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a genus of bacteria, related to actinomycetes; it differs from true bacteria in a number of ways. The young vegetative cells are rodlike (0.5–0.8 × 2.2 microns); they are capable of branching and acquiring V or Y shapes. In old cultures spherical cells predominate. Mycobacteria, which do not form endospores, are nonmotile, gram-positive, and strictly aerobic. They reproduce mainly by dividing and budding. Mycobacteria contain carotenoids, and, as a result, their colonies are often pigmented (yellow, orange, or red). Owing to their cell composition (including lipides and wax), some myco-bacteria, in contrast to other bacteria, are acid-fast.

Mycobacteria are widely distributed in soils and are active in the mineralization of plant remains. Some species of Mycobacterium are nitrogen-fixing microorganisms; others are capable of metabolizing the carbohydrates of petroleum and natural gas and, when cultured, accumulate protein, which is used for fodder and other purposes. Some species of Mycobacterium are pathogenic to humans (for example, mycobacteria are the causative agents of tuberculosis and leprosy).


References in periodicals archive ?
The microbiological and clinical effects of combined therapy according to guidelines on the treatment of pulmonary Mycobacterium avium complex disease in Japan--including a follow-up study.
Species identification of Mycobacterium avium complex isolates by a variety of molecular techniques.
HP secondary to Mycobacterium avium complex (MAC) in immunocompetent patients has been reported after presumed exposure to large inhaled inoculums during hot tub and swimming pool use, and even after exposure to water-damaged buildings.
Approved December 23, 1992 for the prevention of Mycobacterium avium complex in patients with advanced HIV.
His research interests include the epidemiology of Mycobacterium avium, metal oxidation and reduction in biofilms and predatory bacteria ecology.
The overwhelming majority (>90%) of these infections are caused by Mycobacterium avium complex (MAC).
Mycobacterium avium subspecies paratuberculosis is present in gut tissues from a significantly greater percentage of patients with Crohn's disease than from those with ulcerative colitis or diseases not specifically related to inflammatory bowel disease, according to a prospective study.
Editor's note: The story reporting on recent research efforts on a microorganism called Mycobacterium avium paratuberculosis ("Reducing the Risk of Crohn's Disease, " May/ June 2004) continues to generate interest and hope among patients facing Crohn's disease.
Vaccinations, such as those against pneumococcal pneumonia and influenza, as well as prophylaxis against Pneumocystis pneumonia and Mycobacterium avium complex, are intended to prevent specific clinical diseases.

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