Healthcare professionals may inappropriately order urine cultures for patients with catheters, on the basis of subjective signs rather than evidence-based guidelines, according to a study published in Open Forum Infectious Diseases.

The objectives of this chart-review and survey study were to analyze clinical practice patterns and to assess knowledge and application of established guidelines for ordering urine cultures to investigate potential catheter-associated urinary tract infections (CAUTIs) in patients with indwelling urinary catheters. Laboratory testing alone is not sufficient to differentiate catheter-associated asymptomatic bacteriuria from CAUTI.

Misdiagnoses based on positive urine cultures can lead to unnecessary antibiotic treatment or potential delays in diagnosis of another infectious agent, such as a Clostridioides difficile infection. Further, because asymptomatic bacteriuria is a clinically nonsignificant condition, antibiotic treatment is unlikely to confer clinical benefit.

Clinical practice patterns for urine culture orders were investigated in a retrospective chart review at 3 hospitals within the Yale New Haven Health System for all patients identified with National Healthcare Safety Network (NHSN) CAUTIs between October 1, 2015, and September 30, 2017. After the chart review, researchers distributed a voluntary, anonymous survey to physicians and nurses to assess knowledge regarding appropriate indications for urine culture orders.


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Of the 184 cultures identified as meeting the 2017 NHSN CAUTI surveillance definition, 87.6% were determined to have been ordered inappropriately based on subjective findings or nonspecific symptoms, 65.5% were ordered as an initial workup despite an alternative infectious cause. Further, 63.4% of physicians used results from pan-culturing (a secondary blood, urine, respiratory, or stool culture within 6 h of initial urine culture) rather than symptom-directed decision-making for culture orders. In 11% of the identified cases (n=20), patients experienced partial or delayed treatment for other infectious or medication-reactive causes.

Survey results were used to assess knowledge and adherence to the 2009 Infectious Diseases Society of America CAUTI and 2005 asymptomatic bacteriuria guidelines. Overall mean assessment survey score was 7.2 out of a possible 12, with physicians having a mean score of 7.77 and nurses having a mean score of 6.50 (P <.05). Nurses in tertiary medical centers were more likely than physicians to order a culture based on the change in urine appearance (61% vs 23%; P < .05) and urine odor (74% vs 42%; P < .05). In contrast, 70% of physicians reported basing culture orders on patient-reported symptoms, rather than a pan-culture. Survey results from community medical centers had a significantly lower overall mean assessment score of 6.8 (P =.03). Both physicians and nurses in community medical centers were more likely to order a urine culture based on cloudiness or odor of urine, sediment in catheter tubing, and use of pan-culturing to meet criteria.

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Limitations of the study included the focus of the retrospective review on NHSN CAUTIs, which may have underreported the effect of inappropriate culture orders on catheter-associated bacteriuria, the potential for hindsight bias in retrospective reviews, and use of a regression analysis that was underpowered for determining the significance of some results.

Researchers highlighted the importance of guideline adherence in the practice of ordering urine cultures solely for high-risk patients. Further, they noted that because the positive predictive value of urine cultures relies heavily on symptoms and collection techniques, pan-cultures may not be the best practice as it is likely to detect colonization and/or contamination. The researchers concluded that the “lack of symptom-directed evaluation, reliance on pan-culturing, and inappropriate culturing practices may have led to overdiagnosis of [National Healthcare Safety Network catheter-associated urinary tract infections] in our health care system.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Advani SD, Gao CA, Datta R, et al. Knowledge and practices of physicians and nurses related to urine cultures in catheterized patients: an assessment of adherence to IDSA guidelines.Open Forum Infect Dis. 2019;6(8):pii: ofz305.