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Practice Practice Pointer

Reducing unnecessary urine culture testing in residents of long term care facilities

BMJ 2023; 382 doi: (Published 09 August 2023) Cite this as: BMJ 2023;382:e075566
  1. Katrina L Piggott, geriatrician1,
  2. Johanna Trimble, patient author2,
  3. Jerome A Leis, infectious disease physician1
  1. 1Sunnybrook Health Sciences Centre, Toronto, Canada
  2. 2Roberts Creek, British Columbia
  1. Correspondence to: Jerome Leis Jerome.leis{at}

What you need to know

  • Asymptomatic bacteriuria is a positive result from a urine culture test in the absence of minimum symptoms of urinary tract infection, and is present in 30-50% of residents in long term care homes

  • Indiscriminate testing leads to detection of asymptomatic bacteriuria and prompts unnecessary antibiotic treatment

  • Strategies to reduce unnecessary urine cultures include targeted education supported by system changes such as modification of order sets and routine panels, elimination of urine dipsticks, and changes to laboratory processing and reporting

An older woman with moderate stage dementia living in a long term care home has new confusion and slurred speech. Her nurse notes an “unusual smell” while collecting a urine specimen and sends it for culture testing to the microbiology laboratory. The care home physician is notified that afternoon of the clinical finding and performs a focused examination, which is unremarkable, and then signs off the urine culture order. The urine culture returns with significant growth of Escherichia coli and the woman is prescribed a course of antibiotics. Five days later, she experiences an acute decline in her clinical status, including worsening dysarthria and right sided weakness, and is transferred to hospital, where a stroke is diagnosed. Focusing on a diagnosis of urinary tract infection (UTI), despite the absence of correlating symptoms, has resulted in delayed recognition of stroke symptoms and timely treatment.

Overdiagnosis of UTI is one of the most common reasons for unnecessary use of antibiotics in long term care, including nursing and care homes.1 Most residents in these settings who have a positive result on urine culture testing do not actually have a UTI but rather asymptomatic bacteriuria (ASB), defined as the presence of significant levels of bacteria isolated in the urine (greater than 105 colony forming units/mL) in the absence of localising symptoms of UTI, and regardless of the presence of pyuria.234 Surveillance studies across North America and Europe that systematically assessed symptoms and urine cultures consistently show that in residents of long term care who do not have a catheter, the prevalence of ASB is 30-50%, whereas UTI is far less common, with prevalence of less than 2%.56 Residents with a catheter have at least a twofold increased risk of UTI, but also have higher rates of ASB that are nearly 100% by the time a urinary catheter has been in place for four weeks.67

At least nine randomised controlled trials have shown the lack of clinical benefit of treating ASB with antibiotics in adults, as well as significant potential harms.891011 Recommendations from Choosing Wisely and international guidelines from the Infectious Disease Society of America, the National Institute for Health and Care Excellence, and the European Association of Urology, each recommend against antibiotic prescribing for ASB (table 1).234121314 Despite this, observational studies in long term care settings across different countries show that 30-80% of residents with ASB receive antibiotics.151617

Table 1

International guideline statements on reducing urine tests and antibiotics for asymptomatic bacteriuria

View this table:

This gap, between strong international consensus not to prescribe antibiotics for ASB and what happens in practice, is created by pervasive over-ordering of urine cultures in long term care. This article explores the use of urine cultures in residents in long term care facilities and highlights the changes needed to improve this practice and reduce antibiotic overuse in this patient population.

Evidence for change

Prospective cohort studies and randomised controlled trials (RCTs) have shown a lack of benefit in treating ASB in non-pregnant populations in terms of morbidity,910 mortality,1018 or quality of life.19 RCTs consistently show that antimicrobial treatment in a patient without clear signs or symptoms of a UTI does not improve the risk of progression to a symptomatic UTI or sepsis.71011 Recurrence rates of ASB are high, and sustained sterilisation of the urine is seldom achieved, as shown in cohort studies and randomised trials.8910 In people with delirium who have no systemic symptoms of sepsis or localising urinary signs or symptoms, antibiotic therapy for ASB does not appear to lead to improved resolution of mental status.20212223 Two recent North American cohort studies of people with delirium and ASB admitted to hospital found that the functional outcome of those who received antibiotics was not statistically different by day 7 based on the brief confusion assessment method, nor up to two months in terms of risk of death, need for ongoing institutional care, or functional status based the Older Americans Resources and Services questionnaire.2021

