Survival of BALB/c mice after intraperitoneal infection with Mycobacterium lepraemurium

In an attempt to develop a single, quantitative method of studying the disease that follows infection of susceptible mice with Mycobacterium lepraemurium, survival of BALB/c mice was measured as a function of time following i.p. inoculation with the organisms. Survival was found to be inversely related to the challenge dose of M. lepraemurium and unrelated to the organ-source of the organisms; survival was prolonged by treatment with isoniazid. Mice infected with M. lepraemurium were protected against i.v. challenge with M. marinum administered early in the disease, whereas they demonstrated enhanced susceptibility to the same challenge administered later. Conversely, prior M. marinum infection of mice in the hindfoot pad conferred protection against subsequent challenge with M. lepraemurium.