Skin cultures for the recovery of Mycobacterium spp. should be incubated at which temperature?

• A. 42°C
• B. 22°C
• C. 35°C
• D. 30°C

Answer: (D)

Certain cutaneous mycobacteria, especially M. marinum, grow best at cooler temperatures than the usual body temperature. Incubating skin samples at around 30°C provides optimal conditions for their growth, allowing colonies to develop reliably. At higher temperatures like 35–37°C, these organisms may grow poorly or not at all, which can delay or miss recovery. The other options are less suitable: 42°C is too high for these species, and 22°C is cooler than ideal and may slow growth or fail to yield robust colonies. Therefore, 30°C is the best choice to recover skin-associated Mycobacterium species.