Infections with which species are usually acquired by the respiratory route?

• A. Mycobacterium avium complex
• B. Mycobacterium bovis
• C. Mycobacterium ulcerans
• D. Mycobacterium kansasii

Answer: (D)

The main idea is how different mycobacteria enter the body. Mycobacterium kansasii is classically acquired through inhalation of aerosols from environmental water sources, so it typically causes pulmonary disease after being breathed in. This strong association with the respiratory route makes it the best match for the question. In contrast, the other species have different common routes: ulcerans tends to infect through skin inoculation; bovis is most often linked to ingestion of unpasteurized dairy products (with respiratory transmission being less typical); avium complex can cause lung disease but is also well known for disseminated infection in immunocompromised hosts, with inhalation being just one of several possible routes.