What is Shigellosis?
Shigellosis is an acute anthroponous infectious disease with fecal-oral transmission mechanism. General intoxication and predominant lesion of the mucous membrane of the distal colon, cramping abdominal pains, frequent loose stools with an admixture of mucus and blood, and tenesmus are characteristic.
Clinical descriptions of the disease are given for the first time in the writings of the Syrian physician Areteus of Cappadocia (I century BC) under the name “bloody, or strained, diarrhea” and in ancient Russian manuscripts (“bloody womb”, “washed”).
In the medical literature of the XVII – XIX century, the tendency of the disease to widespread in the form of epidemics and pandemics was emphasized. The properties of the main causative agents of dysentery are described at the end of the 19th century (Raevsky A.S., 1875; Chantemess D., Vidal F., 1888; Kubasov P.I., 1889; Grigoryev A.V., 1891; Shiga K., 1898), Later, several other types of pathogens were discovered and described.
Pathogenesis during Shigellosis
In the pathogenesis of shigellosis infection, two phases are distinguished: small intestine and large intestine. Their severity is manifested by the clinical features of the options for the course of the disease. When infected, shigella overcome nonspecific oral defense factors and the acid barrier of the stomach, then attach to enterocytes in the small intestine, secreting enterotoxins and cytotoxins. With the death of Shigella, endotoxin (a lipopolysaccharide complex) is released, the absorption of which causes the development of intoxication syndrome.
In the colon, the interaction of Shigella with the mucous membrane passes through several stages. Specific proteins of the outer shigella membrane interact with receptors of the plasma membrane of colonocytes, which causes adhesion, and then invasion of pathogens into epithelial cells and the submucosal layer. There is an active reproduction of shigella in the intestinal cells; hemolysin released by them ensures the development of the inflammatory process. Inflammation supports the cytotoxic enterotoxin secreted by shigella. When pathogens die, a lipopolysaccharide complex is released that catalyzes common toxic reactions. The most severe form of dysentery is caused by the Shigella Grigoryev-Shiga, capable of releasing the thermolabile protein exotoxin (Shiga toxin) in vivo. Homogeneous preparations of Shiga toxin exhibit both cytotoxic activity, enterotoxicity and neurotoxicity, which determines the low infectious (infectious) dose of this pathogen and the severity of the clinical course of the disease. Currently, there are reports that shigapodobny toxins can emit other types of shigella. As a result of the action of Shigella and the response of the macroorganism, disorders of the functional activity of the intestine and microcirculatory processes, serous edema and destruction of the mucous membrane of the colon develop. Shigella toxins in the colon develop acute catarrhal or fibrinous necrotic inflammation with the possible formation of erosion and ulcers. Dysentery constantly occurs with the phenomena of dysbiosis (dysbiosis), preceding or concomitant with the development of the disease. Ultimately, all this determines the development of exudative diarrhea with hypermotor colon dyskinesia.
Diagnosis of Shigellosis
Acute dysentery is differentiated from foodborne infections, salmonellosis, escherichiosis, rotavirus gastroenteritis, amebiasis, cholera, ulcerative colitis, intestinal tumors, intestinal helminthiases, mesenteric vascular thrombosis, intestinal obstruction and other conditions. With the colitic variant of the disease, acute onset, fever and other signs of intoxication, cramping abdominal pain with predominant localization in the left iliac region, scanty stool with mucus and streaks of blood, false desires, tenesmus, sigmoid colon tightness and tenderness during palpation are taken into account. With a mild course of this option, intoxication is weak, liquid stool of fecal character does not contain blood impurities. The gastroenteric variant is clinically indistinguishable from that of salmonellosis; with a gastroenterocolitic variant in the dynamics of the disease, the phenomena of colitis become more pronounced. The acute course of acute dysentery is the most difficult to clinically diagnose.
Differential diagnosis of chronic dysentery is carried out primarily with colitis and enterocolitis, oncological processes in the colon. When making a diagnosis, anamnesis data are assessed indicating acute dysentery for the past 2 years, persistent or occasionally occurring mushy stools with abnormal impurities and abdominal pain, often spasm and sigmoid colon pain during palpation, weight loss, manifestations of dysbacteriosis and hypovitaminosis.
The most reliable diagnosis is confirmed by the bacteriological method – the release of shigella from feces and vomit, and with Grigoriev-Shiga dysentery – and from the blood. However, the frequency of Shigella sowing under the conditions of various medical institutions remains low (20-50%). The use of serological laboratory diagnostic methods (RNGA) is often limited by a slow increase in the titers of specific antibodies, which gives the doctor only a retrospective result. In recent years, rapid diagnostic methods have been widely introduced into practice, which detect shigella antigens in feces (RCA, RLA, RNGA with antibody diagnosticum, ELISA), as well as CSC and aggregate hemagglutination reaction. To adjust the therapeutic measures, it is very useful to determine the form and degree of dysbiosis by the ratio of microorganisms of the natural intestinal flora. Endoscopic studies are of particular importance for the diagnosis of dysentery, but their use is only advisable in complex cases of differential diagnosis.
In the presence of satisfactory sanitary conditions, patients with dysentery can in most cases be treated at home. Hospitalization is for people with severe dysentery, as well as elderly people, children under 1 year old, patients with severe concomitant diseases; hospitalization is also carried out according to epidemic indications.
