A reliable combination method to identification and typing of epidemic and endemic clones among clinical isolates of Acinetobacter baumannii.

The multi-drug resistant (MDR) Acinetobacter baumannii as an important nosocomial pathogen has emerged a global health concern in recent years. In this study, we applied three easier, faster, and cost-effective methods including PCR-based open reading frames (ORFs) typing, sequence typing of blaOXA-51-like and RAPD-PCR method to rapid typing of A. baumannii strains. Taken together in the present study the results of ORFs typing, PCR-sequencing of blaOXA-51-like genes and MLST sequence typing revealed there was a high prevalence (62%, 35/57) of ST2 as international and successful clone which detected among clinical isolates of multi-drug resistant A. baumannii with ORF pattern B and blaOXA-66 gene. Only 7% (4/57) of MDR isolates belonged to ST1 with ORF pattern A and blaOXA-69 gene. Interestingly, we detected singleton ST513 (32%, 18/57) that encoded blaOXA-90 and showed the ORF pattern H as previously isolated in Middle East. Moreover, our data showed RAPD-PCR method can detect divergent strains of the STs. The Cl-1, Cl-2, Cl-3, Cl-4, Cl-10, Cl-11, Cl-12, Cl-13 and Cl-14 belonged to ST2. While the Cl-6, Cl-7, Cl-8 and Cl-9 belonged to ST513. Only Cl-5 belonged to ST1. It seems that the combination of these methods have more discriminatory than any method separately and could be effectively applied to rapid detection of the clonal complex (CC) of A. baumannii strains without performing of MLST or PFGE.