Acinetobacter radioresistens as a silent source of carbapenem resistance for Acinetobacter spp

Carbapenem resistance results mostly from the expression of acquired carbapenem-hydrolyzing oxacillinases in Acinetobacter baumannii. The bla OXA-23 oxacillinase gene is increasingly reported worldwide and may represent an emerging threat. Our goal was to identify the progenitor of that carbapenemase gene. A collection of 50 Acinetobacter sp. strains corresponding to several Acinetobacter species was screened for blaOXA-23-like genes by PCR and hybridization techniques. Five Acinetobacter radioresistens isolates that were susceptible to carbapenems harbored chromosomally encoded blaOXA-23-like genes. A similar plasmid backbone was identified in several blaOXA-23-positive A. baumannii and A. radioresistens isolates, further strengthening the vectors of exchanges for these bla OXA-23-like genes. Therefore, A. radioresistens, a commensal bacterial species which is identified on the skin of hospitalized and healthy patients (a property shared with A. baumannii), was identified as the source of the blaOXA-23 gene. Copyright © 2008, American Society for Microbiology. All Rights Reserved.