Success! In Clinical Laboratory Science – Microbiology Practice Test

Abiotrophia, historically called nutritionally variant streptococci, has a specific growth factor requirement: pyridoxal, which is vitamin B6. These bacteria cannot synthesize pyridoxal on their own, so they rely on an exogenous source to support growth. In the lab, this is why they may grow poorly on standard media unless the medium is enriched with pyridoxal or uses chocolate agar, and sometimes they show satellite growth near other organisms that provide the factor.

The other items listed are not the growth requirement for Abiotrophia. Hemin is a growth factor needed by Haemophilus species, vitamin B12 is not the typical requirement for these streptococci, and thiophene-2-carboxylic hydrazide is not a growth factor at all.