Diagnostic stewardship programme for urine culture: impact on antimicrobial prescription in a multi-centre cohort

Abstract

Background: Restricting urine culture to patients with genuine urinary tract infection (UTI) reduces excessive antimicrobial prescription for asymptomatic bacteriuria.

Aim: To evaluate the impact of urine culture diagnostic stewardship on antimicrobial consumption.

Methods: This quasi-study involved two general hospitals and 10 community clinics. In the pre-intervention (control) phase (25^th November 2018-2^nd February 2019), microscopy and culture results of all urine specimens were reported. In the post-intervention (study) phase (25^th November 2019-2^nd February 2020), urine cultures were processed and reported only if at least one of the following criteria were met: presence of white blood cells or bacteria on microscopy; patient from obstetrics, urology, paediatrics, oncology or renal transplant ward; specimen labelled as 'pregnancy', 'urological procedure', 'renal transplant' or 'neutropenic'; and ureteric, nephrostomy or suprapubic urine. For urine samples that did not fulfil these criteria, the microscopy results and a rejection comment were reported.

Findings: In total, 12,282 urine specimens were included in the intervention phase. Of these, 4757 (38.7%) specimens did not fulfil the screening criteria, and the microscopy result and a rejection comment were reported. One hundred and sixty-three (3.4%) of these non-reported urine cultures yielded significant bacterial growth, and the majority were Escherichia coli (N=58, 35.6%). Diagnostic stewardship was independently associated with lower antimicrobial consumption [adjusted odds ratio 0.76, 95% confidence interval (CI) 0.70-0.83, P<0.001] on multi-variable logistic regression across all healthcare settings. Diagnostic stewardship had no effect on patient mortality (adjusted hazard ratio=0.95, 95% CI 0.89-1.01, P=0.08). No patients with unreported urine culture developed bacteraemia from untreated UTI.

Conclusion: Diagnostic stewardship of urine culture safely reduced excessive antimicrobial prescription for asymptomatic bacteriuria.

Keywords: Asymptomatic bacteriuria; Diagnostic stewardship; Urine culture.