oa Molecular Diagnosis and Vaccines - Sequencing emm gene for accurate typing of Egyptian-hemolytic streptococci isolates from non-sterile sites



Group A streptococcal (GAS)-mediated diseases continue to be a major problem world wide. Typing of clinical isolates of GAS relies primarily on serologic typing of surface M Protein using polyclonal antibodies. In this study, problems associated with M serotyping such as limited availability of typing sera, newly encountered M types and difficulty in interpretation were avoided by using a system based on sequence analysis of the emm gene that encode M serospecificity. This method relies upon the use of two highly conserved primers that amplify a large portion of the emm gene and the fact that the hyper variable sequence encoding M serospecificity lies adjacent to one of the amplifying primer sequence allowing direct sequencing. One hundred and forty ?-hemolytic streptococci isolates from non sterile sites (94 impetigo, 46 pharengeal) of Egyptian patients were subjected to emm typing. Forty five emm types were identified, 12 of them never been encountered in USA or Egypt and 6 out of these 12 emm type strains were newly discovered worldwide. In addition, several new emm-T-agglutination pattern-associations were found. These findings indicate that Egypt has a unique distribution of group A streptococci strains.


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