What is the most likely identification of mycobacteria isolated from a hospital hot water system that grew at 42C and was non-pigmented?

The identification of mycobacteria that are able to grow at elevated temperatures, such as 42°C, and are non-pigmented points strongly towards Mycobacterium xenopi. This species is commonly associated with water sources, particularly hot water systems, and its ability to thrive at higher temperatures differentiates it from other mycobacterial species that typically have more specific temperature requirements.

Mycobacterium xenopi is notably opportunistic and can be involved in infections predominantly in immunocompromised individuals. Its growth characteristics and ecological niche make it a prime candidate in cases of environmental contamination, especially in hospital settings. The non-pigmented nature further aligns with key identification traits of this organism, solidifying its classification.

Other mycobacterial species listed have distinct growth patterns and temperature tolerances that do not match the conditions described. For example, Mycobacterium marinum typically grows well at lower temperatures and is commonly associated with aquatic environments but does not thrive at 42°C. Mycobacterium ulcerans is primarily known for causing skin lesions and is not typically associated with hot water systems or high temperatures. Mycobacterium haemophilum usually requires enriched media for growth and thrives at 30°C, making it incompatible with