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

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

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

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.

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.

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