Primary and secondary dapsone resistance of M. leprae in Martinique, Guadeloupe, New Caledonia, Tahiti, Senegal, and Paris between 1980 and 1985.

Primary and secondary dapsone resistance were studied among lepromatous patients living in Martinique, Guadeloupe, New Caledonia, Tahiti, Senegal, and Paris. Four hundred fifteen biopsies were taken from clinically active and bacteriologically positive (bacterial index greater than 2) patients in the 6-year period of 1980-1985. Among these, 280 biopsies that contained 5 x 10(4) acid-fast bacilli per ml with a morphological index of at least 0.10 were inoculated into the mouse foot pad, and 229 harbored infective Mycobacterium leprae. Among the 129 infective M. leprae isolated from new cases, 54% had some degree of dapsone resistance, a low degree being prominent in all cases. Among the 100 infective M. leprae isolated from relapsed cases, 79% had a high or an intermediate degree of dapsone resistance. The annual incidence of secondary dapsone resistance was estimated to be about 0.55% in Guadeloupe.