Viridans streptococci | |
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Scientific classification ![]() | |
Domain: | Bacteria |
Phylum: | Bacillota |
Class: | Bacilli |
Order: | Lactobacillales |
Family: | Streptococcaceae |
Genus: | Streptococcus |
The viridans streptococci are a large group of commensal streptococcal Gram-positive bacteria species that are α-hemolytic, producing a green coloration on blood agar plates (hence the name "viridans", from Latin "vĭrĭdis", green), although some species in this group are actually γ-hemolytic, meaning they produce no change on blood agar.[1] The pseudo-taxonomic term "Streptococcus viridans" is often used to refer to this group of species, but writers who do not like to use the pseudotaxonomic term (which treats a group of species as if they were one species) prefer the terms viridans streptococci,[2] viridans group streptococci (VGS), or viridans streptococcal species.
These species possess no Lancefield antigens.[3] In general, pathogenicity is low.[4]