Effect of Minimal Antibiotic Treatment on Bacterial Keratitis

We studied the effect of minimal antibiotic therapy on pseudomonas keratitis in rabbits. Both corneas of 12 rabbits were infected with Pseudomonas aeruginosa and treated 24 and 48 h later with two drops of tobramycin or placebo. Corneal infections in antibiotic- and placebo-treated groups were comparable in appearance 24 and 48 h after inoculation. However, bacterial recovery was significantly less in eyes treated with minimal antibiotic therapy (p = 0.009). Although negative cultures were obtained from 11 of 12 antibiotic-treated eyes, bacteria could be recovered from eight of these culture negative corneas when corneas were ground and cultured. These studies suggest that minimal antibiotic therapy may impair bacterial recovery without completely eradicating live organisms.