Description of non-brachycephalic canine conjunctival microbiome before and after application of an antiseptic preparation.

Objective: To evaluate canine conjunctival microbiome before and after an antiseptic preparation using aerobic culture and DNA sequencing.

Animals Studied: Six healthy non-brachycephalic dogs.

Procedures: Dogs randomly received povidone-iodine 1:50 dilution solution in one eye with the second eye serving as a control. Standardized volumes of solution, number of sterile cotton tipped applicators, and preparation times of 5 min were used. Aerobic culture and DNA sequencing samples were collected from inferior conjunctival fornices at baseline, immediately following, 24 h, and 4 weeks following antiseptic preparation. Aerobic culture data were evaluated using paired t-test and linear regression. Illumina platform was used to sequence bacterial DNA using primers to target the V4 region of bacterial 16S rRNA. Quantitative Insights Into Molecular Ecology (QIIME 2.0) was used to analyze data.

Results: Baseline aerobic cultures consisted of Bacillus (35%), Staphylococcus (30%), Streptococcus (20%), Moraxella (5%), Micrococcus (5%), and Simonsiella spp. (5%). No significant difference was detected in mean number of species cultured at baseline and following treatment (p = .465). Treatment, sample time, or interaction was not significant (p > .393). The most abundant phyla at baseline via DNA sequencing were Proteobacteria (57.04%), Actinobacteria (19.89%), Firmicutes (3.25%), and Bacteroidetes (5.5%). Alpha and beta diversity matrices at baseline and over time revealed no significant change in species richness or bacterial composition. Relative abundance of bacterial taxa did not significantly differ in treated or control eyes over time.

Conclusions: Conjunctival bacterial flora identified differed between culture dependent and independent methods. The bacterial community remained stable over time after application of the antiseptic preparation.