Researchers designed a study to compare aerobic bacterial culture results between samples obtained from the corneal ulcer versus lower conjunctival fornix in eyes with presumed bacterial ulcerative keratitis. The study evaluated 55 client owned animals with ulcerative keratitis diagnosis. Microbial swabs were collected by direct sampling of the infected corneal ulcer as well as the lower conjunctival fornix, of the same eye, using a sterile rayon-tipped swab. Samples were submitted to an outside reference laboratory for aerobic bacterial culture and sensitivity.

Results:

One hundred twelve samples were obtained.

Sixty-eight samples yielded bacterial growth.

Positive growth from both sites was obtained in 31 eyes (55%).

Six eyes yielded bacterial growth from the conjunctival fornix but not from the cornea.

No bacterial growth was obtained from either sampling site in 19 eyes.

Fifty-five percent of corneal samples were positive while 66% conjunctival fornix samples were positive.

Twenty different bacterial isolates were obtained from 68 positive samples with Gram-positive (71%) organisms were more common than Gram-negative (29%).

The most commonly isolated organisms were Staphylococcus pseudintermedius (25%), beta-hemolytic Streptococcus spp. (23%), and Pseudomonas aeruginosa (12%). Methicillin-resistant organisms were isolated in 9% of samples.

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Comparison of bacterial culture results collected via direct corneal ulcer vs conjunctival fornix sampling in canine eyes with presumed bacterial ulcerative keratitis.