Escherichia coli (E. coli) bacteria have several strains and can cause a variety of illnesses. E. coli O157 is a particularly virulent strain of enterohemorrhagic E. coli (EHEC), which is a Shiga-toxin-producing type of E. coli. This strain of E. coli is uncommon and can be found in the intestines of cattle, goats, and sheep.
E. coli O157 occurs worldwide and the infection is particularly dangerous for young children, the elderly, and people with compromised immune systems.
Here are some of the most commonly asked questions about the diagnosis, treatment, and prevention of E. coli O157 infection.
- How do people get E. coli O157 infections? E. coli O157 passes through the oral-fecal route, meaning that people contract the disease by accidentally ingesting infected fecal matter. Infection most often stems from undercooked beef, unpasteurized dairy products, and contaminated raw leaf green vegetables. Contaminated drinking water also poses a risk of infection.
- What are the symptoms of E. coli O157 infections? E.coli O157 can present asymptomatically, meaning that infected people will show no symptoms. However, the infection can also cause diarrhea, hemolytic uremic syndrome (HUS), and hemorrhagic colitis (HC). These latter conditions are characterized by abdominal cramps, diarrhea, intestinal bleeding, kidney damage, anemia, excessive clumping of blood platelets, and even death. HUS is most common in young children and the elderly.
- How is E. coli O157 infections diagnosed? E. coli O157 infection is most commonly diagnosed through laboratory testing of potentially infected stool samples. These tests look for the presence of serotype specificE. coli antigens.
- What is the typical treatment for E. coli O157 infections? There is no specific treatment for E. coli O157; the infection will typically run its course without treatment within 5-7 days. During recovery, people with E. coli should drink plenty of fluids to prevent dehydration; in severe cases of diarrhea and vomiting, if a person cannot keep liquids down, intravenous hydration may become necessary. E. coli should not be treated with antibiotics or with over-the-counter anti-diarrheal medications, as these may increase the risk of developing HUS. If E. coli O157 infection does progress to HUS, treatment may include intravenous fluids, blood transfusion, or temporary dialysis.
- How can I prevent E. coli O157 infections? Proper hygiene is key in preventing the spread of E. coli. Make sure to wash your hands properly after using the toilet, changing a child’s diaper, picking up animal feces, patting or handling animals, or handling any potentially contaminated objects; make sure to teach children proper handwashing techniques. In addition, always practice proper food preparation and handling procedures, including thoroughly washing all raw produce and cooking meat to safe temperatures. Avoid raw milk and unpasteurized dairy products and juices, and avoid swallowing water when swimming in lakes, ponds, streams, or pools.
- What kinds of diagnostic tests are used to test for E. coli O157 infections? To diagnose E. coli O157 infection, your doctor will most likely collect a stool sample to test for E. coliantigens. One such antigen test is an enzyme-linked immunosorbent assay (ELISA), like the IVD E. coli O157 Stool Antigen Detection Microwell ELISA. This test provides precise, rapid diagnosis of E. coliinfection.
Centers for Disease Control (CDC). (n.d.). “E. coli (Escherichia coli)”. Available at
Center for Food Security and Public Health. “Enterohemorrhagic Escherichia coli and Other E. coli Causing Hemolytic Uremic Syndrome.” Iowa State University. Available at http://www.cfsph.iastate.edu/Factsheets/pdfs/e_coli.pdf
Mayo Clinic. (n.d.). “Hemolytic uremic syndrome (HUS)”. Available at