Non-tuberculosis mycobacteria in Africa. 3. Formamidase activity--its evaluation and practical application.
The third study in a series on the prevalence of non-tuberculosis mycobacteria in Africa is devoted to the investigation of the formamidase activity of 288 cultures of mycobacteria, already typed by a battery of standard tests as pathogenic or atypical (184 strains) and saprophytic (104 strains). Of the latter, 96 (92.3%) were formamidase-positive, as compared with only 6 (3.3%) of the former. A close correlation was observed between the speed of growth on Löwenstein-Jensen medium and formamidase activity, 98 (96.1%) of the positive strains showing visible growth within 1-3 days. The relation between formamidase activity and growth on nutrient media was less clear-cut, however, and it was concluded that for the routine differentiation of saprophytic from other mycobacteria the formamidase test should be combined with simple tests such as speed of growth on L-J medium and ability to grow on nutrient media. Russel's method and Nessler's reagent for the detection of ammonia in the formamidase test were compared; the authors consider the former to be preferable, since the reaction is easier to read.
D000349:Africa; D000581:Amidohydrolases / Q000378:metabolism*; D005558:Arylformamidase / Q000378:metabolism; D001431:Bacteriological Techniques; D006801:Humans; D008722:Methods; D009161:Mycobacterium / Q000145:classification* / Q000201:enzymology / Q000302:isolation & purification; D009164:Mycobacterium Infections / Q000453:epidemiology* / Q000382:microbiology
D000581:Amidohydrolases; D005558:Arylformamidase