Bronchiectasis is a condition that results from damage to the airways of the lungs. NTM infection causes your airways (called bronchial tubes) to fill with mucus and over time, may lead to dilation (widening) and scarring of the bronchial tubes. Changes like this, which damage muscle or elastic tissue of the bronchial tubes, is called bronchiectasis. This bronchiectasis may result in the formation of pouches in the bronchial tubes that can trap mucus. If you are unable to clear the mucus normally because it is trapped in the pouches, the mucus stays in the pouches and this can cause an infection.

The specific causes of bronchiectasis are not well understood. Some experts suggest that NTM is most often a subset of bronchiectasis, and we know that NTM without bronchiectasis is not the norm.