Nontuberculous mycobacteriosis

Introduction to non-tuberculous mycobacterial disease Non-tuberculous mycobacteria (NTM) disease refers to lung and extrapulmonary diseases caused by mycobacterial infections other than human, tuberculosis and leprosy, with non-tuberculosis due to HIV infection and AIDS epidemics Mycobacterial disease has also increased. Histopathological findings are similar to tuberculosis, ie exudative lesions, proliferative lesions and sclerosing lesions. basic knowledge The proportion of illness: 0.001% Susceptible people: no special people Mode of infection: non-infectious Complications: pleurisy

The cause of nontuberculous mycobacterial disease

(1) Causes of the disease

Non-tuberculous mycobacteria are widely found in soils, dust, water, fish and poultry in nature. Transmission routes are mainly from the environment, such as sewage, and infection between people is rare. Mycobacterium is less pathogenic to humans than M. tuberculosis, but if there is a predisposing factor that causes local or systemic immune function to be impaired, it can lead to pathology.

The more common pathogens include M. avum complex, M. kansasii, M. xenopi, M. scrofulaceum, Sur M. szulgai, M. simine, M. fortuifum compeex, M. malmoense, M. asiatic, branch M. shimodii, M. celatum. M. marinum, and occasionally M. terrac complex, M. gordonae and stomach Mycobacterium (M. gastri) and the like.

(two) pathogenesis

Infection pathway

(1) Environmentally infected people: It is the main recognized infection route. NTM is widely used in water, soil and dust, aerosol particles generated by water, soil and dust particles, which may form bacteria particles, which are inhaled by healthy people and enter the human body. The portal is the upper respiratory tract, which is confirmed by the separation of NTM from the pharyngeal lymphoid tissue, and the intracellular, Gordon, scorpion and Kansas mycobacteria have been isolated in pools, oceans and tap water, so NTM again It was once named environmental mycobacteria (EM).

(2) Animal-infected humans: Kansas, Intracellular, Gordon and Lycium dysenteriae were isolated from pasteurized milk, and birds were isolated from eggs produced by hens infected with M. avium. Mycobacteria, from animal meat or body such as cattle, pigs, chickens, horses, rats, apes, etc. can cultivate mycobacteria, and poultry breeders suffer from avian mycobacteria, but some people hold different opinion.

(3) Human infection: In patients with a disease reported to be infected with M. kansii, the positive rate of response to kansosin (PPD-Y) increased, and there were also cases of mutual infection in the same family. Some believe that there is no more definite evidence of infection between people.

In addition, drinking water contaminated with NTM can also invade the tonsils, pharyngeal lymph nodes and cervical lymph nodes, causing non-tuberculous mycobacterial tonsillitis, pharyngeal lymphadenitis and cervical lymphadenitis, and small wounds invading the skin by Mycobacterium phlei, which can also cause skin. Non-tuberculous mycobacterial disease.

2. Pathogenic NTM has two major categories of pathogenicity and non-pathogenicity, of which 2/3 are non-pathogenic, only 1/3 are pathogenic, and pathogenicity of pathogenic NTM has the following characteristics:

(1) The pathogenicity to humans is lower than that of Mycobacterium tuberculosis.

(2) causing non-tuberculous mycobacterial diseases in humans, a small part of which is an independent primary disease, most of which is secondary, and is a secondary or accompanying disease of other diseases.

(3) There is a strong opportunity for pathogenicity, which is a significant feature. Therefore, NTM is also called conditional or opportunistic mycobacterium. There are many opportunities or conditions for NTM to cause disease in the human body, such as old age and chronic bronchus. Inflammation, chronic obstructive pulmonary disease, bronchiectasis, malignant tumors, hemodialysis, organ transplantation, the use of corticosteroids, immunosuppressive agents and other opportunities to reduce immune function can be secondary to non-tuberculous mycobacterial lung disease.

