Laboratory diagnosis of bacterial dysentery. Test for dysentery

Test for dysentery is a collective concept that includes general clinical and specific methods studies that help establish not only the final diagnosis of shigellosis (more modern name dysentery), but also to assess the degree of disturbances in various organ systems in the body.

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Laboratory diagnosis of dysentery includes:

• general clinical methods (traditional blood and urine tests);
• coprogram;
• biochemical tests;
• bacteriological method;
• serological reactions;
• allergic skin test (rare);
• instrumental studies.

The expediency of this or that diagnostic study is determined by the current medical documentation, namely the protocols for the provision of medical care. Not only the components of the diagnosis of shigellosis are regulated, but also the frequency of their implementation. This detail is important for the so-called decreed group, that is, people working in the food industry and children's groups - a certain number of negative tests is the basis for admission to work.

General clinical methods

Study of the cellular composition of blood

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This routine research method can be quite informative specifically for dysentery, as it reflects the severity of the disease. With a mild course, a general blood test may not reveal any changes or they will be insignificant. On the contrary, in severe forms of the disease, the accents typical of a bacterial infection are expressed very violently.

In severe forms of shigellosis, the following can be detected:

• a significant increase in the absolute number of leukocytes (that is, hyperleukocytosis);
• a significant shift of the formula to the left, that is, an increase in the absolute and relative number of band lymphocytes, up to the appearance of young forms;
• toxic granularity of neutrophils;
• increased erythrocyte sedimentation rate;
• a decrease in the level of color index and hemoglobin concentration, the number of red blood cells (erythrocytes), that is, classic signs of anemia.

Pronounced changes in the general blood test indicate not only the severe course of the disease, but also the possible development of complications, such as intestinal bleeding.

On the other hand, even pronounced changes in the general blood test are nonspecific, that is, they can be observed in many other diseases, and therefore are not the basis for making a final diagnosis.

Urine examination

Only in the case of a very severe course of the disease are changes observed in the general urine analysis, which are a consequence of severe intoxication. Such signs include the appearance of red blood cells, a large number of white blood cells and casts, as well as an increase in protein concentration. In order to exclude possible pathology urinary tract a general urine test should be repeated after the clinical symptoms of dysentery have subsided.

Coprogram

Stool analysis reflects all changes typical of dysenteric intestinal damage. In addition, the nature and extent of the identified changes is directly related to the severity of the clinical course of the disease.

When examining stool, the following changes are observed:

• increased number of leukocytes (normally there can be only a few);
• the appearance of red blood cells (normally absent);
• mucus in varying quantities (not normally detected);
• undigested food particles and epithelium as a result of disruption of food digestion processes, as well as damage to intestinal epithelial tissue.

It is necessary to understand that the obtained results of the coprogram, as well as general clinical tests of urine and blood, cannot be considered as a final diagnosis of shigellosis. To establish the specific type of Shigella that caused the development of clinical symptoms of the disease in a given patient, as well as to assess its sensitivity to certain antibiotics, a full microbiological diagnosis of dysentery is necessary.

Specific diagnostics

If dysentery is suspected, diagnosis involves isolating the pathogen from the patient's biological fluids (primarily from feces, less commonly gastric lavage and vomit) or determining the titer of protective antibodies that are produced in response to the introduction of a microbial agent.

Bacteriological method

It is the most common, informative and accessible in most cases and in the majority of clinics. Stool collection for examination should be carried out in the first days of illness. Feces obtained naturally, as well as those taken with a sigmoidoscopy tube or a cotton swab (a kind of smear), can be used. Collect biological material in a clean container that has not been treated with disinfectant solutions.

The largest amount of the causative agent of dysentery is detected in those areas of stool where mucus and pus are present. Sowing is done on conventional nutrient media - Levin, Ploskireva, Endo. The doctor receives the result, containing not only comprehensive information about the type of Shigella, but also parameters of sensitivity to antimicrobial drugs, 3-5 days after collecting the material.

Serological method

Less informative in comparison with the bacteriological method. This is due to the fact that the clinical picture of uncomplicated and mild dysentery does not last more than 5-7 days, and the serological method for dysentery takes much longer. It is rare for a patient to spend 2-2.5 weeks in a hospital bed awaiting serological results. Serological tests can be useful and informative as a method of retrospective diagnosis or in scientific research.

Most often, an agglutination reaction is performed: the presence of protective antibodies in a certain concentration is detected in the patient’s blood serum using known antigens. It is advisable to evaluate the information content of the agglutination reaction in dynamics.

The reaction of indirect and/or direct agglutination is less specific. Blood serum is taken no earlier than 4-5 days of illness, and again on days 12-14 from the onset of clinical manifestations. Allergy diagnostics

In the middle of the twentieth century, one of the mandatory tests for shigellosis of any severity was a skin allergy test with dysenterin (Tsuverkalov test). In modern medical practice, due to the allergenicity of the population and the non-specificity of this test, most clinics have refused to perform it.

Instrumental diagnostics

The most common method is sigmoidoscopy. To carry it out, you only need a competent trained specialist and a portable device. There is no need to allocate a separate room, its special equipment and other technical details.

The sigmoidoscope tube is inserted into the anus to a certain depth. The condition of the mucous membrane of the lower rectum and sphincter is visually assessed. When dysentery is detected:

• ulcerative defects of various sizes;
• diffuse swelling and hyperemia of the mucous membrane;
• areas of hemorrhage.

Sigmoidoscopy is intended to assess the effectiveness of the prescribed therapy (whether there are positive dynamics or not, that is, healing of ulcers), as well as to exclude others similar in clinical symptoms diseases (nonspecific ulcerative colitis, tumor formation). In the initial period of shigellosis, this study is not indicated, since the patient’s discomfort from the procedure exceeds its diagnostic value.

Fibercolonoscopy (penetration into higher parts of the intestine) is indicated only if it is necessary to exclude other intestinal diseases (neoplastic tumors).

Thus, only a comprehensive diagnosis of dysentery allows one to correctly assess the severity of the patient’s condition and the effectiveness of the prescribed therapy.

Dysentery.

Dysentery is an infectious disease characterized by general intoxication of the body, loose stools and a peculiar lesion of the mucous membrane of the large intestine. It is one of the most common acute intestinal diseases in the world. The disease has been known since ancient times under the name “bloody diarrhea”, but its nature turned out to be different. In 1875 Russian scientist Lesh isolated an amoeba from a patient with bloody diarrhea Entamoeba histolytica, over the next 15 years, the independence of this disease was established, for which the name amoebiasis was retained. The causative agents of dysentery proper are a large group of biologically similar bacteria, united in the genus Shigelta. The pathogen was first discovered in 1888. A. Chantemes and Vidal; in 1891 it was described by A.V. Grigoriev, and in 1898. K. Shiga, using serum obtained from the patient, identified the pathogen in 34 patients with dysentery, finally proving the etiological role of this bacterium. However, in subsequent years, other pathogens of dysentery were discovered: in 1900. - S. Flexner, in 1915 - K. Sonne, in 1917 - K. Stutzer and K. Schmitz, in 1932. - J. Boyd, in 1934 - D. Large, in 1943 - A. Sax.

Currently genus Shigella includes more than 40 serotypes. All of them are short, immobile gram-negative rods that do not form spores and capsules, which (grow well on ordinary nutrient media, do not grow on a medium with citrate as the only carbon source; do not form H2S, do not have urease; the Voges-Proskauer reaction is negative; glucose and some other carbohydrates are fermented to form acid without gas (except for some biotypes Shigella flexneri: S.manchester And ewcastle); As a rule, they do not ferment lactose (with the exception of Shigella Sonne), adonitol, inositol, do not liquefy gelatin, usually form catalase, and do not have lysine decarboxylase and phenylalanine deaminase. The G+C content in DNA is 49-53 mol%. Shigella are facultative anaerobes, the optimum temperature for growth is 37 ° C, they do not grow above 45 ° C, the optimal pH of the environment is 6.7-7.2. Colonies on dense media are round, convex, translucent; in case of association, rough R-shaped colonies are formed. Growth on MPB in the form of uniform turbidity, rough forms form a sediment. Freshly isolated cultures of Shigella Sonne J4HO form colonies of two types: small round convex (phase I), large flat (phase 2). The nature of the colony depends on the presence (phase I) or absence (phase II) of a plasmid with mm 120 MD, which also determines the virulence of Shigella Sonne.

In Shigella, O-antigens of different specificity were found: common to the family Enterobacteriaceae generic, species, group and type-specific, as well as K-antigens; They do not have N-antigens.

The classification takes into account only group and type-specific O-antigens. In accordance with these characteristics, the genus Shigella is divided into 4 subgroups, or 4 species, and includes 44 serotypes. In subgroup A (type Shigella dysenteriae) included Shigella, which does not ferment mannitol. The species includes 12 serotypes (1-12). Each stereotype has its own specific type antigen; antigenic connections between serotypes, as well as with other Shigella species, are weakly expressed. To subgroup B (type Shigella flexneri) include Shigella, which usually ferments mannitol. Shigella of this species are serologically related to each other: they contain type-specific antigens (I-VI), by which they are divided into serotypes (1-6), and group antigens, which are found in different compositions in each serotype and by which the serotypes are divided into subserotypes. In addition, this species includes two antigenic variants - X and Y, which do not have typical antigens; they differ in sets of group antigens. Serotype S.flexneri 6 has no subserotypes, but is divided into 3 biochemical types based on the fermentation characteristics of glucose, mannitol and dulcitol.

