Viridans type of streptococci has had taxonomic revisions [1,5].    Previously designated as strains of Streptococcus sanguis subsp. carlssonii.  Will also see in the literature as Streptococcus sanguinis, a proposed name change.  

Alpha-hemolytic colonies (0.7- 1.2 mm diameter) o­n blood agar and extensive greening o­n chocolate agar [5,6]. 

Facultatively anaerobic, Gram positive cocci, approximately 1 um in diameter, that grow in short chains in broth cultures.   Carbohydrates are femented primarily to lactic acid and no gas. Catalase negative.  Cell wall contains glycerol teichoic acid and rhamnose. Peptidoglycan type is Lys-Ala_1-3 [5,6]

S. sanguis is similar to S. gordonii but can be differentiated based o­n the following; DNA homology, higher G+C content of the DNA (46  vs 42 mol%), doesn't ferment amygdalin, lacks alkaline phosphatase and B-glucosaminidase activities, has IgA1 protease activity, and by multilocus enzyme analysis [5,6].

4 biovars of S. sanguis differ biochemically and serologically, but all biovars possess the group H antigen [5]

Generally associated with healthy oral microflora, but has been associated with intact enamel in children with no caries [2].  However, it has been suggested that it may play a role in caries production [3].

Has also been associated with infective endocarditis and sinusitis.  S. sanguis and other oral species have been linked to Behcet's disease, a systemic disorder of recurrent acute inflammation, including oral aphthous ulcers, uveitis, skin lesions and genital ulcers [4]