Escherichia coli (E. coli) is a bacteria that normally lives in the intestines of both healthy people and animals. In most cases, this bacteria is harmless. It helps digest the food you eat. However, certain strains of E. coli can cause symptoms including diarrhea, stomach pain and cramps and low-grade fever. Some E. coli infections can be dangerous.
E. coli is a rod-shaped bacterium of the Enterobacteriaceae family. It can live in environments with or without air. These bacteria live in the intestines of healthy people and warm-blooded animals.
Six different strains of E. coli are known to cause diarrhea. These strains are:
The most familiar strains of E. coli that make you sick do so by producing a toxin called Shiga. This toxin damages the lining of your small intestine and causes your diarrhea. These strains of E. coli are also called Shiga toxin-producing E. coli (STEC). The STEC that is most well-known in North America and most often referred to is E. coli O157:H7, or just E. coli O157
There are other types of STEC that are called non-O157 STEC. These strains cause similar illness to the O157 strain but are less likely to lead to serious complications.
Anyone who comes into contact with a disease-causing strain of E. coli can become infected. People who are at greatest risk are:
According to the Centers for Disease Control, about 265,000 STEC infections occur in the United States each year. The STEC O157 strain causes about 36% of these infections and non-O157 STEC strains cause the rest. The actual number of infections is thought to be even higher because many people do not go to their healthcare provider for their illness, many don’t provide a stool sample for testing and many labs do not test for non-O157 STEC strains.
People who get infections with the STEC strain of E. coli can have the following symptoms:
You usually develop symptoms of a STEC infection within three to five days after drinking or eating foods contaminated with this E. coli bacteria. However, you could have symptoms as early as one day after exposure up to about 10 days later.
Your symptoms can last from five to seven days.
Most cases of E. coli infections are mild and do not cause a serious health risk. Cases resolve on their own with rest and drinking plenty of fluids. However, some strains can cause severe symptoms and even life-threatening complications, such as hemolytic uremic syndrome, which can lead to kidney failure and death.
Some people, especially children age five and under, who become infected with a STEC infection (the O157:H7 strain) develop a condition called hemolytic uremic syndrome (HUS). In this condition, toxins in your intestines from STEC cause diarrhea, travel into your bloodstream, destroy red blood cells and damage your kidneys. This potentially life-threatening illness develops in about 5% to 10% of people who are infected with STEC.
Early symptoms of HUS include:
As disease progresses, symptoms include:
If you develop severe diarrhea (lasting longer than three days or you can’t stay hydrated) or if you have bloody diarrhea, go to the hospital for emergency care. HUS, if it develops, occurs an average of 7 days after your first symptoms occur. It is treated with IV fluids, blood transfusions and dialysis (for a short period of time).
Technically, you develop an E. coli infection by ingesting (taking in by mouth) certain strains of E. coli bacteria. The bacteria travel down your digestive tract, releases a destructive toxin, called the Shiga toxin, which damages the lining of your small intestine. The growing infection causes your symptoms.
You come into contact and swallow E. coli by eating contaminated food, drinking contaminated water or by touching your mouth with your hands that are contaminated with E. coli bacteria.
When you hear the word “contagious,” you might immediately think of a cold or the flu – illnesses you can get from breathing in bacteria or viruses lingering in the air of a sick person’s cough or sneeze.
E. coli isn’t an airborne illness. It’s usually spread by eating contaminated food or drinking contaminated water that contains illness-producing strains of E. coli. (Remember not all strains of E. coli are harmful.)
E. coli can, however, be contagious and spread from person to person by the “oral-fecal route.” This means that harmful strains of E. coli are spread when people don’t wash their hands thoroughly with soap and water after they use the bathroom or otherwise touch poop (after changing baby diapers or older person’s incontinence undergarments, or petting zoo or farm animals that may have soiled fur) and they touch other people. People then get the invisible E. coli on their hands and swallow it when it is transferred from their hands to the food they eat or from putting their fingers in their mouth. E. coli spreads from person to person this way in settings such as day care centers and nursing homes.
STEC infections are diagnosed by sending a sample of your poop to a laboratory. Many labs can test for both STEC O157 and non-O157 STEC bacterial infections.
Call your healthcare provider’s office. They may have you come in for an office visit and give you a sterile stool collection cup and specific directions to follow for how to collect a stool sample. They may also email specific instructions for collecting a sample at home.