To subgroup C (type Shlgella boydll) include Shigella, which usually ferments mannitol. Members of the group are serologically different from each other. Antigenic connections within the species are weakly expressed. The species includes 18 serotypes (1-18), each of which has its own main type antigen.

In subgroup D (type Shlgella sonnel) included Shigella, which usually ferments mannitol and is capable of slowly (after 24 hours of incubation and later) fermenting lactose and sucrose. View S. sonnei includes one serotype, but colonies of phases I and II have their own type-specific antigens. For the intraspecific classification of Shigella Sonne, two methods have been proposed:

1) dividing them into 14 biochemical types and subtypes according to their ability to ferment maltose, rhamnose and xylose;

2) division into phage types according to sensitivity to a set of corresponding phages.

These typing methods have mainly epidemiological significance. In addition, Shigella Sonne and Shigella Flexner are typed for the same purpose based on their ability to synthesize specific colicins (colicinogenotyping) and sensitivity to known colicins (colicinotyping). To determine the type of colicins produced by Shigella, J. Abbott and R. Chenon proposed sets of standard and indicator strains of Shigella, and to determine the sensitivity of Shigella to known types of colicins, a set of standard colicinogenic strains of P. Frederick is used.

Resistance. Shigella has a fairly high resistance to factors external environment. They survive on cotton fabric and paper for up to 30-36 days, in dried feces - up to 4-5 months, in soil - up to 3-4 months, in water - from 0.5 to 3 months, on fruits and vegetables - up to 2 food, in milk and dairy products - up to several weeks; at 60 °C they die in 15-20 minutes.

Sensitive to chloramine solutions, active chlorine and other disinfectants.

Pathogenicity factors. The most important biological property of Shigella, which determines their pathogenicity, is the ability to invade epithelial cells, multiply in them and cause their death. This effect can be detected using a keratoconjunctival test (introduction of one loop of Shigella culture (2-3 billion bacteria) under the lower eyelid of a guinea pig causes the development of serous-purulent keratoconjunctivitis), as well as by infection of cell cultures (cytotoxic effect), or chicken embryos ( their death), or intranasally in white mice (development of pneumonia). The main pathogenicity factors of Shigella can be divided into three groups:

1) factors determining interaction with the epithelium of the mucous membrane;

2) factors that ensure resistance to humoral and cellular defense mechanisms of the macroorganism and the ability of Shigella to reproduce in its cells;

3) the ability to produce toxins and toxic products that determine the development of the pathological process itself.

The first group includes adhesion and colonization factors: their role is played by pili, outer membrane proteins and LPS. Adhesion and colonization are promoted by enzymes that destroy mucus - neuraminidase, hyaluronidase, mucinase. The second group includes invasion factors that promote the penetration of Shigella into enterocytes and their reproduction in them and in macrophages with the simultaneous manifestation of a cytotoxic and (or) enterotoxic effect. These properties are controlled by the genes of the plasmid with m.m. 140 MD (it encodes the synthesis of outer membrane proteins that cause invasion) and the chromosomal genes of Shigella: KSR A (causes keratoconjunctivitis), cyt (responsible for cell destruction), as well as other genes not yet identified. Protection of Shigella from phagocytosis is provided surface K antigen, antigens 3, 4 and lipopolysaccharide. In addition, lipid A of Shigella endotoxin has an immunosuppressive effect - it suppresses the activity of immune memory cells.

The third group of pathogenicity factors includes endotoxin and two types of exotoxins found in Shigella - Shiga and Shiga-like exotoxins (SLT-I and SLT-II), the cytotoxic properties of which are most pronounced in S. dysenteriae 1. Shiga and Shiga-like toxins have also been found in other serotypes S. dysenteriae, they are also formed S.flexneri, S.sonnei, S.boydii, ETEC and some salmonella. The synthesis of these toxins is controlled by the tox genes of converting phages. Type LT enterotoxins are found in Shigella Flexner, Sonne and Boyd. Their LT synthesis is controlled by plasmid genes. Enterotoxin stimulates the activity of adenylate cyclase and is responsible for the development of diarrhea. Shiga toxin, or neurotoxin, does not react with the adenylate cyclase system, but has a direct cytotoxic effect. Shiga and Shiga-like toxins (SLT-I and SLT-II) have m.m. -70 kDa and consist of subunits A and B (the latter of 5 identical small subunits). The receptor for toxins is a glycolipid of the cell membrane.

The virulence of Shigella Sonne also depends on the plasmid with m.m. 120 MD. It controls the synthesis of about 40 outer membrane polypeptides, seven of them are associated with virulence. Shigella Sonne, having this plasmid, form phase I colonies and are virulent. Cultures that have lost the plasmid form phase II colonies and lack virulence. Plasmids with m.m. 120-140 MD were found in Shigella Flexner and Boyd. Shigella lipopolysaccharide is a strong endotoxin.

Features of epidemiology. The source of infection is only humans. No animals in nature suffer from dysentery. Under experimental conditions, dysentery can only be reproduced in monkeys. The method of infection is fecal-oral. Routes of transmission: water (predominant for Shigella Flexner), food, especially milk and dairy products (predominant route of infection for Shigella Sonne), and household contact, especially for the species S. dysenteriae.

A feature of the epidemiology of dysentery is a change in the species composition of pathogens, as well as Sonne biotypes and Flexner serotypes in certain regions. For example, until the end of the 30s of the 20th century, the share S.dysenteriae 1 accounted for up to 30-40% of all cases of dysentery, and then this serotype began to occur less and less often and almost disappeared. However, in the 60-80s S.dysenteriae reappeared on the historical arena and caused a series of epidemics that led to the formation of three hyperendemic foci of it - in Central America, Central Africa and South Asia (India, Pakistan, Bangladesh and other countries). The reasons for the change in the species composition of dysentery pathogens are probably associated with changes in collective immunity and changes in the properties of dysentery bacteria. In particular, the return S.dysenteriae 1 and its widespread distribution, which caused the formation of hyperendemic foci of dysentery, is associated with its acquisition of plasmids that caused multidrug resistance and increased virulence.

Features of pathogenesis and clinic. The incubation period for dysentery is 2-5 days, sometimes less than a day. The formation of an infectious focus in the mucous membrane of the descending part of the large intestine (sigmoid and rectum), where the dysentery pathogen penetrates, is cyclical in nature: adhesion, colonization, introduction of Shigella into the cytoplasm of enterocytes, their intracellular reproduction, destruction and rejection of epithelial cells, release of pathogens into the lumen intestines; after this, the next cycle begins - adhesion, colonization, etc. The intensity of the cycles depends on the concentration of pathogens in the parietal layer of the mucous membrane. As a result of repeated cycles, the inflammatory focus grows, the resulting ulcers, connecting, increase the exposure of the intestinal wall, as a result of which blood, mucopurulent lumps, and polymorphonuclear leukocytes appear in the feces. Cytotoxins (SLT-I and SLT-II) cause cell destruction, enterotoxin - diarrhea, endotoxins - general intoxication. The clinical picture of dysentery is largely determined by the type of exotoxins in to a greater extent produced by the pathogen, the degree of its allergenic effect and immune status body. However, many issues of the pathogenesis of dysentery remain unclear, in particular: the features of the course of dysentery in children in the first two years of life, the reasons for the transition of acute dysentery to chronic, the significance of sensitization, the mechanism of local immunity of the intestinal mucosa, etc. The most typical clinical manifestations of dysentery are diarrhea, frequent urge- in severe cases, up to 50 or more times a day, tenesmus (painful spasms of the rectum) and general intoxication. The nature of the stool is determined by the degree of damage to the large intestine. The most severe dysentery is caused by S.dysenteriae 1, most easily - Sonne dysentery.

Post-infectious immunity. As observations of monkeys have shown, after suffering from dysentery, strong and fairly long-lasting immunity remains. It is caused by antimicrobial antibodies, antitoxins, increased activity of macrophages and T-lymphocytes. Local immunity of the intestinal mucosa, mediated by IgAs, plays a significant role. However, immunity is type-specific; strong cross-immunity does not occur.

Laboratory diagnostics. The main method is bacteriological. The material for research is feces. Pathogen isolation scheme: inoculation on differential diagnostic media Endo and Ploskirev (in parallel on enrichment medium followed by inoculation on Endo and Ploskirev media) to isolate isolated colonies, obtaining a pure culture, studying its biochemical properties and, taking into account the latter, identification using polyvalent and monovalent diagnostic agglutinating sera. The following commercial serums are produced:

1. To Shigella, which does not ferment mannitol: to S.dysenteriae 1 to 2 S.dysenteriae 3-7(polyvalent and monovalent), to S.dysenteriae 8-12(polyvalent and monovalent).

2. To Shigella fermenting mannitol:

to typical antigens S.flexneri I, II, III, IV, V, VI,

to group antigens S.flexneri 3, 4, 6,7,8- polyvalent,

to antigens S.boydii 1-18(polyvalent and monovalent),

to antigens S. sonnei I phase, II phase,

to antigens S.flexneri I-VI+ S.sonnei- polyvalent.

To detect antigens in the blood (including as part of the CEC), urine and feces, the following methods can be used: RPHA, RSK, coagglutination reaction (in urine and feces), IFM, RPGA (in blood serum). These methods are highly effective, specific and suitable for early diagnosis.

For serological diagnostics the following can be used: RPHA with the corresponding erythrocyte diagnostic kits, immunofluorescent method (indirect modification), Coombs method (determining titer incomplete antibodies). An allergy test with dysenterine (a solution of protein fractions of Shigella Flexner and Sonne) is also of diagnostic value. The reaction is taken into account after 24 hours. It is considered positive in the presence of hyperemia and infiltrate with a diameter of 10-20 mm.

