Email updates

Keep up to date with the latest news and content from BMC Infectious Diseases and BioMed Central.

Open Access Research article

Distribution of superantigens in group A streptococcal isolates from Salvador, Brazil

Hillary F Berman1, Sara Yee Tartof12, Joice N Reis3, Mitermayer G Reis3 and Lee W Riley1*

Author Affiliations

1 Division of Infectious Disease and Vaccinology, School of Public Health, University of California, Berkeley, CA 94720, USA

2 Kaiser Permanente Southern California Research and Evaluation, Pasadena, CA 91101, USA

3 Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Salvador, Brazil

For all author emails, please log on.

BMC Infectious Diseases 2014, 14:294  doi:10.1186/1471-2334-14-294

Published: 29 May 2014

Abstract

Background

Group A streptococcus (GAS) causes invasive disease, superficial disease, and can asymptomatically colonize humans. Superantigens are one virulence factor found in GAS. Previous studies found associations between the genes that encode superantigens and emm type of GAS. It is unknown if these associations are due to underlying biological factors that limit the distribution of superantigens or, alternatively, if these associations are due to the expansion of local GAS linages where these studies took place. To further address this question we screened GAS isolates collected from Salvador, Brazil for 11 known superantigen genes.

Methods

Seventy-seven GAS isolates were screened by PCR for superantigen genes. These superantigen genes were speA, speC, speG, speH, speI, speJ, speK, speL, speM, ssa, and smeZ. We used Fisher’s two-sided exact test to identify associations between superantigens and GAS emm type. We then compared our results to previous reports of superantigen prevalence and superantigen association with emm type.

Results

In our collection we found several emm type and superantigen genotype combinations that have previously been reported in isolates from Europe and Australia. We also found that speA was significantly associated with emm type 1, and that speC was significantly associated with emm type 12.

Conclusions

Our study reports superantigen genotypes of GAS from a region of the world that is lacking this information. We found evidence of common GAS superantigen genotypes that are spread worldwide as well as novel superantigen genotypes that, so far, are unique to Brazil.

Keywords:
Streptococcus pyogenes; Streptococcal superantigens; Group A streptococcus; Emm types