The mechanism of the negative reaction of chic. Scientific electronic library. Serums and immunoglobulins
Chic's reaction can help in differential diagnosis between atypical diphtheria and other diseases with concomitant carriage of diphtheria bacilli (in cases where the Schick test is performed before the administration of anti-diphtheria serum).
Studies over the past two years of the diagnostic value of the Schick test in the titration method according to V.I. Ioffe, with 1/40, 1/10, 1/5 DLM of diphtheria toxin (1, 4 and 8 skin doses), led to the conclusion that Determining the height of immunity helps in differential diagnosis.
Most carriers of toxigenic diphtheria bacilli have intense antitoxic immunity, expressed by negative reactions not only to one, but also to 4 and 8 skin doses of the toxin (K.V. Blumenthal).
In some patients with diphtheria, in whom it was possible to determine the state of immunity by the Schick reaction before the administration of the serum, the latter turned out to be positive after one skin dose.
Thus, if in case of doubtful clinical picture and the detection of toxigenic diphtheria bacilli, the Schick reaction in the usual formulation (1/40 DLM of the toxin) gives a positive result, the assumption of diphtheria is more reasonable.
The agglutination reaction can also help in differential diagnosis, since with diphtheria there is a natural increase in antibodies in the blood by the 2nd - 3rd week from the onset of the disease, while, according to the authors, concomitant carriage does not give a noticeable increase in antibodies within the specified period .
In conclusion, it should be said that refusal to diagnose diphtheria when diphtheria bacilli are detected in all cases should be sufficiently justified by convincing clinical data.
Considering that differential diagnosis in such cases often poses great difficulties, especially for the local doctor, it is recommended to refer these patients to diagnostic departments. In the absence of diagnostic beds, the diagnosis of diphtheria can be removed only after consultation with an experienced doctor.
“Diphtheria in children”, M.E. Sukhareva, K.V. Blumenthal
The detection of BL in a typical clinical picture of follicular tonsillitis, when suppurating follicles, like millet grains, appear from under the mucous membrane of the tonsil, can also easily be regarded as a concomitant carriage, because islands of diphtheria plaques are always located on the surface of the mucosa. Chronic tonsillitis often accompanied by a more or less long-term carriage of diphtheria bacilli and, because of this, it is often necessary to differentiate atypical diphtheria...
It is not difficult for an experienced doctor to diagnose fungal tonsillitis (caused by leptotrix) with concomitant carriage of diphtheria bacilli, since clinical manifestation mycosis of the pharynx essentially has no resemblance to the diphtheria process; but, apparently, the same reasons, most often chronic damage to the nasopharynx, simultaneously contribute to the long-term vegetation of the fungus and the carriage of diphtheria bacilli. Differential diagnosis is more complex...
Lyuda P., 8 years old, was admitted to the hospital named after. I. V. Rusakova on September 9, 1960 with a diagnosis of “diphtheria of the pharynx?” The girl is properly immunized against diphtheria, and very often suffers from sore throat. Got sick on September 5, temperature 37.5°, headache, moderate sore throat. September 6 - 7 the temperature is within 38 - 39°, bad feeling, the sore throat persisted...
Detection of diphtheria bacilli in cultures from the throat or nose with a typical clinical picture of influenza croup or croup with catarrh of the upper respiratory tract cannot be a decisive argument in favor of the diphtheria etiology of croup. In such cases, identification of the isolated microbes is necessary, but it is quite possible to carry BL in the throat or nose, accompanying non-diphtheria croup. Here is an excerpt from the story...
Borya B., 8 years old, was admitted to the diphtheria diagnostic department of the hospital named after. I. V. Rusakova September 27, 1960 with a diagnosis of “diphtheria of the pharynx?” The boy is properly immunized against diphtheria. Repeatedly suffers from sore throats. I fell ill on September 24, temperature 39.5°, chills, sore throat. 25. IX child was examined by a doctor: the temperature remained high, bright hyperemia of the pharynx was noted, yellowish, loose, but quite extensive...
