Forsblom, B.*1, Sarkiala-Kessel, E.2, Ikonen, M.2, and Jousimies-Somer, H. 1
1Anaerobe Reference Laboratory National Public Health Institute. 2 Faculty of Veterinary Medicine University of Helsinki. Helsinki. Finland.
There is little detailed information available on the anaerobic, gram-negative non-pigmented bacterial flora in subgingival sites of dogs. The purpose of the present study was to phenotypically characterize by conventional biochemical testing a group of "corroding" gram-negative rods isolated from diseased (n=32) and healthy (n=16) subgingival sites of 16 family-owned dogs with spontaneous, clinically diagnosed periodontitis, and to determine the occurrence of these organisms at the subgingival sites. The study is part of a more comprehensive investigation involving detailed characterization of the gram-negative anaerobic (pigmented and non-pigmented) and aerobic bacterial flora in periodontitis lesions in dogs.
Altogether 39 isolates, of which 30 were isolated from diseased sites and nine from healthy site, were characterized. In addition to a common special potency antibiotic disk pattern (Va-R. Ka-S., Co-S) and a positive nitrate reaction, most isolates (28 or 72%) were motile and oxidase positive. Accordingly, they were identified as members of the genus Campylobacter. One isolate was designated Campylobacter-like as motility was observed. Half (14 or 50%) of the Campylobacter isolates were catalase positive and thus phenotypicallv close to the human oral species C.showae. One isolate of Bilophala wadsworthia was identified in the present study. Its phenotypic features conformed to those of correspoding human isolates. The remaining isolates (9 or 23%) were identified as Eikenella corrodens or E. corrodens-like bacteria. They were non-motile and exhibited good or scanty aerobic growth, respectively . They were resistant to metronidazole and exhibited both ornithine and lysine decarboxylase activity, a feature distinguishing them from the newly described species Kingella oralis. No statistically significant difference were detected between the occurrence of Campylobacter sp, E. corrodens or B. wadsworthia in the diseased and healthy subgingival sites.
Further studies including cellular fatty acid analysis and 16S rRNA sequencing are warranted to determine the exact taxonomic position of the organisms characterized in the present study.