Mutations in β-Lactamase AmpC Increase Resistance of Pseudomonas aeruginosa Isolates to Antipseudomonal Cephalosporins.

ABSTRACT: Mutation-dependent overproduction of intrinsic β-lactamase AmpC is considered the main cause of resistance of clinical strains of Pseudomonas aeruginosa to antipseudomonal penicillins and cephalosporins. Analysis of 31 AmpC-overproducing clinical isolates exhibiting a greater resistance to ceftazidime than to piperacillin-tazobactam revealed the presence of 17 mutations in the β-lactamase, combined with various polymorphic amino acid substitutions. When overexpressed in AmpC-deficient P. aeruginosa 4098, the genes coding for 20/23 of these AmpC variants were found to confer a higher (2-fold to >64-fold) resistance to ceftazidime and ceftolozane-tazobactam than did the gene from reference strain PAO1. The mutations had variable effects on the MICs of ticarcillin, piperacillin-tazobactam, az

SUBMITTER: Berrazeg M 

PROVIDER: S-EPMC4576058 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature