Effects of treatment with muramyl dipeptide on resistance to Mycobacterium leprae and Mycobacterium marinum infection in mice.

Studies were carried out to determine whether treatment of mice with the synthetic adjuvant muramyl dipeptide (MDP) afforded resistance to infection with Mycobacterium leprae or M. marinum in mice. Regardless of the timing, dose, or route of administration, there was no evidence that treatment with MDP or 3 of its analogs (desMDP, abuMDP, valMDP) enhanced resistance to food pad infection with M. leprae or M. marinum. In parallel studies, systemic treatment with Propionibacterium acnes failed to protect against either M. leprae or M. marinum. Administration of P. acnes locally into the foot pad afforded marginal resistance to M. marinum when injected prior to infection. Local treatment with P. acnes afforded marked resistance to growth of M. leprae, even when administered months after infection.