For reliable results,the niacin test should be performed only from cultures that are at least:
A)2 weeks old and show at least five colonies on Löwenstein-Jensen medium.
B)3 weeks old and show at least 50 colonies on Löwenstein-Jensen medium.
C)3 weeks old and show at least 50 colonies on Middlebrook 7H11 agar.
D)2 weeks old and show at least five colonies on Middlebrook 7H11 agar.

Question

Quizplus · Accepted Answer

Niacin (nicotinic acid)plays an important role in the oxidation-reduction reactions that occur during mycobacterial metabolism.For reliable results,the niacin test should be performed only from cultures that are at least 3 weeks old and show at least 50 colonies on Löwenstein-Jensen medium;otherwise,adequate niacin may not be produced to be detected.

For Reliable Results,the Niacin Test Should Be Performed Only from Cultures