Many species of mycobacteria exist. The species Mycobacterium tuberculosis is the one that causes tuberculosis. The other mycobacteria species that cause disease are discussed here. These are called nontuberculous mycobacteria. People are usually exposed to these bacteria in the environment when they come in contact with contaminated water or soil. However, most exposures do not cause infection, and many infections do not cause disease.
When nontuberculous mycobacteria (NTM) infections do occur, they usually occur only in the following people:
Frail older people
People with a weakened immune system (such as those with HIV infection)
People with lungs that have been damaged by, for example, smoking for a long time, an old tuberculosis infection, bronchitis, emphysema, or cystic fibrosis
NTM infections are typically acquired from the environment rather than from infected people.
The main symptoms of some NTM infections are cough, fever, and weight loss.
The lungs are most commonly infected, and most lung infections are caused by a group known as Mycobacterium avium complex (MAC), which includes Mycobacterium avium and Mycobacterium intracellulare. Other nontuberculous mycobacteria that are not included in MAC also sometimes cause infections in people.
Mycobacterium avium Complex (MAC) Infections
Other Nontuberculous Mycobacteria Infections
Nontuberculous mycobacteria that are not included in MAC also sometimes infect people.
