E. Coli: What It Is, Causes, Symptoms & Treatment

E. Coli in Raw Meat May Cause Half-a-Million UTIs in the U.S. Every Year, Study Finds
E. Coli in Raw Meat May Cause Half-a-Million UTIs in the U.S. Every Year, Study FindsHealthDay
Medically Reviewed By:
Mark Arredondo, M.D.

Every year, an estimated 265,000 people in the U.S. suffer from infections caused by a type of bacteria known as Shiga toxin-producing E. coli, according to the U.S. Centers for Disease Control and Prevention.

When E. coli outbreaks are in the news, it's typically E. coli O157 making the headlines. This infectious disease can lead to various gastrointestinal symptoms, from mild to severe, including abdominal cramps, diarrhea and vomiting. This article will explore what E. coli infection is, its causes, symptoms and treatment options.

What is E. coli?

E. coli is a common bacterium normally present in our gut. Most strains that live in our gut are normal flora of the intestines and skin, especially around the external genitalia, anus and pelvic area. They are not harmful/pathogenic when present there,” said Dr. Supriya Narasimhan, chief of infectious diseases at Santa Clara Valley Medical Center in San Jose, Calif.

How do you get an E. coli infection?

“When E. coli enters organs where it usually is not found, it can cause an infection," Narasimhan said.

Most people who get E. coli infections are infected by organisms they carry in their gastrointestinal tracts. E. coli can also be present and transmitted by contaminated food and water. Certain strains of E. coli spread this way can cause food-borne illness, including abdominal cramps, diarrhea and vomiting.

The Mayo Clinic says the primary route of E. coli transmission is consumption of contaminated food, including:

  • Ground beef: During the slaughter and processing of cattle, E. coli bacteria from their intestines can come into contact with the meat. Ground beef, which combines meat from various animals, poses an even greater risk of contamination.
  • Unpasteurized milk: E. coli bacteria present on a cow's udder or milking equipment can find their way into raw milk, potentially causing infection if consumed.
  • Fresh produce: Fields where fresh produce grows can become contaminated by runoff from cattle farms. Certain vegetables, such as spinach and lettuce, are particularly susceptible to this type of contamination.

“Traveler’s diarrhea is caused by ... [a form of E.coli nicknamed] O157:H7, which is also transmitted by contaminated food and water and can cause food poisoning with more serious consequences like Hemolytic Uremic Syndrome [a rare disease where red blood cells are destroyed and kidney failure can result],” Narasimhan said.

E. coli is also a common cause of urinary tract infections (UTIs), according to the University of California, San Francisco. UTIs, also known as bladder infections or cystitis, occur when bacteria, primarily E. coli, enter the bladder through the urethra, where they multiply.

Normally, urine is sterile and has no harmful bacteria. However, E. coli, which typically reside harmlessly in the intestinal tract, can cause serious infections if it enters the urinary tract. The short distance between the anus and urethra in women makes them more susceptible.

To prevent UTIs, practicing proper hygiene, especially wiping from front to back after using the toilet for women, is important. Untreated UTIs can progress to more severe kidney infections. Women who are sexually active, pregnant or older are at higher risk for UTIs.

E. coli infection symptoms

The CDC says that the symptoms of infection can differ from person to person, but commonly include intense abdominal cramps, diarrhea (frequently containing blood), and episodes of vomiting. In certain cases, individuals may have a mild fever, typically with a low-grade temperature (below 101 degrees Fahrenheit). A majority recover within five to seven days. While some infections are mild, others can be severe, and in rare instances, even life-threatening.

What are the first signs of E. coli?

Typically, symptoms of an infection emerge three to five days after consumption of food or drink tainted with this strain of E. coli bacteria, according to the Cleveland Clinic. It is, however, possible to experience symptoms as soon as one day after exposure or as late as 10 days after.

Typical E. coli symptoms include:

  • Stomach pains and cramps
  • Diarrhea (can vary between watery to bloody)
  • Vomiting
  • Nausea
  • Loss of appetite
  • Severe exhaustion
  • Low fever (less than 101 degrees F)

Is E. coli contagious?

E. coli can spread from person to person when people do not wash their hands well after they use the bathroom or handle human/animal poop and touch other people, or handle food," Narasimhan said. "It can also cause food and water contamination and spread that way.”

Can E. coli kill you?

E. coli infections have the potential to be fatal. The North Carolina Department of Health and Human Services says about 100 deaths a year in the United States a year are due to E. coli infections.

"As with any bacteria, serious E. coli infections and infections that are not treated promptly or correctly can be fatal," Narasimhan said.

While many E. coli infections result in mild to moderate gastrointestinal discomfort and resolve without major complications, it is essential to seek prompt and appropriate medical attention, especially in severe cases, to reduce the risk of potentially life-threatening outcomes.

E. coli infection treatment

“Many common antibiotics are effective against E coli," Narasimhan said. "The correct choice depends on the site of infection in the body, the patient’s severity of illness and the pattern of resistance. Common antibiotics used are Bactrim, Augmentin, Ceftriaxone, Cefazolin and ciprofloxacin, to name a few, but it is very important to consult with a physician to decide on the best treatment strategy."

Many forms of E.coli diarrhea get better on their own without antibiotics, and only supportive care such as rest and hydration are necessary, she said.

Living with E. coli infection

“People with an E. coli infection should pay special attention to proper handwashing and avoiding contamination of food," Narasimhan said. Hydration is always helpful when dealing with an infection.

Patients should take the treatment recommended by their physician and seek prompt medical attention if they cannot keep fluids down, have bleeding in stools, extreme fatigue, high fevers, low urine output or dizziness/fainting start to develop. "All of these may indicate need for hospitalization,” Narasimhan said.


Supriya Narasimhan, MD, chief, infectious diseases, Santa Clara Valley Medical Center, San Jose, Calif.

U.S. Centers for Disease Control and Prevention: E. Coli (Escherichia Coli)

Mayo Clinc: E. coli

Cleveland Clinic: E. coli Infection

North Carolina Department of Health and Human Services: Escherichia coli (E. coli) Infection

University of California, San Francisco: Urinary Tract Infections

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