Characterization of blaOXA-143 variants in Acinetobacter baumannii and Acinetobacter pittii.

The acquired carbapenem-hydrolyzing oxacillinase (OXA) OXA-143 has thus far been detected only in Acinetobacter baumannii isolates from Brazil. The aim of this study was to characterize three OXA-143 variants: OXA-231 and OXA-253 from carbapenem-resistant A. baumannii isolates and OXA-255 in a carbapenem-susceptible Acinetobacter pittii isolate originating from Brazil, Honduras, and the United States, respectively. The 5' rapid amplification of cDNA ends (RACE) technique identified the same transcription initiation site for all blaOXA-143-like genes and revealed differences in the putative promoter regions. However, all cloned OXA-143 variants conferred carbapenem resistance on A. baumannii ATCC 17978 and OXA-255 conferred carbapenem resistance on A. pittii SH024, which was correlated with blaOXA-255 gene expression. This is the first description of OXA-143-like outside A. baumannii. Detection of OXA-143-like in the United States and Honduras indicates its dissemination through the American continent.