Mycobacterium avium

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The Mycobacterium avium complex causes in man atypical mycobacterial infection (nontuberculous mycobacteria, NTM infection) brought to greater prominence as a significant infection due to AIDS. The symptoms are similar to tuberculosis (TB). The various subspecies of Mycobacterium avium and Mycobacterium intra-cellulare can be involved. MAC bacteria are common in the environment and cause infection when inhaled, swallowed or even from bathroom shower heads from which they may be aerosolised. Include:

  • Mycobacterium avium avium (Mycobacterium avium paratuberculosis, MAP, M. paratuberculosis, Mycobacterium avium silvaticum - wood pigeon isolate)
    • Cattle, pigs, dogs, cats, deer, mink, cattle, birds (serotypes 1, 2, and 3) and immunocompromised man say injesting unpasterised cows milk
    • MAP causes Johne's disease in cattle
    • Some strains of MAP can survive standard pasterisation or chlorination in municipal water supplies.
    • There is an association (contraversal) with Crohn's disease as it is not found in all cases[1]
    • Has been proposed to be restricted to bird associated isolates
  • Mycobacterium avium hominissuis
    • Pig associated isolates
  • Mycobacterium intracellulare
    • Tends to cause pulmonary disease



This is part of the non-chromogen Mycobacteria (Groups III & IV) which are nonpigmented in the light and dark or have only a pale yellow, buff or tan pigment that does not intensify after light exposure. Includes M. tuberculosis, M. avium-intra-cellulare, M. bovis, M. ulcerans, M. fortuitum, M. chelonae