In Vitro Susceptibility to Ceftazidime-Avibactam of Carbapenem-Nonsusceptible Enterobacteriaceae Isolates Collected during the INFORM Global Surveillance Study (2012 to 2014)

The activity of ceftazidime-avibactam was assessed against 961 isolates of meropenem-nonsusceptible Enterobacteriaceae. Most meropenem-nonsusceptible metallo-beta-lactamase (MBL)-negative isolates (97.7%) were susceptible to ceftazidime-avibactam. Isolates that carried KPC or OXA-48-like beta-lactamases, both alone and in combination with extended-spectrum beta-lactamases (ESBLs) and/or AmpC beta-lactamases, were 98.7% and 98.5% susceptible to ceftazidime-avibactam, respectively. Meropenem-nonsusceptible, carbapenemase-negative isolates demonstrated 94.7% susceptibility to ceftazidime-avibactam. Ceftazidime-avibactam activity was compromised only in isolates for which carbapenem resistance was mediated through metallo-beta-lactamases.