Adverse reactions to antibiotics are common, and range from minor rashes and oral or vaginal candidiasis to more severe complications such as severe allergy, acute kidney injury, or drug-drug interactions.91024 One particular complication of antibiotics is infection with Clostridiodes difficile, which can be a life threatening complication in residents of long term care. A retrospective cohort study of residents in two US care homes found that those who received antibiotics for ASB had a 8.5 times higher risk of developing C difficile infection.25 At the facility level, a population based study in Canada found that differences in rates of C difficile infection were explained by the variability in rate of institutional urine culture ordering.26 These data reaffirm that unnecessary urine cultures are the primary drivers of unnecessary antibiotic use and their associated adverse outcomes. Another example is the selection of increasingly antibiotic resistant urinary organisms, which results in fewer therapeutic options, and often with intravenous administration or increased risk of toxicity.1027

An under-appreciated aspect of ASB is that these bacteria that are not causing local infection are part of the normal urinary microbiome that is protective against ascending infection.2728 Thus, antibiotics aimed at erring on the side of caution to prevent or avoid missing a UTI may do the exact opposite, by increasing UTI risk. An RCT of younger women with a known history of recurrent cystitis in Italy found up to threefold increased risk of symptomatic UTI among those systematically screened and treated for ASB compared with those treated based on symptoms.27 Antibiotics beget more antibiotics, and some patients will enter a cycle of recurrent episodes of ASB, UTI, or both, leading to additional antibiotic related harms.

A final harm of treatment of ASB is the premature closure bias that may occur in concluding the presence of UTI, without searching for the true cause of the non-urinary condition or change in a resident’s clinical status.2329

Barriers to change

Requesting urine cultures in the absence of minimum symptoms of UTI leads to detection of ASB, prompting unnecessary antibiotic treatment.8916 Large retrospective and prospective cohort studies conducted in long term care homes across several countries show that only a small fraction of urine specimens collected in long term care meet minimum symptom criteria for culturing, and that up to 80% of residents with ASB had unnecessary urine testing.151617

The urine dipstick, which is known for its sensitivity in ruling out presence of UTI in younger populations and foregoing a urine culture, may contribute to over diagnosis of UTI in older patients.30 Unlike in younger populations, where pyuria is generally absent when non-infected, the prevalence of pyuria among long term care residents is nearly universal, and these positive dipsticks trigger urine cultures and occasionally empiric antibiotics in the absence of localising symptoms of UTI.31

Residents in long term care homes may have cognitive impairment, which can limit available history, and may present atypically with infection. Staff may fear missing a UTI, or even believe that upfront treatment of ASB can prevent a UTI in the future, despite evidence suggesting the contrary.32 A urine culture may be perceived to be a more objective assessment that provides a possible diagnostic explanation for non-urinary complaints. Therefore, the clinical presentations used to evoke the presence of UTI are excessively broad; common presentations such as falls, poor oral intake, lethargy, and delirium frequently trigger a urine dipstick or culture as a means of excluding a UTI, even in the absence of clear localising urinary symptoms—with positive results used to support that diagnosis.1516172330

Urine cultures may also be integrated into existing order sets and routine panels, which drives overuse and detection of ASB.33 A recent US survey presented a case of ASB to 551 primary care physicians, and found that more than 70% would prescribe antibiotics.34 Ninety per cent of those who opted to treat believed the patient had a UTI, even though they lacked any of the cardinal symptoms.

Family members and care givers may specifically request urine testing when a care home resident’s condition is altered. Prior experiences of both prescribers and care givers can generate causal inferences based on prior episodes where urine cultures were positive, and these can become particularly challenging to dissociate if improvement in the person’s condition coincided with receipt of antibiotics previously.32

How can we change our practice?

