SEARCH OF THE NOVEL GENETIC DETERMINANTS IN STREPTOCOCCUS DYSGALACTIAE SUBSPECIES EQUISIMILIS

Streptococcus dysgalactiae subsp. equisimilis (SDSE) previously considered to be a commensal bacterium, is currently recognized as a causative agent of about 60% of infections caused by groups C and G streptococci. Goal of the present study was to search the novel genetic determinants in the genome of four SDSE strains using next generation sequencing and bioinformatic analysis. As result, genome sequences of four SDSE strains were determined, and numerous DNA fragments previously uncharacterized for SDSE were revealed. Most of the fragments were presented by migrating genetic elements such as bacteriophages, transposons, plasmids, integrative conjugative elements etc. For the first time the resistance genes to antibacterial drugs (tetS, tetT - resistance to tetracycline, and lsaE, lnuB - to lincosamides) were determined in the studied SDSE strains. Given that horizontal gene transfer, in particular, virulence genes associated with migrating genetic elements, is a driving force of streptococcal evolution, an emergence of novel virulent SDSE clones is expected.