Retrospective Assessment of Antimicrobial Stewardship Initiative in Outpatient Use of Ertapenem for Uncomplicated Extended Spectrum Beta Lactamase Enterobacteriaceae Urinary Tract Infections

Background: Urinary tract infections (UTI) are often over-diagnosed and over-treated, which can induce and select for resistant pathogens. After observing wide-spread outpatient use of ertapenem, a broad-spectrum antibiotic, a structured antimicrobial stewardship initiative (ASI) to improve appropriate antimicrobial prescribing was undertaken. ASI objectives were to achieve a goal of reducing ertapenem utilization for extended spectrum beta lactamase Enterobacteriaceae (ESBL-EB) UTI by 10% and evaluate the clinical outcomes associated with the ASI. Methods: : A pre-to-post cohort study was conducted at a single-center integrated healthcare system between November 1, 2014 and February 26, 2017. An intensive, 90-day, pharmacist-driven, structured ASI was implemented between November 1, 2015 and January 29, 2016. Female patients aged ≥18 years who were treated for an uncomplicated, ESBL-EB urinary tract infection (UTI) were included. Primary outcome was monthly ertapenem use expressed as number of days of therapy (DOT)/1,000 adjusted patient days (APD). Segmented regression analysis for interrupted time series was performed to estimate ASI intervention effect. Results: A total of 184 patients were included in the study. Ertapenem utilization decreased from 0.0145 DOT/1,000 APD in Nov. 2014 to 0.0078 Dot/1,000 APD Feb. 2017(p<0.01). The mean ertapenem DOT declined 19% overall from the pre vs. post intervention periods (32 vs 26, p<0.01). Frequency of recurrent UTIs was reduced and no adverse effects were reported in patients treated with aminoglycosides. Conclusions: A structured ASI for uncomplicated ESBL-EB UTI was associated with a clinically meaningful decrease in ertapenem utilization and once-daily, 5-day aminoglycoside treatment was well-tolerated.