Treatment. The focus is on restoring normalcy water-salt metabolism, rational nutrition, detoxification, rational antibiotic therapy (taking into account the sensitivity of the pathogen to antibiotics). Good effect gives early use of polyvalent dysentery bacteriophage, especially tablets with a pectin coating, which protects the phage from the action of HC1 gastric juice; In the small intestine, pectin dissolves, phages are released and exert their effect. WITH for preventive purposes the phage should be given at least once every three days (its survival time in the intestines).

The problem of specific prevention. To create artificial immunity against dysentery, various vaccines were used: from killed bacteria, chemical, alcohol, but all of them turned out to be ineffective and were discontinued. Vaccines against Flexner's dysentery have been created from live (mutant, streptomycin-dependent) Shigella Flexner; ribosomal vaccines, but they also have not found widespread use. Therefore, the problem of specific prevention of dysentery remains unresolved. The main way to combat dysentery is to improve the water supply and sewerage system, ensure strict sanitary and hygienic regimes in food enterprises, especially the dairy industry, in child care institutions, public places and in maintaining personal hygiene.

Microbiology of cholera

According to WHO definition, cholera is a disease characterized by acute severe dehydrating diarrhea with feces in the form of rice water, resulting from infection with Vibrio cholerae. Due to the fact that it is characterized by a pronounced ability for wide epidemic spread, severe course and high mortality, cholera is one of the most dangerous infections.

The historical homeland of cholera is India, more precisely, the delta of the Ganges and Brahmaputra rivers (now Eastern India and Bangladesh), where it has existed since time immemorial (cholera epidemics in this area have been observed since 500 years BC). The long existence of an endemic source of cholera here is explained by many reasons. Vibrio cholerae can not only survive in water for a long time, but also multiply in it when favorable conditions- temperature above +12 °C, presence of organic substances. All these conditions are present in India - tropical climate(average annual temperature from +25 up to +29 °C), abundance of precipitation and swampiness, high density population, especially in the Ganges delta, a large amount of organic substances in the water, continuous year-round water pollution wastewater and excrement, low material standard of living and peculiar religious and cult rituals of the population.

The causative agent of cholera Vibrio cholerae was opened in 1883. during the fifth pandemic by R. Koch, however, vibrio was first discovered in the feces of patients with diarrhea back in 1854. F. Pacini.

V.cholerae belongs to the family Vibrionaceae which includes several genera (Vibrio, Aeromonas, Plesiomonas, Photobacterium). Genus Vibrio since 1985 has more than 25 species, of which highest value for a person have V.cholerae, V.parahaemolyticus, V.alginolyticus, dnificus And V. fluvialis.

Key characteristics of the genus Vibrio : short, not forming spores and capsules, curved or straight gram-negative rods, 0.5 µm in diameter, 1.5-3.0 µm in length, mobile ( V.cholerae- monotrich, some species have two or more polarly located flagella); grow well and quickly on ordinary media, chemoorganotrophs, ferment carbohydrates with the formation of acid without gas (glucose is fermented via the Embden-Meyerhof pathway). Oxidase positive, form indole, reduce nitrates to nitrites (V.cholerae gives a positive nitroso-indole reaction), break down gelatin, often give a positive Voges-Proskauer reaction (i.e., they form acetylmethylcarbinol), do not have urease, do not form H S. have lysine and ornithine decarboxylases, but do not have arginine dihydrolase.

Vibrio cholerae is very unpretentious to nutrient media. It multiplies well and quickly in 1% alkaline (pH 8.6-9.0) peptone water (PV) containing 0.5-1.0% NaCl, outpacing the growth of other bacteria. To suppress the growth of Proteus, it is recommended to add potassium tellurite 4 to 1% (PV) (final dilution 1:100,000). 1% PV is the best enrichment medium for Vibrio cholerae. As it grows, after 6-8 hours on the surface of the PV, it forms a delicate, loose, grayish film, which, when shaken, easily breaks down and falls to the bottom in the form of flakes; the PV becomes moderately cloudy. Various selective media have been proposed for the isolation of Vibrio cholerae: alkaline agar, yolk-salt agar, alkaline albuminate, alkaline blood agar, lactose-sucrose and other media. The best medium is TCBS (thiosulfate citrate-bromothymol sucrose agar) and its modifications. However, most often they use alkaline MPA, on which Vibrio cholerae forms smooth, glassy-transparent disc-shaped colonies with a viscous consistency with a bluish tint.

When sown by injection into a column of gelatin, vibrio after 2 days at 22-23 ° C causes liquefaction from the surface in the form of a bubble, then funnel-shaped and, finally, layer-by-layer.

In milk, vibrio multiplies quickly, causing coagulation after 24-48 hours, and then peptonization of the milk occurs, and after 3-4 days the vibrio dies due to a shift in the pH of milk to the acidic side.

B. Heiberg, based on the ability to ferment mannose, sucrose and arabinose, divided all vibrios (cholera and cholera-like) into a number of groups, the number of which is now 8. Vibrio cholerae belongs to Heiberg’s first group.

Vibrios, similar in morphological, cultural and biochemical characteristics to cholera, were and are called differently: paracholera, cholera-like, NAG-vibrios (non-agglutinating vibrios); vibrios not belonging to group 01. The last name most accurately emphasizes their relationship to Vibrio cholerae. As was established by A. Gardner and K. Venkatraman, cholera and cholera-like vibrios have a common H-antigen, but differ in O-antigens. According to the O-antigen, cholera and cholera-like vibrios are currently divided into 139 O-serogroups, but their number is constantly growing. Vibrio cholerae belongs to group 01. It has a common A-antigen and two type-specific antigens - B and C, which distinguish three serotypes V.cholerae- serotype Ogawa (AB), serotype Inaba (AS) and serotype Gikoshima (ABC). Vibrio cholerae in the dissociation stage has an OR antigen. In this regard, for identification V.cholerae O-serum, OR-serum and type-specific sera Inaba and Ogawa are used.

Pathogenicity factors V.cholerae :

1. Mobility.

2. Chemotaxis. With the help of these properties, the vibrio overcomes the mucous layer and interacts with epithelial cells. In Che" mutants (which have lost the ability to chemotaxis), virulence is sharply reduced. Virulence in Mot" mutants (which have lost mobility) either completely disappears or is reduced by 100-1000 times.

3. Adhesion and colonization factors, with the help of which vibrio adheres to microvilli and colonizes the mucous membrane of the small intestine.

4. Enzymes: mucinase, proteases, neuraminidase, lecithinase, etc.

They promote adhesion and colonization, as they destroy substances that make up the mucus. Neuraminidase, by cleaving sialic acid from epithelial glycoproteins, creates a “landing” site for vibrios. In addition, it increases the number of receptors for choleragen by modifying tri- and disialogangliosides into monosialoganglioside Gm b which serves as a receptor for choleragen.

5. The main factor of pathogenicity V.cholerae is an exotoxin-cholerogen, which determines the pathogenesis of cholera. The cholerogens molecule has a m.m. 84 kDa and consists of two fragments - A and B. Fragment A consists of two peptides - A1 and A2 - and has the specific property of cholera toxin. Fragment B consists of 5 identical subunits and performs two functions: 1) recognizes the receptor (monosialoganglioside) of the enterocyte and binds to it;

2) forms an intramembrane hydrophobic channel for the passage of subunit A. Peptide A 2 Cl is used to connect fragments A and B. The actual toxic function is performed by the peptide A t. It interacts with NAD, causes its hydrolysis, and the resulting ADP-ribose binds to the regulatory subunit of adenylate cyclase. This leads to inhibition of GTP hydrolysis. The resulting GTP + adenylate cyclase complex causes the hydrolysis of ATP with the formation of cAMP. (Another way of accumulating cAMP is the suppression of the enzyme that hydrolyzes cAMP to 5-AMP by cholerogens).

6. In addition to choleragen, Vibrio cholerae synthesizes and secretes a factor that increases capillary permeability.

7. Other exotoxins have also been found in Vibrio cholerae, in particular types LT, ST and SLT.

8. Endotoxin. Lipopolysaccharide V.cholerae has strong endotoxic properties. It is responsible for general intoxication of the body and vomiting. Antibodies formed against endotoxin have a pronounced vibriocidal effect (dissolve vibrios in the presence of complement) and are an important component of post-infectious and post-vaccination immunity.

The ability of vibrios not belonging to group 01 to cause sporadic or group diarrheal diseases in humans is associated with the presence of enterotoxins of the LT or ST type, which stimulate either the adenylate or guanylate cyclase systems, respectively.

Cholerogen synthesis is the most important property V.cholerae. The genes that control the synthesis of the A- and B-fragments of cholerogens are combined into the vctAB or ctxB operon; they are located on the vibrio chromosome. Some strains of Vibrio cholerae have two such non-tandem operons. The function of the operon is controlled by two regulatory genes. The toxR gene provides positive control; mutations of this gene lead to a 1000-fold reduction in toxin production. The htx gene exerts negative control; mutations in this gene increase toxin production by 3-7 times.

The following methods can be used to detect cholerogens:

1. Biological tests on rabbits. When cholera vibrios are injected intraintestinal into suckling rabbits (no more than 2 weeks old), they develop a typical cholerogenic syndrome: diarrhea, dehydration and death of the rabbit. At the autopsy - a sharp injection of the vessels of the stomach and small
intestines, sometimes it accumulates clear liquid. But the changes in the large intestine are especially characteristic - it is enlarged and filled with a completely transparent, straw-colored liquid with flakes and gas bubbles. When cholera vibrios are introduced into the ligated area of ​​the small intestine into adult rabbits, they experience the same changes in the large intestine as when suckling rabbits are infected.

