Mycobacterium Infections, Nontuberculous

The disease is caused by infection with nontuberculous mycobacteria, which comprise more than 190 species and subspecies. The supplied material indicates that these organisms are commonly acquired from environmental sources rather than from classic tuberculosis transmission. Specific species repeatedly implicated in human disease include Mycobacterium avium complex, M. abscessus, M. kansasii, and M. xenopi.

After inhalation, NTM are phagocytosed by alveolar macrophages in the lungs, and immune cells are then recruited from the circulation. The literature describes NTM as environmentally dispersed organisms that can produce chronic pulmonary disease and extrapulmonary infection. For Mycobacterium abscessus in particular, intrinsic resistance and persistence contribute to difficult-to-cure lung disease.

The supplied reviews indicate higher concern in people with defective lung structure or immunosuppression, although NTM can also infect apparently immunocompetent children and adults. Pulmonary disease is a major focus of the literature, suggesting underlying lung disease is an important risk context. The material also notes increasing global incidence and greater occurrence in the tropics, but does not define individual-level risk factors beyond these contexts.

Management is described at the level of drug therapy and is species- and syndrome-specific, with a major focus on pulmonary disease. The guideline literature emphasizes antibiotic treatment for common pulmonary pathogens such as Mycobacterium avium complex, M. kansasii, M. xenopi, and M. abscessus, but also notes that treatment is difficult because of resistance and persistence. For M. abscessus disease, the literature highlights use of repurposed antibiotics and the need for oral bactericidal drug classes and combination regimens, while noting the lack of a formally approved antibiotic and the frequent use of toxic parenteral agents.