Pathogenicity islands occurrence in epidemic MRSA strains from Russia and Kazakhstan

Abstract

Background: MLST analysis of MRSA isolates from Southern Europe, the United States, and South America showed that nearly 70% of them belong to five major pandemic clones, namely the Iberian (MLST sequence type [ST] 247; SCCmec IA), Brazilian (ST 239; SCCmec IIIA), Hungarian (ST 239; SCCmec III), NewYork/Japan (ST 5; SCCmec II), and Pediatric (ST 5; SCCmec IV) clones [Aires de Sousa, M., de Lencastre H., 2004]. It is hypothesized that these clones are particularly transmissible and/or well adapted to the hospital environment [Blanc, D. S., et.al. 1999]. In this context, it is important to study the pathogenicity factors of Staphylococcus aureus, including their prevalence in epidemic populations from different geographical regions. Most staphylococcal virulence factors are encoded by accessory genetic elements that aremobile. These elements includeplasmids, transposons, prophages, and the pathogenicity islands. The staphylococcal pathogenicity islands (SaPIs) encodes one or more of the staphylococcal superantigens. Methods: In this study we used a restriction-modification (RM) test [Cockfield JD et al.,2007], MLVA [Sabat A, 2003] and PCR-based detection of SAPI-associated genes to investigate the clonal structure of 56hospitalMRSA strains isolated in six Russianhospitals (St. Petersburg,Moscow, Perm and Kemerovo) and Karaganda city hospital (Kazakhstan) during 2007-2010. The collection also included cultures of the PFGE-type BT2007 that have been endemic since 2007 in two hospitals of St. Petersburg, Russia (burn and trauma units) [Goncharov A, 2010]. Results: The most of Russian and Kazakh strains (51 from 56) including epidemic BT2007 isolates were attributed as clonal complex CC8/239. Four isolates (St. Petersburg) belong to CC1, one (St. Petersburg) to CC45. CC 8 isolates were predominant among epidemic MLVA clonal lines. All pathogenicity islands (vSaalfa, SAPI1-4) were represented in the cultures of this clonal complex, while a combination of identified SAPIswas different for the strains isolated in various hospitals. Conclusion: Each local/regional MRSA population has its own unique combination of SAPIs. Accordingly, the epidemic strains surveillance strategy should include not onlymethods of the clonal relationship evaluation (spa-typing, MLST), but also the identification of additional mobile genetic elements, especially SAPI.