M. avium

Mycobacterium avium complex (MAC) contains 28 serovars of two species of mycobacteria: Mycobacterium avium and Mycobacterium intracellulare. These species are rod-shaped and non-motile. They are slow-growing species that cause opportunistic infections to animals, and immunosuppressed humans. MAC is prevalent in the environment. Mycobacterium avium are acid fast bacillus. They are characterized by a cell wall covalently attached to the long chain of hydrocarbons called mycolic acid in the inner leaflet. This complex between the peptidoglycan and mycolic acids creates the waxy hydrophobic surface of the cell, which greatly restricts the transport of many compounds into and out of the cell, and eventually slows down growth.

Mycobacteria avium