Which Mycobacterium is commonly recovered from water stills and is often referred to as a tap water contaminant?

Which Mycobacterium is commonly recovered from water stills and is often referred to as a tap water contaminant?

• A. M. gordonae
• B. M. intracellulare
• C. M. xenopi
• D. M. marinum

Answer: (A)

This question hinges on recognizing an environmental mycobacterium that is commonly found in water and is usually considered a contaminant rather than a true pathogen. Mycobacterium gordonae is ubiquitous in water sources and is frequently recovered from water stills and taps. Because it is so commonly present in treated water and rarely causes disease in healthy individuals, it’s often described as a tap water contaminant in clinical microbiology. In contrast, the other organisms listed are more typically associated with specific clinical infections (for example, M. xenopi with hot water systems and pulmonary disease, M. marinum with skin infections after aquatic exposure, and M. intracellulare as part of the MAC causing pulmonary or disseminated disease) and are not classically labeled as tap water contaminants.

This question hinges on recognizing an environmental mycobacterium that is commonly found in water and is usually considered a contaminant rather than a true pathogen. Mycobacterium gordonae is ubiquitous in water sources and is frequently recovered from water stills and taps. Because it is so commonly present in treated water and rarely causes disease in healthy individuals, it’s often described as a tap water contaminant in clinical microbiology. In contrast, the other organisms listed are more typically associated with specific clinical infections (for example, M. xenopi with hot water systems and pulmonary disease, M. marinum with skin infections after aquatic exposure, and M. intracellulare as part of the MAC causing pulmonary or disseminated disease) and are not classically labeled as tap water contaminants.