Conducting a Mantoux test

The Mantoux test, also known as the tuberculin test, the Pirquet test, tuberculin diagnostics, and the purified protein derivative (PPD) test, is an intradermal test for the injected drug tuberculin. The result makes it possible to determine the presence of Koch’s bacillus (the causative agent of tuberculosis) in the human body, as well as specific reactivity in infected and / or vaccinated individuals. Regular and annual determination of these indicators is carried out in order to select a contingent for BCG revaccination, as well as to identify risk groups for the incidence of tuberculosis and for prevention.

Historical information about tuberculin diagnostics

The drug tuberculin was invented by the German doctor Robert Koch at the end of the 18th century. The tuberculin diagnostic technique was created by the pediatrician Clemens Pirquet at the beginning of the 19th century, when the doctor applied the drug to the damaged skin and monitored the reaction of the patient’s body.

A little later, the technique was improved and skin scarification began to be carried out using a special lancet. In the mid-90s, the French physician Charles Mantoux suggested injecting tuberculin intradermally. In the Russian Federation, doctors began to conduct a diagnostic test in 1965 and the study is popular today.

Tuberculin (alttuberculin or AT) is recommended for detecting Koch’s bacillus in the human body. Now in many medical institutions for the Mantoux test, the dosage form of tuberculin is used, which includes a phosphate buffer solution, sodium chloride, various stabilizers and hydroxybenzene.

Reaction to the Mantoux test

The reaction to the PPD test is caused by the injection of tuberculin under the skin. The Mantoux test is not a vaccination, but a test to determine if there are tuberculosis bacilli in the body. Neither microbes nor their toxins – tuberculin does not contain. General reactions, for example, an increase in temperature to the Mantoux test, are extremely rare. But if there are tuberculosis bacilli in the body, an inflammatory reaction occurs in the form of swelling and redness, and the reaction will be “positive”.

For evaluation, the diameter of the papule (plaques, buttons) is measured and evaluated according to generally accepted standards. The reaction of the body to the drug is somewhat similar to an allergy, but the mechanism of occurrence of an allergic reaction and the Mantoux test are different. Children with various manifestations of allergies often have negative Mantoux tests. Tuberculosis infection is indicated not so much by the size of the Mantoux test as by its growth. A child can suffer from allergies from birth, and a jump in the Mantoux test is observed only when infected with tuberculosis bacilli.

The effectiveness of the study can be affected by infectious diseases, chronic pathological processes, and age-related changes. Often, changes in the body during menstruation, the special sensitivity of the epidermis, affect the effectiveness of the test.

Negative environmental factors that can distort the results of diagnostics: increased background radiation, emissions of chemicals into the atmosphere by enterprises, explosions and fires. You can get an unreliable test result if the test methodology is violated: improper transportation and storage of the drug, use of low-quality tools, incorrect decoding of the Mantoux reaction.

If tuberculin diagnosis showed a “positive” result, but the patient is not infected with Koch’s bacillus, then the infiltrates, as a rule, do not exceed 5–7 mm in diameter, they are pale, flat, without clear contours, disappearing during the first 1,5–2 weeks. The cause of such a reaction may be infection with non-tuberculous mycobacteria – these mycobacteria cause mycobacteriosis diseases, which are treated with anti-tuberculosis drugs. Therefore, especially in the conditions of an epidemic of tuberculosis, it is more expedient to sanitize cases of any increase in sensitivity to tuberculin. Currently, there is no way to distinguish between positive Mantoux reactions depending on the types of mycobacteria (tuberculous or non-tuberculous). However, with a greater degree of probability, in favor of the tuberculous nature of a positive test, the following are evidence: a significant period (more than 3–5 years) that has elapsed since the moment of BCG vaccination; living in a region with an increased prevalence of Mycobacterium tuberculosis (MBT); recent contact with a bacterioexcretor (open and active forms of TB); the presence in the family of relatives who had TB or infected with MBT. To confirm or refute the diagnosis, a number of tests and laboratory tests should be taken: microbiological sputum culture, chest x-ray, exclude the connection with vaccination against tuberculosis.

Indications and contraindications

The incidence of tuberculosis is currently on the rise worldwide. Russia is among the top ten countries most disadvantaged by this disease. With the help of a diagnostic test, tuberculosis is detected even at the stage of infection – the early period of primary infection.

