An Enterotoxin-Bearing Pathogenicity Island in Staphylococcus epidermidis

Area of Science:

• Microbiology
• Genomics
• Molecular Biology

Background:

• Staphylococcal species frequently interact on human mucosal surfaces, facilitating horizontal gene transfer.
• Staphylococcus aureus pathogenicity islands (SaPIs) are known to encode major toxins and virulence factors.
• Pathogenicity islands have not been previously identified in Staphylococcus epidermidis genomes.

Purpose of the Study:

• To identify and characterize novel pathogenicity islands in Staphylococcus epidermidis.
• To investigate the genetic basis of toxin production in S. epidermidis.
• To explore the potential role of pathogenicity islands in the evolution of staphylococcal virulence.

Main Methods:

• Genomic analysis of Staphylococcus epidermidis strain FRI909.
• Confirmation of taxonomic placement using biochemical tests and multilocus sequence typing.
• Quantitative reverse transcription-PCR (qRT-PCR) and immunoblotting to confirm gene expression.
• Analysis of bacteriophage activity and potential for pathogenicity island mobilization.

Main Results:

• Identification of a composite Staphylococcus epidermidis pathogenicity island (SePI) in strain FRI909.
• Demonstration that the SePI encodes and expresses staphylococcal enterotoxin C3 (SEC3) and staphylococcal enterotoxin-like toxin L (SElL).
• Characterization of the SePI as stable, toxin-expressing, and not readily transmissible by phage transduction.
• Description of a novel bacteriophage in S. epidermidis FRI909, including its genome and replication.

Conclusions:

• This study presents the first evidence of a pathogenicity island in Staphylococcus epidermidis.
• The identified SePI contributes to the toxin-producing potential of S. epidermidis.
• The findings enhance understanding of staphylococcal genome evolution and virulence mechanisms.