Inhibitory Effect Of A Bacteriolytic Enzyme Derived From Streptomyces Griseus RX-17 On Cariogenicity In Rats

Dental caries is a bacterial infectious disease influenced by multiple factors. Streptococcus mutans(S. mutans) has been implicated as one of the most important pathogenic organisms. The cariogenic mechanism is that S. mutans can adhere to the tooth surfaces, be acidogening and be aciduring. So to inhibit S. mutans growth is an important path to the prophylaxis of the disease. Experiment in vitro revealed that bacteriolytic enzyme derived from Streptomyces griseus RX-17, which was isolated from soils, can inhibit S. mutans growth effectively. The RX-17 bacteriolytic enzyme can be used for prophylaxis of dental caries in human.Objective: To investigate the effect of bacteriolytic enzyme derived from Streptomyces griseus RX-17 on the growth of a cariogenic microbe S. mutans and the development of caries in rats.Methods: Wistar rats were fed with cariogenic forage 2000 , and inoculated to the mouths with S. mutans. The rats were divided into 3 groups and administered with distilled water, sodium fluoride, and RX-17 bacteriolytic enzyme respectively. The effect of RX-17 bacteriolytic enzyme on the growth of S. mutans and caries development were observed by measuring plaque pH, plaque bacteria count and Keyes scoring method.Results: Plaque pH of the RX-17 bacteriolytic enzyme group was significantlyhigher than that of the distilled water group (P<0.05) , but lower than that of the sodium fluoride group (P<0.05). The number of S. mutans in the RX-17 bacteriolytic enzyme group was significantly less than in both the distilled water group (P<0.01) and the sodium fluoride group (P<0.05) . According to Keyes scores, the number of RX-17 bacteriolytic enzyme group at E and Ds levels was significantly less than that of the distilled water group (P<0.01) , but there was no significant difference between the RX-17 bacteriolytic enzyme group and the sodium fluoride group (P> 0.05) , Dm and Dx levels dental caries only could be seen in the distilled water group.Conclusions: RX-17 bacteriolytic enzyme could dissolve the S. mutans in rats and make it loss the ability of growth and reproduction. It also could inhibit the development of caries and such effectiveness was as much as that of the sodium fluoride. Morever, unlike fluoride it is without toxic side effect to the human body. RX-17 bacteriolytic enzyme may be used as a safely and effectively anti-caries method.