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.
| Viridans streptococci | Streptococcus pneumoniae | |
|---|---|---|
| Solubility in bile | Insoluble | Soluble |
| Fermentation of inulin | Not a fermenter | Fermenter with acid production |
| Sensitivity to optochin | Not sensitive | Sensitive |
| Pathogenicity to mice | Nonpathogenic | Pathogenic |
| Quellung test | Negative | Positive |
Read more about this topic: Streptococcus Viridans