Susceptibilities of Mycobacterium leprae and M. avium complex to the H2O2-Fe-mediated halogenation system supplemented with antimicrobial agents

The susceptibilities of Mycobacterium leprae and M. avium complex (MAC) to the H2-O2-Fe-mediated halogenation system supplemented with antimicrobial agents were evaluated by fluorescein diacetate-ethidium bromide (FDA/EB) staining. In the case of M. leprae, the number of greenstained bacteria (intact cells) was reduced in the presence of the H2O2-Fe-mediated halogenation system supplemented with agents possessing antileprosy activity, such as rifampin, 4,4'-diaminodiphenylsulfone (dapsone), clofazimine, and ofloxacin. In the case of the MAC strain, although viable units of the organisms were reduced by the halogenation system alone, the number of greenstained cells in the FDA/EB stain was not reduced, even when the halogenation system was used in combination with ofloxacin. Because stainability of the cells is related to structural and functional intactness of the membrane, differences between M. leprae and the MAC strain imply possible differences in the rigidity of the cell membrane.