Acinetobacter radioresistens as a Silent Source of Carbapenem Resistance for Acinetobacter spp

Abstract

ABSTRACT 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 bla OXA-23 -like genes by PCR and hybridization techniques. Five Acinetobacter radioresistens isolates that were susceptible to carbapenems harbored chromosomally encoded bla OXA-23 -like genes. A similar plasmid backbone was identified in several bla OXA-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 bla OXA-23 gene.