Growth of Streptococcus mutans on various selective media

Abstract

The ability of S. mutans to grow on mitis-salivarius (MS) agar, MC agar, mitis-sucrose-bacitracin (MSB), BCY agar and MM10 sucrose agar was studied. Batch cultures of S. mutans serotype a demonstrated no growth on MSB agar. Certain serotype d and g strains did not grow on MC agar. The yield for most strains of other serotypes on these selective media was lower compared with that on MS agar. The number of total colony-forming units on BCY and MM10 sucrose agar was similar to the blood agar results. Similar data were obtained when fermentor-grown strains, harvested in the middle or the end of the logarithmic growth phase, were used for inoculation of the various media. Enumeration of S. mutans from [human dental] plaque samples plated on MC and MSB agar yielded 75% of the counts obtained on MS or the nonselective medium. When the proportions of S. mutans were expressed as a percentage of the total cultivable flora, the selective media (MC and MSB agar) showed .apprx. 10% lower values than the MS, BCY and MM10 sucrose agar.