RESUMEN
INTRODUCTION: There has been a steady rise in antimicrobial resistance among common pathogens in Malaysia. This study aims to determine the in vitro antimicrobial activities of ceftazidime-avibactam and its comparators against clinical isolates of Enterobacterales and Pseudomonas aeruginosa collected in Malaysia from 2013 to 2019, and to determine the rates of resistance among these isolates. MATERIALS AND METHODS: In this retrospective study, four participating study centres located in East (N = 1) and West (N = 3) Malaysia contributed to the collection of clinical isolates of Enterobacterales and P. aeruginosa from 2013 to 2019. Antimicrobial minimum inhibitory concentrations (MICs) and percentage susceptibilities were interpreted according to Clinical Laboratory Standards Institute (CLSI) breakpoints, except for tigecycline and colistin, which utilised the United States Food and Drug Administration (US FDA) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints, respectively. RESULTS: A total of 1,073 isolates of Enterobacterales and 332 isolates of P. aeruginosa were collected in Malaysia from the four centres. Among Enterobacterales isolates, the highest percentages of susceptibility were seen with ceftazidimeavibactam (99.2%), meropenem (98.9%), and tigecycline (96.9%). Whereas P. aeruginosa isolates demonstrated the highest susceptibilities to colistin (95.6%), followed by ceftazidime-avibactam (93.1%) and cefepime (87.1%). All metallo-ß-lactamase (MBL)-negative isolates of Enterobacterales, including ceftazidime-nonsusceptible, meropenem-nonsusceptible, and colistin-resistant phenotypes, were susceptible to ceftazidime-avibactam. Furthermore, ceftazidime-avibactam demonstrated the highest percentage of susceptibility (97.1%) against multidrug-resistant (MDR) isolates of Enterobacterales. CONCLUSION: Ceftazidime-avibactam exhibited potent in vitro activity against clinical isolates of Enterobacterales and P. aeruginosa collected in Malaysia from 2013 to 2019. The results of this study show that ceftazidime-avibactam should be considered in the treatment of indicated infections caused by susceptible strains of aerobic Gramnegative pathogens and is a valuable alternative to carbapenems.