The review identified symptoms of pyelonephritis as:

  • fever
  • back pain
  • nausea
  • vomiting

This review looked at women of all ages but it is reasonable to assume that the symptoms identified are applicable to women aged over 65 years.

A review of the evidence for diagnosis and treatment of acute pyelonephritis in women was conducted by Colgan and others in 2011 (15) [4]. Authors state that history and physical examination are the most useful tools for diagnosis. Most patients have fever, although it may be absent early in the illness. Flank pain is nearly universal, and its absence should raise suspicion of an alternative diagnosis. The authors also list potential symptoms or signs as:

  • tachycardia
  • hypotension
  • possible abdominal or suprapubic tenderness
  • constitutional symptoms (for example, fever, chills, malaise)
  • gastrointestinal symptoms (for example, nausea, vomiting, anorexia, abdominal pain)

A positive urinalysis confirms the diagnosis in patients with a compatible history and physical examination. Urine culture should be obtained in all patients to guide antibiotic therapy if the patient does not respond to initial empiric antibiotic regimens. Outpatient treatment is appropriate for most patients. Inpatient therapy is recommended for patients who have severe illness or in whom a complication is suspected.

An observational study found a positive correlation between being older and reporting urine urgency, painful voiding (dysuria), incontinence, low back-pain, and lower abdominal pain (45) [2b]. Frequency, painful and burning urination and bladder pain was reported less with the older age group (though still reported). Older women reported more generalised unspecific symptoms (lower abdominal pain, lower back pain, chills, constipation, and diarrhoea) and incontinence issues. This study shows that unspecified symptoms such as complaints on low abdomen pain, low-back pain, constipation, cold chills and nausea significantly correlated with age.

Multiple studies have shown a fever is a possible signs of pyelonephritis (15, 48 to 50) [4, 2b, 2b]. When assessing for systemic infection, adults with a temperature 36°C or below are considered at moderate to high risk of severe illness or death from sepsis (13) [N]. Because, of the risk associated with missing this sign of deterioration, a low temperature has been included in this quick reference tool as an indicator for pyelonephritis in older adult and CAUTI groups [Grade E].

Management of pyelonephritis

NICE sets out an antimicrobial prescribing strategy for acute pyelonephritis (upper urinary tract infection) in women and men (NG111) and outline the management of upper UTI for those with a CAUTI (NG113) (32, 49) [N]. This guidance clearly states which antibiotics should be used to manage pyelonephritis in tables and visual summaries that accompany the guidelines. The recommendations state that advice should be given on self-care to all those with expected pyelonephritis. Mid-stream urine specimens should be sent, or if CAUTI, take the sample from the catheter, via a sampling port if provided, and use an aseptic technique. Advice should be given on antibiotic choice and administration.

In the CAUTI guidance, the NICE committee discussed catheter removal or change, for which there was limited evidence, and experts agreed that a catheter should be changed or removed but this should not delay management. The guidance states to reassess if symptoms worsen rapidly or significantly at any time, or do not start to improve within 48 hours of taking the antibiotic, taking account of:

  • other possible diagnoses
  • any symptoms or signs suggesting a more serious illness or condition (such as sepsis)
  • previous antibiotic use, which may have led to resistant bacteria

Admission should be considered in those aged 16 years and over with acute pyelonephritis if they are significantly dehydrated or unable to take oral fluids and medicines, or are pregnant, or have a higher risk of developing complications. Self-care advice includes the use of paracetamol for pain relief and drinking enough fluids to avoid dehydration.

Using symptoms and signs to determine the most appropriate management (see grades, below)

In older adults, if pyelonephritis or sepsis is ruled out, check all for new urinary symptoms including [Grade B]:

  • new onset dysuria alone

or 2 or more of:

  • temperature: 1.5°C above normal twice in the last 12 hours
  • new frequency or urgency
  • new incontinence
  • new or worsening delirium or functional decline
  • new suprapubic pain
  • visible haematuria

If fever and delirium or functional decline only, consider other infections before treating for UTI.

In CAUTI, if pyelonephritis or sepsis is ruled out, check all for new urinary symptoms including [Grade B]:

  • temperature; 1.5°C above normal twice in the last 12 hours
  • new or worsening delirium or functional decline
  • new suprapubic pain
  • visible haematuria

Acute illness can affect blood glucose levels and loss of diabetic control could be evidence of non-specific sign of physiological stress and infection (50) [5].

Arinzon and others conducted an observational study of women aged 45 years and over from a community clinic with confirmed UTI (45) [2b]. Women who presented with urinary symptoms were divided into 2 age groups:

  • aged 45 to 54 years, n = 102, mean age 48.1 years
  • aged over 65 years, n = 94, mean age 69.2 years

Those with a confirmed UTI (>103 cfu/mL of an uropathogen in mid-stream urine culture) were asked questions related to demographics, behaviours, medical history and symptoms. There was a positive correlation between being older and reporting urine urgency, painful voiding (dysuria), incontinence, low back-pain, and lower abdominal pain. Frequency, painful and burning urination and bladder pain was reported less with the older age group (though still reported). Older women reported more generalised unspecific symptoms (lower abdominal pain, lower back pain, chills, constipation, and diarrhoea) and incontinence issues.

