無菌マウスへの歯垢形成性 Streptococcus mntaus の定着性に関する研究

Germfree JCL: ICR strain mice were inoculated intraorally with 1.0×108 colony forming units (CFU) of a plaque-forming streptococcus strain, Streptococcus mutans PK1, bred in the plastic isolator up to 10 weeks and tested at appropriate intervals for the establishment of the organism in the mouth and digestive tract. All specimens isolated from the tooth surface, stomach, duodenum, ilum and colon gave, in every mice tested, a positive reaction for qualitative cultural examinations using thioglycollate culture medium.Growth of the organism was the greatest in the colon among the mouth and digestive tract and followed by the growth in the ileum. Measurement of viable numbers of the organism resulted in an average of 2.5×109CFU/ml for the specimens from the colon. Number of the organism isolated from the digestive tract other than colon varried between less than 2.0×105 to 109CFU/ml. The organism isolated from the specimens of tooth surface were in the level of less than 1.4×104 to 2.7×106CFU/g and 1.8×105 to 9.9×106CFU/g at 2 and 6 weeks after the inoculation, respectively. Addition of sucrose in the drinking water gave no statistically significant increase viable cell numbers in any specimens at least within 4 weeks after inoculation.In conclusion, it was found that Str. mutans PK1 could be established in the mouth and digestive tract of JCL: ICR strain germfree mice by a single inoculation of the organism.