Enterohemorrhagic

Entrohemorrhagic refers to enterohemorrhagic Escherichia coli (EHEC), a pathovar of E. coli that causes hemorrhagic colitis and, in some cases, hemolytic uremic syndrome (HUS). The most prominent member is serotype O157:H7, but non-O157 serotypes also cause disease.

Pathogenesis involves the production of Shiga toxins (Stx1 and Stx2) encoded by bacteriophages. These toxins inhibit protein synthesis and can damage the microvasculature of the kidneys and intestines. EHEC also uses a type III secretion system to produce attaching-and-effacing lesions on the intestinal mucosa, facilitating colonization and inflammation.

Transmission is primarily foodborne and zoonotic. Cattle are common reservoirs, and infections are associated with undercooked ground beef, unpasteurized dairy products, contaminated produce, and contaminated water. Person-to-person transmission can occur, especially in childcare settings and healthcare facilities.

Clinical features typically begin with abrupt abdominal cramps and diarrhea, which may progress from watery to bloody. Nausea and vomiting are common. Most people recover within a week, but a subset, particularly young children and the elderly, may develop HUS within about a week of illness onset. HUS is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury and can be severe.

Diagnosis relies on detection of Shiga toxins in stool or isolation of the organism with toxin-associated testing. Culture and molecular assays are used, with specific methods for O157:H7 versus non-O157 serotypes.

Treatment is primarily supportive, including fluids and electrolyte management. Antibiotics and antimotility agents are generally avoided, as some regimens may increase the risk of HUS. Prevention emphasizes safe food handling, proper cooking of ground beef (to at least 160°F/71°C), pasteurization, avoiding cross-contamination, and good hand hygiene.