Experimental Bacteroides fragilis Keratitis

To determine the corneal pathogenicity of certain anaerobic bacteria, Bacteroides fragilis keratitis was induced in rabbits by the intrastromal inoculation of 10' viable organisms. All eyes inoculated developed central abscesses within 24 hours. Abscesses persisted and became vascularized in two of three eyes that were observed for two weeks, as demonstrated both clinically and histologically. Eyes inoculated superficially with live organisms or intrastromally with solutions of dead organisms did not develop inflammatory lesions. Anaerobically incubated blood agar plates and thioglycollate broth were equally efficient in recovering organisms, although longer incubation times were occasionally necessary to recover organisms from broth cultures. Bacteroides fragilis and other anaerobic bacteria should be considered in the differential diagnosis of bacterial keratitis, and specific methods should be used to recover these organisms.