The Mantoux test helps to identify Koch’s bacillus in infected people (if it persists for more than 12 months with hyperergic reactions to the drug), in patients with an increase in infiltrate by 5-6 millimeters (means there is an infection in the body, but no symptoms appear), in children who should be revaccinated against the disease.

Revaccination is carried out for children and adolescents based on the results of diagnostics at the age of 6-7 and 14-15 years.

In areas with a high incidence of tuberculosis, revaccination is carried out at the age of 6-7, 11-12, 16-17 years. Revaccination against tuberculosis is given only to healthy patients with a negative Mantoux test.

The study is contraindicated if the patient has:

• skin diseases;
• acute and prolonged somatic and infectious diseases (diagnosis can be made 30 days after the disappearance of symptoms or a few days after quarantine is lifted);
• allergic reactions;
• rheumatism;
• epileptic condition, bronchial asthma.

After prophylactic vaccinations, individual intolerance to alttuberculin may be noted, so it is advisable to do the test before any vaccination. If the patient is vaccinated, then the Mantoux test should be carried out after 1-1,5 months.

Tuberculin diagnosis is considered harmless and painless. The composition of the medicinal composition does not contain microorganisms and toxins, and a small dosage does not adversely affect the immune system and internal organs. It is not advisable to conduct such a test for children under one year old, since at this time the child’s immunity is only strengthened and the result of the study may be false.

Mantoux test technique

For injection, special disposable syringes are used (they must have thin needles and a beveled cut). It is not allowed to use expired tuberculin or insulin syringes. Ampoules with tuberculin are processed with a cotton swab, previously moistened with alcohol. Next, the ampoule is carefully opened and 0.2 ml of the drug is taken into the syringe, and then 0.1 ml is removed into a sterile cotton swab.

The patient is invited to sit on the couch, the skin is treated with an alcohol solution and wiped with a sterile cotton pad. The place where alttuberculin will be injected is the inner surface of the forearm. The needle is inserted under the upper layer of the epidermis parallel to its surface (the cut should be on top), then the medicine enters there. After the injection, a tubercle 7-8 millimeters in size is formed under the skin. The place where the injection was made cannot be treated with brilliant green, peroxide, iodine and other medicines. It is forbidden to seal the papule with a plaster or cover it with cotton. The injection area should not be wetted with water for several hours after manipulation. The tubercle may itch, but it is advisable not to touch it.

After the Mantoux test, the patient may experience side effects: an allergic reaction, disruption of the gastrointestinal tract, inflammation of the lymph nodes, fever, chills, nausea, vomiting, severe migraine, dizziness, itching. If any side symptoms occur, you should seek qualified medical help, where, based on the patient’s complaints and laboratory tests, the doctor will prescribe an effective symptomatic treatment.

Evaluation of results

After the introduction of alttuberculin, after 3-4 days, a thickening of the skin is formed, which is called a plaque or papule. In appearance, the infiltrate is a red round area of ​​the epidermis that rises above the skin. The doctor measures the parameters of the papule with a ruler for 2-3 days after the administration of the drug. The ruler should be placed transversely to the longitudinal axis of the forearm. You only need to measure the parameters of the tubercle. The reaction to the Mantoux test is: Negative – with the complete absence of compaction, slight redness at the injection site, the size of the infiltrate is up to one millimeter. Doubtful – with an infiltrate (papule) 2-4 mm in size, the presence of redness of any size without a papule. A positive test result with a “button” of 5 mm or more (from 5 to 9 mm – a weakly positive reaction, from 10 to 14 mm – of medium intensity, from 15 to 16 mm – strong).

A hyperergic reaction (very pronounced) in children and adolescents is observed with a tubercle with a diameter of more than 16 mm, in adults 21 mm or more, and also regardless of the size of the infiltrate, but with a vesiculo-necrotic reaction (i.e. with the formation of vesicles, pustules, tissue necrosis and swollen lymph nodes).

In some patients, a false negative reaction occurs, which may be associated with a recent infection, concomitant use of certain medications, improper storage of alttuberculin, violation of the technology of the procedure, previous bacterial and viral diseases, weakened immunity.

With a “positive” test, you should contact a phthisiatrician and undergo additional examinations to establish an accurate diagnosis. It is recommended that all family members be examined in a tuberculosis dispensary. If the patient has indeed confirmed the diagnosis of tuberculosis, then it is mandatory to carry out preventive therapy with special drugs under the supervision of a qualified phthisiatrician.

Sources of