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Severe soft tissue infection caused by a non-beta-hemolytic Streptococcus pyogenes strain harboring a premature stop

Jonathan Jantsch1, Roman G Gerlach, Armin Ensser

  • 1Mikrobiologisches Institut-Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.

Journal of Clinical Microbiology
|March 22, 2013
PubMed

Insights

A non-beta-hemolytic Streptococcus pyogenes strain caused a severe soft tissue infection. A mutation in the sagC gene, crucial for streptolysin S production, was responsible for the loss of hemolytic activity.

Area of Science:

  • Microbiology
  • Infectious Diseases

Background:

  • Streptococcus pyogenes is a significant human pathogen.
  • Beta-hemolysis, mediated by streptolysin S (SLS), is a characteristic feature of many S. pyogenes strains.
  • SLS production is governed by a specific gene cluster, including the sagC gene.

Observation:

  • A clinical isolate of S. pyogenes from a severe soft tissue infection exhibited a non-beta-hemolytic phenotype.
  • Genetic analysis revealed a premature stop codon in the sagC gene of this isolate.
  • The sagC gene is part of the streptolysin S (SLS) biosynthetic operon.

Findings:

  • The identified point mutation in the sagC gene directly correlated with the absence of beta-hemolytic activity.
  • Restoration of a functional sagC gene via plasmid vector reintroduction successfully restored the beta-hemolytic phenotype in the clinical isolate.
  • This confirms that the non-hemolytic nature of the strain was due to the defective sagC gene.

Implications:

  • This study identifies a novel mechanism for S. pyogenes-associated severe soft tissue infections caused by strains lacking hemolytic activity.
  • The findings expand our understanding of S. pyogenes virulence factors and their role in disease pathogenesis.
  • Clinicians should consider non-beta-hemolytic S. pyogenes strains as potential causative agents in severe soft tissue infections.

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