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

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

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

Answer: (B)

Different Mycobacterium species have different optimal growth temperatures, and the environmental mycobacteria that commonly cause skin infections prefer cooler conditions. Incubating skin specimens at about 30°C provides the best environment for these organisms to multiply, increasing the chance of recovery. Higher temperatures, such as 37°C, favor other mycobacteria (like the tuberculosis complex) and may reduce recovery of the cutaneous, environmental types. Cooler temperatures like 22°C are often too low for robust growth of many mycobacteria, while 42°C is well above their tolerance. Therefore, 30°C is the best choice for isolating Mycobacterium spp. from skin specimens.

Different Mycobacterium species have different optimal growth temperatures, and the environmental mycobacteria that commonly cause skin infections prefer cooler conditions. Incubating skin specimens at about 30°C provides the best environment for these organisms to multiply, increasing the chance of recovery. Higher temperatures, such as 37°C, favor other mycobacteria (like the tuberculosis complex) and may reduce recovery of the cutaneous, environmental types. Cooler temperatures like 22°C are often too low for robust growth of many mycobacteria, while 42°C is well above their tolerance. Therefore, 30°C is the best choice for isolating Mycobacterium spp. from skin specimens.