Which statement about cultivation of Mycobacterium leprae is correct?

• A. Must be cultured in mice foot pads or armadillos
• B. Can be grown on artificial media
• C. Grows well in broth
• D. Is easily cultured

Answer: (A)

Mycobacterium leprae cannot be grown on standard artificial media because it is an obligate intracellular organism that requires living host cells to replicate. This makes in vivo systems essential for propagation. Historically, the only reliable ways to culture it are in animal models: the mouse footpad and armadillos, which provide the intracellular environment and cooler temperatures that the bacterium favors. The doubling time is very long and growth is extremely slow, so in vitro culture on artificial media or in broth is not feasible. This is why the statement about needing to be cultured in mouse footpads or armadillos is the correct description of how M. leprae is grown.