Spectrum of microbial keratitis in South Florida

Abstract

During a nine-year period ending in 1977, we scraped and cultured 663 corneal ulcers. Of these cases of keratitis, 238 were bacterial infections, 133 were fungal, and 292 were culture-negative. Pseudomonas was the predominant bacterial organism, and Fusarium was the most common fungus isolated. November was the peak month for both bacterial and fungal keratitis. Direct inoculation of multiple media, including Sabouraud's agar, blood agar, chocolate agar, thioglycollate liquid, and brain-heart infusion liquid, enhanced the recovery rate; each medium provides special nutrients for different organisms. The Gram and Giemsa stains were satisfactory, but the newer Grocott methenamine silver stain for fungi and the limulus lysate test for gram-negative bacteria proved to be clinically useful. The clinical profile of patients with fungal keratitis differed from that of patients with Pseudomonas keratitis. Thirty-three percent of the patients with Pseudomonas keratitis were wearing contact lenses at the time of their infection, and the remainder had a high incidence of predisposing ocular conditions. Fungal keratitis tended to occur in healthy male patients who had been subjected to outdoor trauma.