In recognising the problem of antibiotic overuse in people in long term care facilities, balanced against the risk of poor outcomes from sepsis in this frail population, minimum criteria for antibiotic initiation have been proposed by international infectious disease experts as a safe threshold for people in long term care (box 1).35 These criteria were validated in a cluster randomised trial in Canada, where they were used for ordering of urine culture and interpreting positive results, resulting in a 25% reduction in antibiotic use without any significant difference in risk of hospital admission or mortality.36 This approach has been endorsed by the Society of Healthcare Epidemiology of America and Choosing Wisely Canada, and Public Health England has a similar approach.35373839 Urine cultures ordered below this threshold are considered inappropriate because they are unlikely to help identify a person with a UTI and lead only to unnecessary antibiotic exposure. Public Health England also recommends against use of urine dipsticks for anyone over 65 or with an indwelling urinary catheter.39

Box 1

The Loeb minimum criteria for diagnosis of urinary tract infection in a resident of long term care

For residents who do not have an indwelling catheter

  • Acute dysuria

  • or

  • Fever (>37.9°C or 1.5°C increase above baseline temperature) AND at least one of the following: new or worsening urgency, frequency, suprapubic pain, gross haematuria, costovertebral angle tenderness, or urinary incontinence

For residents who have a chronic indwelling catheter

  • Presence of at least one of the following: fever (>37.9°C or 1.5°C increase above baseline temperature) without alternative cause, new costovertebral tenderness, rigors, or new onset of delirium


Box 2 describes how to incorporate this definition of UTI in the clinical assessment of a long term care resident with a change in clinical status. For example, a resident without a catheter who has new onset delirium but no other signs of sepsis or localising urinary symptoms should not generate a urine culture but instead prompt assessment for other causes.373839 Such non-specific changes should also mean closer monitoring and reassessment for development of any additional signs and symptoms, and if minimum criteria are met, a urine culture submitted at that time. The need for empiric therapy pending a urine culture should be determined based on clinical suspicion and acuity of illness. Any empiric therapy should be reassessed based on clinical response, and results from culture and susceptibility testing.

Box 2

How to approach changes in a resident’s clinical status while incorporating the minimum criteria for UTI

Resident is at baseline and does not meet minimum criteria for UTI

  • Do not order urine culture and do not initiate antibiotics aimed at urinary tract infection

Resident has a change from baseline but does not meet minimum criteria for UTI

  • Assess for alternative explanations such as volume depletion, constipation, skin breakdown, medication side effects, and other sources of infection such as respiratory or skin and soft tissue

  • Do not order a urine culture but do order other targeted investigations as needed, and consider the need for encouraging increased fluid intake, monitoring, and early re-assessment for development of additional signs or symptoms

Resident has change from baseline and meets minimum criteria for UTI

  • Assess resident for causes of change in status and in absence of clear alternative explanation (eg, medication change leading to delirium, other focus of infection)

  • Urine culture indicated in presence of minimum criteria for UTI without a clear alternative explanation

  • Consider the need for empiric therapy based on clinical suspicion and resident status, with plan to reassess based on urine culture results


Making effective change in practice

Discuss the prevalence and protective role of ASB with prescribers and other members of the care team, including nursing staff, personal care givers, and family members.40Box 3 provides examples of communication strategies for promoting judicious ordering of urine cultures.

Box 3

Examples of communication strategies for clinicians to identify and address family concerns about possibility of UTI

  • I am concerned about the change in clinical status that has occurred and want to assess possible causes

  • What specific symptoms have been voiced and what have you noticed?

    • Discuss findings

      • Based on my assessment, there is no evidence of bladder infection and antibiotics would cause unnecessary harm

      • If we collect a urine culture in this situation, we may identify only protective bacteria and not indicate presence of infection.

    • Implement a safety net plan

      • We should encourage oral intake and I have requested more frequent monitoring over the next 24 hours

      • Should there be any new or worsening symptoms, a fresh assessment should be performed


Pamphlets and posters can be used to target prescribers and nursing staff to reduce urine culture ordering, as well as face-to-face synchronous sessions, webinars, workshops, one-to-one coaching, identified facility team leaders, prompts and best practice advisories, and a centralised support website.4041 Education should focus on dispelling and recalibrating the perceived benefits of treating urine culture results for preventing infection against the harms of UTI over-diagnosis and antibiotic overuse.