CHIC REACTION(Schick) was proposed in 1913 to determine the degree of susceptibility to diphtheria. Sh.r. is performed by strictly intradermal injection of diphtheria toxin in a volume of 0.2 cm 3, containing 1/40 Dim (see Diphtheria). The toxin is injected into the skin of the left arm; into the skin right hand The same amount of toxin, heated at 100° for 10 minutes, is introduced for control. The results of the injection are noted after 24 and 96 hours, and the following phenomena may be observed: 1. When complete absence reactive phenomena at the site of injection of the “control” (warmed) toxin at the site of injection of the active toxin, redness and infiltration appear, accompanied a feeling of lightness burning and itching. These phenomena develop on the first day, reach a maximum on the fourth day, then disappear, leaving skin pigmentation for some time. By the size of the redness and infiltrate, one can judge the degree of the reaction, which is designated as follows: + (“doubtful” reaction - with an unclearly expressed infiltrate and slight redness), + (with redness in diameter no more than 1.5 cm), + +(if the redness has a diameter of 1.5 to 3 cm) and + + + (if redness is more than 3 cm); this type of reaction is called “positive” Sh. 2. In the absence of any reactive phenomena at the injection site of both heated and active toxin, they speak of “negative” Shch. 3. If reactive phenomena are noted on both hands to the same extent, then such a phenomenon is designated as “false” Sh. r. The degree of a false (with heated toxin) reaction is marked (like a positive one) with one, two, three signs. The reaction to a heated toxin has certain qualitative differences from the reaction to an active toxin: rapid appearance and disappearance (usually within 36-48 hours) and the predominance of exudative phenomena over infiltrative ones. 4. If reactive phenomena are noted on both hands, but their degree is different, then they speak of “combined” Sh. r. - with a predominance of phenomena on the side of the active toxin, and about “perverted” Sh. r. - with a predominance of phenomena on the side of the heated toxin. Generally accepted ideas about the essence of Sh. r. boil down to the following: if there is no antitoxin in the blood of the test subject or it is contained in an amount less than /zo -A-E in 1.0 serum, then the injected intradermal toxin causes reactive phenomena, designated as “positive” III If there is a sufficient amount of antitoxin in the blood of the test subject (according to Schick 1/30, according to Behring 1/xoo and more AE in 1.0 serum), then the latter neutralizes the injected toxin, and a “negative” Sh.r is obtained. These provisions are confirmed by the following observation: if a neutral toxin-antitoxin mixture is injected into a subject sensitive to diphtheria toxin, then, as a rule, no reaction is observed at the injection site of this mixture.In addition, a number of simultaneous direct determinations of the amount of antitoxin in the blood have been made according to the Roemer method in parallel with Sh. The sometimes observed discrepancies between these phenomena cannot shake general rule, because they happen quite rarely: Jensen, for example. noted the presence of negative Sh. r. with an insignificant content of antitoxin “I /i 00 AE in 1.0 serum) in 9% of cases. When assessing the results of Sh. it is necessary to take into account that in early infancy a negative Sh. r is often observed. in the absence of antitoxin in the blood. This is explained by the inherent early childhood skin anergy. As for the so-called false Sh. r. and its variants (combined, perverted Sh. r.), i.e., skin reaction to a heated toxin, it is explained by the body’s sensitivity to thermostable metabolic products of the diphtheria bacillus and substances in the nutrient broth. This sensitivity is allergic in nature. As Siegl showed, it consists of two components - specific and nonspecific in relation to diphtheria. Zoller's observations showed complete identity of the false reaction with the intradermal reaction to toxoid (0.2 toxoid, diluted in a ratio of 1: 100) - this is the so-called Zeller reaction. Depending on the result of reactions to