<unk>  is a facultatively anaerobic, gram-positive coccus (round bacterium) commonly found in the human oral cavity and is a significant contributor to tooth decay. It is part of the "streptococci" (plural, non-italic lowercase), an informal general name for all species in the genus Streptococcus. The microbe was first described by James Kilian Clarke in 1924. This bacterium, along with the closely related species Streptococcus sobrinus, can cohabit the mouth: Both contribute to oral disease, and the expense of differentiating them in laboratory testing is often not clinically necessary. Therefore, for clinical purposes they are often considered together as a group, called the<unk>  streptococci (plural, non-italic due to its being an informal group name). This grouping of similar bacteria with similar tropism can also be seen in the viridans streptococci, another group of Streptococcus species.
Streptococcus mutans
Streptococcus bovis
Streptococcus pyogenes
Staphylococcus aureus
Neisseria mucosa
Bacteroides caccae
Neisseria flavescens
Staphylococcus saprophyticus