2. Direct detection of cholerogens using immunofluorescent or enzyme-linked immunosorbent methods or a passive immune hemolysis reaction (cholerogen binds to Gm1 of erythrocytes, and they are lysed with the addition of antitoxic antibodies and complement).

3. Stimulation of cellular adenylate cyclase in cell cultures.

4. Using a chromosome fragment as a DNA probe V.cholerae, carrying an operoncholerogen.

During the seventh pandemic, strains were isolated V.cholerae With varying degrees virulence: cholerogenic (virulent), weakly cholerogenic (low virulent) and non-cholerogenic (non-virulent). Non-cholerogenic V.cholerae, as a rule, they have hemolytic activity, are not lysed by cholera diagnostic phage 5 (CDF-5) and do not cause human disease.

For phage typing V.cholerae(including V.eltor) S. Mukherjee proposed corresponding sets of phages, which were then supplemented with other phages in Russia. The set of such phages (1-7) makes it possible to distinguish among V.cholerae 16 phagotypes. HDF-3 selectively lyses cholera vibrios of the classical type, HDF-4 - El-Tor vibrios, and HDF-5 lyses only cholerogenic (virulent) vibrios of both types and does not lyse non-cholerogenic vibrios.

Cholerogenic vibrios, as a rule, do not have hemolytic activity, are lysed by HDF-5 and cause cholera in humans.

Resistance of cholera pathogens. Vibrios cholerae survive well at low temperatures: in ice they remain viable for up to 1 month; V sea ​​water- up to 47 days, in river water - from 3-5 days to several weeks, in boiled water mineral water persist for more than 1 year, in soil - from 8 days to 3 months, in fresh feces - up to 3 days, on cooked foods (rice, noodles, meat, cereals, etc.) survive for 2-5 days, on raw vegetables - 2- 4 days, on fruits - 1-2 days, in milk and dairy products - 5 days; when stored in the cold, the survival period increases by 1-3 days: on linen contaminated with feces, they last up to 2 days, and on damp material - a week. Cholera vibrios die at 80 °C in 5 minutes, at 100 °C - instantly; highly sensitive to acids; under the influence of chloramine and other disinfectants they die within 5-15 minutes. They are sensitive to drying and direct sunlight, but are preserved well and for a long time and even multiply in open reservoirs and wastewater, rich in organic matter, having an alkaline pH and a temperature above 10-12 ° C. Highly sensitive to chlorine: a dose of active chlorine of 0.3-0.4 mg/l of water in 30 minutes causes reliable disinfection from Vibrio cholerae.

Features of epidemiology. The main source of infection is only a person - a person with cholera or a vibrio carrier, as well as water contaminated by them. No animals in nature suffer from cholera. The method of infection is fecal-oral. Routes of infection: a) main - through water used for drinking, bathing and household needs; b) contact and household and c) through food. All major cholera epidemics and pandemics were waterborne in nature. Vibrios cholerae have such adaptive mechanisms that ensure the existence of their populations both in the human body and in certain ecosystems of open water bodies. The profuse diarrhea caused by Vibrio cholerae leads to the cleansing of the intestines from competing bacteria and contributes to the widespread distribution of the pathogen in the environment, primarily in wastewater and in open water bodies where they are discharged. A person suffering from cholera secretes the pathogen in huge quantities - from 100 million to 1 billion per 1 ml of excrement; a vibrio carrier secretes 100-100,000 vibrios per 1 ml, the infecting dose is about 1 million vibrios. The duration of excretion of cholera vibrio in healthy carriers ranges from 7 to 42 days, and 7-10 days in those who have recovered from the disease. More prolonged discharge observed extremely rarely.

The peculiarity of cholera is that after it, as a rule, there is no long-term carriage and persistent endemic foci do not form. However, as already mentioned above, due to the pollution of open water bodies with wastewater containing large quantities of organic substances, detergents And table salt, in the summer, the cholera vibrio not only survives in them for a long time, but even multiplies.

Of great epidemiological significance is the fact that vibrios cholerae group 01, both non-toxigenic and toxigenic, can persist for a long time in various aquatic ecosystems in the form of uncultivated forms. Using the polymerase chain reaction, with negative bacteriological studies, veterinary genes of uncultivated forms were discovered in a number of endemic areas of the CIS in various water bodies V.cholerae.

When cholera diseases occur, a set of anti-epidemic measures is carried out, among which the leading and decisive one is the active timely identification and isolation (hospitalization, treatment) of patients with acute and atypical forms and healthy vibrio carriers; measures are being taken to suppress possible ways of spreading the infection; special attention is paid to water supply (chlorination drinking water), compliance with the sanitary and hygienic regime at food enterprises, in child care institutions, and public places; Strict control, including bacteriological control, is carried out over open water bodies, immunization of the population is carried out, etc.

Features of pathogenesis and clinic. The incubation period for cholera varies from a few hours to 6 days, most often 2-3 days. Once in the lumen of the small intestine, cholera vibrios are directed to the mucus due to motility and chemotaxis to the mucous membrane. To penetrate through it, vibrios produce a number of enzymes: neuraminidase, mucinase, proteases, lecithinase, some destroy substances contained in mucus and facilitate the movement of vibrios to epithelial cells. By adhesion, vibrios attach to the glycocalyx of the epithelium and, losing mobility, begin to multiply intensively, colonizing the microvilli of the small intestine, and at the same time producing large amounts of exotoxin-cholerogen. Cholerogen molecules bind to monosialoganglioside Gm1 and penetrate the cell membrane, activate the adenylate cyclase system, and the accumulating cAMP causes hypersecretion of fluid, cations and anions Na +, HCO 3 ~, K +, SG from enterocytes, which leads to cholera diarrhea, dehydration and desalination body. There are three types of disease:

1. violent, severe dehydrating diarrheal disease, leading to the death of the patient within a few hours;

2. less severe course, or diarrhea without dehydration;

3. asymptomatic course of the disease (vibrio carriage).

In severe forms of cholera, patients develop diarrhea, stools become more frequent, bowel movements become more abundant, become watery, lose their fecal odor and look like rice water (a cloudy liquid with mucus residues and epithelial cells floating in it). Then comes debilitating vomiting, first with intestinal contents, and then the vomit takes on the appearance of rice water. The patient's temperature drops below normal, the skin becomes bluish, wrinkled and cold - cholera algid. As a result of dehydration, blood thickens and cyanosis develops. oxygen starvation, kidney function sharply suffers, convulsions appear, the patient loses consciousness and death occurs. The case fatality rate for cholera during the seventh pandemic ranged from 1.5% in developed countries to 50% in developing countries.

Post-infectious immunity durable, long-lasting, recurrent diseases are rare. Antitoxic and antimicrobial immunity is caused by antibodies (antitoxins last longer than antimicrobial antibodies), immune memory cells and phagocytes.

Laboratory diagnostics. The main and decisive method for diagnosing cholera is bacteriological. The material for research from the patient is feces and vomit; feces are examined for vibrio carriage; from persons who died from cholera, a ligated segment of the small intestine is taken for research and gallbladder; Among environmental objects, water from open reservoirs and wastewater are most often studied.

When conducting a bacteriological study, the following three conditions must be observed:

1) inoculate material from the patient as quickly as possible (vibrio cholera persists in feces for a short period of time);

2) the container in which the material is taken should not be disinfected chemicals and should not contain traces of them, since Vibrio cholera is very sensitive to them;

3) exclude the possibility of contamination and infection of others.

In cases where there are V.cholerae not 01-groups, they must be typed using appropriate agglutinating sera of other serogroups. Discharge from a patient with diarrhea (including cholera-like) V.cholerae not 01-group requires the same anti-epidemic measures as in the case of isolation V.cholerae 01-groups. If necessary, the ability to synthesize choleragen or the presence of choleragen genes in isolated cholera vibrios is determined using a DNA probe using one of the methods.

Serological diagnosis of cholera is auxiliary. For this purpose, an agglutination reaction can be used, but it is better to determine the titer of vibriocidal antibodies or antitoxins (cholerogen antibodies are determined by enzyme-linked immunosorbent or immunofluorescent methods).

Treatment for patients with cholera should consist primarily of rehydration and restoration of normal water-salt metabolism. For this purpose, it is recommended to use saline solutions, for example, of the following composition: NaCl - 3.5; NaHCO 3 - 2.5; KS1 - 1.5 and glucose - 20.0 g per 1 liter of water. Such pathogenetically based treatment in combination with rational antibiotic therapy can reduce the mortality rate in cholera to 1% or less.

Specific prevention. Various vaccines have been proposed to create artificial immunity, including killed Inaba and Ogawa strains; Cholerogen toxoid for subcutaneous use and enteral chemical bivalent vaccine, sos

UDC 616.935-074(047)

A.M.Sadykova

Kazakh National Medical University

named after S.D. Asfendiyarov, Almaty

Department of Infectious and Tropical Diseases

Reliable diagnosis of dysentery is one of the urgent tasks of AEI surveillance. Accurate diagnosis bacillary dysentery is important for the correct and timely treatment of the patient and for the implementation of necessary anti-epidemic measures. The data presented in the review show that, given the widespread prevalence of dysentery, lack of sensitivity and late appearance of positive results of many diagnostic methods, it is advisable to develop the diagnostic potential for detecting this infection.

Keywords: diagnosis, dysentery, antigen-binding lymphocyte method.

