What causes an E. coli infection?

Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)

Escherichia coli (E. coli) infection is caused by fecal material from cattle, and the bacteria can contaminate meat during processing and also spill over into the water supply used to irrigate crops.

In E. coli poisoning, bacteria multiply on food. After ingestion, E. coli eventually lands in the small intestine. As the body's immune system tries to fight off the bacteria, damage is caused to the lining of the intestinal wall, causing blood to leak into the intestinal tract, creating bloody diarrhea. This condition, known as hemorrhagic E. coli, can travel throughout the bloodstream, putting you at risk for serious complications such as sepsis, or blood poisoning. Seek medical assistance if you think you've contracted this invasive food-borne illness.

This content originally appeared on
An E. coli infection develops when a person comes into contact with the fecal matter or stool of humans or animals, either through contaminated drinking water or food that has been contaminated by feces. E. coli is the name of a species of bacteria that lives in the digestive tract of humans and animals. The vast majority of strains of E. coli are harmless, though some can cause bloody diarrhea, severe anemia, acute renal failure, urinary tract infections and systemic infections that are life-threatening, such as sepsis and septic inflammatory response syndrome. 

The most common way people in the United States become infected with E. coli has been in contact with raw and undercooked meat. During livestock processing, E.coli can infect the butchered meat. If the infected meat is undercooked, the bacteria can survive and infect you when you eat the meat. Other foods can also be infected with E. coli. Bacteria can spread from a cow's udders to its unpasteurized milk and end up in raw milk or dairy products. Due to variable fertilizer use and multipurpose livestock and crop farms, people can be exposed to E. coli from raw fruits and vegetables, such as lettuce, alfalfa sprouts, unpasteurized apple cider or other unpasteurized juices that have come in contact with infected animal feces.

E. coli sometimes infects our water sources as well. When a swimmer accidentally swallows contaminated water that has been improperly treated, he stands a high risk of contracting the E.coli that live in that lake, river, stream, pool or hot tub. E. coli can also spread from person-to-person contact. E. coli can spread from an infected person's hands to another person’s hands or even from objects that are shared. Usually, when an infected person does not wash his hands well enough after a bowel movement, the bacteria E.coli can spread to another unsuspecting person.

Continue Learning about E-Coli Food Poisoning

E. coli: What You Need to Know
E. coli: What You Need to Know
In the United States alone, about 48 million people get sick from foodborne illnesses each year. But only 128,000 of these people are hospitalized as ...
Read More
What are the symptoms of Enterohemorrhagic Escherichia coli infection?
Leigh Vinocur, MDLeigh Vinocur, MD
Symptoms of  enterohemorrhagic E Coli are bloody diarrhea and fever. Most healthy people recover...
More Answers
What is enterohemorrhagic E. Coli?
Leigh Vinocur, MDLeigh Vinocur, MD
A more dangerous strain of E Coli is E Coli 0157:H7, also called enterohemorrhagic E Coli. This ...
More Answers
What are the symptoms of ecoli infection from food or water?
Univ. of Nev. School of Medicine, Family MedicineUniv. of Nev. School of Medicine, Family Medicine
When a person is infected with E. coli from food or water, he generally experiences diarrhea and som...
More Answers

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.