Isolation of obligate anaerobic bacteria from ulcerative keratitis in domestic animals.
OBJECTIVE
To determine the frequency of obligate anaerobic bacterial isolation from corneal samples of domestic animals with ulcerative keratitis and to characterize the historical, clinical, cytological, and microbiological features of culture-positive cases.


METHODS
Three hundred and thirty domestic animals with ulcerative keratitis.


METHODS
Anaerobic bacteriologic culture and Gram stain were performed on corneal samples from consecutive animals examined with suspect septic ulcerative keratitis. Additional corneal diagnostics included: aerobic bacteriologic culture for all species; fungal culture for ungulates; Mycoplasma culture and virus isolation or feline herpesvirus-1 (FHV-1) polymerase chain reaction (PCR) for cats. Historical, clinical, and cytological findings were correlated with microbiologic data.


RESULTS
Anaerobic bacteria were isolated from 13.0% of corneal samples (dogs: 14.0%; horses: 12.9%; cats: 7.9%; alpacas: 18.8%). The most frequent isolates were Clostridium, Peptostreptococcus, Actinomyces, Fusobacterium, and Bacteroides species. The majority of these infections were mixed anaerobic and aerobic bacteria, unless antimicrobial therapy had been administered prior to presentation. The clinical appearance of anaerobic bacterial culture-positive cases was highly variable. Ocular trauma, pre-existing corneal disease, previous corneal surgery, and chronic dermatological disease were significantly (P < or = 0.05) correlated with positive anaerobic cultures in one or more species.


CONCLUSIONS
The results of the present study demonstrate that obligate anaerobic bacteria are present within the intralesional flora of ulcerative keratitis in domestic animals. In most species evaluated, these bacteria were identified infrequently. Anaerobic bacterial infection of the cornea most frequently occurs in association with other ocular pathogens and previous corneal abnormalities.
Ledbetter
Eric C
EC
Department of Clinical Sciences, and College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA. ecl32@cornell.edu
Scarlett
Janet M
JM
D000818:Animals; D000829:Animals, Domestic; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001421:Bacteria, Anaerobic / Q000302:isolation & purification*; D002161:Camelids, New World; D002415:Cats; D003320:Corneal Ulcer / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D004285:Dogs; D015818:Eye Infections, Bacterial / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D006736:Horses
D000900:Anti-Bacterial Agents