How is tuberculosis tested? Diagnostic methods for tuberculosis in adults

Tuberculosis is characterized by a variety of manifestations and forms, due to which its diagnosis is complicated. However, early detection of the disease is of particular importance. The complexity of the treatment depends on this, as well as the outcome. If the disease is diagnosed at an early stage of development, there is a greater likelihood of saving the patient's life. Diagnostics consists of several main stages: detection of symptoms, examination of the patient, and special studies.

At the first stage, when the patient has just applied for medical help, the doctor should detect signs of the disease. Clinical manifestations of tuberculosis include prolonged cough, hemoptysis, fever, sweating, increased fatigue and decreased performance. It is important to pay attention to these symptoms, as they indicate possible development ailment. In addition, at this stage, the characteristics of the evolution of the disease should be clarified. The doctor asks the patient about whether he has had contact with people who have been diagnosed with tuberculosis.

Patient examination

During a clinical examination of a patient, the doctor pays special attention to weight loss, checks the lymph nodes, violation of the amplitude of movement of the chest during breathing. Of course, the first methods for detecting tuberculosis are not completely reliable. To make sure that the disease is developing, other tests are necessary. But it is these two stages that determine the need to refer the patient to special examination... According to them, you can already approximately make clinical picture and put forward the assumption of the presence of an ailment.

Special research

If, during the examination of the patient at the first two stages, there are suspicions of tuberculosis, a series of studies will be required to establish an accurate diagnosis. In adults, testing for tuberculosis requires a mandatory x-ray diagnostics... From her pictures, you can determine the presence of lesions in the lungs. If they are present, the patient is sent for an additional examination, which will reveal the form of the disease, the resistance of the infection to antibacterial drugs... Then he is prescribed treatment.

Diagnosis of tuberculosis in children involves a Mantoux test. By her reaction, you can determine the presence of an ailment. Although, this method is not completely reliable. The reaction can be false positive or false negative. If, after the Mantoux test, doctors still suspect the development of an infection in children's body, it is done again. If she also confirms the presence of a pathological process, the child is sent for additional studies to the TB dispensary.

These methods of diagnosing tuberculosis are intermediate. Some conclusions can already be drawn from them, but it is impossible to establish an accurate diagnosis. To finally make sure of the presence of the disease, you will need to conduct another study. It includes laboratory diagnostics tuberculosis: sputum, blood, urine tests.

X-ray examination

The most accurate diagnostic method in adults is the detection of tuberculosis by X-ray examination. If a pathological process develops, seals and darkening will be noticeable in the images. As for the shadows, special attention should be paid to their number, size, shape, contours, intensity, structure, localization. In addition, a change in the pulmonary pattern is important. Shadows can blend in or have distinct outlines.

On radiological images, the following degrees of damage can be determined:

• minimal (small lesions, signs of decay are absent);
• moderately pronounced (small changes occur, which do not exceed one lung in volume);
• pronounced (the volume of lesions is large).

Mantoux test

The detection of tuberculosis, as a rule, in children, occurs using the Mantoux test. Its essence lies in the fact that antigens of the pathogen are injected under the skin. Thus, the Mantoux test triggers a reaction if a tuberculosis infection is present in the body. In this case, the injection site swells, turns red and becomes inflamed.

Tuberculin, which is injected under the skin during the Mantoux test, is obtained from destroyed Koch sticks.

They are the causative agent of tuberculosis. The Mantoux test is usually done in the forearm. The body recognizes tuberculin as an infection. In the case when the immune system is familiar with it, a focus of inflammation appears at the injection site.

Another option is the Pirquet test. Its essence consists in the cutaneous application of tuberculin. This substance is safe in itself, therefore it is not capable of causing harm to humans. But tuberculin is highly allergenic, due to which it is able to cause appropriate reactions.

Before the result of the Mantoux test is assessed, it is forbidden to influence the injection site in every possible way. Thus, it cannot be wetted, scratched, or smeared with brilliant green, iodine and other antiseptic preparations. It is not recommended to apply adhesive plaster and bandages, as some parents practice, so that the child does not touch the injection site. All this can negatively affect the results and lead to the establishment of an inaccurate diagnosis.

