Which statement is not true of Mycobacterium leprae?

Which statement is not true of Mycobacterium leprae?

• A. Causes Hansen disease
• B. Easily transmitted
• C. Difficult to grow in vitro
• D. Usually grows in peripheral limbs

Answer: (B)

This question centers on how Mycobacterium leprae behaves in terms of transmission, growth in the lab, and preferred sites of infection. Mycobacterium leprae is the cause of Hansen disease, and it is not easily transmitted; it requires close and prolonged contact with an untreated case, and exposure does not reliably lead to disease. In the lab, the organism is notoriously difficult to culture on artificial media, so it is grown in more specialized settings such as animal models (armadillos, mouse footpads) rather than standard in vitro media. Clinically, it favors cooler parts of the body, so lesions and nerve involvement typically appear in the skin and distal regions like the limbs. Because of these characteristics, the statement that it is easily transmitted is not true.

This question centers on how Mycobacterium leprae behaves in terms of transmission, growth in the lab, and preferred sites of infection. Mycobacterium leprae is the cause of Hansen disease, and it is not easily transmitted; it requires close and prolonged contact with an untreated case, and exposure does not reliably lead to disease. In the lab, the organism is notoriously difficult to culture on artificial media, so it is grown in more specialized settings such as animal models (armadillos, mouse footpads) rather than standard in vitro media. Clinically, it favors cooler parts of the body, so lesions and nerve involvement typically appear in the skin and distal regions like the limbs. Because of these characteristics, the statement that it is easily transmitted is not true.