Distribution of Super-Antigens and Toxins in Bulgarian Invasive and Non-Invasive Clinical Isolates Streptococcus pyogenes

Streptococcus pyogenes, or Group A streptococcus (GAS), is the major pathogen of bacterial tonsilo-pharyngitis tonsillopharyngitis and of skin and soft-tissue infections, which can also cause severe invasive disease or dangerous post-streptococcal autoimmune complications. The differences in the pathogenesis are due to the existing variety in the GAS genome, which often occurs as a result of the cumulative effect of a greater number of various virulence genes. The aim of this study was to determine the frequency and distribution of genes encoding super-antigens and toxins in Bulgarian GAS isolates according to their source and kind of infection. Clinical isolates (n=238) from throat samples, wounds, punctures from peri-tonsilar peritonsillar abscesses, middle ears and sinuses, blood cultures and cerebrospinal fluid, identified as GAS, were screened for the presence of 21 virulence genes, using multiplex polymerase chain reaction (PCR). All of the tested strains were shown to carry the typical of GAS genes: slo, speB, sypCEP, sdaB; more than 80%, mac and smeZ; followed by speF, speG, speJ and genes for DNA-ses sdc, sdaD, Spd3 (between 50% and 75%). An attempt was made to seek an association between the PCR-detected GAS virulence genes, the kind of infection and the source of isolates. A large genetic diversity was found in the studied strains. The genes speA, speF, speL and speM or their combinations were detected more often in invasive isolates (p < 0,05) than in non-invasive ones.