The role of staphylococcal superantigens in the pathogenesis of marginal keratitis.

Previous studies have demonstrated an increased incidence of delayed-type hypersensitivity to staphylococcal antigens in patients with blepharitis, but this does not predict subsequent development of marginal keratitis (MK). Superantigens are potent immune-modifying molecules produced by pathogenic organisms including Staphylococcus aureus. To study whether staphylococcal superantigens play a role in the development of MK, conjunctival and lid margin cultures were taken from 26 subjects with MK and 24 controls. Four of 8 eyes with their first episode of MK grew strains of S. aureus, of which only one was superantigen-producing. None of the subjects with recurrent MK and only one control grew S. aureus. We conclude that staphylococcal superantigens are unlikely to play a central role in the development of MK. The absence of S. aureus on the lids of subjects with recurrent MK may reflect an alteration in lid flora due to previous topical antibiotic and steroid treatment.