engleski

Carbapenem-resistance and acquired class D carbapenemases in Acinetobacter baumannii from Croatia, 2009-2010

The molecular epidemiology and the genetic basis of carbapenem resistance was investigated in 185 Acinetobacter baumannii isolates obtained from 13 centers of northern Croatia and Istria during 2009-2010. All isolates were multidrug-resistant, and 35% (n=64) were resistant to both imipenem and meropenem. ISAba1-driven overexpression of the intrinsic blaOXA-51-like gene was observed in all carbapenem resistant isolates, and 69% of these (n=44) also produced acquired OXA-type carbapenemases. The presence of blaOXA-58-like, blaOXA-24/40-like, and blaOXA-23-like genes was demonstrated in 33% (n=21), 27% (n=17) and 9% (n=6) of carbapenem-resistant isolates, respectively. None isolate harbored the blaIMP, blaVIM, blaSIM, blaNDM or blaPER β-lactamase genes, while blaTEM1 was detected in five carbapenem- and ampicillin/sulbactam-resistant isolates. Sequence group determination showed a high prevalence (81%) of isolates belonging to the International clonal lineage (ICL)-I, although the majority (80%) of isolates carrying acquired carbapenemase genes belonged to the ICL-II. Random amplified polymorphic DNA analysis and multilocus-sequence typing of a subset of carbapenem resistant isolates revealed low degree of genetic variability within both ICL-I and ICL-II populations, irrespective of the genetic basis of carbapenem resistance. Overall, an increasing trend of carbapenem resistance was observed for A. baumannii in Croatia, and the emergence of ICL-II strains producing a variety of acquired carbapenemases.

Acinetobacter baumannii; imipenem; carbapenem-hydrolyzing oxacillinases; resistance

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