Mycobacteria
Mycobacterium is a genus of Acinetobacteria, given its own family, the Mycobacteriaceae. The genus includes pathogens known to cause serious diseases in mammals, including tuberculosis and leprosy. Many Mycobactrium species adapt readily to growth on very simple substrates, optimum growth temperatures vary widely according to the species and range from 25 °C to over 50 °C.

Certain species can be very difficult to culture sometimes taking over two years to develop. Others have extremely long reproductive cycles, for example M. leprae may take more than 20 days to proceed through one division cycle making laboratory culture a slow process.

Mycobacteria are widespread organisms, typically living in water (including tap water treated with chlorine) and food sources. Some, however, including the tuberculosis and the leprosy organisms, appear to be obligate parasites and are not found as free-living organisms.

Nontuberculous mycobacteria are all the other mycobacteria which can cause pulmonary disease resembling tuberculosis, lymphadenitis, skin disease, or disseminated disease.