A selective medium for Streptococcus mutans

Summary-A selective medium was developed for the isolation of Streptococcus mutans from human dental plaque. Mitis-salivarius agar was modified by adding 0.2 units/ml bacitracin and by increasing the sucrose concentration to 20 per cent. At these concen-trations, the selective agents allowed the undiminished recovery of Strep. mutans with maximum inhibition of the balance of the streptococcal flora normally encountered on this medium. Enterococci or yeasts were sometimes observed upon direct culturing of plaque samples from children with advanced dentinal lesions