Which species of Mycobacterium is diagnosed by means other than culture?

Mycobacterium leprae, the causative agent of leprosy, is primarily diagnosed through methods other than traditional culture techniques. This is because M. leprae has not been successfully cultured in vitro, which makes culture-based diagnosis challenging. Instead, diagnosis is often based on clinical features, such as the presence of skin lesions, nerve damage, and sensory loss, as well as laboratory tests like skin smears or biopsies that reveal the presence of acid-fast bacilli.

In contrast, other species of Mycobacterium mentioned rely more on culture techniques for diagnosis. For instance, M. bovis can be cultured from clinical specimens, and M. avium can also be isolated from various body fluids or tissues in immunocompromised patients. M. canetti, while less common, can be cultured as well, although it is often considered in special cases. Thus, M. leprae stands out as the species that requires alternative diagnostic approaches due to its inability to be cultured.