E. coli Infection and Food Safety
Although most kinds of E. coli are harmless, others can make you sick. Learn about E. coli and what you can do to help lower the risk of infection.
Learn About E. coli Infection
Escherichia coli (abbreviated as E. coli) are bacteria found in the environment, foods, and intestines of people and animals.
Most E. coli are harmless and actually are an important part of a healthy human intestinal tract. However, some E. coli are pathogenic, meaning they can cause illness, either diarrhea or illness outside of the intestinal tract. The types of E. coli that can cause diarrhea can be transmitted through contaminated water or food, or through contact with animals or people. These are often called pathotypes.
E. coli can cause diarrhea, urinary tract infections, respiratory illness, bloodstream infections, and other illnesses. Other kinds of E. coli are used as markers for water contamination—so you might hear about E. coli being found in drinking water, which are not harmful, but indicate the water is contaminated. It does get a bit confusing—even to microbiologists.
Quick Guide to Understanding E. coli
There are 6 different pathotypes of E. coli that cause diarrhea.
Some E. coli cause disease by making a toxin called Shiga toxin. The bacteria that make these toxins are called "Shiga toxin-producing" E. coli, or STEC, for short.
The most commonly identified STEC in North America is E. coli O157:H7
Other E. coli in the STEC group, including O145, are sometimes called "non-O157 STECs"
What are Shiga toxin-producing E. coli?
One particular pathotype of E. coli causes disease by making a toxin called Shiga toxin. The bacteria that make these toxins are called "Shiga toxin-producing E. coli", or STEC. You might hear them called verocytotoxic E. coli (VTEC) or enterohemorrhagic E. coli (EHEC); these all refer generally to the same pathotype of bacteria. STEC is then often sub-divided into two categories: E.coli 0157 and non-0157 STECs.
- Most common type of STEC: The most commonly identified STEC infections in North America are E. coli O157:H7 (often shortened to E. coli O157 or even just "O157"). When you hear news reports about outbreaks of "E. coli" infections, they are usually talking about E. coli O157.
- Other groups of STEC: Other groups of E. coli in the STEC pathotype are sometimes called "non-O157 STECs."
Concerns about non-O157 STECs
In addition to E. coli O157, many other "non-O157 STECs" also cause disease. Some "non-O157 STECs" cause disease that is often severe, resulting in bloody diarrhea and sometimes hemolytic uremic syndrome (HUS), which is a type of kidney failure.
- Public health surveillance data on the occurrence of non-O157 STECs is improving; many non-O157 STEC infections go undiagnosed or unreported.
- Identifying non-O157 STEC infections is more complex than identifying those from STEC O157.
- First, clinical laboratories must test stool samples for the presence of Shiga toxins (the number of laboratories performing these tests has increased greatly).
- Then, the positive samples must be sent to public health laboratories to look for non-O157 STEC.
- The most common non-O157 STEC serogroups that cause illness in people in the United States are O26, O45, O103, O111, O121, and O145.
About the Illness
- People usually get sick from STEC within 2 to 8 days after swallowing the organism.
- Most people develop diarrhea (often bloody) and abdominal cramps.
- Most illnesses resolve on their own within 7 days. Some illnesses last longer and can be more severe.
- Most people recover within a week but, rarely, people with severe infection may be sick for a long time.
- Postdiarrheal hemolytic uremic syndrome (HUS), a type of kidney failure, can begin as the diarrhea is improving. HUS can occur in people of any age but is most common in children under 5 years old and the elderly.
Problem: One in four burgers turns brown before it has reached the safe internal temperature of 160°F (according to USDA Color of Cooked Ground Beef as It Relates to Doneness).
Solution: Use a food thermometer.
Some people are more at risk for infection from E. coli and other germs
- E.coli can be deadly for some: Escherichia coli O157:H7 and other STEC strains cause bacterial gastrointestinal illness in the United States that can be severe, especially in young children and the elderly.
- Hemolytic uremic syndrome (HUS): HUS can occur in people of any age but is most common in children under 5 years old and the elderly. Overall, HUS occurs in about 6% of patients of all ages with E. coli O157 infection and in about 15% of children under 5 with this infection. HUS occurs less commonly with other STEC infections.
To best protect yourself against E. coli infections
- Know your risk of food poisoning. People at higher risk for foodborne illness are pregnant women and newborns, children, older adults, and those with weak immune systems.
- Consult your healthcare provider if you think you might be ill with E. coli infection.
- Practice proper hygiene, especially good hand washing
- Wash your hands thoroughly after using the bathroom, changing diapers, and before preparing or eating food.
- Wash your hands after contact with animals or their environments (at farms, petting zoos, fairs, even your own backyard).
- Always wash your hands before preparing and feeding bottles or foods to an infant, before touching an infant's mouth, and before touching pacifiers or other things that go into an infant's mouth.
- Keep all objects that enter infants' mouths (such as pacifiers and teethers) clean.
- If soap and water aren't available, use an alcohol-based hand sanitizer. These alcohol-based products can quickly reduce the number of germs on hands in some situations, but they are not a substitute for washing with soap and running water.
- Follow clean, separate, cook, chill guidelines, which can be found at FoodSafety.gov
- Cook meats thoroughly. Ground beef and meat that has been needle-tenderized should be cooked to a temperature of at least 160°F (70˚C). Use a thermometer to verify the temperature, as color is not a very reliable indicator of how thoroughly meat has been cooked.
- Prevent cross-contamination in food preparation areas by thoroughly washing hands, counters, cutting boards, and utensils after they touch raw meat.
- Avoid consuming raw milk, unpasteurized dairy products, and unpasteurized juices (like fresh apple cider).
- Avoid swallowing water when swimming and when playing in lakes, ponds, streams, swimming pools, and backyard "kiddie" pools.
- Please see the FoodSafety.gov page on E. coli to learn more information about E. coli and how to prevent infection.
- Page last reviewed: May 20, 2014
- Page last updated: May 20, 2014
- Content source:
- Content source: National Center for Emerging and Zoonotic Infectious Diseases
- Page maintained by: Office of the Associate Director for Communication, Division of News and Electronic Media