Recognition of shigella infection in clinical practice encounters significant difficulties due to objective factors, which include the clinical pathomorphosis of dysentery, an increase in the number of atypical forms of the disease, the existence of a significant number of infectious and non-infectious nature with clinical manifestations similar to dysentery. In half of the cases, the diagnosis of “clinical dysentery” hides unrecognized diseases of a different etiology.

The greatest difficulties confront the doctor during the initial examination of the patient before receiving the results of paraclinical diagnostic methods. Recognition of dysentery is also difficult in the presence of concomitant diseases of the gastrointestinal tract.

Since the beginning of the use of etiological laboratory diagnosis of dysentery, quite a few methods have been proposed and tested. There are many classifications of methods for etiological diagnosis of infections. Methodologically, the classification proposed by B.V. is the most justified. Punisher. In relation to the diagnosis of dysentery, the principles of methodologically based classification were used by B.V. Karalnik, N.M. Nurkina, B.K. Erkinbekova..

From laboratory methods Diagnosis of dysentery is known bacteriological (isolation and identification of the pathogen) and immunological. The latter include immunological methods in vivo (Tsuverkalov allergy test) and in vitro. Immunological methods in vitro have one undoubted advantage over the Tsuverkalov test - they are not associated with the introduction of foreign antigens into the body.

Most researchers still believe that bacteriological research, which includes isolation of the causative agent of the disease in pure culture with its subsequent identification by morphological, biochemical and antigenic characteristics, is the most reliable method for diagnosing shigellosis infection. The frequency of Shigella isolation from the feces of patients with a clinical diagnosis of “acute dysentery,” according to various authors, ranges from 30.8% to 84.7% and even 91.1%. Such a significant range among different authors depends not only on objective factors influencing the effectiveness of bacteriological research, but also on the thoroughness of the diagnosis (or exclusion) of “clinical dysentery”. The effectiveness of bacteriological research is influenced by such objective factors as the characteristics of the course of the disease, the method of collecting and delivering the material to the laboratory, the quality of the culture media, the qualifications of the personnel, the timing of the patient’s contact with health workers, the use of antimicrobial drugs before taking the material for research. Quantitative microbiological study of feces in acute dysentery shows that for any clinical forms infection, the most massive release of pathogens occurs in the first days of the disease, and starting from the 6th and, especially from the 10th day of illness, the concentration of Shigella in the feces decreases significantly. T.A. Avdeeva found that the low content of Shigella and the sharp predominance of non-pathogenic microorganisms in feces practically exclude the possibility of bacteriological detection of dysentery bacteria.

It is known that bacteriological confirmation of shigella infection is most often possible when examining patients precisely in the first days of the disease - coproculture of the pathogen in the vast majority of cases is first isolated during the first examination. Positive results of bacteriological examination are observed only in the first 3 days of the disease in 45–49% of patients, in the first 7 days – in 75%. Tillett and Thomas also consider the period of examination of patients important factor, which determines the effectiveness of the bacteriological method for diagnosing dysentery. According to T.A. Avdeeva, in the first days of the disease, the most intense release of the pathogen is observed in Sonne dysentery, less intense in Flexner dysentery and the least in Flexner VI dysentery; V late dates disease, high concentrations persist for the longest time in Flexner's dysentery, for a shorter period of time - Shigella Sonne, and for the least long time - Shigella Flexner VI.

Thus, although bacteriological examination of stool is the most reliable method for diagnosing shigellosis infection, significant disadvantages are the limitations of its effectiveness listed above. It is also important to point out the limitations of early diagnosis using the bacteriological method, in which the duration of the analysis is 3-4 days. In connection with these circumstances, the use of other laboratory diagnostic methods is of great practical importance. Another microbiological method for diagnosing dysentery is also based on the detection of living Shigella. This is a phage titer increase reaction (PTR), based on the ability of specific phages to multiply exclusively in the presence of homologous living microorganisms. An increase in the titer of the indicator phage indicates the presence of the corresponding microbes in the environment. Trial diagnostic value RSF for shigella infection was carried out by B.I. Khaimzon, T.S. Vilkomirskaya. RSF has a fairly high sensitivity. A comparison of the minimum concentrations of Shigella in feces captured by the bacteriological method (12.5 thousand bacteria in 1 ml) and RSF (3.0 - 6.2 thousand) indicates the superiority of RSF.

Since the frequency of positive RNF results is directly dependent on the degree of contamination of feces, the use of the method also gives the greatest effect in the first days of the disease and in more severe forms of the infectious process. However, more high sensitivity The method determines its special advantages over bacteriological examination in the later stages of the disease, as well as when examining patients with mild, asymptomatic and subclinical forms of infection, with a low concentration of the pathogen in the feces. RSF is also used when examining patients who have taken antibacterial drugs, since the latter sharply reduce the frequency of positive results of the bacteriological research method, but have a much lesser effect on the effectiveness of RSF. The sensitivity of RSF is not absolute due to the existence of phage-resistant strains of Shigella: the proportion of phage-resistant strains can vary widely - from 1% to 34.5%.

The great advantage of RSF is its high specificity. During examinations healthy people, as well as patients with infectious diseases of other etiologies, positive reaction results were observed only in 1.5% of cases. RSF is a valuable additional method for diagnosing shigella infection. But today this method is rarely used due to its technical complexity. Other methods are immunological. With their help, a pathogen-specific immune response is recorded or pathogen antigens are determined using immunological methods.

Due to the severity of specific infectious allergy processes during shigellosis infection, allergological diagnostic methods were initially used, which included the intradermal allergy test with dysenterine (IDT). The drug "dysenterin", which is devoid of toxic substances specific allergen shigella, was obtained by D.A. Tsuverkalov and was first used in a clinical setting when performing an intradermal test by L.K. Korovitsky in 1954. According to E.V. Golyusova and M.Z. Trokhimenko, in the presence of previous acute dysentery or accompanying allergic diseases with skin manifestations (eczema, urticaria, etc.). positive results of VPD are observed much more often (paraallergy). Analysis of the results of VPD in different periods of acute dysentery shows that a specific allergy occurs already in the first days of the disease, reaches its maximum severity by the 7th – 15th day and then gradually fades away. Positive reaction results were obtained when examining healthy people aged from 16 to 60 years in 15–20% of cases and in people aged from 3 to 7 years – in 12.5% ​​of cases. Even more often, nonspecific positive results of VPD were observed in patients with gastrointestinal diseases - in 20–36% of cases. The introduction of the allergen was accompanied by the development of a local reaction in 35.5 - 43.0% of patients with salmonellosis, in 74 - 87% of patients with coli-0124-enterocolitis. A serious argument against the widespread use of VPD in clinical practice was its allergenic effect on the body. Considering the above, we can say that this method is not very specific. Tsuverkalov's test is not species specific either. Positive reaction results were equally frequent in various etiological forms of dysentery.

In addition to VPD, other diagnostic reactions were also used, with varying degrees of validity, considered as allergic, for example, the allergen leukocytolysis reaction (ALC), the essence of which was specific damage or complete destruction actively or passively sensitized neutrophils upon contact with the corresponding antigen. But this reaction cannot be attributed to early diagnostic methods, since the maximum frequency of positive results was observed on days 6-9 of the disease and amounted to 69%. Allergen leukemia reaction (ALE) has also been proposed. It is based on the ability of leukocytes of a sensitized organism to agglomerate when exposed to a homologous allergen (dysenterin). Due to the lack of proof of the exact mechanisms of such tests and the insufficient correspondence of their results to the etiology of the disease, these methods, after a short period of their use in the USSR, did not subsequently become widespread.

Detection of Shigella antigens in the body is diagnostically equivalent to isolating the pathogen. The main advantages of antigen detection methods over bacteriological research that justify them clinical application, is the ability to identify not only viable microorganisms, but also dead and even destroyed ones, which is of particular importance when examining patients during or shortly after a course of antibacterial therapy.

One of best methods Express diagnostics of dysentery was an immunofluorescence study of stool (Coons method). The essence of the method is to detect Shigella by treating the test material with serum containing specific antibodies labeled with fluorochromes. The combination of labeled antibodies with homologous antigens is accompanied by a specific glow of the complexes, detected in a fluorescent microscope. In practice, two main variants of the Koons method are used: direct, in which serum containing labeled antibodies against Shigella antigens is used, and indirect (two-stage), using non-fluorochrome-labeled serum (or the globulin fraction of anti-Shigella serum) in the first stage. At the second stage, a fluorochrome-labeled serum is used against the globulins of the anti-Shigella serum used in the first stage. A comparative study of the diagnostic value of two variants of the immunofluorescent method did not reveal large differences in their specificity and sensitivity. In clinical practice, the use of this method is most effective when examining patients in early dates disease, as well as in more severe forms of infection. A significant disadvantage of the immunofluorescence method is its lack of specificity. The most important reason for the lack of specificity of the immunofluorescence reaction is the antigenic affinity of Enterobacteriaceae different kinds. Therefore, this method is considered as a guide for recognizing shigella infection.

To detect Shigella antigens without microscopy, use various reactions. These methods make it possible to detect pathogen antigens in the feces of 76.5 - 96.0% of patients with bacteriologically confirmed dysentery, which indicates a fairly high sensitivity. It is most advisable to use these methods precisely in the later stages of the disease. Most authors rate the specificity of these diagnostic methods quite highly. However, F.M. Ivanov, who used RSC to detect shigella antigens in feces, obtained positive results when examining healthy people and patients with intestinal infections of other etiologies in 13.6% of cases. According to the author, the use of the method is more appropriate for identifying specific antigens in urine, since the frequency of nonspecific positive reactions in the latter case is much lower. The use of various research methods makes it possible to detect Shigella antigens in the urine of the vast majority of patients with bacteriologically confirmed dysentery. The dynamics of the excretion of antigens in the urine has some peculiarities - detection of antigenic substances in some cases is possible already from the first days of the disease, but with the greatest frequency and consistency it is possible on the 10th - 15th day and even later. According to B.A. Godovanny et al, the proportion of positive results for detecting shigella antigens in urine (SAC) after the 10th day of the disease is 77% (the corresponding figure for bacteriological examination of stool is 47%). In connection with this circumstance, urine testing for the presence of pathogen antigens is a valuable additional method for dysentery, primarily for the purpose of late and retrospective diagnosis.

