Update on pulmonary disease due to non-tuberculous mycobacteria

• Non-tuberculous mycobacteria (NTM) are an emerging cause of pulmonary infection among apparently immunocompetent persons worldwide.
• NTM pulmonary disease afflicts persons with pre-existing structural pulmonary diseases (e.g. prior tuberculosis, chronic obstructive pulmonary disease, cystic fibrosis), but emerging data suggest that many persons without such diseases are genetically susceptible to pulmonary infection with NTM.
• The diagnosis of NTM pulmonary infection relies on a combination of symptoms (which may be subtle), imaging (primarily high-resolution computed tomography), and microbiological findings (increasingly supplemented by molecular testing).
• The treatment of NTM pulmonary disease is challenging and should be tailored to the particular patient, based on knowledge of the infecting species and appropriate antimicrobial susceptibility testing.

SummaryNon-tuberculous mycobacteria (NTM) are emerging worldwide as significant causes of chronic pulmonary infection, posing a number of challenges for both clinicians and researchers. While a number of studies worldwide have described an increasing prevalence of NTM pulmonary disease over time, population-based data are relatively sparse and subject to ascertainment bias. Furthermore, the disease is geographically heterogeneous. While some species are commonly implicated worldwide (Mycobacterium avium complex, Mycobacterium abscessus), others (e.g., Mycobacterium malmoense, Mycobacterium xenopi) are regionally important. Thoracic computed tomography, microbiological testing with identification to the species level, and local epidemiology must all be taken into account to accurately diagnose NTM pulmonary disease. A diagnosis of NTM pulmonary disease does not necessarily imply that treatment is required; a patient-centered approach is essential. When treatment is required, multidrug therapy based on appropriate susceptibility testing for the species in question should be used. New diagnostic and therapeutic modalities are needed to optimize the management of these complicated infections.