In vitro activity of imipenem/relebactam, meropenem/vaborbactam and comparators against Enterobacterales causing urinary tract infection in Taiwan: results from the Study for Monitoring Antimicrobial Resistance Trends (SMART), 2020

Objectives: Antimicrobial resistance due to β-lactamase production is a worldwide issue, and β-lactamase inhibitors have been developed to overcome the growing problem. This study aimed to evaluate the in vitro activities of two recently introduced carbapenem/β-lactamase inhibitor combinations – imipenem/relebactam and meropenem/vaborbactam – and their comparators against Enterobacterales from patients with urinary tract infections (UTIs). Methods: Enterobacterales isolates from patients with UTIs in Taiwan and participating in the Study for Monitoring Antimicrobial Resistance Trends (SMART) in 2020 were included. Minimum inhibitory concentrations (MICs) for various antibiotics were determined using the broth microdilution method. Susceptibility was interpreted based on the MIC breakpoints of the Clinical and Laboratory Standards Institute 2022. Genes encoding common β-lactamases, including extended-spectrum β-lactamases, AmpC β-lactamases and carbapenemases, were detected using multiplex polymerase chain reaction. Results: A total of 309 Enterobacterales isolates were included, against which both imipenem/relebactam and meropenem/vaborbactam exerted excellent efficacy (275 of 309, 95% and 288 of 309, 99.3%, respectively). Among imipenem non-susceptible isolates, 17 of 43 (39.5%) and 39 of 43 (90.7%) were susceptible to imipenem/relebactam and meropenem/vaborbactam, respectively. Conclusion: Imipenem/relebactam and meropenem/vaborbactam may be appropriate choices for treating UTIs due to Enterobacterales resistant to commonly used antibiotics. Continuous monitoring of antimicrobial resistance is crucial.