According to N.M. Nurkina, if the antibody immunoreagent is obtained from polyclonal sera, positive indication results are possible if related antigens are present in the sample. For example, with an erythrocyte diagnosticum from highly active serum against S.flexneri VI, the antigen S.flexneri I-V is also detected, since Shigella of both subspecies have a common species antigen. Shigella antigens can be determined during the period of illness both in blood serum and in secretions.

Lee Won Ho et al. It has been shown that the frequency of detection of Shigella antigens and their concentration in the blood and urine are higher in the early days of the disease and that the concentration of detected antigens is higher in moderate cases of the disease than in mild ones.

CM. Omirbayeva proposed a method for indicating the Shigella antigen, based on the use of formalinized erythrocytes as a sorbent for antigens from the fecal extract under study, followed by agglutination with immune sera. Assessing the specificity of this method, in our opinion, requires additional research, since fecal extracts contain significant quantities of antigens of other bacteria that are not the causative agent of this intestinal disease.

A number of researchers propose enzyme immunoassay as a method of rapid diagnosis of acute dysentery, which, according to many authors, is considered highly sensitive and highly specific. In this case, the highest level of antigen is detected on days 1-4 of the disease. Despite the obvious advantages of ELISA, which include high sensitivity, the possibility of strict instrumental quantitative accounting, and ease of reaction setup, the widespread use of this method is limited due to the need for special equipment.

To enhance the sensitivity and specificity of various serological methods For antigen detection, it is recommended to use monoclonal antibodies, immunoglobulin fragments, synthetic antibodies, LPS silver staining and other technological improvements.

It is often not possible to detect the antigen of an infectious agent even when using highly sensitive reactions to detect pathogen antigens in biological substrates of the body, since a significant part of the antigenic substances is apparently found in the biosample in the form of immune complexes in the body. When examining patients with bacteriologically confirmed acute dysentery, positive results of antigen determination by RSC were noted, according to some data, only in 18% of cases.

T.V. Remneva et al. They propose to use ultrasound to disintegrate antibody complexes with pathogen particles, and then determine the pathogen antigen in the RSC in the cold. The method was used to diagnose dysentery; urine samples from patients with acute intestinal infections were used as research material.

The use of the precipitation reaction to detect antigen in acute dysentery is not justified due to its low sensitivity and specificity. We believe that the specificity of any methods for indicating Shigella antigens can be significantly increased by using monoclonal antibodies to Shigella.

The coagglutination reaction is also one of the methods for rapid diagnosis of shigellosis, as well as antigens of pathogens of a number of other infections. With shigellosis, pathogen antigens can be determined from the first days of the disease throughout the entire acute period, and also within 1 - 2 weeks after the cessation of bacterial excretion. The advantages of the coaglutination reaction are the ease of manufacturing diagnostics, setting up the reaction, cost-effectiveness, speed, sensitivity, and high specificity.

When conducting diagnostics to determine Shigella antigens from the very beginning of the disease, it is most effective, according to many authors, to examine the feces of patients. As the disease progresses, the ability to detect Shigella antigens in urine and saliva decreases, although they are found in feces with almost the same frequency as at the onset of the disease. It must be taken into account that in the first 3–4 days of the disease, it is somewhat more effective to test feces for antigen in the RPGA. In the middle of the disease, RPHA and RNAb are equally effective, and starting from the 7th day, RNAb is more effective in searching for the Shigella antigen. These features are due to the gradual destruction of Shigella cells and their antigens in the patient’s intestines during the course of the disease. Shigella antigens excreted in urine are relatively smaller in size than antigens in feces. Therefore, it is advisable to examine urine in RNAt. In the urine of women, unlike the urine of men, due to probable fecal contamination, Shigella antigens are equally often detected using RPHA and RNAb.

Although the antigen is detected much more often (94.5 - 100%) in those fecal samples from which Shigella can be isolated than in those samples from which Shigella is not isolated (61.8 - 75.8%), with parallel bacteriological and serological (for antigen) in the study of fecal samples from patients with dysentery, in general, shigella was isolated only from 28.2 - 40.0% of samples, and antigen was detected in 65.9 - 91.5% of samples. It is important to emphasize that the species specificity of the detected antigen always corresponds to the specificity of serum antibodies, the titer of which increases as much as possible in dynamics. When focusing on a conditional diagnostic titer of antibodies, discrepancies in the specificity of such antibodies and the detected antigen can sometimes be observed. This discrepancy is due to the insufficient diagnostic reliability of a single determination of serum antibody activity. In this case, the etiological diagnosis must be made based on the specificity of the detected antigen.

The PCR method for the task of directly identifying the signs of a pathogen is close to methods for indicating antigens. It allows the DNA of the pathogen to be determined and is based on the principle of natural DNA replication, including the unwinding of the DNA double helix, the divergence of the DNA strands and the complementary addition of both. DNA replication cannot begin at any point, but only in certain starting blocks - short double-stranded sections. The essence of the method is that by marking with such blocks a DNA section specific only for a given species (but not for other species), it is possible to reproduce (amplify) this particular section many times. Test systems based on the principle of DNA amplification, in most cases, make it possible to detect bacteria and viruses that are pathogenic for humans, even in cases where their detection cannot be detected by other methods. The specificity of PCR test systems (with the correct choice of taxon-specific primers, the exclusion of false-positive results and the absence of amplification inhibitors in bioassays) in principle allows one to avoid problems associated with cross-reacting antigens, thereby ensuring very high specificity. The determination can be carried out directly on clinical material containing a live pathogen. But, despite the fact that the sensitivity of PCR can reach a mathematically possible limit (detection of 1 copy of the DNA template), the method is not used in the practice of diagnosing shigellosis due to its relative high cost.

In widespread clinical practice, the most widespread among serological research methods are those based on determining the level and dynamics of serum antibodies to the suspected causative agent of the disease.

Some authors have determined antibodies to Shigella in coprofiltrates. Coproantibodies appear much earlier than serum antibodies. Antibody activity reaches a maximum on days 9–12, and by days 20–25 they are usually not detected. R. Laplane et al. suggest that this is due to the destruction of antibodies in the intestine under the action of proteolytic enzymes. Coproantibodies cannot be detected in healthy people.

W. Barksdale et al, T.N. Nikolaeva et al. report an increase in the efficiency of deciphering the diagnosis and identifying convalescents through the simultaneous determination of serum and coproantibodies.

Detection of agglutinins in diagnostic titers is possible with bacteriologically confirmed dysentery only in 23.3% of patients. The limited sensitivity of RA is also manifested in insufficiently high titers of agglutinins detected with its help. There is evidence indicating unequal sensitivity of RA in various etiological forms of shigellosis infection. According to A.A. Klyuchareva, antibodies in a titer of 1: 200 and higher are detected using RA only in 8.3% of patients with Flexner’s dysentery and even more rarely in Sonne’s dysentery. Positive reaction results are not only more often, but also in higher titers observed with Flexner I-V and Flexner VI dysentery than with Sonne dysentery. Positive RA results appear from the end of the first week of the disease and are most often recorded in the second or third week. The first 10 days of the disease account for 39.6% of all positive reaction results. According to A.F. Podlevsky et al., agglutinins in diagnostic titers are detected in the first week of the disease in 19% of patients, in the second week - in 25% and in the third - in 33% of patients.

The frequency of positive RA results and the level of titers of antibodies detected with its help are directly dependent on the severity of the shigella infection. According to V.P. Zubareva, the use of antibacterial therapy does not reduce the frequency of positive results of RA, however, when antibiotics are prescribed in the first 3 days of the disease, agglutinins are detected in lower titers.

RA has limited specificity. When examining healthy people, positive RA results were obtained in 12.7% of cases, and group reactions were observed in 11.3% of cases. Due to the antigenic relatedness of Flexner I-V and Flexner VI bacteria, cross-reactions are especially often observed in the corresponding etiological forms of shigella infection.

With the advent of more advanced methods for serodiagnosis of shigella infection, RA gradually lost its importance. The diagnostic value of the agglutination reaction (“dysenteric Vidal reaction”) (RA) for dysentery is assessed ambiguously by various researchers, however, the results of the work of most authors indicate the limited sensitivity and specificity of this method.

Most often, the indirect (passive) hemagglutination reaction (IPHA) is used to determine antibodies. Detailed studies of the diagnostic value of the passive hemagglutination reaction (RPHA) for shigella infection were carried out by A.V. Lullu, L.M. Shmuter, T.V. Vlokh and a number of other researchers. Their results allow us to conclude that RPGA is one of the most effective methods for the serological diagnosis of dysentery, although it is not without some common disadvantages inherent in the methods of this group.

A comparative study of sensitivity in dysentery RPGA and the agglutination reaction shows the great superiority of the first method. According to A.V. Lullu, the average titers of RPHA in this disease exceed the average titers of RA by 15 times (at the height of the disease by 19-21 times), antibodies in high levels (1:320 - RPHA) are detected when used 4.5 times more often than in the titer (1:160 when performing an agglutination reaction). With bacteriologically confirmed acute dysentery, a positive RPHA reaction in diagnostic titers is noted when examining 53-80% of patients.

