Estimation of the Improved Selective Medium for mutans Streptococci

Abstract

MSB media are frequently used for counting and detection of mutans Streptococci. In recent years, improved MSB media have been developed by improving the demerits of existing MSB media (poor selectivity). In this study, we examined usefulness of improved MSB media for selectivity and the correlation between the levels of Streptococcus mutans and Streptococcus sobrinus in saliva and the prevalence of caries using improved MSB media and drew the following conclusions. 1. There were almost no differences in the ratio of the number of subjects positive for S. mutans and S. sobrinus in saliva when comparing the conventional medium with the improved medium. The improved medium was slightly superior to the conventional medium in terms of the mean count of detected microorganisms. On the other hand, the ratio of the number of subjects and the mean detection count for Non-MS microorganisms were significantly lower in the improved medium. When the numbers of microorganisms detected in the MSB medium and the improved MSB medium were compared, A positive correlation was noted for S. mutans and S. sobrinus. 2. A significant difference in the mean DMFT was observed depending on whether the percentages of S. mutans out of the total Streptococcus count was low or high. Significant differences were also observed in the mean DMFT between the groups in which S. sobrinus was detected and was not detected.