Impact of Changes in Urine Culture Ordering Practice on Antimicrobial Utilization in Intensive Care Units at an Academic Medical Center

Abstract

OBJECTIVE To assess antimicrobial utilization before and after a change in urine culture ordering practice in adult intensive care units (ICUs) whereby urine cultures were only performed when pyuria was detected. DESIGN Quasi-experimental study SETTING A 700-bed academic medical center PATIENTS Patients admitted to any adult ICU METHODS Aggregate data for all adult ICUs were obtained for population-level antimicrobial use (days of therapy [DOT]), urine cultures performed, and bacteriuria, all measured per 1,000 patient days before the intervention (January-December 2012) and after the intervention (January-December 2013). These data were compared using interrupted time series negative binomial regression. Randomly selected patient charts from the population of adult ICU patients with orders for urine culture in the presence of indwelling or recently removed urinary catheters were reviewed for demographic, clinical, and antimicrobial use characteristics, and pre- and post-intervention data were compared. RESULTS Statistically significant reductions were observed in aggregate monthly rates of urine cultures performed and bacteriuria detected but not in DOT. At the patient level, compared with the pre-intervention group (n=250), in the post-intervention group (n=250), fewer patients started a new antimicrobial therapy based on urine culture results (23% vs 41%, P=.002), but no difference in the mean total DOT was observed. CONCLUSION A change in urine-culture ordering practice was associated with a decrease in the percentage of patients starting a new antimicrobial therapy based on the index urine-culture order but not in total duration of antimicrobial use in adult ICUs. Other drivers of antimicrobial use in ICU patients need to be evaluated by antimicrobial stewardship teams. Infect.

FIGURE 1.

Crude and predicted estimates for monthly rates of urine cultures performed, (B) bacteriuria, and (C) antimicrobial days of therapy, before and after the change in urine-culture ordering practice.