In Vitro Activity of Ceftazidime-Avibactam against Clinical Isolates of Enterobacteriaceae and Pseudomonas aeruginosa Collected in Latin American Countries: Results from the INFORM global surveillance program, 2012 to 2015

Abstract

The International Network for Optimal Resistance Monitoring (INFORM) global surveillance program collected clinical isolates of Enterobacteriaceae (n 7,665) and Pseudomonas aeruginosa (n 1,794) from 26 medical centers in six Latin American countries from 2012 to 2015. The in vitro activity of ceftazidime-avibactam and comparators was determined for the isolates using the Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution method. Enterobacteriaceae were highly susceptible (99.7%) to ceftazidime-avibactam, including 99.9% of metallolactamase (MBL)-negative isolates; 87.4% of all P. aeruginosa isolates and 92.8% of MBL-negative isolates were susceptible to ceftazidime-avibactam. Susceptibility to ceftazidime-avibactam ranged from 99.4% to 100% for Enterobacteriaceae and from 79.1% to 94.7% for P. aeruginosa when isolates were analyzed by country of origin. Ceftazidime-avibactam inhibited 99.6% to 100% of Enterobacteriaceae isolates that carried serine -lactamases, including extended-spectrum -lactamases (ESBLs), AmpC cephalosporinases, and carbapenemases (KPC and OXA-48-like) as well as 99.7%, 99.6%, 99.5%, and 99.2% of MBL-negative iso-latesdemonstratingceftazidime-nonsusceptible,multidrug-resistant(MDR),meropenem-non-susceptible, and colistin-resistant phenotypes, respectively. Among carbapenem-nonsusceptible isolates of P. aeruginosa (n 750), 14.7% carried MBLs with or without additional acquired serine -lactamases, while in the majority of isolates (70.0%), no acquired -lactamase was identified. Ceftazidime-avibactam inhibited 89.5% of carbapenem-nonsusceptible P. aeruginosa isolates in which no acquired -lactamase was detected. Overall, clinical isolates of Enterobacteriaceae collected in Latin America from 2012 to 2015 were highly susceptible to ceftazidime-avibactam, including isolates that exhibited resistance to ceftazidime, meropenem, colistin, or an MDR phenotype. Country-specific variations were noted in the susceptibility of P. aeruginosa isolates to ceftazidime-avibactam.