Hematogenous spread of tuberculosis

Introduction Hematogenous disseminated tuberculosis is the result of dissemination of Mycobacterium tuberculosis. More common in children, adults can also occur. There are two types in clinical: 1 acute hematogenous disseminated pulmonary tuberculosis or acute miliary tuberculosis; 2 subacute or chronic hematogenous disseminated tuberculosis. The most common in children are acute miliary tuberculosis; older children often show subacute or chronic hematogenous disseminated tuberculosis. With the aging of the population and the prolongation of the life expectancy of the elderly and the rebound of the tuberculosis epidemic, there is an increasing trend in the dissemination of pulmonary tuberculosis in the elderly.

Cause

Acute hematogenous disseminated tuberculosis or acute miliary tuberculosis is the result of dissemination of tuberculosis from the lesion via blood. A large number of tuberculosis bacteria are caused by the simultaneous entry into the bloodstream at the same time or in a very short time. Subacute or chronic hematogenous disseminated tuberculosis, which is often expressed in older children. Because the tuberculosis enters the blood circulation a small number of times, and the patient has considerable immunity, the incidence is slow and the course of disease is prolonged.

an examination

Related inspection

Mycobacterium tuberculosis test tuberculin test (OT, PPD) blood routine plasma cell membranous effusion protein

1, tuberculosis test is the most specific method for the diagnosis of tuberculosis, the tuberculosis found in the sputum is the main basis for the diagnosis of tuberculosis. The smear anti-acid staining microscopy is quick and simple. It is rare in China for atypical mycobacteria. Therefore, acid-fast bacilli should be used, and the diagnosis of tuberculosis can basically be established. The direct smear positive rate is better than the thin smear, which is commonly used. Fluorescence microscopy is suitable for rapid inspection of a large number of specimens. Innocent or children will not cough, use morning stomach wash to find tuberculosis, admit that you can also go through the fiber bronchoscope, or find tuberculosis from its sputum juice. Positive sputum indicates that the lesion is open and contagious. If the amount of bacteria is more than 100,000 per ml, the direct smear is easy to be positive, and the social infection originates from the small amount of sputum bacteria (less than 10,000 per ml).

The culture method is more precise, in addition to understanding the growth and reproduction ability of tuberculosis, and can be used for drug sensitivity test and bacterial type identification. Tuberculosis grows slowly, using modified Roche medium, which usually takes 4-8 weeks to report. Although it is time-consuming, it is accurate and reliable, and its specificity is high. If the smear is negative or the diagnosis is doubtful, the culture is especially important. The culture strain is further used for drug sensitivity determination, which can provide reference for treatment, especially for re-treatment. The specimens were amplified in vitro by polymerase chain reaction (PCR) method, and the microtuberculosis DNA contained in the tube was amplified and detected by electrophoresis. One tuberculosis contains about 1fg of DNA, and 40 tuberculosis bacteria have positive results. The method does not need to be pre-cultured in vitro, has strong specificity, can be reported in 2 days, is fast, simple, and can identify the type of bacteria. The disadvantage is that false positive or false negative may occur.

2, imaging examination chest X-ray examination can find the location and extent of lesions in the lungs, with or without voids or voids, thick walls and so on. X-rays have different degrees of permeability to various types of tuberculosis lesions. X-ray examination can roughly estimate the pathological nature of tuberculosis lesions, and can detect tuberculosis early, as well as determine the development of the disease and the therapeutic effect, and help determine the treatment plan. It must be pointed out that the lung lesions caused by different causes may present similar X-ray images, so the diagnosis of tuberculosis cannot be easily determined by X-ray examination alone. X-ray film combined with fluoroscopy can improve the accuracy of diagnosis, and can find ribs, mediastinum, diaphragm or cell lesions covered by the heart, and can observe the dynamics of heart, lung and diaphragm. X-ray findings of tuberculosis include: indurated lesions of fibrous calcification, characterized by high density, sharply defined spots, strips or nodules; invasive lesions, characterized by a cloud-like shadow with a denser density and blurred edges; cheese-like lesions It is characterized by high density, varying shades, and voids with a circular boundary light-transmissive area. Tuberculosis lesions are usually in the upper, unilateral or bilateral sides of the lungs, contributing to longer periods of time, and there are mixed lesions of various natures and signs of intrapulmonary dissemination. Exudative or exudative proliferative lesions, caseous pneumonia, cheese-like lesions, and cavities (except for purifying cavities) on X-ray films indicate active lesions; proliferative lesions, tightly packed cheese hard knots And fibrous calcification, etc., are inactive lesions. Tuberculosis can still be found in the sputum of active lesions. Because tuberculosis lesions are mostly mixed, activity should still be considered when full proliferation or fiber calcification is not achieved. CT examination of the lungs is helpful for finding small or insidious lesions, understanding the extent of the lesion and identifying the lesions of the lung.

3, tuberculin (abbreviated as a nodule) test is a reference indicator for the diagnosis of tuberculosis infection. Old knot (OT) is a metabolite of tuberculosis, which is made from tuberculosis bacteria grown in liquid culture and contains mainly tuberculosis proteins. The OT antigen is impure and may cause a non-specific reaction. For census in the crowd, 0.1:50 (51U) of OT dilution of 1:2000 can be used for intradermal injection on the flexion of the left forearm. The diameter of the skin induration is measured after 48-72 hours. If it is less than 5mm, it is negative, 5-9mm. It is weakly positive (indicating tuberculosis or Mycobacterium tuberculosis infection), 10-19mm is a positive reaction, and more than 20mm or localized blisters and necrosis are strongly positive reactions.

