Open Access Outbreak of Carbapenem-Resistant Acinetobacter baumannii Producing

Abstract: The use of carbapenems to eradicate multi-drug resistant (MDR) Acinetobacter baumannii may become com-promised by the spread of carbapenem-hydrolyzing class D -lactamase (CHDL) genes (OXA-23, OXA-40, or OXA-58). Here, we describe the phenotypical and genotypical characterization of MDR A. baumannii isolates, recovered between June and November 2003 in a tertiary-care hospital in Antalya, Turkey. Hundred and sixteen MDR A. baumannii isolates were isolated from 23 patients, mostly from respiratory samples and from 11 environmental samples. These MDR isolates, belonged to a single clone and remained susceptible to colistin and rifampin only. They produced CHDL OXA-58. In addition, they were also positive for the blaOXA-51, for a novel blaAMPC (ADC-43) gene and for ISAba1. The blaOXA-58 gene was located onto a non self-transferable 50-kb plasmid that could be elec-troporated to A. baumannii 7010 reference strain. One isogenic carbapenem-susceptible strain lost its plasmid carrying blaOXA-58 gene. PCR mapping identified similar genetic structures surrounding the blaOXA-58 gene as for the prototype blaOXA-58 gene, e.g. two ISAba3-like insertion sequences bracketing blaOXA-58 gene. This is the first molecular description of an outbreak of OXA-58- producing A. baumannii isolates in Turkey, further un-derlining the global spread of such carbapenemase- producing strains in the Mediterranean area