What is a non-tuberculous mycobacteriosis?

The term non-tuberculous mycobacteriosis summarizes all diseases that are caused by mycobacteria, but not by the pathogens of tuberculosis or leprosy. Mycobacteria are a type of bacteria that is widely distributed in the environment. Many of them are harmless to humans, but there are some species that can cause infectious diseases. These include Mycobacterium tuberculosis and Mycobacterium leprae, which cause the diseases tuberculosis and leprosy. On the other hand, there are other mycobacteria that can cause diseases in humans. These are called non-tuberculous or atypical mycobacteria. In technical language they are often abbreviated as "MOTT - Mycobacteria other than tuberculosis".

Weakened immune system as a risk factor

Non-tuberculous mycobacteria occur throughout the environment. People are therefore in constant contact with this bacterial species. As a rule, however, a disease only occurs in persons whose immune system is weakened. These include, for example, patients who have one of the following risk factors:

  • Cystic Fibrosis
  • AIDS
  • Lung diseases such as COPD
  • lung cancer
  • Chemotherapy or immunosuppressive therapy
  • alcohol addiction
  • Smoke

In healthy people, non-tuberculous mycobacteriosis is extremely rare.

Infection Source Environment

The transmission of non-tuberculous mycobacteria usually takes place via the environment. Examples of sources of infection include water bodies such as lakes and rivers as well as soil and dust, but also drinking water. In addition, infection may occur in unhygienic use of medical devices such as catheters or respirators. A transmission from person to person, however, is not proven.

Lungs most often affected

Non-tuberculous mycobacteriosis can affect various organs of the body. Often the bacteria cause a lung infection similar to that of tuberculosis. This may include symptoms such as coughing with sputum (occasionally bloody), shortness of breath, fever, weight loss and fatigue.

Less common are non-tuberculous mycobacterioses on the skin. A typical skin disorder caused by non-tuberculous mycobacteria is the so-called swimming pool granuloma. It occurs preferably in aquarium owners or people who work in the fish industry and manifests itself by nodular skin lesions on the knees, hands and elbows.

Forms of non-tuberculous mycobacteriosis

Other forms of non-tuberculous mycobacteriosis may include wound infections, abscesses, and bone marrow inflammation of the sternum after open heart surgery. In children under the age of five, one-sided, painless lymph node swelling in the cervical region (cervical lymphadenopathy) with mild fever is often the only symptom of non-tuberculous mycobacteriosis.

Especially in AIDS patients may be a generalized infection with non-tuberculous mycobacteria. The pathogen infects numerous organs such as the liver, spleen, intestine, lungs and bone marrow. However, the symptoms are often unspecific: fever, night sweats, weight loss, diarrhea and abdominal pain can indicate many diseases.

Diagnostics very expensive

Since non-tuberculous mycobacteria occur practically everywhere and can also be found on the mucous membranes of healthy persons, the diagnosis is often quite difficult. Depending on the symptoms, samples are taken from sputum, blood, urine, stool, tissue or lymph nodes and examined for the pathogens. As a rule, however, at least three samples must be examined in order to prevent contamination, for example by mycobacteria in tap water. In addition, if lung infection is suspected, an X-ray or CT image is required to confirm the diagnosis.

Therapy not always necessary

The treatment of a non-tuberculous mycobacteriosis usually takes place by a combination of different antibiotics. However, since the bacteria are resistant to many of the usual antibiotics, often aggressive drugs must be used, which bring with them corresponding side effects. In addition, the therapy duration is up to 24 months. Therefore, after the diagnosis of non-tuberculous mycobacteriosis, it is carefully considered whether the benefit of treatment outweighs the risks.

Criteria for the decision for or against a therapy include the severity of the symptoms, the number of germs in the sample and the findings of the X-ray or CT image. The general condition of the patient must also be taken into account.

Treatment with antibiotics

If a therapy is to be carried out, a combination of three to four of the following antibiotics is usually used:

  • Active substances against tuberculosis such as rifamycins, ethambutol, streptomycin or isoniazid
  • Clarithromycin or Azithromycin
  • Ciprofloxacin, moxifloxacin or levofloxacin
  • Protionamide, amikacin or linezolid
  • Tetracycline or imipenem
  • Sulfonamides or trimethoprim and sulfamethoxazole
  • tigecycline

OP sometimes useful

If non-tuberculous mycobacteriosis is localized - for example, if only one lymph node or a small part of the lung is affected - surgery to remove the affected area may be a useful treatment option. Even with deeper wound or skin infections, surgery combined with antibiotic therapy can be successful.

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