the toxin and toxoid, Zeller divides all people into 4 groups (see table). Zeller imagines the process of immunization against diphtheria as follows: individuals sensitive to diphtheria (group I with Characteristics of the group Reaction | Zeller Schlk reaction f 1 Sensitive to II f dlfterchi III 1 Immune to df-IV / teria + + + 1 Stages +) allergies positive Sh.r.) when encountering a diphtheria bacillus (b-n or carriage) or during artificial immunization, they become sensitized to the microbe and its products. Their skin gives an allergic reaction; but since a sufficient amount of antitoxin has not yet been produced, the skin also reacts to the active toxin (group II with false or combined Sh. r.). Subsequently, the amount of antitoxin in the blood increases so much that the reaction to the active toxin becomes negative, but the allergy still remains ( III group with a perverted Sh. r.); finally the latter disappears, and lasting immunity sets in, characteristic of persons of group IV (with a negative Sh. r.). Sh.r. value how the immune reaction is determined by the prevailing views on the nature of immunity in diphtheria. According to modern concepts, the latter is based on the presence of a sufficient amount of antitoxin in the blood. These ideas, as is known, determine the modern practice of immunization prevention of diphtheria (toxin-antitoxin mixtures, toxoid). From this point of view, Sh. r., conveniently replacing the cumbersome direct determination of antitoxin in the blood using the Remer method, can be considered an ideal way to determine the state of immunity, resp. sensitivity of a person to diphtheria. The question of the minimum amount of antitoxin in the blood required to achieve lasting immunity to diphtheria is controversial; in any case, it is necessary to note the comparative rarity of the disease of diphtheria in persons with a negative Sh. r.; in addition, we can point to direct experimental confirmation of this question: Guetrie, Marshall and Moss infected eight volunteers by smearing the pharynx with a virulent culture of diphtheria, of which four had a positive Sh. negative. As a result, 4 people in the first group underwent a typical disease, of 4 people with negative Sh. 3 had temporary carriage of diphtheria bacilli without any signs of disease. Epidemiological significance of Sh. r. a huge amount of work has been devoted to it. From them it is clear that GL. R. is reliable method determining the degree of the immune layer of the collective in relation to diphtheria. It turned out that if you distribute positive Sh. by age, then a curve (Zin-gher) of age-related sensitivity to diphtheria is obtained, which quite accurately coincides with the age distribution of the incidence of diphtheria. Relatively high immunity of young children infancy(up to six months) can be explained by the passive transfer of immune bodies through mother's milk. As for the decrease in sensitivity to diphtheria with age (starting from one year), accompanied by the accumulation of antitoxin in the blood, some authors (Friedberger and others) consider this phenomenon to be an expression of “physiological serogenesis,” i.e., that the accumulation of antitoxin occurs in physiological order, accompanied by such of. maturation at once human body, and other authors (Zinger, Dedley, Ramon, etc.) believe that people accumulate antitoxin in the blood as a result of an obvious, and more often “silent infection” with diphtheria (see figure). Epidemiological value of Sh. r. also lies in the fact that it is convenient to use for the selection of persons subject to (in the case of positive result) active immunization against diphtheria. It is usually used in children"-~-" $persons with antitoxin in the blood (according to Greer)