Contraindications for Mantoux

Despite the harmlessness of the Mantoux test, in some cases it is not recommended to do it. Contraindications apply to those people who suffer from skin diseases. In this case, the injection can worsen the dermatological disease, lead to its exacerbation. You should not use this diagnostic method in the presence of acute and chronic infectious diseases. In this case, it is allowed to conduct a test a month after recovery. Contraindications are fevers and various allergic reactionsas well as epilepsy.

In order to avoid inaccuracies when carrying out Mantoux, it is recommended not to put it on the same day with vaccinations. Moreover, this applies to any vaccination. In the event that vaccinations were nevertheless given before the introduction of tuberculin, one should not expect results quickly. They will most likely not be received until six weeks later. It is worth saying a few words about the main thing. Some parents mistakenly assume that a trial with subcutaneous administration tuberculin protects the body from tuberculosis by developing immunity. This statement is fundamentally wrong. The test is only a method of research for the presence of this disease. It is by no means a substitute for the BCG vaccine.

Sputum collection

Laboratory diagnostics of tuberculosis includes the analysis of sputum, which is separated by coughing. The quality of the result largely depends on the observance of the rules during collection. There are several of them:

• sputum should be collected in a sterile container issued by a doctor specifically for this purpose;
• it is recommended to rinse well before collecting oral cavity warm water, brush your teeth (food particles should not get into phlegm);
• the collection is performed on an empty stomach, always in the morning, since it is at this time that its accumulation is maximum;
• it is the sputum that should get into the container, not saliva (you can determine the contents by the consistency and color);

When the basic preparations are completed, you can start the process itself. First, two deep breaths are made with holding the breath. After that, you should take a deep breath and exhale the air with force. Further, it is worth breathing and clearing his throat again. Then the container is presented to the mouth and the phlegm is spit out into it. The container must be immediately closed with a lid. If the contents did not separate during coughing, you should knock with your fist on chest... Another option is inhalation over hot water to which a spoonful of baking soda has been added.

Sputum examination

The sputum culture is first examined carefully. If a person has tuberculosis, they may have blood streaks in the mucus that separates when they cough. Then a bacterioscopic examination is carried out - the stained culture is examined under a microscope. By smears, you can determine the presence of infection in the body in adults and children. Sowing may contain elastic or coral fibers, calcareous particles. To identify mycobacterium tuberculosis, sputum is subjected to repeated examination. Sometimes X-ray examination does not show pathological processes occurring in the lungs, and culture indicates their presence.

The essence of the bacteriological method is that the test material is sown on nutrient media. Before this, the sputum is processed to prevent the growth of nonspecific microflora. Sowing is performed on a solid, liquid or semi-liquid nutrient medium. Sometimes mycobacteria, which are determined by this analysis, do not grow under these conditions. The reason for this is the loss of the ability to reproduce, which has happened under the influence of drugs.

Also used biological method sputum tests for tuberculosis - its essence consists in infecting animals with the mucous contents of the patient's lungs. For this they usually use guinea pigs, which express high sensitivity to the mycobacteria of this disease.

Until recently, the bacteriological method was considered the most reliable, but scientists found that mycobacterium tuberculosis, which are contained in sputum cultures, can grow on nutrient media, but in no way affect animals. It's all about the loss of the ability to infect. Thus, in order to obtain a reliable result, it is recommended to investigate the inoculation by several methods.

Bronchoscopy

If it is not possible to collect sputum on your own, bronchoscopy is used. The essence of the method is to use a special device called a bronchoscope, which through the oral or nasal cavity enters the bronchi. Such a study is carried out on an empty stomach. This prevents food particles from entering the airwaysif you have a cough or vomiting.

Before conducting the study, the patient is examined by a doctor. If necessary, sedatives will be prescribed. The procedure is performed under local anesthesia in adults and general anesthesia in children.

Blood test

How to recognize tuberculosis by the patient's blood? When this disease is affected, small changes occur in it. In patients with a common pathological process, as well as severe intoxication, anemia is determined. With exacerbations of the disease eSR indicator (erythrocyte sedimentation rate) increases. At the same time, the number of leukocytes changes, which is also facilitated by the breakdown of lung tissue.

A biochemical blood test shows a high content of protein, uric acid, cholesterol, copper. It is worth noting that all of these indicators do not necessarily indicate tuberculosis. It is possible that another infectious disease develops in the body. Therefore, it is recommended to carry out comprehensive diagnostics.

