Activity of imipenem-relebactam against a large collection of pseudomonas aeruginosa clinical isolates and isogenic β-lactam-resistant mutants

Abstract

Imipenem and imipenem-relebactam MICs were determined for 1,445 Pseudomonas aeruginosa clinical isolates and a large panel of isogenic mutants showing the most relevant mutation-driven β-lactam resistance mechanisms. Imipenem-relebactam showed the highest susceptibility rate (97.3%), followed by colistin and ceftolozanetazobactam (both 94.6%). Imipenem-relebactam MICs remained 2g/ml in all 16 isogenic PAO1 mutants and in 8 pairs of extensively drug-resistant clinical strains that had developed resistance to ceftolozane-tazobactam and ceftazidime-avibactam due to mutations in OXA-10 or AmpC.