°--«> % of persons about positive reaction. Schick (according to Park and Tsknger) bars - incidence of diphtheria Distribution by age: persons with antitoxin in the blood (in%); persons with a positive Schick reaction (in%); incidence of diphtheria (°/ooo each age). at the age of over 5 years, bearing in mind the relative rarity of negative Sh. under 5 years of age. Finally III. R. It is also used as an objective control of the effectiveness of preventive vaccinations against diphtheria. This effectiveness is proven by the transition of a positive (before vaccination) Sh. negative after vaccination (usually 6 weeks after the last vaccination). Technique for the production of Sh. r.: 1. In order to prepare the necessary dilution of the toxin in the required volume, start from Dim toxin. Let's say Dim of toxin = 0.0032. To prepare a toxin containing I / 4l) Dim in 0.2 volume, proceed as follows: take lOODlm, in this case = 0.32, and add physiological solution to 10.0, i.e. 9.68. Take 1.0 of this dilution (i.e. 10 Dim) and add it to 79.0 physiol. solution. Then in 80.0 of the second dilution there is 10.Dim; in 1 cm 3 therefore - V" Dim, and in 0.2 - Vio Dim. For each dilution, it is necessary to take a fresh, dry pipette, washing it at least 10 times. In this case, special precision in measuring and precision of pipettes is required (half of the prepared toxin dilution is poured into a separate flask and placed in a boiling water bath for 10 minutes; thus, a heated toxin is obtained for “control”). In view of the fact that the toxin, diluted physiol. solution, quickly loses its activity, it is more convenient to take etc. for dilution. borate buffer solution (see. Dick's reaction) in which the diluted toxin retains its potency for several months. 2. Injection is carried out strictly intradermally, most conveniently using a tuberculin syringe with a very thin platinum needle (No. 18, 19). The needle should have a short barb. When injecting, the beard should be held outwards. The toxin is administered slowly with a certain tension characteristic of intradermal injection of liquid, and as a result, a well-demarcated bubble (Quaddel) is formed at the injection site, with depressions in place of the hair follicles. 3. The active toxin is injected into the skin of the forearm of the left hand, the heated toxin is injected into the skin of the forearm of the right hand. During mass production III. R. It is recommended that two doctors perform it at the same time - one injects the active, the other heated toxin. 4. Countdown Sh.r. is performed twice: after 24 hours to account for false reactions and after 96 hours, when the true Sh. reaches its climax. Lit.: Zdrodovsky P., Contemporary issues specific prophylaxis of diphtheria, Arch. biol. Sciences, vol. XXXV, ser. A, issue. 2, 1934; Doull J., Factors influencing selective distribution of tn diphtheria, Journ. ol prevent, med., v. IV, 1930; Frost W., Infection, immunity and disease in epidemiology of diphtheria, Ibid., v. II, 1928; Meerseman, Fries et Renard, La diphte-rie chez les suiets a reaction de Schick negative, Compt. rend, de la soc. de biol., v. CXII, 1933; Park W., Toxin-antitoxin immunization against diphtheria, Journ. Amer. med. Ass., v. LXXIX, p. 1584, 1922; Rosl ing E., Die Schickreaktion und Ihre Bedeutung, Seuchen-bekamp-fung, B. VII, 1930; Schick V., Die Diphtherietoxin-Hautreaktion des Menschen als Vorprobe des prophylak-tisohen Diphlherieheilseruminielition, M "inch. med. Wo-chenschr., 1913, No. 47; S iegl J., Zur Frage der Entste-hung der Pseudoreaktion bei der Diphtherietoxinreaktion nach Schick, Arch. f. Kinderheilk., B. XCVІII, 1932; Z i n g he r A., The Schick test, Journ. of Amer. med. Ass., v. LXXVІII, 1922; Zoeller C, L "intradermo- reaction al"anatoxine diphterique ou anatoxf-reaction, Compt. rend. de la Soc. de biol., v. XCI, 1924. See also lit. to Art. Scarlet fever. G. Orlov.
Allergens and toxins
Diagnostic drugs
Human antipertussis immunoglobulin antitoxic (Russia)
Purified concentrated liquid anti-diphtheria serum for horses (Russia)
Serums and immunoglobulins
Dry tuberculosis vaccine BCG-M (for gentle primary immunization, Russia)
Tuberculosis vaccine (BCG) dry for intradermal administration (Russia)
Akt-Hib (Hib-vac, South Korea)
Pertussis monovaccine (Russia)
Contains pertussis bacteria, preservative – merthiolate. Use only for epidemiological indications in areas of pertussis infection.
Contains 10 mcg of polysaccharide per dose Haemophilus influenzae type b, conjugated with tetanus toxoid, preservative – trometamol. Used for vaccination of children from 2 months according to epidemiological indications.
