Oral implantation of Bacteroides asaccharolyticus and Eikenella corrodens in conventional hamsters

Abstract

Oral implantation of Bacteroides asaccharolyticus 381-R' and Eikenella corrodens 1073S-R, which are highly resistant to streptomycin, was examined in conventional hamsters. The hamsters' first molars were ligatured with cotton threads preimmersed in bacterial suspensions. Bacterial inoculation was performed daily for 1 week, followed by a single weekly inoculation for 7 more weeks. Hamsters were fed Keyes' diet no. 2000 or ordinary powdered diet. Bacterial recovery, gingival histological changes, and immunological response were checked 2, 5, and 8 weeks after the daily serial inoculation. B. asaccharolyticus 381-R' was recovered from all hamsters during the experiment (6.7 x 106 to 6.3 x 108 colony-forming units). E. corrodens 1073S-R was recovered from the hamsters fed Keyes' diet no. 2000 throughout the experimental period (2.4 x 105 to 1.2 x 106 colony-forming units), but not in the group fed the ordinary powdered diet. The histological changes in gingival tissues at the second week showed no differences among the control group, the B. assaccharolyticus-inoculated group, and the E. corrodens-inoculated group. However, by the eighth week, the inflammation persisted only in the bacteria-inoculated groups, especially in the B. asaccharolyticus-inoculated group. A relatively increased serum and antibody titer was also observed in the B. asaccharolyticus-inoculated group, but not in the E. corrodens-inoculated group. These findings indicate that the B. asaccarolyticus 381-R' and E. corrodens 1073S-R can be implanted in hamsters' oral cavity with the aid of cotton thread ligature. It was also suggested that B. asaccharolyticus may have some pathogenic role in the destruction of periodontal tissue in hamsters.