Streptococcus pyogenes strains associated with invasive and non-invasive infections present possible links with emm types and superantigens

Streptococcus pyogenes, a notorious human pathogen is responsible to cause a wide range of infections varies from superficial common clinical illness to severe and life threatening infections. To our knowledge this is the first report exploring the emm types and superantigen/exotoxin gene profile of S. pyogenes from Pakistan.

A total of 89 S. pyogenes strains were collected predominantly from throat swabs followed by pus, tissues and wound swabs. Profile of five superantigen genes speA, speB, speC, speF and ssa was screened for all the emm types.

Extensive heterogeneity among S. pyogenes strains was indicated, revealing 34 different emm types/ subtypes. The most prevalent emm types were emm68 and emm104. Some of the emm types were exclusively isolated from invasive infections while others were isolated only from non-invasive infections indicating the possible link between emm types and invasive/ noninvasive infections. Similarly, erythromycin-resistant strains mainly belonged to three particular emm types. Multiplex PCR analysis indicated the presence of speB 100%, speF 76%, speC 20%, speA 18% and ssa 15%. Interestingly, superantigen genes speC and speA were mainly associated with invasive infections. Among the five superantigens tested, one strain of emm12 harbored all the analyzed exotoxin genes, while 4 strains carried 4 superantigen genes.

S. pyogenes clones associated with invasive and non-invasive infections in Pakistan present differences in emm types, superantigens and antimicrobial resistance. The present data indicates the possible link between particular genetic lineage of a bacterium with the manifestation of the infection.