Urine examination

Usually, urinalysis is not able to detect tuberculosis in adults and children. A more accurate diagnostic method is sputum culture or Mantoux test. But to draw up a complete picture, it is necessary to conduct it. Sometimes, urinalysis reveals serious complications. If the kidneys are affected, a large amount of protein, erythrocytes, leukocytes is determined.

Diaskintest

This diagnostic method is new. It allows you to accurately determine tuberculosis, as well as check the effectiveness of the therapy. The essence of the method consists in assessing the body's response to two types of proteins that are present only in Koch's bacillus. The injection is performed, and then the result is checked. If the redness at the injection site has spread by 5 mm or more, the test is considered positive. This means that the patient being examined is infected.

Recently, the rise in the incidence of tuberculosis has been growing inexorably.

In this regard, it is worth thinking about means of protection against such dangerous disease... Every person from the age of 18 must undergo an annual medical examination with x-ray examination... Only in this way it becomes possible to detect tuberculosis in the early stages of development, as well as timely treatment. If there is a suspicion of the presence of a disease, it is necessary to urgently consult a doctor, pass all the necessary tests (sputum culture, blood, urine). When prescribing treatment, you should not interrupt it, as this threatens with negative consequences. Tuberculosis is a dangerous disease that can lead to death.

Earlier tuberculosis was considered an incurable disease, which fell victim to a large number of people every year. To date, medicine has made tremendous strides in the treatment of tuberculosis, but it still remains a very dangerous disease.

Tuberculosis is an infection that has been known since ancient times and was called "consumption", as the sick were withering away before our eyes. This disease is caused by a type of bacteria called Mycobacterium tuberculosis, which usually affects the lungs. Mycobacterium tuberculosis are highly resistant in the external environment. In a dark place in phlegm, they can remain viable for many months. Under the influence of direct sunlight, mycobacteria die after a few hours. They are sensitive to high temperature, activated solutions of chloramine, bleach.

Sources and routes of infection

The main source of tuberculosis infection is a person with pulmonary tuberculosis, who secretes mycobacterium tuberculosis with sputum when coughing, sneezing, talking. Such patients are called bacteria-excretors, and in the apartment in which they live, it is customary to call the focus of tuberculosis infection. Tuberculosis patients release into the external environment a huge amount of tuberculosis bacilli - up to 7 billion a day. The source of infection can also be cattle, from which a person becomes infected with a bovine type of mycobacteria. Human infection from these animals occurs mainly through food: through milk from cows infected or sick with tuberculosis. Dogs and cats can also get TB and therefore be a source of infection. Pigs fed with food waste can get sick with tuberculosis. Infection through the contact-household way usually occurs when a person comes into contact with contaminated sputum objects (clothes, linen, towels, dishes, toothbrush, handkerchief, etc.). The untidiness of the patient is the main reason for this development of events. Alimentary pathway of infection can also occur with contamination food products sputum from a tuberculosis patient, especially if he prepares food himself or comes into contact with prepared foods. The carriers of the infection can also be ordinary flies, which, flying from place to place, transfer mycobacteria from the patient's secretions to food.

Absolute susceptibility to tuberculosis. The course of the infectious process depends on the state of the body and its resistance, nutrition, living conditions, working conditions, etc.

Tuberculosis symptoms

The first signs of tuberculosis:

Fatigue and general weakness;

Decreased or lack of appetite, weight loss;

Increased sweating, especially in the morning and mainly in the upper body;

Shortness of breath with little physical exertion;

Coughing or coughing up mucus, possibly bloody;

Slightly increased body temperature;

- "feverish" shine in the eyes.

If you or your friends have these signs, you should immediately consult a doctor!

Diagnosis of tuberculosis

Important me

the method of mass screening for tuberculosis is routine fluorographic examinations, which are carried out for adolescents and adults. The population undergoes fluorographic examination at least once a year. According to epidemic indications (regardless of the presence or absence of signs of tuberculosis), preventive fluorographic examinations are carried out 2 times a year.

The method of mass examination is the method of microbiological detection of tuberculosis, that is, the identification of the pathogen under a microscope in a smear of sputum in all "coughing, sweating, losing weight" persons.

