A novel selective medium for the isolation and distribution of Rothia dentocariosa in oral cavities

Rothia dentocariosa is an indigenous microbial flora of dental plaque. To examine the bacterium population in oral cavities, a novel selective medium, designated RDSM, was developed for the isolation of R. dentocariosa. RDSM was prepared by adding 0.5 μg/ml of lincomycin, 10 μg/ml of colistin, and 40% sucrose to Heart Infusion (HI). Average growth recovery of R. dentocariosa on RDSM was 93.8% that of HI medium. Growth of other bacteria including Rothia mucilaginosa, Neisseria, Actinomyces, or streptococci was remarkably inhibited on the selective medium. Clinical efficacy was evaluated by the recovery of R. dentocariosa on RDSM from the stimulated saliva samples of 8 volunteers. R. dentocariosa was detected at 2.6 (range: 1.0-4.6) % to total bacteria of 8.0×10(7)CFU/ml on BHI in their oral cavities. The new selective medium, RDSM, was highly selective for R. dentocariosa and was useful for the isolation of R. dentocariosa from clinical samples.