Antimicrobial Activities of Ceftazidime-Avibactam and Comparator Agents against Gram-Negative Organisms Isolated from Patients with Urinary Tract Infections in US Medical Centers, 2012 to 2014

A total of 7,272 unique patient clinical isolates were collected from 71 U.S. medical centers from patients with urinary tract infections in 2012 to 2014 and tested for susceptibility to ceftazidime-avibactam and comparators by broth microdilution methods. Ceftazidime-avibactam inhibited >99.9% of all Enterobacteriaceae at the susceptible breakpoint of <= 8 mu g/ml (there were only three nonsusceptible strains). Ceftazidime-avibactam was also active against Pseudomonas aeruginosa isolates (MIC50, 2 mu g/ml; MIC90, 4 mu g/ml; 97.7% susceptible), including many isolates not susceptible to meropenem, ceftazidime, and/or piperacillin-tazobactam.