E. coli (Escherichia coli) is the name of a germ, or bacterium, that
lives in the
digestive tracts of humans and animals.
There are many types of
E. coli, and most of them are harmless. But some can
cause bloody diarrhea. Some strains of E. coli bacteria (such as a strain called O157:H7) may also
anemia or kidney failure, which can lead to
Other strains of E. coli can cause
urinary tract infections or other infections.
What causes an E. coli intestinal infection?
You get an E. coli infection by coming into
contact with the feces, or stool, of humans or animals. This can happen when
you drink water or eat food that has been contaminated by feces.
E. coli in food
E. coli can get into meat during processing. If
the infected meat is not cooked to 160°F (71°C), the bacteria can survive and
infect you when you eat the meat. This is the most common way people in the
United States become infected with E. coli. Any food
that has been in contact with raw meat can also become infected.
Other foods that can be infected with
E. coli include:
Raw milk or dairy products. Bacteria can
spread from a cow's udders to its milk. Check the labels on dairy products to
make sure they contain the word "pasteurized." This means the food has
been heated to destroy bacteria.
Raw fruits and vegetables, such as
lettuce, alfalfa sprouts, or unpasteurized apple cider or other unpasteurized
juices that have come in contact with infected animal feces.
E. coli in water
Human or animal feces infected with E. coli sometimes get into lakes, pools, and water supplies.
People can become infected when a contaminated city or town water supply has
not been properly treated with chlorine or when people accidentally swallow
contaminated water while swimming in a lake, pool, or irrigation canal.
E. coli from person-to-person contact
The bacteria can also spread from one person to
another, usually when an infected person does not wash his or her hands well
after a bowel movement. E. coli can spread from an
infected person's hands to other people or to objects.
What are the symptoms?
symptoms of an E. coli O157:H7 infection are:
Nausea and vomiting.
Some people do not notice any symptoms.
Children are more likely than adults to have symptoms. Symptoms usually start 3
or 4 days after you come in contact with the E. coli.
Most people get better in about a week. They often
don't see a doctor and don't know that E. coli caused
When E. coli causes
serious problems with the blood or kidneys, symptoms include:
small amounts of urine.
How is an E. coli intestinal infection
Your doctor may suspect that you have an
E. coli infection after he or she asks you questions and
does an exam. Your stool will probably be tested for E. coli.
How is it treated?
infection usually goes away on its own. Your main treatment is to make yourself
comfortable and drink sips of water. Diarrhea causes the body to lose more
water than usual. This can lead to
dehydration, which is especially dangerous for babies
and older adults. Taking frequent, small sips of water will help prevent
If you have bloody diarrhea that may be from an
E. coli infection, do not take diarrhea medicine or
antibiotics. These medicines can slow down the digestion process, allowing more
time for your body to absorb the poisons made by the E. coli. Call your doctor instead.
In some people,
E. coli infection causes serious problems with the blood
and kidneys. These people may need
blood transfusions or
dialysis. Dialysis is a treatment that helps filter
waste products from the blood when the kidneys aren't working right.
How do you prevent an E. coli
Food and water that are infected with E. coli germs look and smell normal. But there are some things
you can do to prevent infection:
beef to at least 160°F (71°C).
In the kitchen, wash your hands
with hot, soapy water often, especially after you touch raw meat.
Wash any tools or kitchen surfaces that have touched raw meat.
only pasteurized milk, dairy, and juice products.
treated, or chlorinated, drinking water.
When you travel to
countries that may have unsafe drinking water, don't use ice or drink tap
water. Avoid raw fruits and vegetables, except those with skin that you peel
Wash your hands often, and always wash them after you
use the bathroom or change diapers.
Children are more likely than adults to
develop symptoms of
E. coli O157:H7 infection. Most people with the
infection will have:
Severe stomach cramps and stomach
Diarrhea, watery at first, but often becoming very
Nausea and vomiting.
Some people who are infected with the bacteria do not
notice any symptoms. They may spread the bacteria to others without knowing
There are many
conditions with symptoms similar to those of E. coli intestinal infection. Diagnosis of E. coli infection can be
complicated by the fact that most bacterial infections that cause diarrhea are
accompanied by a high fever. If you have no fever or only a mild fever, your
doctor may suspect that something other than bacteria is causing your
Bloody diarrhea is common in confirmed cases of
E. coli intestinal infection, but the bacteria also should be
considered a possible cause of non-bloody diarrhea.
