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Severe invasive streptococcal infection by Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis

Shinya Watanabe1, Norihiko Takemoto2, Kohei Ogura2

  • 1Division of Bacteriology, Department of Infection and Immunity, School of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi 329-0498.

Microbiology and Immunology
|January 15, 2016
PubMed

Insights

Streptococcus pyogenes (GAS) causes severe invasive infections, but Streptococcus dysgalactiae subsp. equisimilis (SDSE) is also implicated. Unlike GAS, SDSE lacks key virulence factors and does not exhibit hyper-virulence mechanisms.

Area of Science:

  • Microbiology
  • Genomics
  • Infectious Diseases

Background:

  • Streptococcus pyogenes (GAS) is a primary cause of severe invasive streptococcal infections.
  • Streptococcus dysgalactiae subsp. equisimilis (SDSE) is increasingly isolated from severe invasive cases.
  • SDSE shares significant genomic similarity with GAS but lacks crucial GAS virulence factors.

Purpose of the Study:

  • To review the epidemiology of severe invasive streptococcal infections.
  • To detail the pathogenic mechanisms of GAS and SDSE.
  • To compare GAS and SDSE based on genomic and gene expression analyses.

Main Methods:

  • Review of epidemiological studies on severe invasive streptococcal infections.
  • Comparative genomic analysis of GAS and SDSE.
  • Analysis of gene expression in GAS and SDSE during infection.

Main Results:

  • SDSE is genomically similar to GAS but lacks key GAS virulence factors (e.g., SPE-B, hyaluronan operon, superantigens).
  • GAS can acquire genetic traits like phages, contributing to virulence.
  • GAS exhibits a hyper-virulent phenotype during infection by downregulating its covRS system, a mechanism not observed in SDSE.

Conclusions:

  • GAS and SDSE are significant pathogens in severe invasive streptococcal infections.
  • Differences in virulence factors and regulatory mechanisms, particularly the covRS system in GAS, explain variations in pathogenicity.
  • Genomic and transcriptomic insights are crucial for understanding and combating these infections.
Keywords:
RNA-seqStreptococcus dysgalactiae subsp. equisimilisgenome sequencestreptococcal toxic shock syndrome

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