The study indicates that clinical presentation of UTI in older and younger (study specified pre-and post-menopausal) women is slightly different. The differences are presented not only by the voiding itself and by local symptoms but also by unspecified generalised symptoms that is especially important in older patients. Symptoms were grouped as voiding-related symptoms, local constant symptoms, and generalised symptoms. Local symptoms were predominated followed by voiding and generalised symptoms. In post-menopausal women, predominant symptoms were storage and generalised unspecific symptoms.

A prospective observational study focusing on a Danish population was published by Holm and others in 2021 (24) [2b]. The study looked at symptom likelihood in relation to age for women presenting to general practice with suspected UTI.

The study found that in women aged 75 to 89 years, absence of all symptoms (presence of abdominal pain) resulted in a probability of bacteriuria of 39%. Presence of dysuria was able to increase the probability of bacteriuria to 83% and presence of additional symptoms (absence of abdominal pain) had limited value in this age group, thus continuing to support dysuria as the main symptom even within this age group. This supports that for women aged 75 years and over with dysuria, bacteriuria is likely and treatment without further diagnostics could be considered.

In 2018 Gbinigie and others published a systematic review and meta-analysis assessing the diagnostic accuracy of symptoms and signs in predicting UTI in those aged under 65 years (51) [2a-].

The review included 15 eligible observational studies conducted in outpatient setting of developed countries. There were 66 symptoms considered, however pooled estimates for association with UTI were only possible for continence and dysuria, with the other estimates provided as individual study estimates. There was an association with UTI for incontinence and dysuria for men and women, but although specific, these symptoms were not sensitive, and absence did not help to rule out UTI. One study including women only showed a positive association between urinary incontinence and UTI, and similarly one study with UTI and urinary frequency, and one with UTI and nocturia. As data from all studies showed no significant association between dysuria, haematuria, or urgency with UTI, the authors concluded that typical symptoms are of limited predictive value in older adults. Inability to perform a number of acts of daily living were predictors of UTI, and nocturia and urinary frequency showed high heterogeneity in studies. Two studies reported presence of delirium as a predictor of UTI, and absence weakly helped to rule out UTI (LR+ 1.91, LR- 0.72 and LR+ 1.52, LR- 0.83). Of note, as just 14% of patients were living at home, the evidence is mostly applicable to older women in care homes or requiring assisted living.

In 2005, Loeb and others published a cluster randomised controlled trial in 24 nursing homes in Ontario, Canada, and Idaho, US, with 12 allocated to a multifaceted intervention, and 12 allocated to usual care (47) [2b]. A Delphi process had been published previously to develop a diagnostic and treatment algorithm, which was implemented in the multifaceted intervention (46) [4].

The algorithm suggested that urine cultures should be ordered if there is a fever of over 37.9°C, or a 1.5°C increase above baseline on at least 2 occasions over the previous 12 hours, and one or more of:

  • dysuria
  • urinary catheter
  • urgency
  • flank pain
  • shaking chills
  • urinary incontinence
  • frequency
  • gross haematuria
  • suprapubic pain

If there was no fever at onset, a culture was ordered if there was dysuria or 2 or more of:

  • urgency
  • flank pain
  • shaking chills
  • incontinence
  • frequency
  • haematuria
  • suprapubic pain

If urinary catheter, a culture was ordered if there was one or more of:

  • rigors
  • delirium
  • costovertebral tenderness

If the culture is positive or pending, antibiotics were recommended in those without a urinary catheter if there was 2 or more of:

  • fever
  • urgency
  • flank pain
  • incontinence
  • rigors
  • frequency
  • haematuria
  • suprapubic pain

If the resident had a urinary catheter, they needed one or more of:

  • costovertebral tenderness
  • rigors
  • new delirium
  • fever

Antibiotics should only have been prescribed in cases of systemic symptoms of infection with an in-situ catheter. Fewer courses of antimicrobials were prescribed in the intervention nursing homes than in the usual care homes (weighted mean difference -0.49; 95% CI -0.93 to -0.06). This algorithm is widely used and is a generally accepted tool for diagnosing and treating UTI in older adult care home settings.

Balogun and others published a systematic review in 2014 that looked at the relationship between delirium and UTI (52) [2a-]. A search was conducted for published studies from 1966 through 2012 using the medical subject heading (MESH) terms ‘urinary tract infection’ and ‘delirium’, limited to humans, aged 65 and older.

