Effect of Inoculum Size and Frequency on the Establishment of Streptococcus mutans in the Oral Cavities of Experimental Animals

SPF Sprague-Dawley rats and ICR mice were inoculated with either Streptococcus mutans MT8148R (serotype c) or 6715 (g), and the influence of inoculum size, inoculum frequency, and sucrose on the establishment of S. mutans in the oral cavity was examined. Successful colonization of S. mutans in the experimental animals was absolutely dependent on the number of the cells introduced orally. Furthermore, inoculum frequency and sucrose seemed to act as secondary factors to modify the establishment of S. mutans, and it is suggested that high inoculum frequency may decrease the inoculum size necessary for the colonization of S. mutans in the oral cavity.