In Vitro Antibacterial Activity of the Ceftazidime-Avibactam (NXL104) Combination against Pseudomonas aeruginosa Clinical Isolates

The beta-lactamase inhibitor avibactam (NXL104) displays potent inhibition of both class A and C enzymes. The in vitro antibacterial activity of the combination ceftazidime-avibactam was evaluated against a clinical panel of Pseudomonas aeruginosa isolates. Avibactam offered efficient protection from hydrolysis since 94% of isolates were susceptible to ceftazidime when combined with 4 mu g/ml avibactam, compared with 65% susceptible to ceftazidime alone. Ceftazidime-avibactam also demonstrated better antipseudomonal activity than imipenem (82% susceptibility), a common reference treatment.