Characterization of pABVA01, a Plasmid Encoding the OXA-24 Carbapenemase from Italian Isolates of Acinetobacter baumannii

Two epidemiologically unrelated carbapenem-resistant Acinetobacter baumannii isolates were investigated as representatives of the first Italian isolates producing the OXA-24 carbapenemase. Both isolates were of European clonal lineage II and carried an identical OXA-24-encoding plasmid, named pABVA01. Comparative analysis revealed that in pABVA01, bla(OXA-24) was part of a DNA module flanked by conserved inverted repeats homologous to XerC/XerD binding sites, which in other Acinetobacter plasmids flank different DNA modules, suggesting mobilization by a novel site-specific recombination mechanism.