(4) AIDS patients with Pneumocystis carinii pneumonia accounted for the first place, followed by cytomegalovirus pneumonia, the third is non-tuberculous mycobacterial lung disease, in addition to these opportunistic pneumonia, AIDS patients with tuberculosis infection or concurrency Tuberculosis is also significantly higher than that of healthy people. For example, 50% of AIDS patients in Europe and America are infected with NTM, 10% to 15% of which are intracellular complexes of birds, and 90% of newly diagnosed tuberculosis patients in Africa are HIV-positive.

(5) NTM is mostly resistant to general anti-tuberculosis drugs, which makes the course of disease prolonged for many years and becomes a chronically sterilized or refractory case.

In short, NTM is ill to humans, more than 90% of non-tuberculous mycobacterial lung disease, causing extrapulmonary diseases such as cervical lymphadenitis, osteomyelitis, skin ulcers and abscesses, meningitis, endocarditis, corneal ulcers , dacryocystitis, intestine, myocardium, oral mucosa and facial nerves, Japan reported 1224 cases of non-tuberculous mycobacterial disease, non-tuberculous mycobacterial lung disease was 1188 cases accounted for 97%, in addition, bird complex mycobacteria (MAC) can cause avian mycobacterial hematogenous dissemination (DMAC) when the human immune function is defective. For example, the US CDC reports that AIDS patients have disseminated non-tuberculous mycobacterial infection (DNTM) accounted for 5.5%, of which DMAC infection Accounting for 96.1%, the incidence of DMAC in autopsy of AIDS patients is as high as 50%. Patients with impaired immune function should pay attention to the occurrence of this opportunistic sepsis.

Non-tuberculous mycobacterial disease is similar to the pathological changes of tuberculosis. The two lesions have the same nature, except that the non-tuberculous mycobacteria are mild, with epithelial cell nodules more common, few cheese necrosis, collagen fibrosis and glassy Change, this is the main feature distinguishing from tuberculosis lesions, acid-fast bacilli can be found in the lesions, bacterial culture and bacterial identification can be found in the diseased tissue, or the lesion can be confirmed by TBPCR.

Non-tuberculous mycobacterial disease prevention

Prevention of NTM infection can reduce the risk of bacteremia. The American Institute of Health and Health recommends that rifofbutin should be taken for life for those with HIV-infected CD4<100/mm3.

Chinese patent medicine can be used with Prunella vulgaris and Lianqiao Baidu Pills. The soup should be selected according to the degree of progression of the disease and the clinical manifestations of the patient. Optional experience side:

1. Honeysuckle 10g Male 10g Ding 10g Wild chrysanthemum 10g white peony 10g Salvia 10g Red peony 10g Raw licorice 10g, Shuijianbi, 2 times a day.

2. Honeysuckle 10g Forsythia 15g Chenpi 10g White peony 10g Fritillaria 10g Frankincense J0g Myrrh 10g Tender powder 10g, Shuijianbi, 2 times a day.

3. Prunella 30g, mung bean 30g, boiled juice, add appropriate amount of sugar, 1 day, 2 times a day.

4. Fresh dandelion 50g, fresh Prunella 50g, boiled juice, add appropriate amount of sugar to taste, 1 day, 2 times a day.

Non-tuberculous mycobacterial complications Complications pleurisy

May be associated with pleurisy and empyema.

Non-tuberculous mycobacterial symptoms Common symptoms Low fever HIV infection, fatigue, sputum, pulmonary fibrosis, high fever, skin, soft tissue infection, weight loss, chest pain, chills

Non-tuberculous mycobacteria can cause lung and extrapulmonary lesions, clinical manifestations vary, non-tuberculous mycobacterial lung disease clinical manifestations resemble tuberculosis, most patients have a slow onset, cough, cough, blood stasis, low fever, weight loss and Weakness, etc., can also have no obvious symptoms or only a slight cough, cough, but the lungs X-ray examination found lesions, but also have high fever, chills, cough, chest pain, similar to acute lung infection, some people merge with other Pulmonary lesions, such as chronic obstructive pulmonary disease, bronchiectasis, cystic fibrosis, tuberculosis, pneumoconiosis, or combined with systemic diseases such as diabetes, or long-term use of glucocorticoids, so that clinical manifestations are confused It is difficult to distinguish, and the clinical manifestations of non-tuberculous mycobacterial lung disease or disseminated non-tuberculous mycobacterial disease in HIV-infected and AIDS patients are more atypical.