The main method of early detection of tuberculosis among children and adolescents is tuberculin diagnosis (Mantoux reaction). It is applied to all vaccinated children from 12 months of age and adolescents up to the age of 18 years, systematically once a year, regardless of the previous result.

Prevention of tuberculosis

Prevention is the main focus in the fight against tuberculosis. goal preventive measures - to prevent infection and disease with tuberculosis.

Preventive work is carried out in three main areas: vaccination against tuberculosis (vaccination and revaccination of BCG); chemoprophylaxis; sanitary prevention.

Vaccination in Russia BCG make all newborn children without fail, with the exception of those extremely rare cases when vaccinations are contraindicated for a child for health reasons. Children aged 7 and 14 are subject to revaccination. The second revaccination is necessary at the age of 14, since by this time in many children, anti-tuberculosis immunity disappears again. Children with complications bCG vaccination are sent for consultation to a phthisiatrician who develops treatment tactics.

Chemoprophylaxis necessary for those people who are more at risk of developing tuberculosis than others. Everyone who lived or worked with a diagnosed TB patient (especially children) should undergo prophylaxis in the form of chemotherapy with anti-TB drugs (namely, chemoprophylaxis, not treatment of tuberculosis). Chemoprophylaxis with anti-tuberculosis drugs can reduce the risk of developing tuberculosis in those in contact with a tuberculosis patient.

Sanitary prevention - a very important area in the fight against tuberculosis infection. Its main task is to stop the spread of the disease and prevent it from getting infected and getting sick. healthy people... One of the key components of sanitary prevention is the implementation of preventive and treatment measures in the focus of tuberculous infection. Hygiene and hardening, healthy image life and physical exercise - this is the elementary help that you can independently provide to your own body. And medical workers will take care of carrying out health-improving work in foci of tuberculosis infection, BCG vaccination, chemorophylaxis, early detection and full treatment of tuberculosis patients.

REMEMBER! Your health and the health of your loved ones are in your hands!

Lisenkova G.A. ,

medical laboratory technician

branch No. 7 GBUZ SO PTD

Diagnosis of tuberculosis is a combination of laboratory and molecular genetic methods that make it possible to recognize Koch's bacillus in the body and make an accurate diagnosis. Radiation diagnostics also comes to the rescue.

Why are diagnostics performed?

This pathology belongs to the category that does not go away on its own. Only complex therapy can destroy mycobacteria and reduce the likelihood of irreversible changes in the lung tissue.

Diagnostics helps not only to clarify the diagnosis, but also to determine the form of the disease, the severity, which will affect the treatment regimen.

Types of diagnosis of tuberculosis

How is tuberculosis defined? For this, various methods are used that allow detecting mycobacteria in the body and differentiating the disease from other pathologies of the respiratory system.

• ... The method is usually used to diagnose pathology in schoolchildren. The drug is a mixture of killed human and bovine mycobacteria. The result is assessed after three days.
• If it is impossible to carry out the above test, it is carried out.

Laboratory methods for the detection of Mycobacterium tuberculosis

Early diagnosis of tuberculosis involves the use of the following methods:

• Collection and processing of sputum. The procedure is carried out in the doctor's office, the mucus is collected from the larynx with a tampon, preferably after a cough. The collected material is immediately placed in a closed container and sent to the laboratory, where the analysis is performed using bacteriological methods.

Before visiting a doctor on the day of sputum collection, you must thoroughly cleanse your mouth of food debris, brush your teeth.

• Sputum microscopy. This is a cytological study that allows you to detect Koch's bacilli in a smear prepared from collected sputum. Microscopy is done according to Ziehl-Nelsen.

If mycobacteria are found in the smear, then the patient is immediately sent to the tuberculosis dispensary.

Molecular genetic diagnostic methods

It is impossible to start treating the disease if a thorough diagnosis has not been carried out using various techniques.

Establishing the form of pathology will allow the doctor to choose effective scheme treatment that will guarantee the patient's recovery.

Diagnosis of tuberculosis in children and adults: methods.

Tuberculosis is one of the most dangerous and unpleasant diseases on Earth.

It is also one of the most common, as it is transmitted from person to person through the air.

And this is not a simple cold that can be cured in a week.

