Streptococcus viridans

Taxobox
color = lightgrey
name = "Streptococcus" viridans-group

---

image_width = 240px
regnum = Bacteria
phylum = Firmicutes
classis = Bacilli
ordo = Lactobacillales
familia = Streptococcaceae
genus = "Streptococcus"

"Streptococcus" viridans is a "pseudo-taxonomic" term for a large group of generally non-pathogenic, commensal streptococcal bacteria that are either α-hemolytic, producing a green coloration on blood agar plates (hence the name "viridans"), or non-hemolytic.cite book | author = Ryan KJ, Ray CG (editors) | title = Sherris Medical Microbiology | edition = 4th ed. | pages=293-4 |publisher = McGraw Hill | year = 2004 | isbn =0838585299 ]

Identification

Viridans streptococci can be differentiated from "Streptococcus pneumoniae" using an optochin test, as "Viridans" streptococci are optochin resistant; they also lack either the polysaccharide-based capsule typical of "S. pneumoniae" or the Lancefield antigens of the pyogenic members of the genus.cite book | author = Patterson MJ| chapter = Streptococcus | title = Baron's Medical Microbiology (Baron S "et al", eds.)| edition = 4th ed. | publisher = Univ of Texas Medical Branch | year = 1996 | url = http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mmed.chapter.824 | isbn = 0-9631172-1-1 ]

Pathology

The organisms are most abundant in the mouth and one member of the group, "S. mutans", is the etiologic agent of dental caries. Others may be involved in other mouth or gingival infections.

If they are introduced into the bloodstream they have the potential of causing endocarditis, particularly in individuals with damaged heart valves.

References