Some general instructions for collecting a stool sample at home include:
Most laboratories report back the results within two to four days. Your healthcare provider will call you with the results as soon as they become available or you may be notified of your results electronically if you have an online medical record set up with your doctor or healthcare facility.
Fortunately, most E. coli infections go away on their own. You can help yourself manage E. coli infection by drinking plenty of fluids to replace what you’ve lost through diarrhea and/or vomiting. Also, get as much rest as possible.
Antibiotics are usually not given for STEC O157 infection because they can make your illness worse and put you at risk for hemolytic uremic syndrome (HUS). Also, don’t take any medicines to stop diarrhea (such as bismuth subsalicylate [Pepto-Bismol®, Kaopectate®] or loperamide [Imodium®]), because it could keep the E. coli bacteria in your body and increase your chance of HUS.
You should start to feel better about five to seven days from the time you first developed symptoms.
See your healthcare provider about an E. coli infection if:
You have diarrhea for more than three days and:
The most important thing you can do to protect against E. coli infection is to wash your hands – frequently. Always wash your hands thoroughly before and after cooking and after handling raw meat or poultry.
Wash your hands after using the restroom, changing diapers or after contact with animals.
If you’ve been infected with E. coli, scrub your hands vigorously with soap and clean under your fingernails where bacteria can get caught. Dry your hands with paper towels instead of cloth towels to avoid transferring bacteria.
You can also reduce your risk of an E. coli infection by following these food preparation and cooking tips.
When thawing meats:
When prepping foods:
When cooking and serving meats:
It’s important to keep in mind that most strains of E. coli are harmless. They live naturally in your intestinal tract and help digest your food. Sometimes, however, you may eat food or drink water that is contaminated with illness-causing E. coli. Sometimes a mild E. coli infection will cause a brief bout of diarrhea. Other strains of E. coli, the Shiga toxin-producing E. coli (STEC), cause bloody diarrhea, vomiting, stomach pain and cramps. If you are otherwise healthy, you should recover from an E. coli infection within about a week without any treatment.
Although hemolytic uremic syndrome (HUS) is a serious complication, it is rare and occurs in about 5% to 10% of people. With early treatment and proper care, people can recover from HUS.
E. coli can survive outside the body from hours to months. It can live in soil for about 130 days. E. coli survives in river water for 27 days and in cattle slurry for 10 days. On stainless steel, E. coli was shown to survive for more than 60 days. It survives for at least 12 hours on wooden cutting boards.
Many factors affect how long E. coli can live outside the body including temperature, presence of water, availability of nutrients, pH and solar radiation.
Urinary tract infections are sometimes caused when E. coli from your gastrointestinal tract get into your urinary tract. This can happen more easily in women because the anus (where poop exits your body) is located close to the urethra (the tube from which urine exits the body). E. coli bacteria can travel up the urethra to the bladder and even up to the ureters and kidneys. You may have been told – if you are a woman – to always “wipe from front to back.” This is so you don’t accidently spread E. coli bacteria from your anus to your urethra.
The most common urinary tract infections caused by E. coli are a bladder infection (cystitis), infection of the urethra (urethritis) and kidney infection.
Drink clear liquids, such as broths, clear sodas and water. Stick with bland, low-fiber foods like toast, rice, plain crackers and applesauce. Stay away from high-fiber foods, fatty foods and dairy products.
Check with your healthcare provider. If your infection was part of a local outbreak, your local state health department may have specific instructions about when it’s safe to be around groups of people.
A note from Cleveland Clinic
The best and easiest way to avoid getting an E. coli infection is to frequently wash your hands with soap and water. Wash your hands before and after handling foods (including prepping, cooking and serving foods), after using the bathroom, after touching animals (especially farm or zoo animals), after changing diapers and after shaking hands or being touched by others (you never know what their hands have touched). Washing your hands can not only prevent contracting E. coli, but also many other infectious disease that are spread from person to person. Make frequent hand washing a new habit.
Keep in mind that most strains of E. coli are harmless. Even if you do come down with the STEC O157 strain, your symptoms will resolve on their own within five to seven days. Drink plenty of fluids to stay hydrated and get plenty of rest.
Do call your healthcare provider if you have diarrhea (and especially bloody diarrhea) for more than three days, have trouble keeping fluids down and have continuous bouts of vomiting and have a fever. These symptoms could mean you are developing serious complications that could lead to kidney failure.
Last reviewed by a Cleveland Clinic medical professional on 09/21/2020.