Abiotrophia, formerly known as nutritionally variant streptococci, will not grow on routine blood or chocolate agars because they are deficient in which growth factor?

Abiotrophia, formerly known as nutritionally variant streptococci, will not grow on routine blood or chocolate agars because they are deficient in which growth factor?

• A. Hemin
• B. Pyridoxal
• C. Vitamin B12
• D. Thiophene-2-carboxylic hydrazide

Answer: (B)

Abiotrophia are nutritionally fastidious and require pyridoxal (vitamin B6) for growth. Routine blood or chocolate agar doesn’t supply enough pyridoxal, so these organisms won’t grow or will grow poorly on those media. Providing pyridoxal-supplemented media allows them to grow, which is why they’re historically called nutritionally variant streptococci. Hemin (X factor) is needed by Haemophilus species, not Abiotrophia. Vitamin B12 is a different growth factor for other microbes, and thiophene-2-carboxylic hydrazide isn’t a growth factor for this organism.

Abiotrophia are nutritionally fastidious and require pyridoxal (vitamin B6) for growth. Routine blood or chocolate agar doesn’t supply enough pyridoxal, so these organisms won’t grow or will grow poorly on those media. Providing pyridoxal-supplemented media allows them to grow, which is why they’re historically called nutritionally variant streptococci. Hemin (X factor) is needed by Haemophilus species, not Abiotrophia. Vitamin B12 is a different growth factor for other microbes, and thiophene-2-carboxylic hydrazide isn’t a growth factor for this organism.