In cases of subacute bacterial endocarditis, the causative organism ( streptococcus viridans ) needs a previous heart valve disease to colonize.
2.
The "'viridans streptococci "'are a large group of commensal taxonomic term " Streptococcus viridans " is often used to refer to this group of species, but writers that 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 "', "'viridans group streptococci "'( "'VGS "'), or "'viridans streptococcal species " '.