Genetic and phenotypic diversity among isolates of Streptococcus pyogenes from invasive infections

J Infect Dis. 1996 Apr;173(4):901-8. doi: 10.1093/infdis/173.4.901.


To determine if recent cases of invasive group A streptococcal disease were caused by strains with a unique characteristic, 117 isolates Streptococcus pyogenes from patients with a variety of diseases, including necrotizing fasciitis and toxic shock syndrome, were analyzed. Significant genomic heterogeneity was observed among selected isolates, as determined using pulsed-field gel electrophoresis. The frequency of the bacteriophage-associated streptococcal erythrogenic toxin genes A and C (speA and speC) among the isolates was 44% (49/112) and 34% (38/112), respectively. Forty-three percent of speA-positive isolates produced streptococcal erythrogenic toxin (SPE) A in vitro. Seventy-six percent (85/112) of isolates produced SPE B in vitro, and in contrast to SPE A, little variation in the concentration of SPE B in broth culture supernatants was detected. The genetic and phenotypic heterogeneity observed among isolates from recent cases of severe infection does not support a clonal basis for the resurgence of invasive streptococcal infections.

Publication types

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

MeSH terms

  • Bacterial Proteins*
  • Base Sequence
  • DNA Primers / chemistry
  • DNA, Bacterial / genetics
  • Exotoxins / genetics*
  • Fasciitis / microbiology
  • Genotype
  • Humans
  • Membrane Proteins*
  • Molecular Sequence Data
  • Phenotype
  • Polymorphism, Restriction Fragment Length
  • Shock, Septic / microbiology
  • Streptococcus pyogenes / genetics*
  • Streptococcus pyogenes / pathogenicity


  • Bacterial Proteins
  • DNA Primers
  • DNA, Bacterial
  • Exotoxins
  • Membrane Proteins
  • SpeA protein, Streptococcus pyogenes
  • erythrogenic toxin