Hemagglutinins are detected from the end of the first week of the disease, the frequency of detection and antibody titer increase, reaching a maximum at the end of the second and third week, after which their titer gradually decreases.

There is a clear dependence of the frequency of positive RPGA results and hemagglutinin titers on the severity and nature of the course of shigella infection. Relevant studies have shown that with erased and subclinical forms of infection, positive results of RPGA were obtained less frequently than with acute clinically significant dysentery (52.9 and 65.0%, respectively), while only 4 responded in titers of 1:200 - 1:400. 2% of sera (with a clinically pronounced form - 31.2%) and with prolonged and chronic forms, positive results of RPGA were noted in 40.8% of patients, including in a titer of 1:200 - only 2.0%. There are also reports of different sensitivity of RPHA in certain etiological forms of shigellosis infection. According to L.M. Schmuter, the highest titers of hemagglutinins are observed in Sonne dysentery and significantly lower in Flexner I-V and Flexner VI dysentery. Antibacterial treatment started in the early stages of the disease, by reducing the duration and intensity of antigenic irritation, can cause the appearance of hemagglutinins in the blood serum in lower titers.

Like the agglutination reaction, RPGA does not always make it possible to accurately recognize the etiological form of shigella infection, which is associated with the possibility of group reactions. Cross reactions are observed mainly with Flexner type dysentery - between Flexner I-V and Flexner VI dysentery. The humoral immune response in many patients is weak. The possibility of cross-agglutination due to common antigens cannot be excluded. However, the advantages of this method include the simplicity of the reaction, the ability to quickly obtain results and relatively high diagnostic efficiency. A significant disadvantage of this method is that the diagnosis can be established no earlier than the 5th day of the disease, the maximum diagnostic antibody titers can be determined by the 3rd week of the disease, so the method can be classified as “retrospective”.

For the purpose of diagnosing dysentery, it is also proposed to determine the level of specific circulating immune complexes represented by the O-antigen of S. sonnei, combined with a specific antibody, using an indirect “sandwich option” enzyme immunoassay due to its high sensitivity and specificity, however, the method is recommended to be used only from the 5th day of the disease.

In patients with dysentery, from the very beginning of the disease, a specific increase in the bacteriofixing activity of the blood is detected due to the antigen-binding activity of erythrocytes. In the first 5 days of ACI, determination of the antigen-binding activity of erythrocytes makes it possible to establish the etiology of the disease in 85-90% of cases. The mechanism of this phenomenon is not well understood. It can be assumed that its basis is the binding of the antigen-antibody immune complex by erythrocytes through their C3b receptors (in primates, including humans) or Fcγ receptors (in other mammals).

Among the relatively new methods for recording a specific immune response at the cellular level, the determination of antigen-binding lymphocytes (ABLs) that react with a specific, taxonomically significant antigen attracts attention. Detection of ASL is carried out by various methods - paired agglutination of lymphocytes with antigen, immunofluorescence, RIA, adsorption of lymphocytes on antigen-containing columns, adhesion of mononuclear cells on glass capillaries, indirect rosette formation reaction (IRRO). It should be noted that such highly sensitive methods for recording ASL, such as ELISA and RIA, adsorption of lymphocytes on antigen-containing columns, are technically relatively complex and are not always available for widespread use. The work of a number of authors has shown the high sensitivity and specificity of RNRO for detecting ASL in various diseases. A number of researchers have identified a close relationship between the content of ASL in the blood of patients with various pathologies and the form, severity and period of the disease, its transition to protracted or chronic form.

Some authors believe that by determining the level of ASL in the dynamics of the disease, one can judge the effectiveness of the therapy. Most authors believe that if it is successful, the amount of ASL falls, and if the effectiveness of treatment is insufficient, an increase or stabilization of this indicator is recorded. It is reported that using the determination of ASL, it is possible to quantify sensitization to tissue and bacterial antigens, as well as to antibiotics, which is important diagnostic value. The ASL method has been used to a limited extent for the diagnosis of dysentery.

The possibility of early detection of ASL, already in the first days after infection, is very important for early diagnosis and timely treatment, which is necessary for the clinician.

Thus, the data presented in the review show that, given the widespread prevalence of dysentery, lack of sensitivity and late appearance of positive results of many diagnostic methods, it is advisable to develop the diagnostic potential for detecting this infection. Data obtained for many infectious diseases high efficiency ASL method, the early appearance of its positive result determine the prospects for studying and using this method for shigellosis.

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A.M.Sadykova

Dysentery laboratories diagnostics

Tү yin: Zhedel іshek infectionslaryn baqylauda, ​​dysentery nakty diagnostics ең өзу мәсеLeсі мљселі віліп сайлади. Bacterials dysentery durys koyylgan diagnoses science uaqytynda we eat zhurgizuge zhane epidemic karsy sharalardy Otkіzu ushіn manyzdy. Review of corsetilgen malimetter, dysentery ken taraluyn negіzhіpіv, sesimtaldygynyn zhetkіlіxіzdіgі zhane kop degen diagnosticalyk adіsterdіn on natizhesіnі ң cache anyktaluyna baylanysty, wasps infectious anyktauda diagnosticalyk potentialdy maksatty tүrde damytu kerek ekenіn korsetedi.

Tү withө zder: diagnosis, dysentery, antigenbaylanystyrushy adis.

A.M.Sadycova

Laboratory diagnostics of dysentery

Resume: Reliable diagnosis of diarrhea is one of the most important issue to control the exact intestinal infection. Exact diagnosis of bacteriosis diarrhoea have vitae meaning for correct and accurate treatment of a patient and to take necessary antiepidemic measures aswell. The members given in the survey, taking into consideration the widespread diarrhoea, shows the lack of sensibility and late occurrence of positive results of many diagnostic methods. It is essential aimily to develop the diagnostic potential to desine the infection.

Keywords: diagnostics, dysentery, antigen binding lymphocytes method.

Contents of the article: classList.toggle()">toggle

Dysentery is a common infectious disease, better known to the common man as an intestinal infection. This disease is actually localized in the large intestine (its distal section) and is caused by a bacterial agent of the genus Shigella.

Dysentery has a characteristic acute course and can provoke a number of complications. Timely identification of the problem in the early stages of its development will make it possible to more effectively fight the infection by prescribing highly targeted antibacterial therapy and using other measures for life-saving indications.

Indications for diagnostic testing for dysentery

A direct indication for prescribing a comprehensive diagnosis is the suspicion of the presence of shigellosis with a preliminary diagnosis made by a general medical specialist. He issues a referral for examination after the patient’s initial appointment, recording his complaints, and collecting an anamnesis.

Indications for appropriate measures are inextricably linked with acute, pronounced symptoms of dysentery. Its main stages include:

• Manifestation of the first signs of bacterial infection several hours or days after infection (the specific period depends on the route of entry of the pathogen into the body). There is a general malaise, headache, chills;
• Occurrence of main symptoms– pain in the abdomen, upset stool and digestion, high fever, lethargy and severe weakness, loss of appetite;
• Peak negative events– very frequent and loose stools with mucus, blood clots, pus, constant discomfort in the lower abdomen, increasing asynchronously, regardless of physical activity and food intake. In addition, the skin turns pale, the mucous membranes change color towards darker shades, the tongue becomes covered with a brown coating. An unpleasant odor from the mouth is often diagnosed. The pain syndrome in the abdominal area acquires a cramping, frequently changing character; when palpating the iliac region on the left side, it intensifies significantly. There is also a decrease in blood pressure and rapid heartbeat.

Diagnostic methods

Modern medicine offers the patient a wide range of methods for diagnosing dysentery, aimed both at a general search for Shigella and at determining their specific group type and serotype.

It is worth noting that none of the following analyzes can be 100 percent objective and informative– their reliability ranges from 60 to 85 percent, depending on specific activities, the qualifications of laboratory personnel, the quality of the samples taken, the patient’s compliance with all recommendations before donating the material and the conditions of its storage, the modernity and accuracy of diagnostic equipment and other factors.

That is why the final diagnosis of shigellosis can be made only after receiving positive results for several alternative methods studies that are independent of each other, but conducted in a single time period.

Most often, laboratory diagnosis of dysentery includes:

• Coprogram;
• General blood analysis;
• Bacteriological culture;
• General urine analysis;
• Serological studies;
• Antibody test;
• Blood chemistry;
• Immunological testing;
• Sigmoidoscopy;
• Other activities if necessary.

An important stage in identifying shigellosis is also a comprehensive professional differential diagnosis, which makes it possible to exclude other infections or pathologies with similar symptoms.

Coprogram or stool analysis

Coprogram – essential analysis if dysentery is suspected, allowing to determine deviations from the norm in the stool being tested. A laboratory worker, diagnosing the provided material, evaluates its composition, the presence of impurities, physical and chemical properties.

Before submitting this type of analysis, it is necessary to properly prepare for laboratory research.:

1. 10 days before sampling, you should stop drinking alcohol;
2. At least 5 days before the test, you should adhere to diet No. 5 according to Pevzner;
3. Feces cannot be tested if it was obtained through an enema or if it contains foreign impurities, for example, urine, traces of menstruation;
4. 3 days before the coprogram you should stop taking any medicines(both anally in the form of suppositories, and orally, intravenously, etc.), and also do not conduct research using auxiliary agents (vaseline or castor oil, bismuth, barium);
5. The material should be collected after spontaneous defecation from 4-5 random areas, placing it using a medical spatula in a special plastic container, filling the container to a maximum of 1/3. The sample must be delivered within a maximum of 10 hours after direct collection, subject to storage conditions in the refrigerator at a temperature of 4 to 6 degrees.

