Culture of streptococcus viridans resemble-
**Core Concept**
Streptococcus viridans is a type of Gram-positive, facultatively anaerobic coccus that belongs to the viridans group of streptococci. These bacteria are typically found in the oral cavity and are known for their ability to cause endocarditis, particularly in individuals with pre-existing heart conditions.
**Why the Correct Answer is Right**
The correct answer is related to the colony morphology of Streptococcus viridans. These bacteria form small, pinpoint colonies on blood agar that are typically 0.5-1.5 mm in diameter. They are often referred to as "satellite colonies" because they form around the alpha-hemolytic zone of other bacteria.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Streptococcus pneumoniae forms large, mucoid colonies on blood agar, not small, pinpoint colonies.
**Option B:** This option is incorrect because Enterococcus faecalis forms large, mucoid colonies on blood agar with a characteristic golden-brown color, not small, pinpoint colonies.
**Option C:** This option is incorrect because Neisseria gonorrhoeae forms small, translucent colonies on chocolate agar, not small, pinpoint colonies on blood agar.
**Clinical Pearl / High-Yield Fact**
Streptococcus viridans is often associated with endocarditis, particularly in individuals with pre-existing heart conditions. This is because these bacteria can colonize the heart valves and cause infection.
**Correct Answer: D.**