Topically administered corticosteroids: effect on antibiotic-treated bacterial keratitis.

The effect of a topically administered corticosteroid, 1.0% prednisolone acetate, on bacterial replication in rabbit cornea receiving adequate antibiotic therapy was determined. Staphylococcus aureus keratitis was treated either with neomycin sulfate or gentamicin sulfate, while Pseudomonas aeruginosa keratitis was treated either with gentamicin or polymyxin B sulfate. Each antibiotic was administered topically at hourly intervals in both the commercially available concentration and as a formulation containing four times the quantity of drug found in the commercial preparations. In each instance, the antibiotic regimen sharply reduced the number of viable organisms in the cornea, although the concentrated preparations did so more rapidly and effectively. The addition of 1.0% prednisolone acetate had no measurable effect on outcome. In no instance was there a statistically significant difference between number of residual viable organisms in antibiotic-treated corneas and antibiotic/corticosteroid-treated corneas.