Pulmonary tuberculosis symptoms

If there are obvious symptoms of the disease, which do not go away for more than three weeks, an urgent need to consult a doctor.

The specialist will prescribe tests that confirm or deny the presence of the disease. Most often it is an x-ray.

When the suspicion of the disease is confirmed, sputum culture is done, which helps to choose a method of treatment.

Diagnosis of pulmonary tuberculosis

It is the diagnosis that is the most important step towards recovery.

If tuberculosis is detected in time, it will be possible to quickly get rid of the disease.

In addition, the body will be less damaged by the disease.

There are not very many diagnostic methods, but they are all effective:

• microbiological;
• tuberculinodianology;
• x-ray.

Microbiological diagnostics are carried out in two ways:

1. sputum smear microscopy;
2. bacteriological examination of sputum.

The microbiological method is of great importance. It is effective for detecting tuberculosis in early stage... Thanks to the microbiological method, it is possible to confirm the diagnosis.

Qualitatively and effectively, it is possible to observe changes in the patient's well-being, to make sure that the chosen treatment is correct. Helps to identify how contagious the disease is.

Often, patients whose cough does not stop for more than three weeks are offered to take sputum for analysis.

This is done in order to confirm or deny.

If the fears are confirmed, then they reveal how dangerous the form of the disease is.

Also, this analysis is safer, less complex, and more affordable.

Collecting sputum for diagnosis is necessary following a number of rules. These rules are easy to follow.

It is extremely important to understand that it is the phlegm that needs to be collected, not the saliva.

After all, it will be impossible to reveal something from it. Usually as many as three portions of sputum are collected, and it is collected for two days.

You don't have to do it yourself. You can go to a medical institution, the collection of sputum will be done in the ward designated for this.

If there is no way to go to the hospital, you can collect it at home.

To do this, you need to go out into the air, there should be no people around. Immediately after collection, the sputum is taken to a medical facility.

Before donating sputum, rinse your mouth with water. This is necessary to clear food debris from your mouth.

After the patient has a couple of times to draw air into the lungs and hold his breath, then take a control breath and exhale harder.

So that you can clear your throat well. Spit out any sputum into a container.

Close the container itself well, and then wash your hands with a disinfectant.

X-ray examination is another diagnostic method. Usually a chest x-ray is used.

This helps to identify the presence of tuberculosis, as it often manifests itself in lung damage.

This method cannot be reliable without considering other analyzes. Helps to clarify the properties and quality of the disease affecting the body.

Tuberculin diagnostics, also known as the Mantoux intradermal test, is a way to detect the presence of tuberculosis.

The Mantoux test is necessary in order to detect the presence of infection with Koch's bacillus in a patient. - everyone decides for himself.

If an infection is detected, then a more serious examination is started to confirm the presence of tuberculosis.

The test is used to diagnose tuberculosis in people with HIV or AIDS.

The reaction can be assessed after 2 or 3 days. After that, it will be possible to draw up a further plan of action and treatment.

Treatment of pulmonary tuberculosis

The most important thing in the treatment of this disease is to identify it in time.

This will help heal the patient without serious harm to health.

If the disease is detected in an advanced form, then the treatment will be rather difficult and lengthy.

What to do during tuberculosis treatment:

• directly affect the infection;
• affect the body as a whole;
• affect the processes occurring in the body;
• getting rid of the symptoms of the disease;
• the use of various methods of treatment, including surgical.

In the course of treatment, special drugs are used.

You need to take these drugs regularly, at a certain time and in the required amount.

Reception breaks medicines lead to addiction.

Therefore, even a short break can harm your health.

The drugs are taken under the supervision of a specialist.

There are many. In total, there are more than 11 groups of such drugs. In addition, use and surgical techniques treatment.

Treatment is divided into two stages - the main stage and the aftercare stage.

The main stage is a period of intensive treatment with drugs that affect the reproduction of bacteria in the body.

And these bacteria are outside the cells. Treatment takes place in a special medical institution before the period of abacillation.

The follow-up stage includes a completely different group of drugs that are aimed at slowing down the multiplication of bacteria located in cells.

This period of treatment is allowed to be carried out at home, not in the hospital, but under the supervision of a specialist.

