Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

E. coli Gastroenteritis


Jonathan Gotfried

, MD, Lewis Katz School of Medicine at Temple University

Reviewed/Revised Jun 2023
Topic Resources

E. coli gastroenteritis is a type of gastroenteritis Overview of Gastroenteritis Gastroenteritis is inflammation of the lining of the stomach and small and large intestines. It is usually caused by infection with a microorganism but can also be caused by ingestion of chemical... read more Overview of Gastroenteritis in which certain strains of the bacterium Escherichia coli infect the large intestine and cause diarrhea and sometimes other serious complications.

  • Organisms that cause E. coli gastroenteritis are usually acquired from contaminated ground beef or water or unpasteurized milk.

  • Abdominal cramps and diarrhea that may be bloody are the usual symptoms.

  • The diagnosis is based on a doctor's evaluation and sometimes on the results of stool tests.

  • Treatment involves drinking plenty of fluids.

  • Preventive measures include thorough cooking of meat and thorough washing of hands.

There are many strains of Escherichia coli (E. coli) that cause diarrhea or bloody diarrhea (hemorrhagic colitis). In North America, the most common strain that causes bloody diarrhea is E. coli O157:H7 E. coli O157:H7 infection Escherichia coli (E. coli) are a group of gram-negative bacteria that normally reside in the intestine of healthy people, but some strains can cause infection in the digestive... read more . These bacteria naturally occur in the intestines of about 1% of healthy cattle. Outbreaks can be caused by eating undercooked ground beef or by drinking unpasteurized milk or juice. Consuming food or water contaminated with cow manure or raw ground beef can also spread the infection. People can become infected after touching animals in a petting zoo. The infection can be transmitted from person to person, particularly from children in diapers to other people. Inadequately chlorinated recreational water parks can be a source of infection.

Types of E. coli gastroenteritis

E. coli occur naturally and harmlessly in the digestive tract, but some strains have acquired genes that enable them to cause intestinal infection. The following subtypes of E. coli can cause diarrhea:

Symptoms of E. coli Gastroenteritis

The most common symptoms of gastroenteritis are diarrhea and abdominal cramps. Although usually mild, the infection also can cause abdominal pain, abdominal expansion (distention) from gas, severe diarrhea, and dehydration Dehydration Dehydration is a deficiency of water in the body. Vomiting, diarrhea, excessive sweating, burns, kidney failure, and use of diuretics may cause dehydration. People feel thirsty, and as dehydration... read more .

Hemorrhagic colitis due to E. coli infection causes severe abdominal cramps that begin suddenly along with watery diarrhea, which may become bloody within 24 hours. The diarrhea usually lasts 1 to 8 days. Fever is usually absent or mild but occasionally can exceed 102° F (39° C).

About 5 to 10% of people, mostly children under 5 years of age and adults over 60 years of age, who have hemorrhagic colitis develop a severe complication called hemolytic-uremic syndrome Hemolytic-Uremic Syndrome (HUS) Hemolytic-uremic syndrome (HUS) is a serious disorder that usually occurs in children and involves the formation of small blood clots throughout the body that block the flow of blood to vital... read more . Symptoms of hemolytic-uremic syndrome include a low red blood cell count (anemia, characterized by fatigue, weakness, and pale skin color) caused by the destruction of red blood cells (hemolytic anemia), a low platelet count (thrombocytopenia Overview of Thrombocytopenia Thrombocytopenia is a low number of platelets (thrombocytes) in the blood, which increases the risk of bleeding. Thrombocytopenia occurs when the bone marrow makes too few platelets or when... read more Overview of Thrombocytopenia ), and sudden kidney failure.

Diagnosis of E. coli Gastroenteritis

  • Sometimes stool tests

Stool tests are not done in most people who have diarrhea because most infectious diarrhea goes away on its own, and the symptoms are treated the same regardless of the cause.

However, stool tests are done to look for strains of E. coli bacteria or the toxins they produce in certain people, including those who have the following:

  • Bloody stool (hemorrhagic colitis) or blood in the stool that is too small to see

  • Fever

  • Moderate to severe diarrhea

  • Diarrhea lasting more than 7 days

  • A weakened immune system caused by a disorder such as HIV/AIDS or who are taking a drug that can weaken the immune system such as chemotherapy drugs

  • Inflammatory bowel disease

  • Age 70 years or older

  • High risk of spreading the infection to others (for example, health care, day care, or food service workers)

Stool tests are also done during known or suspected outbreaks.

