In vitro cultivation of Mycobacterium lepraemurium and its identification by animal inoculation.

The primary in vitro cultures from lepromata of mice or rats previously infected with the Hawaiian strain of Mycobacterium lepraemurium were obtained on Ogawa egg-yolk medium at 34 degrees C in approximately 90 days of incubation. Optimal growth of subcultures was achieved in 40 to 60 days of incubation and such cultures were used to test their pathogenicity in animals. The in vitro grown subcultures provoked in mice subcutaneous lepromata identical to those produced by the in vitro grown M. lepraemurium. Also, mice infected subcutaneously and intravenously with the in vitro grown subcultures developed lesions in livers, spleens, and kidneys similar to those of mice infected with the mouse passage murine leprosy bacilli. Microscopically and histopathologically, the acid-fast bacilli derived from organs infected with the in vitro or in vivo grown cultures were indistinguishable from each other.