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Diagnosis of shigellosis (bacterial dysentery)
Last reviewed: 03.07.2025
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Clinical diagnostics of dysentery is based on the typical colitic variant of the disease. To clarify the diagnosis in cases not confirmed by laboratory tests, a rectoscopy is performed, which in all cases of shigellosis reveals a picture of colitis (catarrhal, hemorrhagic or erosive-ulcerative) with damage to the mucous membrane of the distal colon, often sphincteritis. Gastroenteric and gastroenterocolitic variants are diagnosed only in case of laboratory confirmation. The most reliable method of laboratory diagnostics of shigellosis is the isolation of a coproculture of shigella. For the study, particles of feces containing mucus and pus (but not blood) are collected; material can be collected from the rectum with a rectal tube. For sowing, 20% bile broth, combined Kaufman medium, selenite broth are used. The results of the bacteriological study can be obtained no earlier than 3-4 days after the onset of the disease. Blood culture is important in Grigoriev-Shiga shigellosis. In some cases of gastroenteritis, presumably of shigellosis etiology, a bacteriological study of gastric lavage is carried out. The diagnosis can also be confirmed by serological methods. Of these, the most common is the method with standard erythrocyte diagnosticums. The diagnostic is considered to be an increase in antibodies in paired sera taken at the end of the first week of the disease and after 7-10 days and a fourfold increase in titer. ELISA, RKA are also used, it is possible to use aggregation-hemagglutination reactions and RSK. An auxiliary diagnostic method is a coprological study, which reveals an increased content of neutrophils, their accumulations, the presence of erythrocytes and mucus in the smear.
Of the instrumental methods, endoscopic diagnostics of dysentery (rectoscopy and colonofibroscopy) is of primary importance, confirming the characteristic changes in the mucous membrane of the colon.
Ultrasound and X-ray examination methods are used for the purpose of differential diagnosis.
Indications for consultation with other specialists
Urgent consultation with a surgeon and/or gynecologist if acute surgical and gynecological pathology of the abdominal organs is suspected, urgent consultation with a resuscitator - if there are signs of infectious toxic shock, consultation with other specialists - if concomitant diseases worsen.
Indications for hospitalization
- Clinical: severe and moderate course of the disease, presence of significant concomitant diseases.
- Epidemiological: persons of decreed groups.
Differential diagnosis of dysentery
Most often it is carried out with other diarrheal infections, acute surgical pathology of the abdominal organs, ulcerative colitis, tumors of the distal colon.
Salmonellosis presents difficulties for differential diagnosis in the presence of colitic syndrome, acute appendicitis - in the case of an atypical course (diarrhea, unusual localization of pain), mesenteric thrombosis - in the presence of blood in the stool, acute or subacute variants of ulcerative colitis - in cases with fever, rapid increase in diarrhea and the appearance of blood in the stool, cancer of the distal colon - in the case of a low-symptom course of the disease, if diarrhea and intoxication develop due to infection of the tumor.
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Example of diagnosis formulation
Acute shigellosis, colitic variant, moderate severity.