Non-tuberculous mycobacterial extrapulmonary lesions include: lymphadenitis, skin and soft tissue infections, osteoarticular lesions, reproductive system, digestive and neurological disorders, and systemic disseminated lesions.

Non-tuberculous mycobacterial disease examination

Sputum and bronchoalveolar lavage smear and culture are the most common methods of examination, smear acid-fast staining (Ziehl-Neelsen) positive, but the detection rate is low, and can not be identified with M. tuberculosis, need to be cultured and Biochemical tests such as niacin test, catalase test and aromatic sulfatase activity.

However, when the test is time-consuming, the test results cannot be obtained early. In recent years, some rapid culture and bacterial identification methods have been clinically applied (Table 2).

For example, BACTEC liquid radionuclide medium combined with nucleic acid probes can significantly save detection time, providing rapid and accurate diagnosis of common avian Mycobacterium, Kansas mycobacteria, etc., but due to genetic heterogeneity, The sensitivity to detection of certain Mycobacterium tuberculosis is not high, and the incidence of resistance to non-tuberculous mycobacteria to common anti-tuberculosis drugs is high, so drug resistance should be determined.

Chest X-ray plain film often shows single, bilateral lung fiber nodular shadows, when the disease progresses, the lesion expands and merges, and the boundary is blurred, and thin-walled voids appear. The infiltration and scattered lesions around the cavity are less, chronic cavity Thick-walled and honeycomb-like shadows are common in the lower lobe of the lower lungs. Diabetes and other immunosuppressive patients often present with small, nodular lesions in the middle and lower fields, and less pleural effusions (Table 3).

Chest CT examination of high-resolution chest CT scans can more clearly show lung lesions, as well as the accompanying multiple bronchiectasis.

Diagnosis and identification of non-tuberculous mycobacterial diseases

Diagnostic criteria

The diagnosis of nontuberculous mycobacterial lung disease needs to be combined with exposure history, susceptibility, underlying disease, clinical manifestations, chest X-ray findings, pathogen examination, and even histopathological examination.

1. Chest X-ray examination Chest X-ray plain film often shows single, bilateral lung fiber nodular shadow, when the disease progresses, the lesion expands and merges, and the boundary is blurred, and thin-walled voids appear, infiltration and dissemination around the cavity. There are few lesions, and the chronic cavities are thick-walled and honeycomb-like. The lesions in the lower lobe of the two lungs are also common. Diabetes and other immunosuppressive patients often show small and nodular lesions in the middle and lower fields, and less pleural effusion. Resolution Chest CT scans provide a clearer indication of lung lesions, as well as the accompanying multiple bronchiectasis.

2. Bacterological examination of sputum and bronchoalveolar lavage smear and culture is the most common test method, smear acid-fast staining (Ziehl-Neelsen) positive, but the detection rate is low, and can not be distinguished from Mycobacterium tuberculosis It requires culture and biochemical tests such as niacin test, catalase test and aromatic sulfatase activity.

However, when the test is time-consuming, the test results cannot be obtained early. In recent years, some rapid culture and bacterial identification methods have been clinically applied. For example, BACTEC liquid radionuclide medium combined with nucleic acid probe can significantly save detection time, and common bird compound scores. Mycobacteria, Mycobacterium kansii, etc. can provide rapid and accurate diagnosis, but due to the heterogeneity of genes, the sensitivity to detection of certain Mycobacterium tuberculosis is not high, and non-tuberculous mycobacteria are commonly used for anti-tuberculosis drugs. The incidence of drug resistance is high, so drug resistance should be measured.

