Mycobacterium marinum M,ATCC BAA-535

Mycobacterium marinum, a ubiquitous pathogen of fish and amphibia, is a near relative of Mycobacterium tuberculosis, the etiologic agent of tuberculosis in humans. It is Gram-positive, rod-shaped, facultative anaerobic bacterium commonly found in various aquatic environments around the world, including swimming pools and drinking water. In 1926, Joseph D. Aronson isolated a Mycobacterium from tubercles observed predominantly in the spleen and liver of diseased fish that had died in the Philadelphia Aquarium and named it M. marinum. It was subsequently shown to also be a human pathogen when it was isolated again much later in a swimming pool-associated outbreak of human granulomatous skin lesions, although in this report the Mycobacterium was mistakenly given a new species name, Mycobacterium balnei, a name that is no longer used. This bacterium causes a tuberculosis-like disease in frogs, fish and other poikilothermic animals, and a peripheral granulomatous disease in humans. M. marinum infection of humans, called fish tank or aquarium tank granuloma, typically occurs when M. marinum is inoculated through the skin by cuts and scratches following direct contact with an infected fish or contaminated aquatic environments. The ensuing granulomatous infection generally limited to the skin and soft tissues extremities is pathologically indistinguishable from M. tuberculosis dermal disease.