General characteristics and clinical features
Pathogenic strains of E. coli are divided into six subgroups according to the WHO classification, whereas non-pathogenic E. coli are a natural part of the normal intestinal microflora. The disease is registered in children of various age groups, with the peak incidence occurring between one and three years of age. A winter-spring seasonality is typical.
Unlike most other acute intestinal infections, the onset of escherichiosis is most often gradual or subacute. Fever is usually absent or remains within subfebrile values. Abdominal pain is mild. The leading clinical manifestation is recurrent vomiting, which becomes persistent in infants. The severity of the patient's condition directly depends on the degree of exicosis (dehydration), which can reach grade II–III.
Enteropathogenic (EPEC) and enterotoxigenic (ETEC) escherichiosis
These two forms have the greatest clinical significance in pediatrics.
Enteropathogenic escherichiosis is caused by serovars O18, O26, O55, and O111. The incubation period lasts from 2 to 7 days.
- Clinical presentation: The disease begins with lethargy, loss of appetite, and persistent vomiting (regurgitation in infants). Marked flatulence is characteristic. Stools become copious, "spurt-like", watery, yellow with a moderate amount of mucus. The peak of diarrhea occurs on days 5–7.
- Complications: Intensive fluid loss leads to systemic disorders. Cardiovascular manifestations include tachycardia, a drop in blood pressure, and muffled heart sounds. The kidneys respond with a decrease in diuresis down to anuria. Regarding the central nervous system, initial anxiety is replaced by deep lethargy and the threat of coma. In older children, EPEC proceeds as a typical foodborne toxic infection (FTI).
Enterotoxigenic escherichiosis (serovars O6, O8, O9, O20, O75) has a short incubation period ranging from a couple of hours to 3 days. In infants, the infection develops in a cholera-like scenario: repeated vomiting and frequent watery stools without pathological impurities against a normal temperature. There is a high risk of rapid dehydration, though recovery usually occurs by the end of the first week. In older children, the disease manifests acutely, resembling an FTI, with uncontrollable vomiting and epigastric pain.
Enteroinvasive (EIEC) escherichiosis
Infection caused by enteroinvasive strains (O28, O124, O144, O151) proceeds in a shigellosis-like manner. The incubation period is 1–3 days.
This form is characterized by an acute start with a rise in temperature to subfebrile or febrile levels. Patients are troubled by cramping abdominal pain, and in rare cases, false urges to defecate (tenesmus) occur. On physical examination, a painful and spastic sigmoid colon is palpated. The stool pattern is specific: it is scanty (resembling a "rectal spit"), contains a lot of mucus, green elements, and may have streaks of blood.
Enterohemorrhagic (EHEC) escherichiosis
The O157:H7 serogroup dominates among the pathogens of this group. This form of infection is considered the least studied but the most dangerous. The risk group includes children of all ages, except for infants in the first months of life.
The main threat of enterohemorrhagic escherichiosis lies in the high risk of developing hemolytic-uremic syndrome (HUS). The pathogenesis of this complication is associated with massive damage to blood vessels and red blood cells.
- Laboratory signs of HUS: a sharp drop in hemoglobin levels and platelet counts, a rapid increase in blood nitrogenous waste products (creatinine and urea).
- Clinical manifestations: development of acute renal injury (ARI) and severe anemia.
When signs of HUS develop, the patient is indicated for emergency transfer to hardware hemodialysis to save life and restore renal function.
The abbreviation AAT will help you remember the "sinister triad" of hemolytic-uremic syndrome in EHEC: Anemia, Anuria, Thrombocytopenia.
Class and exam questions
How to clinically distinguish enteropathogenic escherichiosis from enteroinvasive?
In the enteropathogenic variant, the stool is copious, watery, yellow, and accompanied by severe vomiting without high fever. The enteroinvasive variant proceeds with fever, spastic pain, and scanty stools with mucus and blood (resembling dysentery).
At what age do escherichiosis infections pose the greatest danger?
They pose the greatest danger to infants in the first year of life due to the risk of the rapid development of exicosis (dehydration) against the background of persistent vomiting and diarrhea.
What happens to the central nervous system during severe exicosis?
In the early stages of dehydration, the child exhibits marked anxiety. As exicosis progresses to grade II–III, agitation is replaced by deep lethargy, sluggishness, and a high risk of developing a coma.
What else to study on this topic
- Degrees of exicosis and principles of calculating rehydration therapy
- Pathogenesis and intensive care of hemolytic-uremic syndrome
- Differential diagnosis of EIEC and shigellosis
- Laboratory diagnosis of escherichiosis and E. coli strain typing
- Features of the course of foodborne toxic infections in older children
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