Abstract

"Streptococcus pyogenes continues to be an epidemiological problem due to emergence of invasive infections such as necrotizing fasciitis (NF) and toxic shock syndrome (TSS). At present, S. pyogenes characterization is limited to species identification while molecular studies are restricted to a few specialized laboratories. The literature describes several methods of molecular typing (MLEE, PFGE and emm sequence) that are laborious and costly. Alternatively, a technique based on the vir-regulon polimorphism (emm, emm l, scpA, virR) provides a more simple approach and allows the differentiation of the M types based on virRFLP. The purpose of this study was the molecular characterization of S. pyogenes from invasive infections based on vir-regulon polymorphism. A total of 30 S. pyogenes isolates were tested (TSS/NF: 8; skin and tissue infections: 13; sterile site infections: 9) by Long PCR-virRFLP. The PCR product size varied from 4,2 to 7,8 Kb (28/30, 93%). Two strains amplified a small fragment of 1.5 - 1.6 Kb. Fourteen patterns were generated by DNA restriction endonuclease digestion with HaeIII and three genetic groups were established. Two genetic groups were similar to those described for the M protein types and related to the clinical outcome: group I/M1/sterile sites infection and group III/M3/TSS-NF. Group II presented M type heterogeneity and included skin and tissue infections. Genetic diversity in S. pyogenes is common. Nevertheless, isolates from invasive diseases tend to group according to M serotype and clinical outcome."