Development of a paper strip test for detection of niacin produced by mycobacteria.

The development of a reagent-impregnated paper strip test for niacin is described. The test system is based on the formation of cyanogen chloride by the reaction of chloramine-T and potassium thiocyanate in the presence of citric acid. Rupture of the pyridine ring of niacin by cyanogen chloride yields gamma-carboxy glutaconic aldehyde and coupling with a primary aromatic amine produces a yellow color. Sensitivity to niacin, both in known solutions and from extracts of 378 clinical mycobacteria isolates, equalled or exceeded that of other methods for detection of niacin. Correlation with other tests for mycobacterial niacin was excellent.