Medicines are categorized as first-line and second-line medicines. First-line drugs are more effective and contain fewer toxins.

They are taken during the main period of treatment. But second-line drugs are used during the aftercare period.

Sometimes in the case when the patient develops intolerance or addiction to other drugs. They are less effective and much more toxic.

The drugs are selected taking into account many factors.

Few of them are the patient's weight, side effects of drugs, individual drug tolerance, patient pathology.

Patients are required to comply with the terms and methods of treatment that were prescribed by the attending physician.

If you do not complete the course of treatment, half of the bacteria will die, and the remaining bacteria will develop resistance to drugs.

The disease will turn into a different form, which will be dangerous for the patient and the people around him.

Related Videos

Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis. Mycobacterium was discovered in 1882 by the German bacteriologist R. Koch, therefore it is often called Koch's bacillus.

Mycobacterium tuberculosis is widespread in the environment. Sick people and cattle are carriers and sources of infection. Infection occurs more often through the respiratory tract and less often through the alimentary route.

After entering the human body, mycobacteria infect macrophages, further forming mycobacterial phagosomes. Mycobacteria counteract the further transformation of the phagosome, disrupting the lysis processes bacterial cell... This defense mechanism allows mycobacteria to survive in host cells. While in the macrophage, mycobacteria multiply. After the death of a macrophage, bacteria enter the extracellular environment. The further existence of bacteria depends on the immune properties of the organism - the activity of macrophages and T-lymphocytes.

Mycobacterium species and human health

Several dozen species belong to the genus of mycobacteria. The main threats to human health are human mycobacteria (Mycobacterium tuberculosis) and bovine mycobacteria (Mycobacterium bovis). In addition to them, mycobacterium Mycobacterium africanum, M. microti, M. canetti, M. caprae, M. pinnipedii have pathogenic properties. These types lead to the development of human tuberculosis with its typical clinical and morphological signs. The listed mycobacteria make up the so-called mycobacterium tuberculosis complex (MTBC). The Mycobacterium avium complex (M.avium, M. avium paratuberculosis, etc.) is also isolated. It includes bacteria that cause disseminated processes of extrapulmonary localization in humans.

Non-tuberculous mycobacterium species that lead to the development of mycobacteriosis include such species as Mycobacterium chelonae, M. kansassi, M. xenopi and others. These mycobacteria cause lung diseases similar to tuberculosis, but they are more effectively treated with anti-tuberculosis drugs.

One type of mycobacterium causes another serious illness - leprosy. The causative agent in this case is Mycobacterium leprae.

Resistance of mycobacteria

Mycobacteria are extremely resistant in the external environment. In dried sputum and dust, they can be up to 1 year, in the soil up to six months. Their high resistance creates significant difficulties in the fight against this infection.

An important feature of mycobacteria is their property for a long time in the human body in a latent state. In certain situations, the latent phase proceeding without clinical manifestations, can go into active form. The latent course of the infection and the blurring of clinical manifestations significantly complicate the early detection of the disease. That is why the diagnosis of latent tuberculosis is extremely important.

Laboratory tests to identify mycobacteria

A large number of laboratory tests have been developed to identify Mycobacterium tuberculosis in various biological fluids and tissues. The main ones are microscopy of biological fluids with Ziehl-Nielsen staining of smears, bacteriological culture, serological research methods, the use of the polymerase chain reaction (PCR) method.

Microscopic method

The microscopic method for detecting mycobacteria is based on their ability to stain red when using special dyes, while other microflora becomes blue. The disadvantage of this method is its low sensitivity, since the detection of mycobacteria requires their sufficient content in the test sample. The increase in the sensitivity of the microscopic method can be increased by using luminescence microscopy.

Serological diagnostic methods are highly sensitive methods for diagnosing tuberculosis. After a person meets the tuberculosis bacillus, as with any other foreign agent (viruses, bacteria, helminthic invasion), the human immune system begins to produce specific proteins - antibodies that block the vital activity of bacteria. This is one of the types of protection of the human body from numerous pathogenic microbes and viruses.

After the introduction of tuberculosis bacteria, the cells immune system begin to develop specific antibodies of various classes - IgM, IgA, IgG, which circulate in the bloodstream. Serological diagnostics of tuberculosis is based on the detection of such specific antibodies.

