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. 2020 Jan;23(1):135-140.
doi: 10.1111/vop.12698. Epub 2019 Jul 22.

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

Candace R Auten  1 , Jennifer L Urbanz  1 , Darryl Dustin Dees  2
Affiliations

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

Candace R Auten et al. Vet Ophthalmol. 2020 Jan.

Abstract

Objective: To compare aerobic bacterial culture results between samples obtained from the corneal ulcer versus lower conjunctival fornix in eyes with presumed bacterial ulcerative keratitis.

Animals studied: Fifty five client-owned dogs diagnosed with ulcerative keratitis.

Procedures: Ophthalmic examinations were performed on each dog including slit-lamp biomicroscopy and indirect ophthalmoscopy. 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 from 56 eyes (55 dogs). 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. Overall, 31/56 (55%) corneal samples were positive and 37/56 (66%) conjunctival fornix samples were positive. Comparison of organisms isolated from the two collection sites of the same eye revealed an exact correlation in 42/56 (75%) eyes and differed in 14/56 (25%) eyes. Twenty different bacterial isolates were obtained from 68 positive samples. 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.

Conclusion: Sampling from the conjunctival fornix may be a suitable alternative to direct ulcer sampling in eyes with compromised corneal structural integrity.

Keywords: Pseudomonas aeruginosa; Staphylococcus pseudintermedius; canine; conjunctival fornix; microbial culture; ulcerative keratitis.

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References

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