Novel genetic context of multiple bla OXA-58 genes in Acinetobacter genospecies 3

Objectives: The detection in Acinetobacter genospecies 3 isolates of OXA-type carbapenemases, resulting in reduced susceptibility to carbapenem antibiotics, is increasingly reported. We identified an Acinetobacter genospecies 3 isolate carrying the gene for OXA-58 and aimed to resolve the genetic environment surrounding the blaOXA-58 gene. 
Methods: Species identification was confirmed by 16S-23S rRNA restriction analysis. MICs of imipenem, meropenem and ertapenem were determined, and the isolate was screened by PCR for blaOXA-23-like, blaOXA-40-like, blaOXA-51-like and blaOXA-58-like genes. The sequence surrounding blaOXA-58 was determined through amplification by inverse PCR and genome walking followed by sequencing. Genetic localization was investigated by Southern blotting. 
Results: Isolate A164 was confirmed as belonging to Acinetobacter genospecies 3 and had reduced susceptibility to the carbapenems. The isolate was found to encode two blaOXA-58 genes that may have been duplicated by the insertion sequence ISAba125, two copies of which were inserted into ISAba3 elements. The blaOXA-58 genes appear to be plasmid borne. 
Conclusions: This is the first report of β-lactamase duplication in Acinetobacter genospecies 3 and of gene duplication mediated by ISAba125.