Viridans streptococci (not Streptococcus viridans, which is no longer accepted as a species) are a group of streptococci that typically inhabit the oral cavity and are the most common pathogens of SBE. Most laboratories do not routinely speciate this group of bacteria because speciation typically does not change management. The other organisms listed can cause SBE on occasion but are much less common. IV drug users may develop SBE from Candida and gram-negative species.