For more information on
when to call a doctor about non-bloody diarrhea, see:
E. coli infection usually end in about a week with no
further problems. But
severe blood and kidney problems may occur within 2 weeks after the onset of diarrhea. These problems can
cause kidney failure and sometimes long-term disability or death in some
children and older adults.
Exams and Tests
The medical evaluation for diarrhea
that may be caused by
E. coli O157:H7 bacteria usually starts with a
physical examination and a medical history.
During the medical
history, your doctor will ask questions about your symptoms, such as:
When did diarrhea begin, how long has it
lasted, and how frequent are bowel movements?
Is there blood in the
diarrhea? If so, how much?
Have you had chills or a
Have you had any abdominal cramps, nausea, or
Do you feel tired or irritable?
fainted or felt lightheaded?
Infection with E. coli is easily
other conditions with similar symptoms, such as other infectious
A doctor may suspect you have E. coli infection if you have been exposed to the bacteria. During the
medical history, your doctor may ask if you have:
Been in a day care center, school, nursing
home, or other adult care institution.
Eaten recently at a
Consumed any undercooked meat or unpasteurized milk, dairy products, or
Had contact with
anyone with recent or ongoing diarrhea.
Used antibiotics recently.
During the physical examination, a doctor will
Take your temperature.
blood pressure and determine your pulse rate.
Look at your skin
color to see whether you are unusually pale.
Check your stomach for
Perform a rectal exam to find out whether you have
blood in your stool.
Doctors who suspect E. coli
infection will order a type of
stool culture that detects strains of E. coli. Because the bacteria can leave the body in only a few
days, the sample should be obtained as soon as possible after symptoms
Other tests are sometimes used when the diagnosis is
unclear, but these are not yet widely available.
If a child or
older adult is diagnosed with E. coli infection, he or
she may be watched for development of
severe blood or kidney problems. Monitoring requires
blood and urine tests to measure essential elements of blood and body
Treatment of infection with
E. coli O157:H7 bacteria involves managing
dehydration caused by diarrhea.
Careful regulation of fluids and essential
Dialysis, to filter waste products from
your blood. Some people with kidney failure caused by E. coli infection require dialysis.
Blood transfusion, to treat anemia by giving you additional oxygen-rich red
Medicines to avoid
Most people recover from
E. coli infections in 5 to 10 days without the need for
Antibiotics are not recommended. Tell your doctor if
you think you may have E. coli infection and are taking
Nonprescription or prescription diarrhea medicines
usually are not used to treat E. coli infection. Many
antidiarrheal products slow the rate at which food and waste products move
through the intestines. This may allow more time for the body to absorb the
poisons produced by the bacteria, increasing the risk of complications such as
severe blood and kidney problems.
Avoid these nonprescription
products if you have or suspect you have an E. coli
Loperamide products. These include Imodium, Maalox, and other antidiarrheal products. Note: Only those products that list
loperamide in their ingredients should be avoided.
containing salicylates. These include Pepto-Bismol and similar bismuth-based
antidiarrheal products, aspirin, and ibuprofen (such as Advil). Salicylates can
increase bleeding from the intestines. Also, salicylates are associated with
Reye syndrome, a rare but serious illness in
Prescription diarrhea medicines may be harmful when given
to a person with E. coli infection. A doctor may
prescribe one of these medicines if he or she does not know that E. coli caused the diarrhea. Be sure to discuss your symptoms with your
doctor. Sharing information is important to get the proper diagnosis of your
Avoid these prescription medicines if you have or think
you may have an E. coli infection:
Loperamide (prescription-strength Imodium)
Home treatment of infection with
E. coli O157:H7 bacteria consists of keeping yourself
comfortable and preventing the spread of the bacteria. If you aren't infected,
take steps to prevent infection.
If you think that you or someone
in your care may be infected with E. coli, contact a
doctor immediately. Do not treat diarrhea symptoms with any nonprescription or
Home treatment for diarrhea or bloody diarrhea caused by
E. coli infection
Do not use nonprescription antidiarrheal
products if you have bloody or non-bloody diarrhea that you suspect may be
caused by E. coli infection. These products include
Imodium and Maalox Anti-Diarrheal. Do not take other medicines that you have
left over from a previous illness.
