Which Mycobacterium species is commonly associated with tap water and is often considered a nonpathogenic contaminant?

Which Mycobacterium species is commonly associated with tap water and is often considered a nonpathogenic contaminant?

• A. M. gordonae
• B. M. kansaii
• C. M. avium-intracellulare
• D. M. bovis

Answer: (A)

M. gordonae is the classic tap water bacillus. It is commonly recovered from municipal and natural water sources and is typically nonpathogenic, so in routine cultures it is often considered a contaminant rather than a true pathogen. That environmental association with water, and its generally benign clinical significance, makes it the best match for a organism described as commonly linked to tap water and not usually causing disease. In contrast, M. kansaii tends to cause pulmonary infections reminiscent of tuberculosis; M. avium-intracellulare (the MAC complex) can cause disseminated disease in immunocompromised individuals and pulmonary disease in others; M. bovis is a member of the tuberculosis complex and is a recognized pathogen.

M. gordonae is the classic tap water bacillus. It is commonly recovered from municipal and natural water sources and is typically nonpathogenic, so in routine cultures it is often considered a contaminant rather than a true pathogen. That environmental association with water, and its generally benign clinical significance, makes it the best match for a organism described as commonly linked to tap water and not usually causing disease.

In contrast, M. kansaii tends to cause pulmonary infections reminiscent of tuberculosis; M. avium-intracellulare (the MAC complex) can cause disseminated disease in immunocompromised individuals and pulmonary disease in others; M. bovis is a member of the tuberculosis complex and is a recognized pathogen.