When should the test be performed?
The niacin test is used to identify Mycobacterium tuberculosis by assessing the bacilli’s ability to metabolize nicotinic acid (niacin). Indications for performing the test include:

  • Differentiating Mycobacterium tuberculosis from other mycobacterial species
  • Confirming whether bacterial isolates belong to the M. tuberculosis complex
  • Verifying culture results in tuberculosis diagnostics

Test description

The niacin test is based on differences in niacin (nicotinic acid) production among mycobacterial species. Mycobacterium tuberculosis produces and accumulates free niacin in the culture medium, which allows its differentiation from most other Mycobacterium species that either metabolize or retain niacin intracellularly.

  • The test involves a chemical reaction in which free niacin reacts with specific reagents to produce a yellow color on the reaction strip.

  • It is performed on bacterial isolates obtained from cultures grown on egg-based media, such as Löwenstein–Jensen.

  • This is a simple, rapid, and cost-effective method that supports the identification of M. tuberculosis in classical TB diagnostics.