Emergence of ceftolozane-tazobactam-resistant Pseudomonas aeruginosa during treatment is mediated by a single AmpC structural mutation

Abstract

Ceftolozane-tazobactam is a cephalosporin--lactamase inhibitor combination that exhibits potent in vitro activity against Pseudomonas aeruginosa, including strains that are resistant to other -lactams. The emergence of ceftolozane-tazobactam resistance among clinical isolates of P. aeruginosa has rarely been described. Here we characterized ceftolozane-tazobactam-resistant P. aeruginosa strains recovered from a patient who was treated with this agent for 6 weeks for a recurrent wound infection. The results showed that the resistance was mediated by a single AmpC structural mutation.