In vitro activity of ceftazidime/avibactam against Gram-negative pathogens isolated from pneumonia in hospitalised patients, including ventilated patients

• Isolates were from hospitalised pneumonia patients, including ventilated patients.
• SENTRY Antimicrobial Surveillance Program (2009–2011), Europe, China and USA.
• Ceftazidime-avibactam (CAZ/AVI) was active against resistant phenotypes.
• CAZ/AVI was active against Enterobacteriaceae and Pseudomonas aeruginosa.

The activities of the novel β-lactam/non-β-lactam β-lactamase inhibitor combination ceftazidime/avibactam and comparators were evaluated against isolates from pneumonia in hospitalised patients including ventilated patients (PHP, pneumonia not designated as VABP; VABP, pneumonia in ventilated patients). Isolates were from the European–Mediterranean region (EuM), China and the USA collected in the SENTRY Antimicrobial Surveillance Program between 2009 and 2011 inclusive. A total of 2393 organisms from PHP were from the EuM, 888 from China and 3213 from the USA; from VABP patients there were 918, 97 and 692 organisms collected, respectively. Among Enterobacteriaceae from PHP, ceftazidime/avibactam MIC90 values against Escherichia coli ranged from 0.25–0.5 mg/L and Klebsiella spp. MIC90 values were 0.5 mg/L in each region. Among VABP isolates, MIC90 values for ceftazidime/avibactam against E. coli were 0.25 mg/L; for Klebsiella spp. from VABP patients, MIC90 values were similar to those obtained against PHP isolates. The MIC of ceftazidime/avibactam was ≤8 mg/L against 92–96% of Pseudomonas aeruginosa isolated from PHP patients. Isolates of P. aeruginosa from VABP patients were of lower susceptibility to all antibacterial agents (e.g. depending on region, meropenem susceptibilities were 51.2–69.4% in contrast to 68.3–76.7% among PHP patients). However, ceftazidime/avibactam inhibited 79.2–95.4% of VABP isolates at an MIC of ≤8 mg/L. Acinetobacter spp. were resistant to many agents and only rates of susceptibility to colistin were >90% across all regions both for PHP and VABP isolates. Ceftazidime/avibactam was generally active against a high proportion of isolates resistant to ceftazidime from PHP and VAPB patients.