Biochemical and Genetic Characterization of Carbapenem-Hydrolyzing β-Lactamase OXA-229 from Acinetobacter bereziniae
ABSTRACTAcinetobacter bereziniae(formerlyAcinetobactergenomospecies 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 inEscherichia coliidentified 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 theblaOXA-229gene did not identify an insertion sequence but did identify mutations in the promoter sequences in comparison to the fully susceptibleA. bereziniaereference strain. The overexpression ofblaOXA-229inA. bereziniaeNec as a source of carbapenem resistance was identified by quantitative real-time PCR.