what is viridans streptococci
(Redirected from Streptococcus viridans). The viridans streptococci are a large group of commensal streptococcal bacteria species that are either Î±-hemolytic, producing a green coloration on blood agar plates (hence the name viridans, from Latin vÄ­rÄ­dis, green), or nonhemolytic.iridans streptococci have the unique ability to synthesize dextrans from glucose, which allows them to adhere to fibrin-platelet aggregates at damaged heart valves.