Of the 11 identified studies, 5 met inclusion criteria of being primary studies that addressed the association of UTI and delirium. The studies were 4 cross-sectional observational studies and one case series. The methodological strength of the studies was evaluated using 6 standards adapted from an earlier systematic review. Only 2 of the 5 studies matched or statistically adjusted for differences in comparison groups. None of the studies evaluated subjects with equal intensity for the presence of delirium and UTI, nor did they have objective criteria for either diagnosis. In subjects with delirium, UTI rates ranged from 25.9% to 32% compared to 13% in those without delirium. In subjects with UTI, delirium rates ranged from 30% to 35%, compared to 7.7% to 8% in those without UTI.

Though the studies examined conclude that there is an association between UTI and delirium, all of them had significant methodological flaws that likely led to biased results. It is difficult to ascertain the degree to which UTIs cause delirium and more research is needed to clarify the relationship. The authors conclude that it is reasonable to assume that there is an association between delirium and sufficiently symptomatic UTI, just as there is for delirium and multiple other infections or conditions. It is also reasonable to conclude that ASB, without dysuria, frequency, bladder discomfort, or fever, is unlikely to cause a patient to become delirious and that factors other than an abnormal urinalysis play a more dominant role in the development of delirium.

Sending urine for culture and other management points

Always send a urine culture if feasible before antibiotics are taken and other UTI management points [Grade Nat].

NICE produce antimicrobial prescribing for Urinary tract infection (lower) and the Urinary tract infection (catheter-associated) (3, 32) [N]. This guidance sets out an antimicrobial prescribing strategy for lower urinary tract infection. It aims to optimise antibiotic use and reduce antibiotic resistance. It is clearly stated which antibiotics should be used for infections in tables within the guidelines and these tables are also included in the visual summaries that accompany the guidelines.

The recommendations state that advice should be given on self-care to all those with expected a lower UTI. This includes paracetamol for pain, adequate intake of fluids, and no evidence was found on cranberry products to treat a lower UTI.

Guidance states to obtain urine specimens (mid-stream, or if CAUTI, take the sample from the catheter via a sampling port if provided using aseptic technique) before prescribing antibiotics if possible but not to delay treatment. Men and people with a urinary catheter should receive an immediate antibiotic. Consider a back-up antibiotic prescription or an immediate antibiotic prescription for women with lower UTI who are not pregnant.

Taking into account:

  • the severity of symptoms
  • the risk of developing complications
  • previous urine culture and susceptibility results
  • previous antibiotic use which may have led to resistant bacteria
  • preferences of the woman for antibiotic use

If a urine sample has been sent for culture and susceptibility testing and an antibiotic prescription has been given, review the choice of antibiotic when microbiological results are available, and change the antibiotic according to susceptibility results if bacteria are resistant and symptoms are not already improving, using a narrow spectrum antibiotic wherever possible.

Urinary catheter management considerations

Use national guidance to guide urinary catheter management [Grade Nat]

According to NICE Healthcare-associated infections: prevention and control in primary and community care, when changing urinary catheters in patients with a long-term indwelling urinary catheters, do not offer antibiotic prophylaxis routinely (53) [N].

Only consider antibiotic prophylaxis for patients who have a history of symptomatic urinary tract infection after catheter change or experience trauma (the guideline development group (GDG) defined trauma as frank haematuria after catheterisation or 2 or more attempts of catheterisation) during catheterisation.

Guidance from Public Health Wales supports best practice when managing a non-draining or leaking long-term urinary catheter and guides the appropriate use of catheter patency solutions in order to reduce CAUTI and associated bacteraemia (54) [N].

It lists multiple reasons a catheter might leak or stop draining that need to be assessed for before using catheter patency solutions. These include:

  • kinked tubing or poorly supported drainage bag or tight clothing
  • overfull draining system
  • bladder spasm
  • bladder stones
  • wrong length or size of catheter
  • over or under inflated catheter balloon
  • constipation
  • low fluid intake or dehydration
  • blood or debris
  • encrustation
  • UTI
  • drainage bag located above bladder
  • drainage bag too low producing negative pressure causing mucosa to be sucked into outlet eyelets

More information is provided on the management of a blocked urinary catheter and use of catheter patency solutions.

Delirium and symptoms not suggestive of a UTI

If delirium present and symptoms do not suggest a UTI, check for other causes and manage as indicated [Grade D].

In 2019, Mayne and others published a systematic review of association between UTI and confusion (56) [2a-]. The review included 22 studies published before August 2015. The quality of studies varied. Criteria used to define UTI and confusion were overall poor. Study size and design varied.

Reported outcomes included the rate of confusion in patients with suspected UTI (n = 13) and rate of suspected UTI in patients with confusion (n = 10). Some studies reported rate of confusion in patients with bacteriuria (n = 4) and one study reported rate of bacteriuria in patients with confusion. Most studies reported confusion as delirium (n = 15), followed by confusion (n = 3), altered mental state (n = 2), and mental status changes (n = 1), with one study reporting both delirium and altered mental status.

