Topical antibiotic therapy of staphylococcal keratitis

The in vivo antibacterial effectiveness in the rabbit cornea of a number of commercially available ophthalmic antibiotic preparations was determined against a single strain of penicillinase-producing Staphylococcus aureus isolated from a human corneal ulcer. Each antibiotic was instilled topically at hourly intervals, and the number of residual viable organisms in the cornea subsequently was ascertained. In vivo measurements demonstrated that five antibiotics--neomycin sulfate, gentamicin sulfate, erythromycin, tetracycline hydrochloride, and chlortetracycline hydrochloride--were equally effective in suppressing growth of the strain of S aureus studied. Therapeutic results were the same whether the corneal epithelium was present of absent for each of the drugs studied. With one exception (chloramphenicol), there was excellent correlation between in vivo and in vitro findings.