What is NTM?

Non-tuberculous mycobacteria (NTM) are common in the environment, for example in soil and water sources.  When they infect people, NTM most often cause lung problems.  However, they can affect other parts of the body such as the skin and lymph nodes (the “glands”).  NTM outside of the lung will usually cause local symptoms, for example a skin wound that does not heal despite antibiotics or a swelling of the affected glands.  

The information on this page is mostly about NTM lung infection.

The symptoms of NTM lung infection

Many patients have no specific symptoms and doctors detect the NTM during investigation or treatment for other conditions.  However, you may experience some or all of the following symptoms:

  1. Cough – persistent cough, which may or may not produce sputum or phlegm.  Rarely, you might cough up blood.

  2. Fever – a low-grade fever may occur and if so, fever and sweating are often more prominent at night.

  3. Lack of Energy – many patients feel tired or even severely fatigued.

  4. Shortness of breath – mainly on exertion.

Other symptoms include wheezing and chest pain.  There may be loss of appetite and weight but loss of appetite is commoner during antibiotic treatment.

 

How do we develop it?

NTM can infect people with normal lungs but it more commonly gets into damaged lungs – usually in people who have bronchiectasis or other conditions such as chronic bronchitis, emphysema, cystic fibrosis and previous tuberculosis (TB).  It may occur in people who suffered lung damage in childhood after infections such as pertussis (whooping cough).  

Gastroesophageal Reflux Disease or GERD is the term for overflow of acid and other material (usually during sleep) from the stomach into the lungs.  This both damages the lungs and lets NTM in.  This is because NTM from our surroundings has been swallowed and is present in the stomach. GERD is relatively common and is not always experienced as frank heartburn.  

NTM lung disease was thought to be uncommon but now we know that increasing numbers of patients are diagnosed each year.  You may have heard of other mycobacterial diseases. The two most well known examples are TB and leprosy.  However, NTM should never be confused with TB or leprosy, which are contagious.  It is important to stress that NTM cannot usually be passed from person to person.

Making the diagnosis

The diagnosis of NTM lung disease involves the following:

  1. Medical History – a careful history of your current symptoms, as well as the other illnesses you have had, including childhood illnesses.

  2. Sputum tests: sputum is examined under a microscope and then put in a culture to grow the bacteria. This can tell your doctor what type of NTM it is, which drugs will work (drug sensitivity) and which ones will not work (drug resistance) on your strain of NTM.  

  3. Chest CT (computed tomography) – A CT scan is a three-dimensional image of the lungs, which is more useful than a chest x-ray to assess the state of your lungs and the extent of NTM infection.    

  4. Lung Function Tests: although CT scans are helpful, they do not always tell the doctor exactly how your lungs work in getting oxygen into the body and carbon dioxide out.  Lung function tests show how well you breathe and can monitor how you improve with treatment or airways clearance.

Medical Treatments

The standard NTM medical treatment is with three or more antibiotics for usually 12 to 24 months. These usually include the antibiotics clarithromycin or azithromycin, rifampicin and ethambutol (See more in ‘Coping with the medicines’).  Combinations of antibiotics work better because they attack the mycobacteria in more than one way. This stops the NTM becoming resistant to any particular antibiotic.  Drug combinations may aim to treat a specific strain of NTM. That is why your sputum samples are sent to a special laboratory for precise identification of the particular NTM or NTMs that are in your lung.

 

Other treatments

Not all NTM infections need antibiotics.  Your doctor will advise you on whether or not you need them.  Many other things help.  These include stopping smoking; airway clearance exercises to reduce the amount of sputum in the lungs; breathing exercises and chest physiotherapy; dietary interventions to improve health and prevent weight loss; treating associated conditions such as GERD; and psychological approaches to help you cope with the disease and its treatment.