Genetics and Expression of the Carbapenem-Hydrolyzing Oxacillinase GeneblaOXA-23inAcinetobacter baumannii

Abstract
The genetic structures surrounding the plasmid-carried blaOXA-23 oxacillinase gene, encoding resistance to carbapenems, were studied in Acinetobacter baumannii. ISAba1 and the novel element ISAba4 were detected upstream of the blaOXA-23 gene, providing promoter sequences for its expression. These insertion elements were likely involved in transposition processes at the origin of acquisition of this beta-lactamase gene.