In vitro activities of ceftazidime-avibactam, ceftolozane-tazobactam, meropenem-vaborbactam and other comparators against Pseudomonas aeruginosa isolates with discrepant resistance to carbapenems: Data from the Antimicrobial Testing Leadership and Surveillance (ATLAS) program, 2012-2021

Objectives: This study aimed to investigate the in vitro susceptibility and & beta;-lactamase-encoding genes of Pseudomonas aeruginosa (P. aeruginosa) isolates with discrepant resistance to various carbapenems. Methods: Data on P. aeruginosa isolates were obtained from the Antimicrobial Testing Leadership and Surveillance program from 2012-2021. Minimum inhibitory concentrations of P. aeruginosa isolates were determined using the broth microdilution method. & beta;-lactamase-encoding genes were identified using multiplex polymerase chain reaction assays. Results: Among the P. aeruginosa isolates that were tested, the percentages of isolates resistant to imipenem, meropenem and doripenem were 26.9% (14 447 of 53 617), 20.5% (14 098 of 68 897) and 17.5% (3660 of 20 946), respectively. Imipenem-resistant P. aeruginosa isolates were more susceptible to all tested antimicrobial agents (except colistin) than the meropenem-resistant or doripenem-resistant P. aeruginosa isolates. Carbapenemase genes were detected in 14.3% (2020 of 14 098) of meropenem-resistant P. aeruginosa isolates. Imipenem-resistant meropenem-susceptible P. aeruginosa isolates had higher susceptibility profiles, fewer carbapenemase genes (0.3% [five of 1858] vs. 4.1% [10 of 242]; P < 0.05) and a lower risk of being classified as multidrug-resistant than the imipenem-susceptible meropenem-resistant isolates (16.1% [299 of 1858] vs. 73.6% [178 of 242]; P < 0.05). Among all & beta;- lactam combination agents, ceftazidime-avibactam and ceftolozane-tazobactam had higher susceptibility rates than meropenem-vaborbactam for meropenem-resistant P. aeruginosa (61.8% and 55.5% vs. 30.2%; P < 0.05). Conclusion: Discrepancy in the resistance of different P. aeruginosa isolates to various carbapenems sug-gests their different underlying resistance mechanisms. These findings can be useful for effective resis-tance trend monitoring and accurate antimicrobial treatment in the future. & COPY; 2023 Elsevier Ltd and International Society of Antimicrobial Chemotherapy. All rights reserved.