In the identification of mycobacterial isolates, the niacin test involves the:
a. accumulation of niacin in the medium in which the organism is growing.
b. metabolism of niacin to nicotinic acid by enzymatic action.
c. testing of the isolate for susceptibility to niacin.
d. utilization of niacin in metabolic pathways to produce nicotinic acid.
A
Niacin (nicotinic acid) plays an important role in the oxidation-reduction reactions that occur during mycobacterial metabolism. Niacin therefore accumulates in the medium in which these organisms are growing. A positive niacin test is preliminary evidence that the organism that ex-hibits a buff-colored, slow-growing, rough colony may be M. tuberculosis.
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