To the main modern methods serological diagnostics include test systems based on technologies used in immunochemistry - ELISA (enzyme-linked immunosorbent assay), RIA (radioimmunoassay), immunochromatographic methods (Hexagon TB, TB Check-1), immunoblot. Increasing the sensitivity of ELISA methods is gradually leading to the displacement of expensive radioimmune methods in the diagnosis of tuberculosis.

The first antibodies to appear in the blood are IgM antibodies. As a rule, they are detected in the blood serum 2-3 weeks after meeting the infection and can be detected within two years. Most tests based on ELISA technologies are designed to detect IgG antibodies and total antibodies (IgG + IgA + IgM).

The immunoblot method refers to confirmatory methods for diagnosing the presence of an infectious process, since it allows you to simultaneously detect several types of antibodies of different classes of immunoglobulins to various proteins bacteria. The TB-Spot method can be considered a type of immunoblot, where two substances are used as antigens that are quite specific for mycobacteria (lipoarabinomannan and a 38 kDa protein). In the presence of antibodies to mycobacterium tuberculosis in the blood serum, they bind to these proteins, accompanied by a characteristic color.

Mycobacterium tuberculosis contains various substances (antigens) against which the human body produces antibodies. The more specific / unique the bacterial antigen, the more specific antibodies will be formed for this antigen. The problem of increasing the specificity consists in the detection of such antigens and the creation of highly specific ELISA test systems for the diagnosis of tuberculosis. One of these proteins used in a one-step test system is the A60 protein, which is specific for mycobacterium. This protein, after special purification, is fixed on the membrane. After adding the serum of a sick person and the presence of antibodies in it, they bind to the protein. The binding site is colored red-purple.

The use of immunoassay research methods is important trick in the diagnosis of latent tuberculosis. The detection of antibodies using enzyme immunoassay technologies is possible not only in blood serum, but also in urine, pleural fluid, sputum, cerebrospinal fluid.

The bacteriological method (sowing the material on special media) for detecting mycobacterium tuberculosis is a highly specific method, but it has a significant drawback: it takes about 4-8 weeks to identify bacteria when inoculated on classical media. This method of isolating mycobacteria is more sensitive than the microscopic method and allows, after detecting mycobacteria, to conduct a study to determine the sensitivity to anti-tuberculosis drugs. The use of new culture media and specialized bacteriological equipment makes it possible to determine the growth of mycobacteria within 2 weeks.

Polymerase chain reaction (PCR) method

After the DNA of mycobacterium tuberculosis was deciphered and the polymerase chain reaction (PCR) method was introduced into laboratory practice, this method became widely used in the diagnosis of this disease. The method is highly specific and allows researching a small amount of material. According to a number of researchers, the PCR method is superior in sensitivity and specificity to the cultural diagnostic method in extrapulmonary forms of tuberculosis.

Cytological and histological methods diagnostics of tuberculosis can reveal the characteristic morphological signs of the presence of the disease. The detection of Langhansa cells may indicate the presence of tuberculosis. It should be borne in mind that these cells can appear with other infectious diseases - sarcoidosis, syphilis, brucellosis.

Mantoux test

One of the most early methods diagnosis of tuberculosis is the Mantoux reaction (since 1908). The essence of this reaction is the introduction of intradermal tuberculin, which is a purified mixture of killed cultures of human and bovine mycobacteria. The result of the sample is assessed by the size of the infiltrate after three days.

The modern development of immunology and immunochemistry has led to the introduction of new tests in the diagnosis of tuberculosis - "diaskintest" and "quantiferon test".

Carrying out diaskintest consists in the intradermal administration of two proteins present in mycobacteria that are dangerous to humans, followed by an assessment of the reaction at the injection site.

The quantiferon test is performed in a test tube of blood taken from the patient. The test is based on the ability of proteins isolated from mycobacterium tuberculosis to stimulate the production of interferon gamma by sensitized human T-lymphocytes, that is, an infected patient.

The accumulated experience in the treatment of tuberculosis indicates the difficulties of diagnosing this disease. The use of one method is often not enough, therefore there is a need to use various techniques from the arsenal of instrumental and laboratory methods. It should be borne in mind that each of the methods has its own shortcomings, and their combination can lead to a more reliable conclusion.

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