Which organism is alpha-hemolytic and optochin resistant with bile solubility negative?

Prepare for the CAMLPR Microbiology Test. Utilize flashcards and engaging multiple-choice questions, each equipped with descriptions and explanations. Ready yourself for an excellent performance!

Alpha-hemolysis on blood agar means there’s partial hemolysis giving a greenish zone around colonies. Among alpha-hemolytic streptococci, Streptococcus pneumoniae is inhibited by optochin and is bile soluble, so it shows optochin sensitivity and positive bile solubility. The viridans group, on the other hand, is alpha-hemolytic but optochin resistant and bile insoluble (bile solubility negative). The description—alpha-hemolytic, optochin resistant, and bile solubility negative—fits the viridans streptococci. They are common oral inhabitants and often implicated in subacute endocarditis after dental work. The other organisms listed do not match this pattern: they are not the viridans streptococci, and their test profiles differ (for example, actinomyces and Clostridium tetani are not alpha-hemolytic streptococci, and Streptococcus gallolyticus typically has different bile-related characteristics).