Molecular epidemiology of multidrug resistant Acinetobacter Baumannii clinical Solates from two Bulgarian hospitals

Objectives : To investigate the molecular epidemiology of multidrug resistant (MDR) Acinetobacter baumannii isolates collected from patients in two Bulgarian Hospitals (H1, H2) during the period 2005–2012. Materials and Methods : A total of 93 nonduplicate MDR A. baumannii isolates collected from Intensive care units (ICUs) and surgical wards were studied. Antimicrobial susceptibility was tested by VITEK 2 (bioMerieux, Marcy l’Etoile) and Phoenix (BD) and the results were interpreted according to the current CLSI guidelines. Detection of carbapenemase encoding genes was performed by PCR. Isolates were genotyped by PFGE and rep-PCR DiversiLab system (bioMerieux) and compared against a library of A. baumannii strains representing the international clones (IC) 1–8. Results : Twenty seven isolates were carbapenem resistant and were associated with OXA-23 and OXA-58 enzymes. The majority of the investigated isolates (n=65) clustered with ICs 1, 2 and 8. Twenty five isolates from H2, collected during the period 2005–2007, did not cluster with any of the representative strains for the ICs 1–8 and formed a separate unique clone, which was found to persist in 2012. Conclusions : Our results reveal the epidemic and endemic potential of A. baumannii as well as persistence of clones over time. Multidrug resistance in A. baumannii from the investigated Bulgarian hospitals was associated with intrahospital dissemination of IC1, 2 and 8 and with unique local clones.