Nontuberculous mycobacterial infections are caused by a group of bacteria known as nontuberculous mycobacteria (NTM), which are found in the environment, particularly in soil and water. Unlike Mycobacterium tuberculosis, the bacteria responsible for tuberculosis, NTM typically do not spread from person to person. These infections can affect the lungs, skin, and other parts of the body, often occurring in individuals with weakened immune systems or underlying lung conditions. Symptoms may include cough, fatigue, and weight loss, and treatment usually involves a prolonged course of antibiotics tailored to the specific type of NTM involved.