Findings discussed the issues with flawed research in this area due to poor case definition for UTI or confusion, or inadequate control of confounding factors introducing significant bias. No conclusions about the association between UTI and confusion were therefore drawn. One study of acceptable quality shows an association between confusion and bacteriuria. However, this sample of patients in whom they tested bacteriuria and pyuria were patients already suspected of having a UTI, introducing a bias into their calculation.

In 2017, Pryor and others published a review that describes a simple mnemonic called PINCH ME (Pain, INfection, Constipation, deHydration, Medication, Environment) that can help identify potential underlying causes of delirium superimposed on dementia (DSD) and considerations for care planning in patients with dementia (57) [5]. The mnemonic can easily be adapted to different clinical settings.

This review explores the dichotomy in healthcare provision for ‘physical’ and ‘mental’ health, and the unique role nurses have when caring for people with DSD. In the review, dementia is contrasted with delirium and subtypes of delirium presentation are discussed. Nurses can recognise DSD through:

  • history gathering
  • implementation of appropriate care
  • effective communication with families and the multidisciplinary team

Several members of the steering group use the PINCH ME mnemonic in their clinical practice. Participants of the needs assessment (carers and GP staff) reported it was very useful and reflected their own practice and experience of patients with confusion.

In 2006, Potter and others updated the guidelines for the diagnosis and management of delirium in the elderly (1997) compiled by Dr Lesley Young and Dr Jim George based on the work of the multidisciplinary working party on Confusion in Crises, Royal College of Physicians, 1995 (58) [5]. The update was overseen by a multi-professional GDG including representatives from nursing, care of the elderly, and old age psychiatry.

Main points indicated that the most important action for the management of delirium is the identification and treatment of the underlying cause. The patient should be nursed in a good sensory environment and with a reality orientation approach, and with involvement of the multidisciplinary team. Keep the use of sedatives and major tranquillisers to a minimum. Use one drug only starting at the lowest possible dose and increasing in increments, if necessary, after an interval of 2 hours. Review all medication at least every 24 hours. One-to-one care of the patient is often required and should be provided while the dose of psychotropic medication is titrated upward in a controlled and safe manner.

In 2010, NICE published guidance on Delirium: prevention, diagnosis and management in hospital and long-term care (59) [N]. This guideline covers diagnosing and treating delirium in people aged 18 years and over in hospital and in long-term residential care or a nursing home. It also covers identifying people at risk of developing delirium in these settings and preventing onset. It aims to improve diagnosis of delirium and reduce hospital stays and complications.

This guidance outlines ways that delirium can be addressed or prevented including ensuring that the environment is appropriate, and that people are:

  • cognitively engaged
  • addressing dehydration or constipation
  • ensuring infections are identified and treated
  • addressing pain
  • supporting mobility
  • ensuring good nutrition
  • addressing sensory impairment
  • ensuring good sleep patterns

The guidance also discussed the need to address infection by looking for and treating infection and avoiding unnecessary catheterisation.

Rationale for sending urine for culture and interpreting results in all adults

This section covers review needs for culture when considering treatment [see Grades below].

When to send a urine culture

Symptomatic older adults [Grade B]

In 2017, Rosello and others published a retrospective population-based study to compare the frequency of antibiotic resistance of urinary tract bacteria from residents of long-term care facilities for older adults and adults aged 70 years or older living in the community (60) [2b]. Positive urine specimens reported to any diagnostic microbiology laboratory in the West Midlands region (England) from 1 April 2010 to 31 March 2014 were collected and analysed from individuals aged 70 years or older.

The resistance of E. coli and Klebsiella spp. to trimethoprim, nitrofurantoin, third-generation cephalosporins and ciprofloxacin and the rate of laboratory-confirmed E. coli and Klebsiella spp. UTI were assessed in long-term care facility residents and in the community.

In the community, 37% of samples had trimethoprim-resistant E. coli and 26% trimethoprim-resistant Klebsiella spp. compared to 60% and 41% respectively in long-term care facilities. In community samples 4% and in long-term care facilities 7% had E. coli resistant to nitrofurantoin (35% community and 41% long-term care for Klebsiella spp.).

Residents of long-term care facilities for the elderly had more than double the rate of E. coli and Klebsiella spp. UTI and more than 4 times the rate of E. coli and Klebsiella spp. UTI caused by antibiotic-resistant bacteria compared with those living in the community.

The authors conclude that a very high proportion of these UTIs in the elderly living in LTCFs (and a high proportion of those living in their own homes) will not respond to trimethoprim treatment. However, resistance to nitrofurantoin remains low in UTIs caused by E. coli but high in UTIs caused by Klebsiella spp., demonstrating the need to understand further the mechanisms for the selection of resistance.

Because of the high level of resistance demonstrated in older adults, this quick reference tool recommends that all older adults who have a suspected UTI have a urine culture sent for analysis.