Mycobacterium bovis BCG-1. The vaccine strain was obtained by long-term (for 13 years) cultivation of bovine mycobacterium tuberculosis under unfavorable conditions on a potato-glycerin medium with the addition of bile. Used for specific prevention of tuberculosis. Vaccination is carried out on days 5-7 of life, when the body is free from mycobacterial infection. All healthy children, adolescents and adults under 30 years of age who react negatively to tuberculin are subject to revaccination. The mechanism of immunity in tuberculosis has not been fully disclosed. IN clinical practice the main criterion for the intensity of vaccine immunity is the transition of negative skin reaction positive for tuberculin.
Contains live bacteria of the vaccine strain freeze-dried in a 1.2% sodium glutamate solution Mycobacterium bovis BCG-1. Used for gentle specific prevention of tuberculosis (primary vaccination) in newborns in areas with an unfavorable situation for tuberculosis.
Contains antibodies against diphtheria bacilli exotoxin. Antitoxic activity is expressed in international units (10,000 and 20,000 IU/ml). Used to treat patients with diphtheria. In addition to therapeutic purposes, anti-diphtheria serum is used to determine the toxigenicity of diphtheria bacilli cultures in the gel precipitation reaction.
Contains an immunologically active fraction of donor blood plasma with antibodies to the exotoxin of the pertussis microbe (at least 750 units of antitoxic anti-pertussis antibodies). Used to treat whooping cough.
Contains purified diphtheria toxin in 0.2 ml of 1/40 DLM toxin preparation for guinea pig. Used for intradermal tests for the purpose of immunodiagnosis. In persons at the injection site, inflammatory reaction. If the blood contains more than 0.03 IU of antitoxin, the test is negative. Previously, the Schick test was often used to identify individuals susceptible to diphtheria. Currently, due to the possibility of complications, its use is limited to strict epidemic indications.
Toxins (from the Greek toxikon - poison), substances bacterial origin, capable of inhibiting physiological functions, which leads to disease or death in animals and humans. By chemical nature, all toxins are proteins or polypeptides. Unlike other organic and inorganic toxic substances, toxins, when they enter the body, cause the formation of antibodies.
For some infectious diseases (diphtheria, scarlet fever), intradermal tests using appropriate diluted toxins are used to determine the strength of the immune system and susceptibility of children. Positive reaction(local inflammation of the skin in the area where the toxin is administered) is caused by the toxic effect of the toxin on skin tissue. The negative result of the reaction is explained by the neutralization of the toxin introduced into the skin by the corresponding antitoxin contained in the immune body in sufficient quantity for this purpose.
Toxins are obtained from toxigenic strains of microbes (diphtheria bacillus or scarlet fever streptococcus) by inoculation on liquid nutrient medium(open hearth broth) followed by filtration through bacterial filters. From the obtained toxins, the diagnostic toxins Schick (diphtheria) and Dika (scarlet fever) are prepared. Toxins are administered intradermally, in the amount of 0.2 ml (Shika) and 0.1 ml (Dika), in middle part inner surface of the forearm.
Anatoxins are filtrates of broth cultures of toxigenic microorganisms that have lost their toxicity due to special treatment, but have retained to a significant extent the antigenic and immunogenic properties of the original toxins.
When introduced into the human or animal body, toxoids cause the formation of antitoxic immunity, this property allows them to be used for the prevention of those infectious diseases, which are based on the action of exotoxins secreted by pathogens, as well as for hyperimmunization of animals that produce antitoxic serums.
Regardless of the type of toxoid, its immunogenicity and antigenicity are determined by the corresponding properties of the original toxin. Therefore, laboratories producing these drugs pay great attention to creating optimal conditions for toxin formation.
To obtain toxins high strength strains are required that have a particularly pronounced ability to form toxins in artificial conditions. Not all strains of toxigenic bacteria have these properties. For production purposes, strains are used that are adapted to artificial environments and persistently retain the ability to form toxins.
