Clinical relevance and diagnosis of nontuberculous mycobacterial pulmonary disease in populations at risk

The lungs are the most common disease site of nontuberculous mycobacteria (NTM). However, the isolation of NTM in a respiratory specimen does not indicate lung disease (LD). Differentiation between NTM colonization and NTM-LD remains challenging. In this brief review, we summarize the clinical impact of NTM-LD on morbidity and mortality in high-risk populations. The diagnosis criteria for NTM-LD-including clinical features, radiological presentations, and microbiological evidence-are also reviewed, according to the latest American Thoracic Society (ATS)/Infectious Disease Society of America (IDSA) guideline and the British Thoracic Society (BTS) guideline. However, the diagnosis of NTM-LD does not necessitate the initiation of anti-NTM treatment. Both environmental, host, and bacterial factors should be considered to identify patients that require NTM-LD treatment.