Family members and care givers are valuable partners in the de-adoption of ordering urine culture in long term care. Communication tools may help emphasise that not ordering cultures for those who do not meet minimum criteria does not mean no care is offered. On the contrary, not settling on a diagnosis of UTI prematurely means that other diagnostic possibilities for non-urinary concerns will be considered and are less likely to be missed. Other important interventions, such as a physical examination, detailed medication review, encouraging oral intake, and increasing monitoring for new signs or symptoms, may all be reasonable and highly accepted interim plans pending reassessment for whether a urine culture is warranted.32

Additional system changes to support practice change

Beyond education and training, system changes are usually needed to support change in practice.33 In settings that utilise order sets, these should be updated to remove all non-evidence based urine testing outside of minimum accepted UTI symptoms. Removing access to urine dipsticks in long term care homes can reduce unnecessary urine cultures.3839

Decision support systems and requiring the input of clinical indication for each urine culture may have limited impact, possibly because prescribers select UTI for all cases,42 but a US intervention across 11 hospitals and 70 outpatient clinics showed a 20% reduction in urine cultures with this approach.43 Audit and feedback of urine culture ordering or prescriptions of antibiotics commonly used for UTI may also drive reductions and at minimum limit antibiotic duration.444546 Finally, interventions within the laboratory to reject or modify reporting of urinary isolates that are likely to be ASB can markedly improve antibiotic prescribing practices while preserving prescriber autonomy, although these strategies require additional study in long term care settings.47484950 One example is increasing the threshold for defining significant growth in urine culture based on data suggesting that low colony counts are only rarely associated with infection in older adults admitted to hospital wards.50 Further research in long term care homes is needed before implementing this change more broadly.

Finally, a key lesson from the cluster randomised trial that implemented minimum criteria for UTI diagnosis is that although educational algorithms alone led to early practice changes, the reduction in urine culture ordering was not sustained.36 The combination of multiple process changes is likely necessary to enable a shift in the established culture of culturing across many long term care homes.

Strategies to reduce unnecessary urine cultures in long term care facilities

Interventions targeting individuals

  • Education initiatives to address knowledge gaps in healthcare providers, patients, and family members

  • Clinical decision support, academic detailing, audit, and feedback

Interventions targeting processes of care

  • Removing urine cultures from order sets

  • Making urine dipsticks unavailable

Interventions targeting urine culture processing and reporting

  • Rejection of urine specimens that do not meet clinical indication for urine culture

  • Increase in the threshold of colony forming units for “positive” urine culture reporting

  • Modification of culture reporting to include messaging to the healthcare provider about prevalence of asymptomatic bacteriuria

Education into practice

  • What investigations do you order for a resident in long term care who appears generally unwell or confused? Do they include urine culture?

  • How are urine specimens collected and submitted for culture at your institution? Are they collected by healthcare personnel, prior to an order being written by a physician?

How patients were involved in the creation of this article

This article was co-authored by Johanna Trimble, a dedicated caregiver of a patient who has experienced adverse drug effects and unnecessary polypharmacy. Johanna is a published advocate for older adults related to medication misuse and drug safety. Her input was particularly valuable in describing the barriers to change, including the caregiver’s perspective.


  • This article is part of a series of Education articles based on recommendations from international Choosing Wisely campaigns. The BMJ thanks Wendy Levinson and Karen Born at Choosing Wisely for valuable advice and supporting the selection of topics. Choosing Wisely had no input into the peer review process or editorial decision.

  • Contributorship and guarantor: All authors made substantial contributions to the article’s conceptual framework and text, and were involved in drafting and revision of the work and in final approval. All authors accept responsibility for the accuracy and integrity of the work. Author JT is a care giver of a patient and contributed valuable insight and experience to this manuscript. KLP and JAL are the guarantors.

  • Patient consent: No patient information, explicit or anonymised, has been included in this article. The case example is based on the combined clinical experience of the three contributing authors and contains no specific patient information.

  • Competing interests: The BMJ has judged that there are no disqualifying financial ties to commercial companies. Further details of The BMJ policy on financial interests is here:

  • Provenance and peer review: commissioned; externally peer reviewed.

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