The heterogeneity of endemic community pediatric group a streptococcal pharyngeal isolates and their relationship to invasive isolates

J Infect Dis. 2002 Apr 1;185(7):915-20. doi: 10.1086/339407. Epub 2002 Mar 19.


By use of molecular techniques, the genetic heterogeneity of 63 community pediatric pharyngeal group A streptococcal (GAS) isolates circulating within a 3-week period were compared with 17 contemporaneous invasive pediatric isolates. Pharyngitis isolates represented 16 pulsed-field gel electrophoresis (PFGE) patterns with 12 emm serotypes, and invasive isolates represented 10 PFGE patterns with 9 emm serotypes. One-fourth of the pharyngeal isolates (16/63) were identical to at least 1 invasive isolate; conversely, 10 (59%) of 17 invasive isolates were identical to at least 1 pharyngeal strain. sic allele analysis of emm1 strains demonstrated additional heterogeneity and overlap. More pharyngeal (71%) than invasive isolates (35%) were positive for both speA and speC (P<.02). Many pharyngitis GAS strains circulate simultaneously. Most invasive pediatric GAS strains are identical to acute pharyngitis strains; thus, childhood pharyngitis is a major reservoir for strains with invasive potential. Pharyngeal isolates were more likely to be speA and speC positive than were the invasive isolates.

MeSH terms

  • Adolescent
  • Bacterial Proteins / genetics
  • Child
  • Child, Preschool
  • Electrophoresis, Gel, Pulsed-Field
  • Endemic Diseases*
  • Exotoxins / genetics
  • Genetic Variation*
  • Humans
  • Infant
  • Infant, Newborn
  • Membrane Proteins / genetics
  • Pharynx / microbiology*
  • Serotyping
  • Streptococcal Infections / epidemiology*
  • Streptococcal Infections / microbiology
  • Streptococcus pyogenes / classification*
  • Streptococcus pyogenes / genetics
  • Streptococcus pyogenes / isolation & purification
  • Streptococcus pyogenes / pathogenicity


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