Biochemical and Genetic Characterization of Carbapenem-Hydrolyzing β-Lactamase OXA-229 from Acinetobacter bereziniae

Abstract

ABSTRACT Acinetobacter bereziniae (formerly Acinetobacter genomospecies 10) isolate Nec was recovered from a skin sample of a patient hospitalized in Paris, France. It was resistant to penicillins, penicillin-inhibitor combinations, and carbapenems. Cloning and expression in Escherichia coli identified the carbapenem-hydrolyzing class D β-lactamase OXA-229, which is weakly related to other oxacillinases (66% amino acid identity with the closest oxacillinase, OXA-58). It hydrolyzed penicillins, oxacillin, and imipenem but not expanded-spectrum cephalosporins. Sequencing of the genetic context of the bla OXA-229 gene did not identify an insertion sequence but did identify mutations in the promoter sequences in comparison to the fully susceptible A. bereziniae reference strain. The overexpression of bla OXA-229 in A. bereziniae Nec as a source of carbapenem resistance was identified by quantitative real-time PCR.