Which Mycobacterium species is nonchromogenic?

Which Mycobacterium species is nonchromogenic?

• A. Mycobacterium avium complex
• B. Mycobacterium chelonei
• C. Mycobacterium kansasii
• D. Mycobacterium tuberculosis

Answer: (C)

Nonchromogenic Mycobacterium species do not produce pigment in either light or dark conditions. This lack of pigment is a key labeling feature used alongside growth characteristics to help identify the organism. Mycobacterium kansasii is described as nonchromogenic in many teaching resources, so it fits the nonpigmenting profile expected in this question. The other listed species are typically characterized by pigment production under certain conditions (either after light exposure or in the dark), which is the opposite of nonchromogenic.

Nonchromogenic Mycobacterium species do not produce pigment in either light or dark conditions. This lack of pigment is a key labeling feature used alongside growth characteristics to help identify the organism. Mycobacterium kansasii is described as nonchromogenic in many teaching resources, so it fits the nonpigmenting profile expected in this question. The other listed species are typically characterized by pigment production under certain conditions (either after light exposure or in the dark), which is the opposite of nonchromogenic.