A diet is required (table No. 4), taking into account the individual tolerance of the products. In moderate and severe cases, a half-bed or bed rest is prescribed. In acute dysentery of moderate and severe course, the basis of etiotropic therapy is the appointment of antibacterial drugs in medium therapeutic doses for a course of 5-7 days – fluoroquinolones, tetracyclines, ampicillin, cephalosporins, as well as combined sulfonamides (cotrimoxazole). Without denying their possible positive clinical effect, antibiotics should be used with caution due to the development of dysbiosis. In this regard, the indications for the appointment of eubiotics (bifidumbacterin, bifikol, colibacterin, lactobacterin, etc.) have been expanded to 5-10 doses per day for 3-4 weeks. In addition, the increasing resistance of dysentery pathogens to etiotropic drugs should be taken into account, especially in relation to chloramphenicol, doxycycline and cotrimoxazole. Preparations of the nitrofuran series (for example, furazolidone 0.1 g each) and nalidixic acid (nevigramone 0.5 g each) 4 times a day for 3-5 days are currently still prescribed, but their effectiveness is reduced.
The use of antibacterial drugs is not indicated for the gastroenteric variant of the disease due to a delay in the terms of clinical recovery and rehabilitation, the development of dysbiosis, and a decrease in the activity of immune reactions. In cases of dysenteric bacteriocarrier, the feasibility of etiotropic therapy is doubtful.
According to indications, detoxification and symptomatic therapy are carried out, immunomodulators are prescribed (for chronic forms of the disease under the control of an immunogram), enzyme complex preparations, enterosorbents, antispasmodics, astringents.
During the period of convalescence in patients with severe inflammatory changes and delayed repair of the mucous membrane of the distal colon, therapeutic microclysters with tinctures of eucalyptus, chamomile, rosehip oil and sea buckthorn, vinyl, etc. have a positive effect.
In cases of chronic dysentery, treatment is difficult and requires an individual approach to each patient, taking into account his immune status. In this regard, the treatment of patients in the hospital is much more effective than outpatient. In relapses and exacerbations of the process, the same means are used as in the treatment of patients with acute dysentery. However, the use of antibiotics and nitrofurans is less effective than in acute form. For maximum sparing of the gastrointestinal tract, diet therapy is prescribed. Physiotherapeutic procedures, therapeutic enemas, eubiotics are recommended.
Epidemiological surveillance includes control over the sanitary condition of food facilities and DDU, compliance with the proper technological regime in the preparation and storage of food products, sanitary and communal improvement of settlements, the condition and operation of water supply and sanitation facilities and networks, as well as the dynamics of the incidence in the served territories, biological properties of circulating pathogens, their species and type structure.
In the prevention of dysentery, a decisive role belongs to hygienic and sanitary-communal measures. It is necessary to observe the sanitary regime in food enterprises and markets, in public catering establishments, grocery stores, children’s institutions and water supply facilities. Of great importance are the cleaning of the territory of populated areas and the protection of water bodies from pollution by sewage, especially sewage from medical institutions. Compliance with the rules of personal hygiene plays a significant role. Of great importance in the prevention of shigellosis is health education. Hygiene skills should be taught to children in the family, child care facilities and school. It is important to ensure effective sanitary-educational work among the population to prevent the use of drinking water of dubious quality without heat treatment and bathing in contaminated water bodies. Of particular importance is hygienic education among people of certain professions (employees of food enterprises, public catering facilities and food trade, water supply, kindergartens, etc.); when applying for such places of work, it is desirable to surrender sanitary minimums.
Persons entering work at food and equivalent enterprises and institutions are subjected to a single bacteriological examination. When isolating the causative agents of dysentery and acute intestinal diseases, people are not allowed to work and sent for treatment. Children newly enrolled in nursery groups in kindergartens during the seasonal rise in the incidence of dysentery are taken after a single examination for intestinal infections. Children returning to the institution after any illness or prolonged (5 days or more) absence are accepted if there is a certificate indicating the diagnosis or cause of the illness.
Patients are subject to hospitalization for clinical and epidemiological reasons. If the patient is left at home, he is prescribed treatment, explanatory work is carried out on the procedure for caring for him and current disinfection is carried out in the apartment.
Reconvalescents after dysentery are prescribed no earlier than 3 days after normalization of stool and body temperature with a negative result of a control one-time bacteriological study conducted no earlier than 2 days after the end of treatment. Employees of food enterprises and persons equated with them are discharged after a 2-fold negative control bacteriological examination and are allowed to work according to a doctor’s certificate. Young children who attend and do not attend childcare facilities are discharged in compliance with the same requirements as for catering workers, and are admitted to collectives immediately after recovery. After discharge, convalescents should be monitored by a doctor in the infectious diseases office of the clinic. For persons suffering from chronic dysentery and secreting the pathogen, as well as bacterium carriers, a follow-up observation is established for 3 months with a monthly examination and bacteriological examination. Employees of food enterprises and persons equated to them who have had acute dysentery are subject to follow-up for 1 month, and those who have had chronic dysentery for 3 months with monthly bacteriological examination. After this period, with full clinical recovery, these individuals may be allowed to work in the specialty. Children with dysentery who attend preschool institutions, boarding schools, children’s health facilities, are also subject to follow-up for 1 month with a double bacteriological examination and clinical examination at the end of this period.
For persons in contact with a patient with dysentery or a carrier, establish medical supervision for 7 days. Employees of food enterprises and persons equated with them are subjected to a single bacteriological examination. If the test result is positive, they are suspended from work. Children attending kindergartens and living in a family with dysentery are admitted to the institution, but they are under medical supervision and a single bacteriological examination is carried out.