Take frequent, small sips of
water or a
rehydration drink to replace lost fluids and help
dehydration. Because dehydration can be more dangerous
in babies, call your doctor if you think your baby may be dehydrated. Your
stomach cannot handle too much fluid at one time. Seek medical care if you
develop signs of
moderate dehydration, which include:
Dry appearance inside the
Eyes that don't tear.
Low output of dark brown
Especially in children and adults age 65 and older, watch
for symptoms of
severe blood and kidney problems, such as fever,
weakness, pale skin, or passing small amounts of urine. If any of these
symptoms develop, see a doctor immediately.
Tips for protecting yourself against E. coli infection from contaminated food and water
Cook ground beef to a temperature of at least
Ground beef should be cooked until all pink color is
gone, but don't rely only on color. Check the temperature with a meat
thermometer. Cut open restaurant and home-cooked hamburgers to ensure that they
have been completely cooked. The juices should be clear or yellowish, with no
trace of pink. Never eat raw or undercooked ground beef.
Wash your hands often with hot, soapy
water, especially after handling raw meat.
Always wash cooking
tools, cutting boards, dishes, counter tops, and utensils with hot, soapy water
immediately after they have come into contact with raw meat. Do not put cooked
meat back onto a plate that has held raw meat unless the plate has been
thoroughly washed with soap and water and dried.
cutting boards for raw meat and for other food items.
meat, poultry, and seafood separate from vegetables, fruits, breads, and other
foods that have already been prepared for eating.
pasteurized milk, dairy, and juice products. Check
product labels for the word "pasteurized." Juice made from concentrate is the
same as pasteurized.
Use only treated (chlorinated) drinking
Travelers to countries where the water supply may not be safe
should be especially careful not to put ice in their drinks or drink tap water.
All water consumed should be boiled or bottled. Eat meals when they are hot.
Avoid raw fruits and vegetables, except those with skin that you peel
Tips for preventing person-to-person spread of E. coli bacteria
Wash your hands often, and always wash
them after bowel movements or changing diapers. If your home has more than one
bathroom, restrict the infected person to the use of one bathroom
Dispose of soiled diapers and stools carefully. If the
infection is suspected in a young child, use disposable diapers instead of
cloth diapers until the illness has passed.
Adults should make sure that
children who have diarrhea wash their hands thoroughly after using the
bathroom. Children infected with E. coli should avoid
contact with other children, particularly during swimming.
handles on toilets and sinks with an antibacterial cleaner.
who have been diagnosed with E. coli infection should
not handle food or work in a day care center or other institution until they
have tested negative for the bacteria in two stool samples. If you have taken any antibiotic, the stool sample
should be taken at least 48 hours after you took the last dose.
Chlorinate water in swimming pools and hot tubs.
Other Places To Get Help
Centers for Disease Control and Prevention (CDC) (U.S.)
International Food Information Council
Foundation: Food Insight (U.S.)
National Institute of Allergy and Infectious Diseases (U.S.)
Partnership for Food Safety Education: Fight Bac! (U.S.)
Safe Tables Our Priority (STOP) (U.S.)
Other Works Consulted
American Academy of Pediatrics (2009). Escherichia coli diarrhea (including hemolytic-uremic
syndrome). In LK Pickering et al., eds., Red Book: 2009 Report of the Committee on Infectious Diseases, 28th ed., pp. 294–298. Elk Grove
Village, IL: American Academy of Pediatrics.
American Public Health Association (2008).
Diarrhea, acute. In DL Heymann, ed., Control of Communicable Diseases Manual, 19th ed., pp. 179–195. Washington, DC:
American Public Health Association.
Donnenberg MS (2010). Escherichia section of Enterobacteriaceae. In
GL Mandell et al., eds., Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 7th ed., vol. 2,
pp. 2820–2826. Philadelphia: Churchill
Donnenberg MS (2010). Infections due to
Escherichia coli and other enteric Gram-negative bacilli. In EG Nabel, ed., ACP Medicine, section 7, chap. 8. Hamilton, ON: BC Decker.
Procop GW, Cockerill F III (2001). Enteritis caused by
Escherichia coli and Shigella and
Salmonella species. In WR Wilson et al., eds.,
Current Diagnosis and Treatment in Infectious Diseases,
pp. 548–556. New York: McGraw-Hill.
Primary Medical Reviewer
E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer
W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
How this information was developed to help you make better health decisions.