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Group A Streptococcus virulence factors genes in north India & their association with emm type in pharyngitis

V Dhanda1, H Vohra, R Kumar

  • 1School of Public Health, Postgraduate Institute of Medical Education & Research, Chandigarh, India.

The Indian Journal of Medical Research
|February 16, 2011
PubMed

Insights

Group A Streptococcus (GAS) strains from Indian children show high virulence factors, contributing to rheumatic fever. Virulence is linked to specific isolates, not just types, highlighting the need for targeted interventions.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Genetics

Background:

  • Group A Streptococcus (GAS) pharyngitis is a significant cause of rheumatic fever (RF) and rheumatic heart disease (RHD) in India.
  • GAS exhibits genetic diversity, encoding various virulence factors that contribute to disease.
  • Understanding these factors is crucial for managing GAS infections, particularly in pediatric populations.

Purpose of the Study:

  • To investigate the prevalence and characteristics of virulence factor genes in GAS isolates from children in North India.
  • To compare GAS isolates from children with pharyngitis (mild and severe) and asymptomatic carriers.
  • To explore the association between specific emm types and the presence of virulence factors.

Main Methods:

  • Cultured GAS isolates from 50 North Indian children (aged 5-15 years) with pharyngitis or as asymptomatic carriers.
  • Performed emm typing and Polymerase Chain Reaction (PCR) to characterize virulence factor genes.
  • Analyzed the association between emm type and virulence factors in pharyngitis cases.

Main Results:

  • Identified 20 emm types, 6 sequence types, and 1 non-typeable GAS strain.
  • Emm 74 (12%), 11 & StI129 (8%), and emm 68 & NS292 (6%) were the most prevalent types.
  • The speB gene was significantly more common in opacity factor (OF)-negative isolates; emm types 3, 11, 77, 86, 87, 109, and StI129 harbored the most virulence genes.

Conclusions:

  • GAS isolates from North Indian children possess highly virulent antigens.
  • The study suggests that virulence is associated with specific GAS isolates rather than solely with emm type.
  • Findings underscore the importance of understanding isolate-specific virulence in GAS infections.
Abstract

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