Because the clinical manifestations of non-tuberculous mycobacterial lung disease are often confused with tuberculosis, affecting the diagnosis and treatment, patients with "pulmonary tuberculosis" should be tested for non-tuberculous mycobacteria at the same time as anti-tuberculosis drugs.

(1) The sputum culture was positive, but the colony morphology and occurrence did not match the human tuberculosis.

(2) For the first time, the newly diagnosed patients were isolated from mycobacteria for resistance to primary and secondary anti-tuberculosis drugs.

(3) The patient was treated with various anti-tuberculosis drugs, and the sputum continued to be positive.

(4) Newly discovered patients with tuberculosis, the lesions are extensively empty and the symptoms are mild. After regular chemotherapy for 3 to 6 months, the bacteria are still sterilized, or there is no invasive lesion, and the patients who have been treated with regular chemotherapy for more than 6 months are still sterilized.

(5) Patients with lung diseases with immunodeficiency, such as diabetes, silicon deposition, long-term use of immunosuppressive agents and HIV/AIDS patients.

(6) Acid-fast bacilli were found in sputum, and the clinical manifestations were not consistent with tuberculosis.

3. Atypical (non-tuberculous) mycobacterial lung disease diagnosis pilot program (Chinese Medical Association Tuberculosis Science Association, 1988)

(1) Chest film: There are abnormal shadows, and the lesions are often parallel with the bacteria, and those who have been infected with tuberculosis have been excluded.

(2) Bacterial examination:

1 The newly discovered case had the same pathogenic mycobacteria twice in 3 times in 1 month.

2 Patients with chronic lung disease were treated with sputum once a month for 6 months, and more than 3 times proved to be the same pathogenic mycobacteria.

3 In the sterilized puncture, biopsy, surgical specimens, biopsy lung lesions found in non-tuberculous mycobacteria, and no other pathogens (Note: diagnosis of intracellular mycobacterial infection, sputum culture of colonies at least There are 1 time at 100 or more).

4. Diagnostic criteria for non-tuberculous mycobacterial diseases (American Society of Chest Diseases, 1997)

(1) Clinical criteria:

1 clinical symptoms, signs: common cough, fatigue, severe cases of fever, weight loss, hemoptysis and shortness of breath, clinical symptoms of patients with underlying diseases deteriorated.

2 exclude other diseases: such as tuberculosis, tumors, histoplasmosis.

(2) X-ray standard:

1 invasive lesions with or without nodular lesions (continuous 2 months, or progression); cavitary lesions; single or multiple nodules.

2HRCT showed multiple small nodules or multifocal bronchiectasis with or without pulmonary nodules.

(3) Bacteriology standards:

There were at least 3 sputum or bronchial lavage specimens in 11 years, of which 3 cultures were positive, while AFB smears were negative, or 2 cultures were positive, and 1 AFB smear was positive.

2 If only one bronchial lavage specimen is obtained, the sputum specimen is not obtained, the culture is positive, and the smear is positive.

3 If the sputum or bronchial lavage fluid specimens indicate that the diagnosis is not confirmed or other diseases are not excluded, the bacterial culture and histopathological examination by bronchial biopsy or lung biopsy will yield positive results.

Risk factors for HIV-negative patients with negative serum include: local immunosuppression, such as alcoholism, bronchiectasis, cyanotic heart disease, cystic fibrosis, pulmonary fibrosis, smoking and chronic obstructive pulmonary disease, systemic severe immunosuppression, such as leukemia , lymphoma, organ transplantation and other immunosuppressive therapy, HIV serum test positive, CD4 <200.

Differential diagnosis

Nontuberculous mycobacterial lung disease is mainly identified with tuberculosis.

If the shadow of the lungs is nodular or spherical, it should be differentiated from benign and malignant tumors of the lung.

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