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Age influences the emm type distribution of pediatric group A streptococcal pharyngeal isolates

Preeti Jaggi1, Robert R Tanz, Bernard Beall

  • 1Children's Memorial Hospital, Chicago, IL 60614, USA. jaggi@childrensmemorial.org

The Pediatric Infectious Disease Journal
|December 24, 2005
PubMed

Insights

Common group A streptococcal (GAS) emm types shift with age in children. Uncommon GAS types increase with age, while specific common types like emm 12 and emm 4 decrease, suggesting developing immunity.

Area of Science:

  • Microbiology
  • Epidemiology
  • Pediatrics

Background:

  • Group A Streptococcus (GAS) pharyngitis is common in children.
  • Specific emm types (12, 1, 28, 3, 4, 2, 6) dominate US GAS pharyngitis, comprising 78% of isolates.

Purpose of the Study:

  • To investigate age-related differences in the distribution of common pharyngeal GAS emm types among children.
  • To analyze how the prevalence of specific emm types changes across different age groups.

Main Methods:

  • emm typing of 3356 GAS isolates from the US and Canada (2000-2003).
  • Analysis of prevalence variations by age for the 7 most common emm types and an 'uncommon' category.
  • Statistical assessment using chi-squared tests.

Main Results:

  • The prevalence of uncommon GAS emm types significantly increased with age (18% in youngest to 37% in oldest group).
  • Specific common types, emm 12 and emm 4, showed a significant decrease in prevalence with increasing age.
  • No significant age-related decline was observed for other common types (emm 1, 2, 3, 6, 28).

Conclusions:

  • Age-dependent shifts in pharyngeal GAS emm type distribution occur during childhood.
  • These changes may indicate the development of immunity to more prevalent emm types following early-life exposure.
Abstract

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