title: Radiometric macrophage culture assay for rapid evaluation of antileprosy activity of rifampin.
abstract: The antileprosy effect of rifampin was evaluated by a newly developed rapid in vitro assay wherein 31 human-derived strains and 1 armadillo-derived strain of Mycobacterium leprae were maintained for 2 and 3 weeks, respectively, in murine and human macrophages in the presence of [3H]thymidine. Of these strains, 27 showed significant incorporation of the radiolabel in cultures of live bacilli as compared with control cultures of heat-killed bacilli of the same strain. Consistent and significant inhibition of [3H]thymidine uptake was observed in M. leprae resident cultures with 3 to 200 ng of rifampin per ml as compared with similar cultures without the drug. In general, an increase in percent inhibition was seen from 3 to 20 ng/ml, with marginal increases at 40, 50, and 100 ng/ml. M. leprae strains appear to be remarkably susceptible to this drug in the in vitro assay.
mesh_terms: D000818:Animals; D001135:Armadillos / Q000382:microbiology; D002478:Cells, Cultured; D006801:Humans; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008826:Microbial Sensitivity Tests / Q000379:methods; D009166:Mycobacterium leprae / Q000187:drug effects*; D011874:Radiometry; D012293:Rifampin / Q000494:pharmacology*; D013936:Thymidine / Q000378:metabolism
chemical_list: D013936:Thymidine; D012293:Rifampin