mycobacterium

a genus of gram-positive, aerobic, acid-fast bacteria, occurring as slightly curved or straight rods. It contains many species, including the highly pathogenic organisms that cause tuberculosis (M. tuberculo´sis) and leprosy (M. lep´rae). M. a´vium causes tuberculosis in birds and pigs and pulmonary disease in humans. M. bo´vis is the bovine tubercle bacillus and can cause tuberculosis in humans who drink infected milk (strict testing of cattle makes this uncommon in developed countries); an attenuated strain is used to prepare BCG vaccine. M. chelo´nae is an opportunistic pathogen that causes synovial lesions, gluteal abscesses, and gross lesions in various organs. M. fortu´itum causes lesions of the lung, bone, or soft tissue following trauma. M. haemo´philum causes skin lesions. M. ho´minis is a common inhabitant of the vagina and cervix and causes infections of the male and female reproductive tracts, as well as respiratory disease and pharyngitis. M. intracellula´re occasionally causes chronic pulmonary disease in adults and lymph node infection in children. M. kansa´sii causes a tuberculosis-like disease. M. mari´num (also known as M. bal´nei) is the agent of swimming pool granuloma.

A genus of acid-fast, nonmotile, non–spore-forming bacilli of the family Mycobacteriaceae, which includes the causative agents of tuberculosis and leprosy. The organisms are slender, nonmotile, gram-positive rods and do not produce spores or capsules.

Species include M. africanum, M. avium intracellulare, M. bovis, M. chelonei, M. fortuitum, M. gastri, M. gordonae, M. kansasii, M. marinum, M. scrofulaceum, M. terrae, M. triviale, M. smegmatis, and M. xenopi.

The causative species of tuberculosis in cows and, less commonly, in humans.

A causative species of tuberculosis-like pulmonary disease in humans.

The causative species of leprosy.

An atypical mycobacterium that thrives in water and produces skin infection resembling sporotrichosis. It is the cause of swimming pool granuloma.

Any mycobacterium that does not cause tuberculosis. There are four main classes. Three of these groups grow more slowly than M. tuberculosis and one group grows more rapidly. These organisms may cause various skin, lung, or other conditions or they may be harmless.

An emerging but still uncommon acid-fast bacillus that grows slowly. It differs from M. avium in having distinct mycolic acids and ribosomal RNA.

The causative agent of tuberculosis in humans. See: tuberculosis; illustration

A causative agent of infections of the skin and the underlying soft tissues. It is a common cause of illness in tropical and subtropical Africa and South America, where it is responsible for Buruli ulcer. It is thought to be the third most common disease-causing mycobacterium (after M. tuberculosis and M. leprae) in humans.