The pure protein derivative (PPD) of the nodule is refined from the tuberculosis protein extracted from the old knot filtrate, which is a pure knot and does not produce a non-specific reaction. The commonly used PPD-RT23 in the world has replaced OT. China has made PPD (PPD-C) from human tuberculosis and BCG-PPD from BCG. It has good purity and has been widely used in clinical diagnosis. Intradermal injection of 0.1ml (5IU) induration with an average diameter of 5bm is positive. reaction. The sputum test can cause a systemic reaction in addition to causing a local skin reaction. The clinical diagnosis usually uses 51U. If there is no response, 5IU can be used after one week (the effect of enhancing the production of the nodule). If it is still negative, the tuberculosis infection can be roughly excluded.

The lignin test is still one of the commonly used methods in the comprehensive diagnosis of tuberculosis, which helps to determine whether there is tuberculosis infection. If it is strongly positive, it is often expressed as active tuberculosis. The diagnostic value of the sputum test for infants and young children is greater than that of adults. The younger the age, the lower the infection rate. The strong positive responders under 3 years old should be regarded as newly infected active tuberculosis, and it is necessary to treat them. If the sputum reaction increases from <10 mm to more than 100 mm within 2 years and increases by 6 mm or more, a new infection can be considered. In the case of a negative test of the nodule test, in addition to the absence of tuberculosis infection, the following should be considered. It takes 4-8 weeks after tuberculosis infection to establish a sufficient allergy, and the lignin test can be negative before the allergic reaction occurs. The use of immunosuppressive drugs such as glucocorticoids, or malnutrition, measles, whooping cough, etc., can also temporarily disappear. Severe tuberculosis and various critically ill patients do not respond to the nodules, or only weakly positive, and are related to the temporary suppression of human immunity and allergic reactions. When the condition improves, it can be converted into a positive reaction. Other factors such as lymphocyte immune system defects (such as septicemia, lymphoma, sarcoidosis, AIDS, etc.) are also often negative for the former or elderly.

4, other examinations of tuberculosis patients usually have no changes in blood, severe pathology often secondary anemia, acute miliary tuberculosis decreased the total number of white blood cells or leukemia-like reactions. Increased blood is common in active tuberculosis, but it has no specific diagnostic value. Normal erythrocyte sedimentation cannot exclude active tuberculosis. When the patient is innocent or sputum negative and needs to be differentiated from other diseases, the specific antibody in the serum of the patient is detected by enzyme-linked immunosorbent assay (ELISA), which may provide a reference for the diagnosis of extrapulmonary tuberculosis. Fiberoptic bronchoscopy has important diagnostic value for the discovery of endobronchial tuberculosis, understanding of tumors, secretions, unblocking or pathogens and exfoliated cells, and biopsy. Superficial lymph node biopsy helps differential diagnosis of tuberculosis. With the application of molecular biology and genetic engineering techniques, non-culture methods are used to detect and identify tuberculosis bacteria in clinical specimens, demonstrating their advantages of sensitivity, rapidity and specificity, such as accounting probes and chromosome fingerprinting.

Diagnosis: Tuberculosis test is not only the main basis for the diagnosis of tuberculosis, but also an important indicator for assessing the efficacy and follow-up of the disease. The sputum of patients with pulmonary tuberculosis can be intermittently sterilized, so it should be checked several times in succession. X-ray examination is a necessary means to diagnose tuberculosis, and it is of great value for early diagnosis, determination of lesion location, extent, nature, understanding of its evolution and treatment selection.

Differential diagnosis

(1) Acute hematogenous disseminated pulmonary tuberculosis or acute miliary tuberculosis is the result of dissemination of tuberculosis from the lesion via blood. A large number of tuberculosis bacteria are caused by the simultaneous entry into the bloodstream at the same time or in a very short time. Therefore, acute miliary tuberculosis is just a manifestation of systemic miliary tuberculosis in the lungs. Acute miliary tuberculosis not only invades the lungs, it can cause miliary changes in the body. The most common complication is tuberculous meningitis, which can also cause miliary nodular lesions in the liver, spleen, kidney, and bone.

(2) Subacute or chronic hematogenous disseminated tuberculosis, which is often expressed in older children. Because the tuberculosis enters the blood circulation a small number of times, and the patient has considerable immunity, the incidence is slow and the course of disease is prolonged. Clinical symptoms can be seen: general fever, night sweats, fatigue, poisoning symptoms are milder than acute miliary tuberculosis, respiratory symptoms may be more obvious, but there may be only chest radiograph changes without obvious symptoms. Signs on the upper lungs of the lungs may have mild dullness and wet rales; ESR increases; tuberculosis is positive or negative; X-ray shows: noisy shadows on the lungs of different sizes, density, uneven distribution . The lesions are proliferative; they are invasive; they can also be fused and dissolved. In addition, there are fibrous cord-like shadows and compensatory emphysema. If it can be treated in time, the prognosis is good. If extensive fibrosis, it can affect cardiopulmonary function.

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