Effects of alpha-toxin-deficient Staphylococcus aureus on the production of peripheral corneal ulceration in an animal model

Purpose: To examine the role of Staphylococcus aureus alpha-toxin in contact lens-induced peripheral ulceration (CLPU). Materials and Methods: Proteolytic enzyme, hyaluronidase, alpha-toxin, and beta-toxin production by S. aureus 8325-4 and its alpha-toxin-deficient mutant (S. aureus DU1090) were exarnined. Using a rabbit model of CLPU, animals were fitted with hydrogel contact lenses colonized by either S. aurcus 8325-4 or the mutant strain. The clinical presentation, bacterial cultures, and histology of the ulceration were examined. Results: Both strains of S. aureus produced similar levels of caseinase, gelatinase, elastase, hyaluronidase, and beta-toxin. S. aureus DU1090 induced weaker haernolysis of rabbit blood cells than S. aureus 8325-4. Ulceration in the S aureus DU1090 eye was less frequent and less severe than that caused by S. aureus 8325-4. Conclusions: The enzyme production profile of S. aureus DU 1090 was similar to the parent strain. S. aureus strains may produce CLPU-like lesions irrespective of alpha-toxin production, but severe infectious lesions are produced only in the presence of alpha-toxin.