Definition:

Mycobacteria species other than the obligate pathogens Mycobacterium tuberculosis complex and Mycobacterium leprae are known as nontuberculous mycobacteria (NTM) or atypical mycobacteria. NTM are normal inhabitants of soil and treated water. Although generally of low pathogenicity to humans, NTM can cause a wide range of clinical diseases, for instance, pulmonary disease is most frequent, followed by lymphadenitis in children, skin disease and other extrapulmonary or disseminated infections in the severely immunocompromised.