Antibiotic resistance, biofilm formation, and virulence factors of isolates of from healthy dogs and dogs with keratitis.

Canine bacterial keratitis is a common infection that can potentially threaten vision. () is an opportunistic pathogen that has been isolated from the canine conjunctival sac but there are only a few reports on the role of this bacterium in canine keratitis. This study focused on the distribution rate of in the canine conjunctival sac, and the antibiotic resistance, biofilm-producing ability, and dissemination of virulence factors in strains of isolated from healthy dogs and dogs with keratitis. The study included 35 healthy dogs and 40 dogs with keratitis. Bacterial species were confirmed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Strains of were screened for resistance against nine different antibiotics by the Kirby-Bauer assay. The ability to produce biofilm was investigated by microtiter plate assay (MtP) and amplification of and genes. Virulence factors in the strains were also evaluated. A total of 132 aerobic bacteria were isolated from the 119 samples in the study. Among them, 67 bacterial strains were isolated from 70 eyes of healthy dogs, and 65 bacterial strains were isolated from 49 eyes of dogs with keratitis. The prevalence of , which was the most frequent bacterial isolate in both the groups, was 20.9% in the healthy group and 23.08% in the keratitis group. Most of the isolates of were sensitive to rifampin (96.6%), oxacillin (100%), and neomycin (96.6%), and resistant to tetracycline (96.6%). Virulence factors such as (96.6%), (96.6%), and (96.6%) were found in most of the isolates, and 89.66% of isolates were classed as biofilm producers. In conclusion, was the common bacterium in the conjunctivital sac of the healthy dogs and dogs with keratitis in Yangzhou, China, and the presence of virulence factors and biofilm-formation ability were high in the strains isolated from the dogs with keratitis.