Nontuberculous mycobacterial lung disease is a non-contagious, non-tuberculosis infection caused by bacteria commonly found in water and soil. The disease can also affect other areas of the body, such as the skin, bones, and lymph nodes. Nontuberculous mycobacterial lung disease more commonly affects people with compromised immune systems and pre-existing lung disease, such as chronic obstructive pulmonary disease and cystic fibrosis.