Differentiation of bovine tubercle bacilli from other mycobacteria by the determination of nicotinamidase activity.

Human infection with M. tuberculosis val'. bovis in the United States is no longer an important problem. In other countries, however, this is not so. Urech (1) in 1957 reported 4.5 per cent bovine infections among 441 tuberculous patients in Germany. The major differences between the human and bovine strains are based on cultural characteristics and animal pathogenicity studies. Konno and associates (2-4) reported a biochemical method which would differentiate human tubercle bacilli from all other types of mycobacteria. This method is based on the fact that the human strains have a significantly greater niacin content than all of the other mycobacteria tested. Halpern and Grossowicz (5) studied the amidase activities of cell-free extracts from M. phlei and BeG, using various substrates, and reported a higher nicotinamidase activity in M. phlei than in BeG. Bonicke and Lisboa (6) compared the nicotinamidase activity of bacterial emulsions of human and bovine tubercle bacilli and reported no nicotinamidase activity in the bovine variety. The purpose of this report is to distinguish bovine tubercle bacilli from other mycobacteria (human and avian tubercle bacilli, unclassified mycobacteria, and nonpathogenic acid-fast bacilli) by determining the nicotinamidase activity of the cell-free extracts.