Nontuberculous Mycobacterial Lung Disease: An Emerging Disease in the Elderly

Multiple recent population-based studies document the rising prevalence of lung disease caused by the envi- ronmentally ubiquitous nontuberculous mycobacteria (NTM), particularly among older women. The reasons for this changing epidemiology are unclear, and the specific predisposing conditions and pathophysiologic mechanisms underly- ing the development of NTM lung disease among affected individuals are poorly understood. Progress in our understand- ing of this disease has been hampered by the lack of animal models for NTM lung disease. Various systemic immune de- fects, structural lung diseases, and a constellation of factors among a subset of post-menopausal women with a distinct body morphotype have all been evaluated among affected individuals, yet the majority of NTM lung disease remains in- completely explained. This review summarizes the available literature describing NTM as an emerging pathogen particu- larly among the aging population, including the changing epidemiology, clinical features of NTM lung disease, and pro- posed pathophysiologic mechanisms underlying disease susceptibility and manifestations particularly among the elderly. The rising prevalence of NTM lung disease and significant gaps in our understanding and tools for study highlight this disease as an important subject of further research.