Cultures of toxin-forming agents are stored either in a dried state or on media optimal for a given type of bacteria. Before use for seeding mass batches, strains are passaged on the medium used to obtain the toxin.
All other things being equal, the strength of toxins is determined by the quality of the culture medium, so laboratories pay attention to the preparation of culture media. Raw materials, chemicals and other ingredients included in the environment are subject to the most careful control in the biochemical laboratories of production institutes.
For toxin formation, liquid nutrient media are used, which include meat water and products of peptic (Martin broth, Ramon's medium) or tryptic (Pope's medium) digestion of meat.
The process of meat hydrolysis is controlled by determining the total amine nitrogen and the protein breakdown coefficient, which is calculated from the ratio of amine nitrogen to total. Meat-free casein, semi-synthetic media are also used.
Carbohydrates (glucose, maltose or a mixture of them) are added to the nutrient medium intended for toxin formation. When carbohydrates are fermented, a large amount of energy is released, which is necessary for the synthesis processes occurring in the developing culture. Adding carbohydrates dramatically increases the strength of the toxins produced in the environment.
In addition to carbohydrates, some metals are required in minimal doses for toxin formation. Toxin formation of the diphtheria bacillus is inhibited by an excess of iron in the environment as much as by its absence. In the presence of optimal amounts of iron, toxin formation increases sharply.
Toxin formation occurs fully at a certain pH of the environment. Meanwhile, during the growth of the culture, the pH value changes and can reach values that will inhibit the formation of the toxin.
To eliminate this, buffer substances are added to maintain the desired pH value. One of these substances that has buffer properties is sodium acetate, which is added to the broth in an amount of 0.5-0.75 %.
Depending on the biological characteristics of the toxin-producing microbe, different conditions cultivation and, in particular, the aeration of the environment is regulated. Diphtheria bacillus forms a toxin under conditions of maximum aeration; on the contrary, tetanus bacillus and other toxigenic anaerobes do not require oxygen. According this is the first time In this case, the crop is grown in a thin layer of medium with a large surface contact with air, in the second - the medium is poured in a high layer and various oxygen adsorbents (cotton wool, dry red blood cells) are added.
The cultivation temperature and duration vary for different microbes. Common to the process of toxin formation is the need for perfect temperature control in the thermostat. Temperature fluctuations negatively affect the strength of the toxin. Therefore, thermostats in which toxin formation occurs are equipped with precise thermostats.
In each individual case, the duration of growing a culture is determined by the intensity of toxin formation in a given series of media. To resolve the issue of when to stop cultivation, the strength of the toxin and pH of the medium is determined. different dates growing.
When the strength of the toxin reaches its maximum, it is separated from microbial bodies; this is done by filtration through special bacterial filters (anaerobic microorganisms) or ordinary paper filters (diphtheria bacillus).
The transfer of toxic filtrates to vanatoxin is carried out by prolonged exposure to formaldehyde at a temperature of 39-40 °C. Formalin is combined with free amino groups of amino acids, polypeptides and toxin proteins, and therefore loses its toxic properties. The transition of vanatoxin toxin occurs within 3-4 weeks. For proper toxoid formation, the pH of the toxin is important. The most favorable is a neutral or slightly alkaline reaction of the environment.
Anatoxins are characterized by complete harmlessness to animals. However, if they are not completely neutralized, they may retain toxin residues, which cause late damage to the sensitive body. Therefore, when checking the harmlessness of toxoids, animals are monitored over a long period of time. The harmlessness of toxoids is irreversible. No impact leads to the restoration of lost toxicity.
Toxoids retain almost completely the antigenic properties of toxins. This can be checked various methods in vitro (flocculation reaction, toxoid binding reaction) and in experiments on animals in which the administration of toxoid causes the formation of corresponding antitoxins and the creation of antitoxic immunity.
Toxoids are persistent; they tolerate repeated freezing and thawing, resist the action high temperature and are stable during long-term storage.
