non-tuberculous mycobacteria
Non-tuberculous mycobacteria are the many cousins of the TB germ that live freely in the environment rather than spreading person to person. They lurk in soil, tap water, showerheads and household plumbing, and are breathed in or swallowed by everyone — yet only sometimes cause disease, usually in lungs that are already damaged.
Unlike TB, NTM are generally not contagious between people; you catch them from the environment, not from another patient. They tend to take hold where defences are weakened — in lungs scarred by bronchiectasis or COPD, in certain body shapes, or in people with impaired immunity — producing a slow, grumbling chronic chest infection with cough, fatigue and gradual decline.
They share the acid-fast staining of TB, so a positive smear cannot tell them apart from the TB bacterium; species identification needs culture or molecular testing. Treatment differs from TB, often requiring several drugs for many months or longer, and the decision to treat is nuanced because finding NTM in a sample does not always mean it is causing disease.
A woman with long-standing bronchiectasis grows Mycobacterium avium complex on repeated sputum cultures, consistent with NTM lung disease rather than TB.
Environmental mycobacteria taking hold in damaged lungs.
Mycobacterium avium complex (MAC) is among the most common NTM causing lung disease; species and disease relevance must be established before committing to long treatment.