Pregnancy [Grade A]

NICE recommend that women should be offered routine screening for bacteriuria by mid-stream urine culture early in pregnancy, because identification and treatment of ASB reduces the risk of pyelonephritis and premature delivery (61) [N].

Sepsis or pyelonephritis [Grade D]

A diagnosis of pyelonephritis is usually made on the basis of flank pain (usually unilateral), fever, rigors, raised C-reactive protein (or erythrocyte sedimentation rate), and evidence of urine infection on a mid-stream urine sample (62) [5].

Men [Grade Nat]

National guidance states you should obtain a mid-stream urine sample before prescribing antibiotics for pregnant women and men with lower UTI and send for culture and susceptibility testing (3).

Persistent symptoms or recurrent UTI [Grade A]

In 2018, Hawkey and others published a report from a working party making recommendations in antimicrobial prescribing for the treatment of infections caused by multidrug-resistant gram-negative bacteria (63) [4]. The guidance has been derived from current peer-reviewed publications and expert opinion with open consultation. Methods for systematic review were NICE compliant and in accordance with the SIGN 50 Handbook. Critical appraisal was applied using AGREE II. Published guidelines were used as part of the evidence base and to support expert consensus.

The guidance includes recommendations for stakeholders (including prescribers) and antibiotic-specific recommendations. The authors recommend no antibiotic prescriptions for treating the elderly with ASB. The authors also list risk factors for patients with urinary tract infections caused by multi-drug resistant gram-negative bacteria in the UK.

Patients are at increased risk if they have:

  • recurrent UTI
  • persistent urinary symptoms after an initial antibiotic
  • over 7 days hospital admission in the last 6 months
  • residence in a care home
  • recent travel and especially healthcare in a country with increased antimicrobial resistance
  • previously known UTI (within one year) caused by bacteria resistant to amoxicillin or clavulanate, cephalosporins or quinolone or recent treatment with these agents

In 2010, Costello and others published a systematic review. Findings showed that individuals prescribed an antibiotic in primary care for a respiratory or urinary infection develop bacterial resistance to that antibiotic (64) [2a]. The effect is greatest in the month immediately after treatment but may persist for up to 12 months.

In 5 studies of urinary tract bacteria (14,348 participants), the pooled odds ratio for bacterial resistance was 2.5 (95% CI 2.1 to 2.9) within 2 months of antibiotic treatment, and 1.33 (95% CI 1.2 to 1.5) within 12 months of treatment.

If urinary catheter [Grade Nat]

This NICE guideline sets out an antimicrobial prescribing strategy for catheter-associated UTI (CAUTI) (32) [N]. It aims to optimise antibiotic use and reduce antibiotic resistance. The guideline states that the longer a catheter is in place, the more likely bacteria will be found in the urine.

Antibiotic treatment is not routinely needed for ASB in people with a catheter (apart from in pregnant women with ASB). When urine culture and susceptibility results are available, review the choice of antibiotic and change the antibiotic according to susceptibility results if the bacteria are resistant, using narrow-spectrum antibiotics wherever possible.

Risk factors for resistance

Abnormality of the genitourinary tract and renal impairment [Grade C]

The current European Association of Urology (EAU) guidelines state that a complicated UTI (cUTI) occurs in an individual in whom factors related to the host or specific anatomical or functional abnormalities related to the urinary tract (for example obstruction, incomplete voiding due to detrusor muscle dysfunction) are believed to result in an infection that will be more difficult to eradicate than an uncomplicated infection.

Clinicians must also recognise that symptoms, especially lower urinary tract symptoms, are not only caused by UTIs but also by other urological disorders, such as, for example, benign prostatic hyperplasia and autonomic dysfunction in patients with spinal lesions and neurogenic bladders.

Medical conditions, such as diabetes mellitus and renal failure, which can be related to urological abnormalities, are often also present in a cUTI. The authors state that laboratory urine culture is the recommended method to determine the presence or absence of clinically significant bacteriuria in patients suspected of having a cUTI (1) [4].

Care home resident, hospitalisation, recent travel, previously resistant UTI or recent exposure to antibiotic [Grade C]

The review published in 2018 by Hawkey and others lists risk factors for resistance for patients with urinary tract infections caused by multi-drug resistant gram-negative bacteria in the UK (63) [4].

The review was used to inform a working party report making recommendations in antimicrobial prescribing for the treatment of infections caused by multidrug-resistant gram-negative bacteria.

Patients are at increased risk if they have:

  • recurrent UTI
  • persistent urinary symptoms after an initial antibiotic
  • over 7 days hospital admission in the last 6 months
  • residence in a care home
  • recent travel and especially healthcare in a country with increased antimicrobial resistance
  • previously known UTI (within one year) caused by bacteria resistant to amoxicillin or clavulanate, cephalosporins or quinolone or recent treatment with these agents

A review of the global antibiotic resistance challenge indicates that there are significant global resistance patterns to the bacteria most commonly responsible for UTIs (65) [5].

