Pyridine extractability of acid-fastness from Mycobacterium leprae

Various mycobacteria were tested for their ability to retain acid-fastness after treatment with pyridine: a) Mycobacterium leprae separated from organs of 20 experimentally infected armadillos (which were sacrificed); b) M. leprae separated from a biopsy of a lepromatous patient; c) direct smears of lepromatous tissues from armadillos; d) eighteen cultivable mycobacteria obtained from the American Type Culture Collection (ATCC); E) cultivatable mycobacteria separated from the lymph nodes of a wild-caught armadillo and also the same organism grown in culture and Skinsnes' alleged M. leprae culture. A loss of acid-fastness was observed microscopically from M. leprae separated from experimentally infected armadillo tissues, M. leprae separated from a lepromatous patient biopsy, and M. leprae found in direct smears prepared from infected armadillo tissues. The eighteen cultivatable mycobacteria from ATCC, cultivatable mycobacteria separated from the tissue of a wild-caught armadillo (and also grown in culture) and Skinsnes' alleged M. leprae culture retained their acid-fastness. Testing of pyridine extractability of acid-fastness combined with those of D-DOPA oxidase testing proved to be extremely reliable in our laboratory in differentiating M. leprae from other mycobacteria.