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Genetic diversity and exotoxin A production of group A streptococci causing sepsis

Eun Ha Koh1, Nam Yong Lee, Eui Chong Kim

  • 1Department of Laboratory Medicine, Institute of Health Sciences, Gyeongsang National University School of Medicine, Chilamdong, Jinju, Korea.

Journal of Korean Medical Science
|April 15, 2006
PubMed

Insights

Group A Streptococcus (GAS) sepsis virulence factors, M protein (emm types) and streptococcus pyrogenic exotoxin A (SPE A), were analyzed. Low mortality may be linked to less common virulent strains and lower SPE A production.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Genetics

Background:

  • Group A Streptococcus (GAS) causes various infections, with M protein and streptococcus pyrogenic exotoxin A (SPE A) being key virulence factors.
  • Understanding the genetic diversity and toxin production of GAS strains is crucial for managing infections like sepsis.

Purpose of the Study:

  • To characterize the emm types and SPE A production in GAS strains isolated from sepsis patients.
  • To investigate the clonal structure of these GAS isolates.
  • To correlate strain characteristics with the observed low mortality rate of GAS sepsis.

Main Methods:

  • emm gene sequencing to determine M protein types.
  • Pulsed-field gel electrophoresis (PFGE) for clonality analysis.
  • Assays to detect the presence and production of SPE A.

Main Results:

  • No predominant GAS clones were identified among the isolates.
  • emm genotypes were diverse, with emm13 being the most common (17.9%).
  • SPE A production was observed in 21.4% of the isolates.

Conclusions:

  • The genetic variability of GAS strains and the relatively low prevalence of highly virulent emm types (emm1, emm3) may contribute to the low mortality rate in GAS sepsis.
  • Low production rates of SPE A might also play a role in reduced disease severity.

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