Dispersion of successful clones of multidrug-resistant bacteria is common, often via the movement of people. b-Lactamase production is a common resistance mechanism in Gram-negative bacteria, and the rapid dissemination of novel genes reflects their evolution under the selective pressure of antibiotic usage.

Antibiotic use and environmental factors all have a role in the emergence and spread of resistance. This article reviews some of the new mechanisms and recent trends in the global spread of multi drug resistant bacteria. It indicates that there are significant global resistance patterns to the bacteria most commonly responsible for UTIs.

Collecting a urine sample

Mid-stream sample, women hold labia apart, but no additional cleaning for any group [Grade B].

The guidance by the UK Standards for Microbiology Investigations state that mid-stream urines and clean-catch urine are recommended for routine use but cleaning the area beforehand makes little difference in contamination (18) [N]. A urine sample may be obtained either from a transient (‘in and out’) catheterisation or from an indwelling catheter. In the latter case, the specimen is obtained aseptically from a sample port in the catheter tubing or by aseptic aspiration of the tubing.

A systematic review of clinical studies conducted in primary care to compare the result of urine culture obtained with 2 or more collection techniques in women with symptoms of urinary tract infection (66) [2a]. Seven studies investigating urine sampling technique in 1,062 symptomatic patients in primary care were included. Mid-stream-clean-catch had a positive predictive value of 0.79 to 0.95 and a negative predictive value close to one compared to sterile techniques. Two randomised controlled trials found no difference in infection rate between mid-stream-clean-catch, mid-stream-urine and random samples. The authors conclude that at present, no evidence suggests that sampling technique affects the accuracy of the microbiological diagnosis in non-pregnant women with symptoms of urinary tract infection in primary care.

This randomised study of 242 women who presented with symptoms suggestive of UTI found that there was no difference in contamination rates between samples obtained with no technique (not mid-stream and no cleansing: 29%; contaminated: n=77; samples obtained mid-stream with perineal cleansing and spreading of the labia: 32% contaminated: n=84; samples obtained mid-stream with perineal cleansing and a vaginal tampon in place: 31% contaminated; n=81) (67) [2b]. Contamination rates were nearly identical and there was no significant difference between the no-cleaning and mid-stream/combined cleansing group.

This prospective study obtained a series of urine samples (a new sample was obtained each day for 8 days, using a different set of instructions each day) from 111 healthy young women (68) [2b]. There was no statistically significant difference in contamination rates between the following techniques:

  • no precautions (31%)
  • mid-stream sample (23.9%)
  • mid-stream sample with perineal cleansing (20.4%)
  • mid-stream and holding labia apart (21.1%)

However, holding the labia apart as the sole technique was associated with a lower contamination rate (13%) in this study.

NHS guidance states that a sample can be collected any time during the day or night unless advised otherwise by doctor or nurse (70) [5]. The process includes labelling the sterile screw top container, washing hands, starting urination then catching the sample mid-stream, closing the lid and washing hands. Further information is provided on why to collect a mid-stream specimen, how to store the sample, and what it might be used for.

A systematic review concluded that if non-invasive collection is being considered for women, mid-stream collection with cleansing is recommended, but no recommendation for or against is made for mid-stream collection without cleansing (70) [2a].

For urine specimens collected from men, there was a reduction in contamination in favour of mid-stream clean-catch over first-void specimen collection. The strength of this evidence was rated as high. However, there was no benefit to cleaning beforehand in either sex. Overall evidence quality for the studies specific to women was rated as low and for men was fair but not strong enough for the panel to make recommendations.

A literature search to determine the validity of alternative sampling methods compared to in and-out catheterisation and suprapubic aspiration in older adults who are unable to self-collect urine specimens and/or cooperate with the urine collection (71) [4]. Six studies meeting the research question criteria were identified. The authors of all 3 studies concluded that the clean catch collection method is valid and that it can avert the use of more invasive methods.

Use of condom catheters [Grade D]

In the late 1980s the validity of condom catheters to collect urine specimens in elderly men was explored by 2 studies (71) [4]. With a sensitivity of 86% to 98% and a specificity of 90% to 97% the condom catheter method can potentially replace catheterisation for urine collection. The authors listed a number of limitations with the studies they found that kept them being able to make recommendations. These included limited recent research, small sample sizes, and limited consensus on minimum colony-forming units. They conclude that larger diagnostic studies in adults are needed to confirm findings before recommendations can be made.

Collecting a sample from urinary catheters [Grade Nat]

This NICE guideline sets out an antimicrobial prescribing strategy for CAUTI (32) [Grade Nat]. It aims to optimise antibiotic use and reduce antibiotic resistance. The guideline states that a clinician should obtain a urine sample before antibiotics are taken (from the new catheter if changed) or a midstream specimen of urine if catheter removed. Take the sample from the catheter, via a sampling port if provided, and use an aseptic technique.

