抄録
Among the genus Rothia, Rothia dentocariosa and Rothia mucilaginosa are found in oral cavity and pharynx of humans. Furthermore, there is only one report that Rothia aeria,which is capable of causing serious systemic infections, has been also detected in the mouths of healthy individuals. A suitable selective medium for the isolation of R. aeria is necessary to assess the veritable prevalence of this organism in the oral cavity. To examine the bacterium population in the oralcavity, a novelselective medium, designated RASM,was developed for the isolation of R. aeria. RASM consists of sodium gluconate, tryptone,lablemco powder and aztreonam. Average growth recovery of R. aeria on RASM was 96.1％ compared with that on BHI-Y agar. Growth of other representative oral bacteria including R. dentocariosa, R. mucilaginosa, genera Actinomyces, Neisseria, and Corynebacterium were remarkably inhibited on the selective medium. Though the inhibitions of certain strains of streptococci were not complete, they formed small or pin colony on RASM and could be distinguished from R. aeria colony. Clinical efficacy was evaluated by the recovery of R. aeria on RASM from the stimulated saliva samples of ten volunteers. R. aeria was detected at 3.1（range: 0.5-14.4)％ to totalbacteria of 7.0×107 CFU/ml on BHI-Y agar in their oral cavities. The new selective medium, RASM, was usefulfor the isolation of R. aeria. Moreover, we examined the antibiotic susceptibility of twenty isolates from four subjects. The bacterium was susceptible to most antibiotics;however R. aeria isolates from one subject were highly resistant to erythromycin, lincomycin, and clindamycin.
