Isolation of obligate anaerobic bacteria from ulcerative keratitis in domestic animals.

The research investigates the frequency and nature of obligate anaerobic bacterial infections in domestic animals suffering from ulcerative keratitis, a type of eye disease. The study involved conducting various tests on corneal samples from animals with the disease, exploring the types of bacteria present, and linking these findings to historical, clinical, and cytological data.

Methods

• The study involved 330 domestic animals suffering from ulcerative keratitis – an infection of the cornea, which is the clear, front surface of the eye.
• Several laboratory tests were conducted on corneal samples collected from these animals. These tests included anaerobic and aerobic bacteriological cultures and a Gram stain. These procedures aim to identify the presence and type of bacteria in the samples.
• For certain species, additional tests were carried out, such as fungal cultures for ungulates and Mycoplasma cultures and FHV-1 PCR for cats.
• The researchers also analyzed historical, clinical, and cytological data corresponding to the sampled animals.

Results

• Anaerobic bacteria, which are bacteria that do not require oxygen to grow, were found in 13.0% of tested samples. The rates varied slightly between species – 14.0% in dogs, 12.9% in horses, 7.9% in cats, and 18.8% in alpacas.
• The most regularly identified bacteria were Clostridium, Peptostreptococcus, Actinomyces, Fusobacterium, and Bacteroides species.
• Often, the infections were a mix of anaerobic and aerobic bacteria, unless the animal had received antimicrobial treatment before the tests.
• The clinical appearance of animals with positive anaerobic bacteria cultures varied greatly. Certain conditions such as ocular trauma, pre-existing corneal disease, previous corneal surgery, and chronic dermatological disease were significantly more likely to correlate with positive anaerobic cultures.

Conclusions

• The study found that obligate anaerobic bacteria are common within the intralesional flora of ulcerative keratitis in domestic animals, but they were identified relatively infrequently in most evaluated species.
• The researchers concluded that anaerobic bacterial corneal infections often occur in association with other ocular pathogens and previous abnormalities of the cornea.