Evaluation of the occurrence of genetic determinants of multi-drug resistance among Acinetobacter baumannii strains

Introduction: The aim of the study was the analysis of occurrence of genetic determinants of multi-drug resistance and the assessment of genetic relationship among Acinetobacter baumannii strains. Methods: Multiplex-PCR method was performed in order to: (1) confirm the phenotypic identification and (2) detect the presence of CHDL oxacillinases in the group of thirty A.baumannii strains. Further PCR studies included the analysis of the occurrence of genetic determinants associated with efflux pump, insertion sequence and biofilm formation. The relationship between bacterial strains was assayed using 6 primers in RAPD-PCR method. Results: Detection of the blaOXA-51-like gene confirmed that the strains belong to the A. baumannii species. In the multiplex-PCR, the presence of the blaOXA-23-like and blaOXA-40-like genes was detected in 3 (10%) and 27 (90%) isolates, respectively. Moreover, some strains showed the coexistence of the blaOXA-51-like and blaOXA-23-like genes (10%, n=3) or blaOXA-51-like and blaOXA-40-like (90%, n=27). In the group of analysed strains the presence of the efflux pump gene (adeA) and the insertion sequence ISAba1 were demonstrated in all tested isolates. Biofilm-related genes (abaI, csuE) were found in 100% and 97% (n=29) tested strains adequately. The RAPD-PCR studies revealed the presence of 10 unrelated genotypes. Conclusions: The obtained results suggest that the phenomenon of multi-drug resistance in the studied A. baumannii strains could be attributed to the occurrence of CHDL oxacillinases, AdeABC efflux pump, insertion sequence ISAba1 and the biofilm formation.