Main clinical variants
Depending on the localization of the lesion, three main clinical variants of acute shigellosis are distinguished:
- Colitic syndrome (typical). Characterized by involvement of the distal large intestine. Palpation reveals a painful, indurated, and spastic sigmoid colon. Stools are frequent but scant in volume, liquid, with mucus and blood streaks.
- Gastroenterocolitic variant. In addition to the sigmoid and rectum, the right colon (cecum, ascending colon) is involved in the pathological process. Stools are voluminous, and blood impurities may be absent. Assessment of the degree of dehydration (I–IV) is required.
- Gastroenteritic variant. Proceeds without clinical signs of large intestine involvement. The diagnosis is confirmed mainly by bacteriological and serological methods.
Diagnostics
Diagnosis is based on medical history (including epidemiological history), clinical presentation, and test results.
- Laboratory diagnostics. Complete blood count (CBC) shows leukocytosis with a stab neutrophil shift and accelerated ESR. In severe cases, toxic granularity of neutrophils is observed. CBC changes are most pronounced in the colitic variant.
- Bacteriological method. Stool culture on nutrient media (Endo, Ploskirev, etc.). Final identification takes 3 days.
- Serological methods. Indirect hemagglutination assay (IHA), agglutination test (rising antibody titers from days 5–7), ELISA (earlier detection). Rapid diagnostics (coagglutination reaction) are possible from the first hours of the disease.
- Instrumental diagnostics. Sigmoidoscopy (indicated for mild/mildly symptomatic, protracted forms, and for differential diagnosis). Reveals catarrhal, catarrhal-hemorrhagic, erosive, or ulcerative proctosigmoiditis.
Differential diagnosis
Shigellosis must be differentiated from other conditions accompanied by intoxication, diarrhea, and hemocolitis:
- Foodborne toxic infections (FBTI). Acute onset, acute gastroenteritis syndrome (repeated vomiting, cramping mesogastric pain, copious foul-smelling diarrhea). Pathological impurities in stool are absent.
- Enterohemorrhagic escherichiosis (EHEC). Associated with meat semi-finished products and fast food. Blood in the stool appears in 1–2 days. Severe complications such as hemolytic uremic syndrome (HUS) are possible.
- Amebiasis, balantidiasis, enteroinvasive escherichiosis.
Briefly: answers to topical questions
Which species of the genus Shigella are the most common causative agents of the disease?
The provided materials do not specify which Shigella species are the most frequent pathogens, so it is not possible to name the "most common" species based on these sources.
The sources mention the following Shigella species/variants:
- S. sonnei — Sonne dysentery; favorable prognosis.
- S. flexneri — Flexner dysentery; more serious prognosis.
- S. dysenteriae / S. dysenteriae type 1 — Shiga-Kruse dysentery; relatively unfavorable prognosis, bacteremia is characteristic of S. dysenteriae type 1 in 8% of cases.
- S. newcastle — mentioned among Shigella species of the intestinal group.
What complications are characteristic of severe forms of shigellosis?
In extremely severe forms, shigellosis may be accompanied by the following life-threatening conditions and complications:
- Shock states: infectious-toxic shock; mixed shock — intoxication and hypovolemic shock due to dehydration.
- Intestinal complications: perforation of intestinal ulcers with the development of diffuse peritonitis; intestinal hemorrhage.
- Neurological complications: fatal encephalopathy syndrome; cerebral edema and brain swelling.
- Endocrine disorders: acute adrenal insufficiency.
- Generalization of the process: bacteremia.
- Hematological and renal complications: hemolytic uremic syndrome with anemia, thrombocytopenia, and acute kidney injury.
- Cardiovascular complications: acute cardiovascular failure, myocarditis, thromboendocarditis.
- Respiratory complications: pulmonary edema.
- Thromboembolic complications: thromboembolism of small and medium branches of the pulmonary artery; segmental thrombosis of the superior mesenteric artery.
Class and exam questions
Can an "acute shigellosis" diagnosis be made with negative lab tests?
Yes, in the presence of a typical clinical picture, the diagnosis is valid even with negative laboratory results. The clinical variant and severity must be specified.
In which cases is sigmoidoscopy absolutely contraindicated in shigellosis?
Sigmoidoscopy is absolutely contraindicated in cases of acute hemocolitis (abundant mucus and blood impurities in the stool, severely painful and spastic sigmoid colon).
What are the stool characteristics in the typical colitic variant of shigellosis?
Stools are frequent and liquid, but scant in volume (low fecal mass), with the mandatory presence of mucus and blood streaks.
What else to study on this topic
- Criteria for assessing the degree of dehydration (I–IV)
- Reiter's syndrome as a complication of intestinal infections
- Features of taking an epidemiological history in children and the elderly
- Pathogenesis of infectious-toxic shock in FBTI
- Hemolytic uremic syndrome (HUS) in escherichiosis
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