Stec

Shiga toxin-producing Escherichia coli (STEC), also known as verocytotoxin-producing E. coli (VTEC) or enterohemorrhagic E. coli (EHEC), is a group of pathogenic bacteria strains of the genus Escherichia coli that can produce Shiga toxins. These toxins can cause severe illness in humans, including bloody diarrhea, hemolytic-uremic syndrome (HUS), and sometimes death. The most well-known STEC serotype is E. coli O157:H7, but there are many other serotypes that can also cause illness.

Epidemiology

STEC infections are zoonotic, meaning they can be transmitted between animals and humans. The primary reservoirs for STEC are ruminant animals, particularly cattle. Humans can become infected through consumption of contaminated food or water, direct contact with animals or their environment, or person-to-person transmission. Outbreaks have been associated with undercooked ground beef, unpasteurized milk and juice, contaminated water, and raw vegetables.

Pathogenesis

STEC strains produce Shiga toxins (Stx1 and Stx2), which are primarily responsible for the virulence of these bacteria. These toxins inhibit protein synthesis in host cells, leading to cell death. The damage caused by the toxins, particularly in the kidneys and blood vessels, can lead to hemolytic-uremic syndrome (HUS), a serious condition characterized by hemolytic anemia, acute kidney failure, and low platelet count.

Clinical Features

The incubation period for STEC infection ranges from 1 to 10 days, with an average of 3-4 days. Symptoms include severe abdominal cramps, watery diarrhea that may become bloody, vomiting, and sometimes fever. In some cases, particularly in young children and the elderly, the infection can progress to HUS, which requires prompt medical attention.

Diagnosis

Diagnosis of STEC infection is based on the detection of the bacteria in stool samples. Laboratory tests can identify the specific serotype of E. coli and determine whether it produces Shiga toxins. Polymerase chain reaction (PCR) assays are commonly used for this purpose.

Treatment

There is no specific treatment for STEC infections. Antibiotics are generally not recommended, as they can increase the risk of developing HUS. Treatment focuses on supportive care, including hydration and, in severe cases, hospitalization for management of HUS, which may involve dialysis and blood transfusions.

Prevention

Preventive measures include practicing good hygiene, such as washing hands thoroughly with soap and water after using the bathroom or handling animals, cooking meat to safe temperatures, avoiding unpasteurized dairy products and juices, and washing fruits and vegetables before eating.

See Also

• Hemolytic-uremic syndrome
• Escherichia coli
• Foodborne illness