ADS 32 - Urine Culture Lab Stewardship: Preliminary Review of Using More Stringent Urinalysis Screening for Reducing of Unnecessary Urine Cultures

Background: Urine cultures (UCX) are frequently sent for diagnostic work-up of fevers, even when little else suggests there is an urinary track infection (UTI). Yet, UCXs are very easily contaminated, often misleading caregivers. In normal hosts, it is very unlikely that a patient has a UTI, even if their UCX shows growth, unless there is concomitant inflammation/increased white blood cells (WBC) in the urine. Urinalysis (UA) measures urine WBCs and can be used to screen if urine should be reflexed for UCX. With rare exception, UA with ≤5 WBCs/high-powered field (HPF) need not be reflexed for UCX, while UA with > 10 WBCs/HPF should be reflexed for UCX. We sought to determine if UAs with 6-10 WBCs/HPF were likely to have significant bacterial growth reflecting an underlying UTI.

Methods: We conducted a multicenter retrospective study of all UAs with reflex UCX from 10/01/2019-10/31/2020. All UAs found to have 6-10 WBCs per HPF and associated UCXs were examined. Clinical charts were reviewed for evidence to support/dismiss UTIs.

Results: 39,855 urine specimens were reviewed. 2,275 met inclusion criteria. Only 77 (3.4%) were flagged as “abnormal” UCXs. Chart review ruled out UTIs in all but 20 (0.9%) cases. 2,198 (99.6%) urines either had no growth (1,593 - 70.0%), scant growth (353 - 15.5%) or other findings consistent contaminated cultures (252 - 11.1%).

Conclusions: The overwhelming majority of urine specimens with 6-10 WBCs were unlikely to have an UTI and did not require reflex UCX. Decreasing the number of urine specimens that are reflexed to UCX would decrease unnecessary resource utilization in the lab and help reduce the number of misleading contaminated UCXs not from true UTIs. This could help to improve antibiotic stewardship, reduce antibiotic resistance pressures, reduce hospital onset C. difficile infection, and some cases with Foley catheters would no longer be reported as catheter-associated UTIs.