The specimen should not be obtained from the collection bag. Delays and storage at room temperature allow organisms to multiply, which may generate false positive results.

Handling the sample for all

Incubate urine within 4 hours of collection (Grade D), and refrigerate, or use boric acid preservative if delays in processing unavoidable. Don’t use dipsticks once boric acid is used [Grade Nat].

A review discussed previously found data from 9 studies (rated as fair in quality) that suggest that boric acid and refrigeration both preserve urine specimens for up to 24 hours before processing (70) [2a]. Data from 3 studies indicates that urine held for more than 4 hours before processing should not be used due to overgrowth of flora. However, evidence quality for this is rated as low.

Where delays in processing are unavoidable, refrigeration is recommended. Use of a boric acid preservative may also be useful. Boric acid preservative holds the bacterial population steady for 48 to 96 hours. Toxicity to some organisms has been reported, but this often reflects under filling of the container.

Boric acid may be inhibitory to some organisms and may inhibit tests for leucocyte esterase, so you should not use with urine dipsticks. Carry-over contamination is a potentially problem for devices that analyse urine and this should be assessed for during their validation and verification. One strategy to limit this is to use sample aliquots if a dipstick is required before sending it for culture.

How to interpret a urine culture result if you suspect a UTI, and follow up patients

Asymptomatic bacteriuria in non-pregnant women

It is not beneficial to screen and treat for asymptomatic bacteriuria (ASB) in non-pregnant women, as this does not reduce morbidity or mortality [Grade A].

Studies have shown treatment of asymptomatic bacteria is not required because it does not impact mortality or morbidity (33, 36) [2b, 2a-]. NICE publish national guidance on the management of lower urinary tract infection (3) [N]. They recommend that pregnant women who have ASB should be offered and immediate antibiotic as they are at risk for pyelonephritis and premature delivery, taking into account urine culture/susceptibility results and previous use of antibiotics.

Investigation of Urine: UK Standards for Microbiology Investigations (UK SMIs) comprise a collection of recommended algorithms and procedures covering all stages of the investigative process in microbiology from the pre-analytical (clinical syndrome) stage to the analytical (laboratory testing) and post analytical (result interpretation and reporting) stages (18) [N]. This publication includes updates from 2019 and is NICE accredited. Standards are produced in partnership with UKHSA, NHS, Royal College of Pathologists and professional societies. This guidance is used to underpin many of the recommendations specific to the interpretation of urine culture; however, other references are included where warranted.

Urine culture results in patients with urinary symptoms that usually indicate UTI [Grade Nat]

As follows:

  • when interpreting a culture, the guidance states that studies conducted in the 1950s remain the basis for interpreting urine culture results showing that bacterial counts of >108 cfu/L (>105 cfu/mL) are indicative of an infection and counts below this may indicate contamination
  • the guidelines state that women with acute UTI symptoms may have urine culture results of a single isolate as low as 105 cfu/L (102 cfu/mL) in voided urine (referencing Stamm and Kuplain)
  • in men counts as low as 106 cfu/L (103 cfu/mL) of a pure or predominant organism have been shown to be significant in voided urine
  • a pure isolate with counts between 107 and 108 cfu/L (104 to 105 cfu/mL) should be evaluated based on clinical information or confirmed by repeat culture; if there are 2 isolates and each organism >106 cfu/L (>103 cfu/mL) including possible pathogens such as E. coli or S. saprophyticus, the patient might have a UTI
  • routine culture methods may not be sensitive enough to detect low bacteria levels (for example ≤107 cfu/L / ≤104 cfu/mL) and increased sensitivity will be achieved by increasing the inoculum size

In 1984, Stam and others published a prospective study that aimed to examine the conventional criteria for diagnosing coliform infection of the lower urinary tract (72) [2b]. The authors examined 187 sexually active young women with dysuria and urinary urgency.

When a cut-off of 102 cfu/mL mid-stream urine was used, the sensitivity was 95% with a negative predictive value of 94%, whereas specificity declined from 99% to 85%. Thus, low cut-off of ‘coliform’ bacteria in mid-stream urine more accurately predicted bladder infection in symptomatic women than in asymptomatic.

Many additional studies support the observation that low bacterial concentrations of E. coli in particular have diagnostic relevance, even in mixed flora.

Epithelial cells or mixed growth [Grade Nat]

UK SMI states that:

  • mixed bacterial growth is probably related to contamination but that one should consider a re-test if the patient is symptomatic

A retrospective cross-sectional study looked to determine the value of using quantitative squamous epithelial cells as a predictor of urinalysis contamination (73) [3b]. The authors sampled adults presenting to a tertiary academic medical centre who had urinalysis with microscopy and urine culture performed. A total of 19,328 records were included. The authors concluded that squamous epithelial cells are a poor predictor of urine culture contamination but may predict poor predictive performance of traditional urinalysis measures.

