Nontuberculous Mycobacteria

What is nontuberculous mycobacteria?

Mycobacteria are a type of germ. Nontuberculous mycobacteria (NTM) generally refer to mycobacteria other than mycobacterium tuberculosis and leprae. NTM are widely distributed in the environment. Organisms can be found in soil and water, including natural and treated water sources. Lung infection from this bacteria happens when a person inhales the organism from their environment.

NTM may cause asymptomatic infection and/or disease in humans. Currently, there are over 150 different species of NTM, and many more will be discovered.

Alternative names

NTM, NTM pulmonary disease, NTM lung disease, NTM infection.

Causes & risk factors

Despite the fact that NTM are ubiquitous in the environment, relatively few individuals develop NTM lung disease, suggesting a possible intrinsic predisposition, such as a deficit in the immunity.

Even though healthy individuals can have NTM infections, there are some factors that increase the likelihood of this disease:

  • Weak immune system (HIV, antitumor TNF alpha agents)
  • Old age (although it can affect any age group)
  • Transplant recipients
  • Those with pre-existing lung damage (from smoking or previous tuberculosis)
  • Those with lung diseases (such as COPD, cystic fibrosis, bronchiectasis or emphysema)

Unlike in tuberculosis, there is no risk of NTM being transmitted from person to person or animal to animal.

Symptoms

NTM infections have the potential of infecting the airways and lung tissue, leading to disease. This causes inflammation in the respiratory system. Once this takes place, these infections are characterized by a few noticeable symptoms:

  • Cough, sometimes with blood and/or phlegm
  • Fatigue
  • Shortness of breath
  • Weight loss
  • Lack of appetite
  • Night sweats

Complications

In patients with a relatively normal immune system, NTM is usually isolated to the lungs. However, patients with severe immunosuppression such as HIV can have disseminated disease. Symptoms of disseminated NTM are generally nonspecific and include fever, night sweats, abdominal pain and diarrhea.

Exams and tests

Unlike tuberculosis, the isolation of NTM in pulmonary samples does not mean there is active lung disease.

The diagnosis of NTM pulmonary disease requires the presence of symptoms, radiologic abnormalities and microbiologic cultures. For this reason, clinical evaluation and tests such as high resolution CT scan and sputum cultures are essential for the diagnosis of NTM.

Treatment

NTM infections can become chronic and require ongoing treatment. However, some patients don’t require treatment for less severe infections, and most individuals naturally clear the NTM organisms from the lung and don’t get infected.

For those who do need treatment for NTM, they require antibiotics for 1-2 years, a rather long period of time because NTM’s fatty cell walls make it resistant to antibiotics.

Outlook (Prognosis)

For those suffering from a severe case of NTM lung disease, their quality of life may be significantly impacted. It’s rare for NTM lung disease to be linked directly to instances of death.

The University of Florida has a dedicated NTM/bronchiectasis clinic, which focuses on the diagnosis and treatment of these diseases.

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