Identification of superantigen genes speM, ssa, and smeZ in invasive strains of beta-hemolytic group C and G streptococci recovered from humans

FEMS Microbiol Lett. 2003 Dec 12;229(2):259-64. doi: 10.1016/S0378-1097(03)00842-5.


Group C and G Streptococcus dysgalactiae subspecies equisimilis (GCSE and GGSE) cause a substantial percentage of invasive disease caused by beta-hemolytic streptococci. To determine whether Streptococcus pyogenes superantigen (SAg) genes commonly exist within these organisms, 20 recent invasive GCSE and GGSE human isolates and one group G Streptococcus canis human isolate were tested for the presence of SAg genes speH, speJ, speL, speM, ssa and smeZ by polymerase chain reaction (PCR). Prior to this work, sequence-based evidence of the speM, ssa, and smeZ genes in GCSE, GGSE, and S. canis had not been documented. Eleven of the 21 isolates were PCR-positive for the presence of one to two of the SAgs speM, ssa, or smeZ, with four of these isolates carrying ssa+speM or ssa+smeZ. No isolate was positive for speH, speJ and speL. All six ssa-positive GGSE strains harbored the ssa3 allele, previously only found among S. pyogenes strains. All three smeZ-positive GGSE isolates carried one of two smeZ alleles previously only found within S. pyogenes, however the single S. canis isolate carried a new smeZ allele. All five GCSE and GGSE speM-positive isolates harbored a newly discovered speM allele. The identification of these SAgs within S. dysgalactiae subsp. equisimilis and S. canis with identical or near-identical sequences to their counterparts in S. pyogenes suggests frequent interspecies gene exchange between the three beta-hemolytic streptococcal species.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antigens, Bacterial / genetics*
  • Bacterial Proteins / genetics
  • Bacterial Toxins / genetics*
  • Exotoxins / genetics*
  • Humans
  • Molecular Sequence Data
  • Streptococcal Infections / microbiology*
  • Streptococcus pyogenes / genetics*
  • Superantigens / genetics*


  • Antigens, Bacterial
  • Bacterial Proteins
  • Bacterial Toxins
  • Exotoxins
  • SpeJ protein, Streptococcus pyogenes
  • SpeM protein, Streptococcus pyogenes
  • Superantigens
  • mitogenic exotoxin Z protein, Streptococcus
  • speL protein, Streptococcus pyogenes
  • streptococcal superantigen SSA

Associated data

  • GENBANK/AE006622
  • GENBANK/AE010110
  • GENBANK/AE014169