Which two mycobacteria are commonly isolated from subcutaneous skin and thrive at 30°C?

The correct choice identifies Mycobacterium haemophilum and Mycobacterium ulcerans as the two mycobacteria commonly isolated from subcutaneous skin infections and that thrive at around 30°C.

Mycobacterium haemophilum is particularly known for causing skin and soft tissue infections, especially in immunocompromised individuals. It typically requires a warmer, more suitable temperature for growth that aligns with the human body, but it shows a preference for growth at around 30°C, making it notable in cases of cutaneous disease.

Mycobacterium ulcerans is also associated with subcutaneous infections and is the causative agent of Buruli ulcer, a disease that can lead to severe ulceration primarily in the skin. Its growth at lower temperatures complements its ecological niche, often found in aquatic environments and associated with soil and stagnant water, where temperatures can be relatively cool.

Both species thus form a crucial part of discussions concerning mycobacterial infections of the skin, particularly in cases involving environmental exposures or in patients with compromised immune systems. This reason reinforces their common clinical association with subcutaneous presentations and temperature preferences.