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What are nontuberculous mycobacteria?

Mycobacteria are a diverse group of rod-shaped bacteria that include more than 150 different species. Most mycobacteria live in the soil and water in both rural and urban settings throughout the world. Mycobacteria except for Mycobacterium tuberculosis complex (which cause the disease tuberculosis (TB)) and the causative agents of leprosy (Mycobacterium leprae and Mycobacterium lepromatosis) are referred to in the literature variously as nontuberculous mycobacteria (NTM), mycobacteria other than tuberculosis (MOTT), atypical mycobacteria, and/or environmental mycobacteria. The terms are used interchangeably, depending on author preference when writing journal articles. For the purpose of this article, this group will be referred to as NTM.

NTM are found widely in the environment. They can be found in aerosols, rivers and swamps, in treated city water, public swimming pools, hot spas, humidifiers, aquariums, garden soils, food, and many other places. Because they are protected by their waxy lipid-rich cell wall, mycobacteria are resistant to disinfectants and water treatment measures.

Almost half of the NTM species identified are associated with opportunistic infections in animals and humans, and several have caused sporadic outbreaks. NTM are acquired through environmental exposure to water, aerosols, soil, and dust – through inhalation, ingestion, and through breaks in the skin due to injuries, tattoos, surgical procedures, IV catheters and the like. Unlike M. tuberculosis, they are generally not passed from person-to-person. NTM can cause infections of almost any organ, but most commonly the lungs, lymph nodes, bones and skin and soft tissues. In heavily immunocompromised persons NTM infections may be spread widely through the body infecting many sites.

Under the right circumstances anyone may develop an infection with a NTM, but people with suppressed immune systems (such as those with HIV/AIDS and transplant recipients), people with pre-existing lung damage (for example from smoking or previous tuberculosis) and those with chronic lung diseases (such as emphysema or cystic fibrosis) are most likely to be affected. NTM infections can be challenging and time-consuming to treat since the organisms are often resistant to commonly prescribed antibiotics.

Last Review Date: June 7, 2017