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Corneal pathogenesis of Staphylococcus aureus strain Newman
Joseph J Dajcs1, Megan S Austin, Gregory D Sloop
1Department of Microbiology, Immunology, and Parasitology, Louisiana State University (LSU) Health Sciences Center, New Orleans, Louisiana 70112-1393, USA.
Investigative Ophthalmology & Visual Science
|March 30, 2002
Summary
Staphylococcus aureus toxins alpha and gamma contribute to keratitis virulence in rabbits. Alpha-toxin specifically causes corneal epithelial erosions, indicating a dual role in ocular infection.
Area of Science:
- Ophthalmology
- Microbiology
- Infectious Diseases
Background:
- Staphylococcus aureus is a common cause of bacterial keratitis.
- The specific roles of alpha-toxin and gamma-toxin in S. aureus keratitis pathogenesis are not fully understood.
Purpose of the Study:
- To elucidate the pathogenic contributions of alpha-toxin and gamma-toxin in a rabbit model of Staphylococcus aureus keratitis.
Main Methods:
- Intrastromal injection of S. aureus strains with varying toxin profiles into rabbit corneas.
- Slit lamp examination (SLE) and colony-forming unit (CFU) counts to assess ocular damage and bacterial load.
- Histological examination of corneas and immunization studies against alpha-toxin.
Main Results:
- Both gamma-toxin-deficient and alpha-toxin-deficient strains caused significantly less ocular damage and inflammation compared to the wild-type strain.
- Alpha-toxin was identified as the primary mediator of corneal epithelial erosions.
- Immunization against alpha-toxin reduced ocular damage and prevented erosions.
Conclusions:
- Both alpha-toxin and gamma-toxin play significant roles in the virulence of S. aureus strain Newman during keratitis.
- Alpha-toxin is crucial for inducing corneal epithelial erosions.
- The study suggests the involvement of an additional, uncharacterized toxin in corneal damage.