Comprehensive diagnosis of feces with coprogram includes studies according to the following criteria:

• Consistency. Normally it should be dense, with dysentery it should be mushy or liquid;
• Form. Normally structured, homogeneous and formed, with shigellosis - heterogeneous, partially formed, poorly structured;
• Color. Normally brown, with bacterial damage it is discolored, sometimes pinkish or reddish (in the presence of blood clots);
• Slime. Normally absent, with an intestinal infection it may be in large quantities;
• Blood. Normally it is not, but with dysentery it is;
• Leukocytes. Normally they are not detected; with shigellosis, up to 50 cells are diagnosed in the visual zone, mainly neutrophils;
• Epithelial cells. Normally there are trace amounts, but with a bacterial intestinal infection there are quite a lot of them.

The results of the coprogram are provided to the patient or doctor on average 3-4 days after submitting the material.

Sowing

Another common method for detecting shigellosis in patient tests is considered to be bacteriological culture. The essence of the activities is to place individual parts of the submitted material on a variety of nutrient media adapted for the growth of different pathogens bacterial infections. If Shigella is present in the body, then in a specific “soil” it will begin to actively reproduce, forming new colonies.

The technique is usually used as confirmation of primary tests showing the presence of dysentery, since the results of bacterial culture become known after a week.

In addition to identifying the pathogen, this analysis also allows you to most accurately select a highly targeted antibacterial drug that will effectively destroy the infection.

The identified sample is divided into several parts, after which various antibiotics are added there and the entire group of samples is placed in a thermostat - samples where the colonies die out faster and will be considered the most successful, which will allow the doctor to replace antibacterial drugs wide range actions in conservative treatment to more effective ones.

Blood and urine in dysentery

Taking general blood and urine tests is a mandatory aspect of complex diagnostics in the process of identifying and confirming the diagnosis of shigellosis.

• Blood analysis. With an intestinal infection of the above type, during the period of active development, a drop in hematocrit and immunoglobulin indices may be detected. Also, leukocytosis is often detected with a predominance of neutrophils and toxicological granularity of these components, a decrease in the concentrations of eosinophilic and platelet components. In addition, lymphopenia, lymphocytosis, a decrease in the lymphocyte index and an increase in ESR are possible;
• Analysis of urine. When diagnosing this liquid medium in the case of the development of shigellosis, a significant increase in the concentrations of casts and direct protein is observed, and red blood cells are often present in the urine.

Serological study

A modern serological test is a comprehensive test for antibodies to Shigella, which can be present in human blood. The reason for this process is active work immune system, which secretes its own plasma protein compounds that fight infectious bacterial infections.

The most accurate and fastest method for identifying the elements described above is the so-called indirect hemagglutination reaction. The essence of the method is the placement of a number of antigens of various strains of infection on the erythrocyte elements, after which a serum extract of the patient’s blood is added to the samples. In positive samples, reactions of interaction between antibodies and antigens begin with the adhesion of red blood cells, which makes it possible to identify Shigella.

Differential diagnosis of dysentery

A rather important stage in identifying dysentery and confirming the diagnosis is differential diagnosis - professional technique“screening out” other diseases and pathologies with similar symptoms, manifested by intoxication of the body and intestinal damage. Most often, shigellosis is compared with:

• Salmonellosis. This lesion has almost identical manifestations, but the general intoxication is weakly expressed and is present only in an erased form;
• Asherichiosis. This type of disease is caused by pathogens that attack the small intestine rather than the large intestine. Manifestations of intoxication are slightly weaker than with shigellosis;
• Cholera. Cholera bacillus affects the gastrointestinal tract and intestines, and there is pronounced dehydration due to extremely severe, frequent and profuse diarrhea. There is no mucus or blood in the stool, while the general intoxication symptoms are weaker than with dysentery;
• Yersiniosis. With yersiniosis, in addition to severe intoxication, numerous damage to organs and systems (kidneys, liver, central nervous system, etc.) are observed, accompanied by impaired urine outflow, jaundice and other syndromes.
• Rotavirus infection. In addition to the intestines, rotavirus infection almost always affects the upper respiratory tract;
• Acute appendicitis. This pathological condition associated with irritation of the peritoneum, a significant increase in temperature, as well as severe pain in the right lower abdomen.

Bacterial dysentery, or shigellosis, is an infectious disease caused by bacteria of the genus Shigella, which primarily affects the colon. The name of the genus is associated with K. Shigi, who discovered one of the pathogens

dysentery.

Taxonomy and classification. The causative agents of dysentery belong to the department Gracilicutes, family Enterobacteriaceae, genus Shigella.

Morphology and tinctorial properties. Shigella - gram-negative rods with rounded ends, 2-3 µm long, 0.5-7 µm thick (see Fig. 10.1); do not form spores, do not have flagella, and are immobile. Many strains have common type villi and sex pili. Some Shigella have a microcapsule.

Cultivation. Dysentery bacilli are facultative anaerobes. They are undemanding to nutrient media and grow well at a temperature of 37 °C and a pH of 7.2-7.4. On dense media they form small transparent colonies, in liquid media -

diffuse opacification. Selenite broth is most often used as an enrichment medium for the cultivation of Shigella.

Enzyme activity. Shigella has less enzymatic activity than other enterobacteria. They ferment carbohydrates to form acid. An important sign allowing Shigella to be differentiated is their relationship to mannitol: S. dysenteriae does not ferment mannitol, representatives of groups B, C, D are mannitol-positive. The most biochemically active are S. sonnei, which can slowly (within 2 days) ferment lactose. Based on the relationship of S. sonnei to rhamnose, xylose and maltose, 7 biochemical variants are distinguished.

Antigenic structure. Shigella has an O-antigen, its heterogeneity makes it possible to distinguish serovars and subserovars within groups; Some members of the genus exhibit K-antigen.

Pathogenicity factors. All dysentery bacilli form endotoxin, which has an enterotropic, neurotropic, and pyrogenic effect. In addition, S. dysenteriae (serovar I) - Shigella Grigoriev-Shiga - secrete an exotoxin that has an enterotoxic, neurotoxic, cytotoxic and nephrotoxic effect on the body, which accordingly disrupts water-salt metabolism and the activity of the central nervous system, leads to the death of epithelial cells of the colon, damage to the renal tubules. The formation of an exotoxin is associated with a more severe course of dysentery caused by this pathogen. Other species of Shigella can also produce exotoxin. The RF permeability factor has been discovered, which causes damage to blood vessels. Pathogenicity factors also include an invasive protein that promotes their penetration into epithelial cells, as well as pili and outer membrane proteins responsible for adhesion, and a microcapsule.

Resistance. Shigella has low resistance to various factors. S. sonnei is more resistant, which survives in tap water for up to 2"/2 months; in water from open reservoirs it survives up to 5/2 months. S. sonnei can not only survive for quite a long time, but also multiply in products, especially dairy products.

Epidemiology. Dysentery is an anthroponotic infection: the source is sick people and carriers. The mechanism of transmission of infections is fecal-oral. The routes of transmission can be different - with Sonne's dysentery, the food route predominates, with Flexner's dysentery - water, for Grigoriev-Shiga dysentery the contact-household route is typical. Dysentery occurs in many countries around the world. In recent

Over the years, there has been a sharp rise in the incidence of this infection. People of all ages are affected, but children aged 1 to 3 years are most susceptible to dysentery. The number of patients increases in July - September. Different kinds shigella by individual

regions are distributed unevenly.

Pathogenesis. Shigella enters the gastrointestinal tract through the mouth and reaches the colon. Possessing tropism for its epithelium, pathogens attach to cells with the help of pili and proteins of the outer membrane. Thanks to the invasive factor, they penetrate inside the cells, multiply there, as a result of which the cells die. Ulcerations form in the intestinal wall, in place of which scars then form. Endotoxin, released when bacteria are destroyed, causes general intoxication, increased intestinal motility, and diarrhea. Blood from the resulting ulcers ends up in the stool. As a result of the action of the exotoxin, a more pronounced disturbance of water-salt metabolism, central nervous system activity, and kidney damage is observed.

Clinical picture. The incubation period lasts from 1 to 5 days. The disease begins acutely with an increase in body temperature to 38-39 ° C, abdominal pain and diarrhea appear. There is an admixture of blood and mucus in the stool. Grigoriev-Shiga dysentery is the most severe.

Immunity. After an illness, immunity is not only species-specific, but also variant-specific. It is short-lived and fragile. Often the disease becomes chronic.

Microbiological diagnostics. The patient’s feces are taken as the material to be studied. The basis of diagnosis is the bacteriological method, which makes it possible to identify the pathogen and determine its sensitivity to

antibiotics, carry out intraspecific identification (determine the biochemical variant, serovar or colicinogenovar). In the case of protracted dysentery, it can be used as an auxiliary serological method, which consists of diagnosing RA, RNGA (by increasing the antibody titer when the reaction is repeated, the diagnosis can be confirmed).

Treatment. Patients with severe forms of Grigoriev-Shiga and Flexner dysentery are treated with broad-spectrum antibiotics with mandatory consideration of the antibiogram, since Shigella often includes not only antibiotic-resistant

active, but also antibiotic-dependent forms. For mild forms of dysentery, antibiotics are not used, since their use leads to dysbacteriosis, which aggravates the pathological process, and disrupts the recovery processes in the mucous membrane of the colon.

Prevention. The only drug that can be used in foci of infection for prophylactic purposes is dysentery bacteriophage. Nonspecific prevention plays the main role.