Three simple tests as an adjunct to the niacin test for the small mycobacteriology laboratory.

With the change in the management of tuberculosis, many bacteriology laboratories should be prepared to examine sputum for the presence of acid-fast bacilli. The niacin test is the most reliable test that can be performed in any mycobacteriology laboratory to differentiate Mycobacterium tuberculosis from the other acid-fast bacilli, but it is not perfect. Other tests can be used to supplement it are cord formation, growth at 24 C, and the catalase test at 68 C. Incompletely identified strains should be submitted to a reference laboratory.