Antimicrobial Susceptibility of Pseudomonas aeruginosa to Ceftazidime-Avibactam, Ceftolozane-Tazobactam, Piperacillin-Tazobactam, and Meropenem Stratified by U.S. Census Divisions: Results from the 2017 INFORM Program.

Pseudomonas aeruginosa isolates (n = 1,909) were collected from 70 U.S. medical centers, and their susceptibilities were tested using the broth microdilution method. Ceftazidime-avibactam (MIC50/MIC90, 2/8 mg/liter) and ceftolozane-tazobactam (MIC50/MIC90, 0.5/2 mg/liter) were the most active (i.e., had the highest susceptibility rates) compounds after colistin, with national susceptibility rates of 96.9% and 97.5%, respectively. Overall, piperacillin-tazobactam (MIC50/MIC90, 4/128 mg/liter) and meropenem (MIC50/MIC90, 0.5/16 mg/liter) were active against 77.5% and 76.0% of the isolates, respectively. Susceptibility variations across census divisions were documented for many antimicrobials.