A genus of nonmotile, non-spore-forming, non-acid-fast, aerobic to facultatively anaerobic bacteria (family Actinomycetaceae) containing gram-positive, coccoid, diphtheroid, or filamentous cells; metabolism is fermentative, and glucose fermentation yields primarily lactic acid but no propionic acid. These organisms are normal inhabitants of the human oral cavity and are opportunistic pathogens. The type species is Rothia dentocariosa. [G. D. Roth]