It forms smooth to rough colonies after 7 or more days of incubation and is considered a slow grower.

If grown in a lighted incubator, most strains form dark red crystals of β-carotene on the surface and inside of colony.

Its physiology is described as growth on Middlebrook 7H10 agar at 37°C within 7 days or more, resistant to pyrazinamide and susceptible to ethambutol.

Rarely it causes disseminated disease in patients with severely impaired cellular immunity (such as organ transplants or AIDS).

[9]: 341  It is unclear where people acquire the infection and person-to-person spread is not thought to occur.