408. Benchmarking the Use of New β-lactams Utilizing a Novel Metric of Microbiological Burden

Abstract

Background. Several methods are used to account for various hospital characteristics when comparing antimicrobial use (AU) between heterogenous hospitals. Recently, a new antimicrobial stewardship metric that adjusts AU by microbiological burden (a-AU) of the bacteria was proposed (Figure 1). It accounts for the resistant phenotypes observed at a given institution, allowing for a more balanced comparison of AU across hospitals. This multicenter retrospective cohort study examined the use of new β-lactams for Gram-negative bacteria (GNB) with difficult-to-treat resistance (DTR) by both AU and adjusted (a-AU) metrics in the southeastern United States. Methods. AU of new β-lactams was determined in 9 hospitals within the Southeastern Research Group Endeavor (SERGE-45) between 2015 to 2020. New β-lactams included ceftolozane/tazobactam, ceftazidime/avibactam, meropenem/vaborbactam, imipenem/cilastatin/relebactam, and cefiderocol. AU was adjusted for prevalence of GNB with DTR including Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter species. DTR was defined as nonsusceptibility to all of the following: cefepime or ceftazidime, levofloxacin or ciprofloxacin, meropenem or imipenem, and piperacillin/tazobactam if tested. Hospitals were ranked by AU and a-AU from lowest to highest. Descriptive statistics were utilized. Results. The cumulative mean AU and a-AU from 2015 to 2020 were 1.96 (range 0.10 to 6.44) and 2.3 (range 0.20 to 8.05) days of therapy (DOT)/1000 patient days, respectively (Figure 2). After adjusting for the prevalence of GNB with DTR, 6 hospitals moved by at least 1 position in ranking (2 hospitals moved up; 4 hospitals moved down) and 1 hospital moved by at least 2 positions in ranking. Conclusion. Overall, the AU of new β-lactams increased after adjusting for the local microbiological burden suggests a potential higher use of antibiotics in relationship to the observed prevalence of GNB with DTR. More than half of the hospitals had a shift in ranking after microbiological adjustment reflecting a more balanced comparison of antibiotic use across heterogenous hospitals.