[Molecular characterization of the multidrug-resistant Acinetobacter baumannii strains and assessment of their sensitivity to the phage AP22].

The molecular analysis of 130 multidrug-resistant nosocomial Acinetobacter baumannii strains was performed. The strains were obtained from patients admitted to different Russian hospitals (Chelyabinsk, Moscow, Nizhni Novgorod, and St. Petersburg) in 2005-2010. Species identification was performed using the amplified 16S rRNA gene restriction analysis and by determining intrinsic for A. baumannii blaQXA-51-like genes using PCR. The genetic typing of the strains was performed by RAPD-PCR. All strains fell into two clusters: A and B with dominant RAPD-groups A1 and B1, respectively, including 82% (107 of 130) of all studied strains. The susceptibility to the bacteriophage AP22 of the strains was determined. The phage was found to infect specifically and to constitute 69% of 130 strains and 82% (88 of 107) of the A. baumannii strains from the dominant RAPD groups. The ability of the bacteriophage AP22 to constitute a broad range of the clinically relevant A. baumannii strains makes it an attractive candidate for designing the phage cocktails intended to control the A. baumannii-associated nosocomial infections. Moreover, the phage can be used for the identification of A. baumannii in bacteriological analysis of clinical materials.