If E. coli O157:H7 is suspected, doctors do a stool test for Shiga toxins, which are produced by these bacteria. This test provides results quickly.

Other tests, such as sigmoidoscopy, may be done if a doctor suspects that other diseases may be causing the bloody diarrhea.

Treatment of E. coli Gastroenteritis

  • Drinking fluids

  • Sometimes fluids by vein

  • Sometimes antibiotics

Usually the only treatment needed for E. coli gastroenteritis is getting bed rest and drinking an adequate amount of fluids.

If diarrhea is prolonged or the person becomes severely dehydrated,fluids and electrolytes are given by vein (intravenously).

Because children can become dehydrated more quickly, they should be given fluids with the appropriate mix of salts and sugars. Any of the commercially available solutions designed to replace lost fluids and electrolytes (called oral rehydration solutions Treatment Dehydration is loss of water from the body, usually caused by vomiting and/or diarrhea. Dehydration occurs when there is significant loss of body water and, to varying amounts, electrolytes... read more ) are satisfactory. Carbonated beverages, teas, sports drinks, beverages containing caffeine, and fruit juices are not appropriate. If the child is breastfed, breastfeeding Breastfeeding Breast milk is the ideal food for newborns and infants. Although babies may be fed breast milk or formula, the World Health Organization (WHO) and American Academy of Pediatrics (AAP) recommend... read more Breastfeeding should continue.

The doctor may prescribe a medication to control the diarrhea, such as diphenoxylate, or instruct the person to use an over-the-counter medication, such as loperamide. These medications (called antidiarrheal medications) are typically safe for adults who have watery diarrhea. These medications are not given to children under 18 years of age with acute diarrhea. Antidiarrheal medications are also not given to people who have recently used antibiotics, who have bloody diarrhea, who have small amounts of blood in the stool that are too small to be seen, or who have diarrhea and fever.

Antibiotics are not given to people who have hemorrhagic colitis caused by strain E. coli O157:H7 because they do not lessen symptoms, they do not prevent spread of the infection, and they actually increase the risk of developing hemolytic-uremic syndrome Hemolytic-Uremic Syndrome (HUS) Hemolytic-uremic syndrome (HUS) is a serious disorder that usually occurs in children and involves the formation of small blood clots throughout the body that block the flow of blood to vital... read more . Antibiotics may be given, however, to people who have diarrhea caused by the other subtypes of E. coli. For example, antibiotics are given to people who have diarrhea caused by enterotoxigenic E. coli, which is the most common cause of traveler’s diarrhea Treatment Traveler’s diarrhea is an infection characterized by diarrhea, nausea, and vomiting that commonly occur in travelers to areas of the world with poor water purification. Traveler's diarrhea can... read more . But doctors do not know what the cause of the diarrhea is until results of stool tests are available, typically after the first doctor evaluation. Therefore, they estimate a person's risk of the various types of E. coli gastroenteritis when deciding whether to prescribe antibiotics before test results are available.

Hemorrhagic colitis eventually goes away on its own. However, people who develop complications such as hemolytic-uremic syndrome are likely to require intensive care in the hospital and may need kidney dialysis Dialysis Dialysis is an artificial process for removing waste products and excess fluids from the body, a process that is needed when the kidneys are not functioning properly. There are a number of reasons... read more Dialysis and other specific treatment.

Did You Know...

  • Antibiotics are not given for hemorrhagic colitis suspected to be caused by E. coli O157:H7 because they do not lessen symptoms, they do not prevent spread of the infection, and they actually increase the risk of developing hemolytic-uremic syndrome.

Prevention of E. coli Gastroenteritis

  • Thorough cooking of meat

  • Handwashing

Improved meat-processing procedures in the United States have helped reduce the rate of meat contamination with E. coli. Despite these measures, ground beef can still be contaminated. Thus, ground beef should be cooked to an internal temperature of 160° F (71° C) or until juices run clear. People should drink only pasteurized milk and milk products.

People should properly dispose of the stool of infected people, practice good hygiene, and wash their hands with soap and water to limit the spread of infection. If soap and clean water are unavailable, an antibacterial hand sanitizer should be used.

Children should not have diarrhea and should have two negative stool tests before they are allowed to return to the day care center.

People should report outbreaks of bloody diarrhea to a local public health departments, because intervention can prevent infection in other people.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Cafcit, NoDoz, Stay Awake, Vivarin
Anti-Diarrheal, Imodium A-D, Imodium A-D EZ Chews , K-Pek II, Medique Diamode
quiz link

Test your knowledge

Take a Quiz!