Escherichia coli (E. coli) are bacteria that live in human and animal intestines. Shiga toxin-producing strains of E. coli, or STECs, are responsible for most food-related E. coli infections. E. coli O157:H7 and other STECs like E. coli O111, E. coli O145 and E. coli O121:H19 produce a toxin called Shiga toxin, which causes illness in humans. E. coli bacteria do not make animals such as livestock and deer, which harbor the bacteria in their intestines, ill.

It is estimated that E. coli infections account for over 2,000 hospitalizations in the United States each year, according to a 2011 CDC report.

Sources of E. coli

E. coli O157:H7 is most commonly found in cows, although chickens, deer, sheep, and pigs have also been known to carry it. Meat becomes contaminated during slaughter, when infected animal intestines or feces come in contact with the carcass. Ground or mechanically tenderized meats are considered riskier than intact cuts of meat because E. coli bacteria, can be mixed throughout the meat in the grinding process or during tenderization.

Other foods that sometimes become contaminated with E. coli bacteria include unpasteurized milk and cheese, unpasteurized juices, alfalfa and radish sprouts, lettuce, spinach, and water. However, any food is at risk of becoming contaminated with E. coli through cross-contamination. One can also get E. coli bacteria from contact with feces of infected animals or people.

The breakdown of sources of E. coli bacteria from 1998-2007 was as follows:

  • Food: 69%
  • Water: 18%
  • Animals or their environment: 8%
  • Person-to-person: 6%

Symptoms of E. coli

E. coli symptoms change as the infection progresses. Symptoms usually begin two to five days after infection. The initial symptoms include the sudden onset of cramps and abdominal pain, followed by diarrhea within 24 hours. Diarrhea will become increasingly watery, and then noticeably bloody. People with E. coli infection also often feel nauseated and experience headaches. Less common symptoms include fever and chills.

HUS: A Rare but Serious Complication

Hemolytic Uremic Syndrome, or HUS, follows around 10 percent of E. coli O157:H7 infections. HUS occurs when Shiga toxins get into the bloodstream and cause the part of the kidney that filters toxins out of the blood to break down, causing kidney injury and sometimes kidney failure.  Some HUS patients also suffer damage to the pancreas and central nervous system impairment.

Diagnosis of E. coli

Shiga toxin-producing E. coli infection can be diagnosed in a doctor’s office or hospital by laboratory analysis of a stool sample.

Bacteria isolated from patients’ stool samples can be compared through laboratory analysis, helping to match strains of E. coli to the food or other source it came from, a process called “fingerprinting.”

Treatment for E. coli Infection

Illness from E. coli usually goes away within a week and does not cause any long-term problems.  One should make sure to remain hydrated and get proper nutrition while sick.

Antibiotics are not used as E. coli treatment, as they do not improve the illness, and some studies show that they can increase the risk of HUS.

HUS is treated by hospitalization. Since there is no way to directly cure HUS, treatment includes care to alleviate symptoms.

Preventing Infection from E. coli Bacteria

Any food that you eat has the potential to be contaminated with E. coli bacteria. This is why it is important to take precautions in preparing food and before eating at restaurants. You should also be aware that E. coli bacteria can survive for several weeks on surfaces, so keeping countertops clean is important. Other simple steps you can take to reduce your risk of E. coli infection include:

  • Wash hands thoroughly before and after eating and after going to the bathroom
  • Sanitize all fruits and vegetables before eating by skinning them if possible and washing them before eating
  • Check with your local department of health to find out which restaurants in your area have had recent problems with sanitation
  • Avoid allowing raw meats to come into contact with other foods while cooking
  • Do not allow children to share bath water with anyone who has diarrhea or symptoms of stomach flu
  • Wash hands thoroughly after any contact with farm animals
  • Wear disposable gloves when changing diapers of children with diarrhea
  • Make sure ground meat (such as hamburger patties) reaches an internal temperature of at least 160°F
  • Avoid drinking any non-chlorinated water

Additional Resources for E. coli is a comprehensive site with in-depth information about E. coli bacteria and E. coli infection. is a Website that provides information about lawsuits and litigation brought on behalf of victims of E. coli outbreaks nationwide.

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