Resumo

Background: Group A streptococci (GAS) produce a variety of proteins, including the antiphagocytic M protein, encodes by the emm gene. M proteins are streptococcal surface proteins that probably represent one of the best-known virulence determinants of this pathogen. M proteins are cell-surface attached proteins that are composed of two polypeptide chains that form an alpha-helical coiled-coil configuration. They have an LPXTG motif at their carboxy terminal part which is a sorting signal required for correct anchoring of the protein into the cell wall. Electron microscopic analysis revealed that the proteins are arranged in a hair-like structure on the bacterial surface. Each chain of the M protein homodimer is built up of 4 repeat regions (A to D) that differ in size and amino acid sequence. The amino-terminal region (A repeat region) is highly variable and constitutes the serotype specificity of GAS. The emm typing is considered a major tool in surveys aimed on GAS epidemiological data achievement. Objectives: To identify the different M protein types of GAS using emm gene sequence analysis, and to acquire epidemiological data related to the S. pyogenes strains involved in clinical outcomes. Methods: Eight clinical GAS isolated from blood, oropharynx, skin lesion and abcess from a hospital in South Brazil were evaluated. All isolates were identified by biochemical tests and by the Real-Time PCR reaction of 16S RNAr gene. The complete DNA of emm gene was sequenced directly in both directions using primers described by CDC. Alignments of all sequences were obtained using the ClustalW2 software program. The nucleotide sequences were compared with all types and subtypes of S. pyogenes using BLASTN (GenBank). Conclusions: In the present study, five different emm types were detected among the eight clinical isolates. Two isolates presented the same type and subtype (19.1) and two isolates had the same type (emm 12) but showed different subtypes ( emm 12 and emm 12.17). There was no relationship between emm type and the site of collection. The most common sites of collection were blood (3 isolates) and oropharynx (3 isolates). The other two isolates were collected from skin lesion and abscess. This is the first study aimed on GAS M protein determination in Southern Brazil. Supporting Instituition: CAPES/CNPQ