In addition to specific proteins, toxoids also contain ballast substances from which they can be freed different methods. They are based on the ability of toxoids to precipitate when saturated with neutral salts, salts of heavy metals, acids (hydrochloric, trichloroacetic, metaphosphoric), as well as in the presence of ethyl and methyl alcohol at low temperatures. These methods are currently used to obtain purified, concentrated toxoids.
Toxoids are adsorbed on various insoluble substances (phosphorus salts, aluminum hydroxide), this is used to prepare sorbed toxoids, which are characterized by slow absorption in the body, as a result of which a more intense immune system can be obtained.
Due to their harmlessness, high antigenicity and immunogenicity, toxoids are with the most valuable means prevention and therapy of a number of diseases.
Currently, toxoids have been obtained: diphtheria, tetanus, botulinum, staphylococcal, dysentery, from toxins produced by pathogens of gas gangrene, as well as from snake venom.
The Schick reaction indicates the presence or absence of the required level of antitoxin in the blood to protect the body from diphtheria. Currently, this reaction is used less frequently due to the introduction of more sensitive methods (RPGA) into practice.
The Schick reaction is carried out on children vaccinated against diphtheria who have completed vaccination and at least one revaccination. At the age of 13 years and older, the reaction can be diagnosed even with an unknown vaccination history. The state of anti-diphtheria immunity is checked no earlier than 6 months after the last revaccination and no earlier than two months after an acute illness.
The Schick reaction is also given to newly arrived children in groups disadvantaged by diphtheria, when there is no information about vaccinations. Children with a negative Schick reaction do not receive additional vaccinations. Additional vaccinations, regardless of the immune layer in the team, are given to children with positive and questionable reactions.
The results of Schick's reaction are entered into the accounting card preventive vaccinations(f. 63) indicating the date the reaction was performed and tested, the batch of toxin and the institute that produced the toxin.
To perform the Schick reaction, diluted active (unheated) diphtheria toxin is used. 0.2 ml contains one Chic dose.
To perform the Schick reaction, one-gram (tuberculin) syringes should be used, carefully tested with precise graduations, which do not allow liquid to pass between the walls of the syringe and its piston.
It is strictly prohibited to perform the Schick reaction in the premises where revaccination against tuberculosis was carried out that day, as well as to use syringes, needles and other instruments used for immunization against tuberculosis.
The skin at the injection site is wiped with cotton wool moistened with 70% ethyl alcohol. The toxin (0.2 ml) is injected intradermally into the middle part of the palmar surface, usually the left forearm. The introduction is carried out slowly with a known voltage, characteristic of intradermal injection of liquid. The injection is made with a very slight inclination of the syringe towards the forearm, almost parallel to the surface of the skin. The cut of the needle should completely enter the skin and be visible through the epidermis. At the injection site, a whitish, well-defined vesicle (papule) with a diameter of about 1 cm should form, with an indentation in place of the hair follicles (“lemon peel”). This vesicle (papule) resolves within 10 to 15 minutes. If, when a toxin is injected, a vesicle (papule) does not form or disappears too quickly, this indicates that the injection was made incorrectly, deeply, and the toxin that entered subcutaneously may not cause a reaction. As a result, incorrect results may be obtained.
The reaction is taken into account after 72 or 96 hours. The results are assessed as follows:
a) the Schick reaction is positive if redness and infiltration appear at the site of toxin injection. The degree of reaction is indicated: “+” - if the redness has a diameter of 1 -1.5 cm, (+ + " - if 1.5 - 3 cm, "+ + + " - if more than 3 cm;
b) the Schick reaction is negative when there is no redness or infiltrate at the site of toxin injection;
c) the Schick reaction is questionable if the redness and infiltrate upon administration of the toxin are either unclearly expressed, or if the reaction is pronounced, the diameter of the redness is approximately 0.5 cm (indicated by “±”).
Contraindications to the Schick reaction: spasmophilia, epilepsy, pustular diseases, contact with patients viral hepatitis, bronchial asthma.