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Direct and synergistic hemolysis caused by Staphylococcus phenol-soluble modulins: implications for diagnosis and

Gordon Y C Cheung1, Anthony C Duong, Michael Otto

  • 1Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, The National Institutes of Health, Bethesda, MD 20892, USA.

Microbes and Infection
|December 20, 2011
PubMed

Insights

Phenol-soluble modulin (PSM) peptides from Staphylococcus species lyse human red blood cells. Their hemolytic activity is enhanced by β-toxin, suggesting a broader role in staphylococcal infections.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Pathogenesis

Background:

  • Phenol-soluble modulins (PSMs) are amphipathic α-helical peptides secreted by staphylococci.
  • Certain PSMs are potent cytolysins against human neutrophils, acting as key virulence factors in Staphylococcus aureus infections.
  • The hemolytic potential of PSMs against human erythrocytes remains largely unexplored.

Purpose of the Study:

  • To investigate the capacity of PSMs from S. aureus and Staphylococcus epidermidis to lyse human erythrocytes.
  • To determine if PSMs exhibit synergistic hemolytic activity with S. aureus β-toxin.
  • To elucidate the role of PSMs in staphylococcal pathogenesis and hemolysin diversity.

Main Methods:

  • Erythrolysis assays using purified PSMs from S. aureus and S. epidermidis.
  • Assessment of synergistic hemolysis between PSMs and purified S. aureus β-toxin.
  • CAMP assays utilizing the β-toxin-producing S. aureus strain RN4220.

Main Results:

  • Many S. aureus and S. epidermidis PSMs were found to lyse human erythrocytes.
  • Synergistic interactions between several PSMs and S. aureus β-toxin significantly enhanced hemolytic activity.
  • PSMα peptides, in particular, demonstrated substantial contribution to synergistic hemolysis.
  • CAMP assays indicated PSMs' role in synergistic hemolysis, not suitable for δ-toxin detection but useful for Agr functionality assessment.

Conclusions:

  • PSMs possess hemolytic activity against human erythrocytes, expanding their known pathogenic roles.
  • Synergism between PSMs and β-toxin is a significant factor in staphylococcal virulence, especially in mixed infections.
  • The diversity of staphylococcal hemolysins is greater than previously understood, with PSMs contributing significantly.

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