Detection of intrinsic blaOXA-51-like by multiplex PCR on its own is not reliable for the identification of Acinetobacter baumannii.

Three clinical A. baumannii isolates Ab-508, Ab-511, and Ab-653 were recovered from South Africa, South Korea, and Turkey, respectively. Multiplex PCR to detect OXA-type carbapenemases showed atypical blaOXA-51-like amplification products. The aim of this study was to investigate the background of changes in blaOXA-51-like PCR products. Isolates were confirmed as A. baumannii using gyrB multiplex and rpoB sequencing and were epidemiologically unrelated by rep-PCR-based DiversiLab. Sequencing of blaOXA-51-like revealed an insertion of ISAba15 in blaOXA-66 (isolate Ab-511) and an insertion of the novel ISAba19 in blaOXA-78 (isolates Ab-508 and Ab-653). Detection of the intrinsic blaOXA-51-like by OXA-multiplex PCR should not be considered a fully reliable method for identification of A. baumannii when used without an additional independent method. Other species identification methods such as gyrB multiplex PCR and rpoB sequencing should be used to reliably identify A. baumannii.