Another study looked at 247 patients yielding mixed urine cultures in order to understand the frequency with which isolation of more than one bacterial species from urine signifies treatable mixed infection versus contamination or colonization occurs (74) [2b].

Specimens were collected by clean catch from 88 and from closed drainage systems from 159. A second specimen was collected within 48 hours, and the results of the 2 cultures were compared.

The percentages in which the initial mixed culture was found to represent probable, possible, and improbable treatable mixed infection were as follows:

  • for clean-catch specimens, 11%, 20%, and 67%
  • for closed drainage systems specimens, 3%, 21%, and 77%

The authors have found that empiric antibiotic therapy and reporting of mixed cultures based on culture morphology without complete identification or antibiotic susceptibilities (except for certain colony types suggesting potentially multi-drug resistant strains) with request for resubmission represents a cost-effective solution to the mixed culture problem in the diagnosis and treatment of urinary tract infection.

Red cells: may be present in UTI [Grade Nat]

UK SMI state that:

  • chemical tests for the presence of blood may be more sensitive than microscopy as a result of the detection of haemoglobin released by haemolysis; when haematuria is present, finding one to 2 red blood cells (RBCs) or high power field is not considered to be abnormal
  • haematuria may be caused by non-infective pathological conditions of the urinary tract or by renal mycobacterial infection, with or without associated pyuria; apparent haematuria may be the result of menstruation

A joint consensus statement on the initial assessment of haematuria from the Renal Association and British Association of Urological Surgeons states that haematuria in association with UTI is not uncommon (75) [5].

Following treatment of UTI, a dipstick should be repeated to confirm the post-treatment absence of haematuria. Other causes of transient haematuria include exercise induced haematuria, rarely myoglobinuria and menstruation. Refer to urology:

  • all patients with visible haematuria (any age)
  • all patients with s-NVH (any age)
  • all patients with a-NVH aged 40 years or over

White blood cells or leucocytes [Grade Nat]

UK SMI state that:

  • generally, a pure growth of between 107 to 108 cfu/L (104 to 105 cfu/mL) is indicative of UTI in a carefully taken specimen; a level of >108 WBC/L (>105 WBC/mL) has been suggested as being more appropriate in discriminating infection

Sterile pyuria [Grade Nat]

UK SMI state that:

Sterile pyuria (that is pyuria in the presence of no growth on routine culture media) may be the result of many factors, including:

  • a result of prior treatment with antimicrobial agents
  • catheterisation
  • calculi (stones)
  • bladder neoplasms

Other conditions, which may lead to sterile pyuria, include genital tract infection and sexually transmitted diseases, for example, C. trachomatis or an infection with a fastidious organism or renal tuberculosis.

If there is no growth and symptomatic marked or persistent pyuria, the guidance suggests that you can look at a culture as low as 102 cfu/mL.

Increased inoculum sizes are also required for persistently symptomatic patients without bacteriuria if the patient has recurrent ‘sterile pyuria’, or for specimens where lower counts are to be expected, such as suprapubic aspiration.

Follow-up [Grade Nat]

NICE guideline on the management of recurrent UTI states to refer or seek specialist advice on further investigation and management for: men aged 16 years and over, people with recurrent upper UTI, people with recurrent lower UTI when the underlying cause is unknown, pregnant women, children and young people under 16 years in line with the NICE guideline on urinary tract infection in under 16s, people with suspected cancer in line with the NICE guideline on suspected cancer: recognition and referral (76) [N].

The NICE Suspected Cancer: Recognition and referral guideline covers the identification of children, young people, and adults with symptoms that could be caused by cancer (77) [N]. It includes the investigation of cancer in primary care and when to refer people for specialist opinion. It states that you should refer people aged 45 and older with unexplained visible haematuria without urinary tract infection, those with visible haematuria that persists or recurs after treatment, or those aged 60 years and over with unexplained non-visible haematuria and either dysuria or a raised white cell count on a blood test. It also says that you should consider non-urgent referral for bladder cancer in people aged 60 years and over with recurrent or persistent unexplained urinary tract infection. Refer to full guidance for further criteria.

Feedback

We welcome opinions on the advice given. Send comments with corresponding evidence by email to email [email protected] or by post to:

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Acknowledgements

These decision tools have been produced by UKHSA through review of published literature, and through consultation with key medical, subject matter, and patient experts within the UK.

We would like to acknowledge the following people for their contribution to the review of these resources.

Steering group members:

Christina Stokes, Claire Jones, Dr Claire Neill, Diane Holland, Dr Donna Lecky, Eirwen Sides,  Elizabeth Beech, Emily Cooper, Dr Harry Ahmed, Leslie Macleod-Downes, Liam Clayton, Dr Linda Strettle, Naomi Fleming, Dr Philippa Moore, Rob Annan, Tony Denham.

A full list of contributors through the expert review and public consultation will be provided after publication of this resource.

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Data sources

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