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Bacterial & Viral Infections

E. Coli

Lee este articuloThat big, juicy burger looked delicious and it was cooked just the way Jon liked — charred on the outside, pink in the middle. But a couple of days later, Jon found himself in the bathroom with a bad case of diarrhea. That yummy burger, unfortunately, came with a side of E. coli bacteria.

Infections due to Escherichia coli (E. coli) bacteria can cause severe, bloody diarrhea. Some cases can lead to serious health problems. Fortunately, most healthy people who get the infection don’t develop serious problems and recover on their own without needing treatment.

How It Spreads

Some strains of E. coli naturally live in our intestines and are usually harmless. Others, like E. coli O157:H7, spread through contaminated food or water, or from other infected people or animals, and can cause problems.

Most often, E. coli is transmitted when someone eats food containing the bacteria. At-risk foods include:

  • undercooked ground beef (such as in hamburgers that are pink inside)
  • produce grown in manure from cows, sheep, goats, or deer
  • produce washed in contaminated water
  • unpasteurized dairy or juice products

Top Things to Know about E. ColiThe bacteria also can spread from person to person on unwashed hands and surfaces, by swimming in contaminated water, and from touching animals at farms or petting zoos.

Symptoms & Complications

Some types of E. coli bacteria make a toxin (a poisonous substance) that can damage the lining of the small intestine. This can lead to bad stomach cramps, vomiting, and diarrhea (often with blood in it). When that happens, people can get dehydrated.

Symptoms usually start 3-4 days after a person has come into contact with the bacteria and end within about a week. An infection is contagious for at least as long as the person has diarrhea, and sometimes longer.

Most people recover completely, although some develop a serious kidney and blood problem called hemolytic uremic syndrome (HUS). Signs of HUS include:

  • decreased urination
  • a pale or swollen appearance
  • unexplained bruises
  • bleeding from the nose or gums
  • fatigue
  • seizures

HUS can be life threatening and requires treatment in a hospital.

When to Call the Doctor

Call your doctor if you have any symptoms of an E. coli infection, especially stomach pain or persistent, severe, or bloody diarrhea.

Call immediately if you see signs of dehydration, such as decreased urination, or of hemolytic uremic syndrome, especially if you’ve had a recent gastrointestinal illness.


If you think you have an infection, your doctor might take a stool sample to look for E. coli bacteria. Your doctor’s office may order a blood test to check for possible complications.

Some things to know about treating E. coli infections:

  • Antibiotics aren’t helpful in treating infections caused by E. coli O157:H7. In fact, they can be harmful.
  • Anti-diarrheal medicines can increase the risk of complications. If you think you have an E. coli infection, don’t use them.
  • If you have an E. coli infection, rest as much as possible and drink plenty of fluids to avoid dehydration.

Someone who becomes dehydrated might need to be hospitalized to get IV fluids, and those with HUS may require dialysis for kidney failure and/or blood transfusions.

While recovering from an infection, you can go back to your normal activities after two stool cultures are free of the bacteria. Don’t use swimming pools or water slides until 2 weeks after your symptoms have gone away.


E. coli outbreaks have been traced to a wide variety of foods, including fresh spinach, hamburgers, ground beef, bologna, hazelnuts, packaged cheeses, shredded lettuce, and prepackaged cookie dough.


Practicing safe food preparation is a key step in protecting yourself from an E. coli infection:

  • Cook meat thoroughly until it reaches a temperature of at least 160ºF/70ºC at its thickest point.
  • Thoroughly clean anything that comes into contact with raw meat.
  • Choose pasteurized juices and dairy products.
  • Clean raw produce well before eating.

Don’t forget the importance of hand washing. Wash your hands often and well, especially after going to the bathroom, touching animals, coming in from outside, and before eating or preparing food. Avoid swallowing water while swimming.

Reviewed by: Larissa Hirsch, MD
Date reviewed: July 2014