Abstract:

Objective：To study the colonization ability of Streptococcus oligofermentans (S. oligofermentan) in the condition of high sucrose in oral cavity of rats. Methods: In this study, 48 SPF-SD rats aged 21 days were selected. From 24th to 27th days, the rats were fed with water of antibiotic and fed with high glucose diet continuously. On the 28th day, the rats were divided into four groups randomly, 12 rats per group. From the 28th day to 30th day, the first group (SM group) was inoculated with S. mutans, the second group (SO group) with S. oligofermentan, the third group (SO+SM group) with mixture of S. mutans and S. oligofermentan, the control group not with any bacteria. On the next day and the 10th day after inoculation of bacteria, the samples of dental plaque of the rats were acquired by scrubbing occlusal, buccal and lingual surfaces of bilateral mandibular molars with sterile swabs. The samples of SM group were inoculated on MSB and BHIS, of SO group on MSAE, of SO+SM group on MSB, MSAE and BHIS,of the control group on MSB and MSAE. S. mutans were screened and calculated on MSB, the suspected colonies of S. oligofermentan were screened and identified by the analysis of 16S rDNA. Results:On the next day, the detection rate of S. oligofermentan was 33.3% (4/12) in the group of SO; in the group of SO+SM, the detection rate of S. oligofermentan was 0, the detection rate of S. mutans 100.00%, and the proportion of S. mutans 14.70%±4.53%; in the group of SM, the detection rate of S. mutans was 100.00%, the proportion of S. mutans 12.42%±4.27%. On the 10th day, in the group of SO, the detection rate of S. oligofermentan was 0; in the group of SO+SM, the detection rate of S. oligofermentan was 0, the detection rate of S. mutans 100.00%, and the proportion of S. mutans 15.78%±5.10%; in the group of SM, the detection rate of S. mutans was 100.00%,and the proportion of S. mutans 17.08%±5.75%. Conclusion: In the condition of the experiment where high glucose was maintained in the oral cavity in rats, S. oligofermentan appeared transiently and couldn’t colonize in the rats.

Key words: Streptococcus oligofermentans, Streptococcus mutans, Rats, Sprague-Dawley