EHEC

Enterohaemorrhagic Escherichia coli (EHEC) is a pathotype of Escherichia coli distinguished by the production of Shiga toxins and its ability to cause hemorrhagic colitis and, in some cases, hemolytic uremic syndrome (HUS). The most well-known serotype is O157:H7, but many non-O157 serotypes also cause disease. EHEC is a significant cause of foodborne illness worldwide.

Transmission occurs through ingestion of contaminated food or water and can result from undercooked ground beef, unpasteurized dairy products, raw sprouts, leafy greens, and other contaminated foods. Symptoms typically begin after a few days and include sudden abdominal cramps, nonbloody or bloody diarrhea, and vomiting. Fever is usually absent or mild. Most infections are self-limited, but a minority of patients, particularly young children and the elderly, can develop HUS, a serious complication characterized by acute kidney injury, hemolytic anemia, and low platelet count.

Pathogenesis involves adherence to intestinal cells via a type III secretion system, forming attaching-and-effacing lesions, while Shiga toxins (Stx1 and/or Stx2) disrupt protein synthesis and can cause systemic effects. Diagnosis is based on stool testing, including culture with selective media for O157:H7 or PCR for Stx genes, and may involve toxin detection or serotyping to identify the serotype.

Treatment centers on supportive care, including hydration and electrolyte management. Antibiotics and antimotility agents are generally avoided, as some agents may increase the risk of HUS. In cases of HUS, careful monitoring and, if needed, renal support such as dialysis are important. Preventive measures focus on proper food handling, cooking meat to safe temperatures, pasteurization, avoiding raw milk, washing produce, and good hand hygiene. Reservoirs include ruminants, especially cattle.