Which type of streptococcus is resistant to optochin?

The viridans group of streptococci is indeed characterized by its resistance to optochin. This group includes various species of streptococci that are part of the normal flora of the mouth and upper respiratory tract, and they are not significantly pathogenic in healthy individuals. In laboratory settings, one of the primary tests to differentiate Streptococcus pneumoniae from other alpha-hemolytic streptococci is the optochin sensitivity test; Streptococcus pneumoniae is sensitive and will be inhibited by optochin, while viridans streptococci will grow in its presence, indicating resistance.

In contrast, Streptococcus pneumoniae, which is a significant pathogen known for causing pneumonia, meningitis, and otitis media, is sensitive to optochin. Streptococcus pyogenes, associated with pharyngitis and other infections, is also not subjected to optochin testing as it is beta-hemolytic and behaves differently in culture. Enterococcus, on the other hand, is a distinct group of streptococci often associated with urinary tract infections and is resistant to optochin as well, but it is categorized differently than viridans streptococci. The critical point is thus the