An exfoliative toxin A-converting phage isolated from Staphylococcus aureus strain ZM

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Staphylococcal scalded-skin syndrome (SSSS) is a blistering disease primarily affecting children.
• Exfoliative toxin A (ETA) is the primary virulence factor responsible for SSSS.
• The genetic basis of ETA production was previously attributed to chromosomal DNA.

Purpose of the Study:

• To investigate the genetic basis of exfoliative toxin A (ETA) production in Staphylococcus aureus.
• To identify potential mobile genetic elements involved in ETA gene transfer.
• To challenge the prevailing understanding of ETA gene localization.

Main Methods:

• Isolation of temperate phages from an ETA-producing Staphylococcus aureus strain (ZM).
• Use of a restriction-minus indicator strain (1039) for phage isolation.
• Polymerase chain reaction (PCR) assay to detect the eta gene.

Main Results:

• A temperate phage, designated phi-ZM-1, was successfully isolated.
• Lysogenic conversion experiments demonstrated that phi-ZM-1 mediates ETA production.
• PCR analysis confirmed that the eta gene is located on the phage genome of phi-ZM-1.

Conclusions:

• The eta gene, responsible for exfoliative toxin A, is carried by the temperate phage phi-ZM-1.
• This finding indicates that ETA production in this strain is mediated by a phage, not solely chromosomal DNA.
• Phage-mediated toxin production is a significant factor in the pathogenesis of staphylococcal scalded-skin syndrome.