The term nontuberculous mycobacteriosis includes all diseases caused by mycobacteria but not by the causative agents of tuberculosis or leprosy. Mycobacteria are a genus of bacteria that are 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. Second, there are other mycobacteria that can cause disease in humans. These are called nontuberculous 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 are found everywhere in the environment. People are therefore in virtually constant contact with this type of bacteria. However, disease usually only occurs in people whose immune systems are weakened. This includes, for example, patients who have any of the following risk factors:
- Cystic fibrosis
- AIDS
- Lung diseases such as COPD
- Lung cancer
- Chemotherapy or immunosuppressive therapy
- Alcohol dependence
- Smoking
In healthy people, non-tuberculous mycobacteriosis is extremely rare.
Non-tuberculous mycobacteriosis: source of infection environment.
Transmission of nontuberculous mycobacteria usually occurs through the environment. Sources of infection include bodies of water such as lakes and rivers, as well as soil and dust, and also drinking water. In addition, infection can occur during unhygienic use of medical equipment such as catheters or ventilators. Human-to-human transmission, on the other hand, has not been demonstrated.
Lungs most commonly affected
Various organs of the body can be affected by nontuberculous mycobacteriosis. Often, the bacteria cause a lung infection that is similar to tuberculosis. Symptoms may include cough with sputum (occasionally bloody), shortness of breath, fever, weight loss, and fatigue. Less frequently, non-tuberculous mycobacterioses occur on the skin. A typical skin disease caused by non-tuberculous mycobacteria is the so-called swimming pool granuloma. It occurs preferentially in aquarium keepers or persons working in the fish industry and manifests as nodular skin lesions on the knees, hands, and elbows.
Forms of nontuberculous mycobacteriosis.
Other forms of nontuberculous mycobacteriosis may include wound infections, abscesses, and osteomyelitis of the sternum after open heart surgery. In children under five years of age, unilateral, painless swelling of the lymph nodes in the neck (cervical lymphadenopathy) with mild fever is often the only symptom of nontuberculous mycobacteriosis. Generalized infection with nontuberculous mycobacteria may occur, especially in AIDS patients. In this case, the pathogens affect numerous organs such as the liver, spleen, intestines, lungs and bone marrow. However, symptoms are often nonspecific: fever, night sweats, weight loss, diarrhea, and abdominal pain may indicate many diseases.
Diagnosis very complex
Because nontuberculous mycobacteria are found virtually everywhere and can also be found on the mucous membranes of healthy individuals, diagnosis is often quite difficult. Depending on the symptoms, samples of sputum, blood, urine, stool, tissue, or lymph nodes are taken and examined for the pathogens. As a rule, however, at least three samples must be examined to rule out contamination – for example, by mycobacteria in tap water. In addition, if a lung infection is suspected, an x-ray or CT scan is required to confirm the diagnosis.
Therapy not always necessary
Treatment of nontuberculous mycobacteriosis usually involves a combination of different antibiotics. However, because the bacteria are resistant to many of the usual antibiotics, aggressive agents must often be used, which bring with them corresponding side effects. In addition, the duration of therapy is up to 24 months. Therefore, after the diagnosis of non-tuberculous mycobacteriosis, thorough consideration is given to whether the benefits of treatment outweigh the risks.Criteria in the decision for or against therapy include the severity of the symptoms, the bacterial count in the sample, and the findings of the X-ray or CT image. The patient’s general condition must also be considered.
Nontuberculous mycobacteriosis: treatment with antibiotics.
If therapy is to be given, a combination of three to four of the following antibiotics is usually used:
- Agents 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 nontuberculous mycobacteriosis is localized – for example, if only one lymph node or a small part of the lung is affected – surgery to remove the relevant area may be a reasonable treatment option. Surgery combined with antibiotic therapy may also be successful for deeper wound or skin infections.
