Escherichia Infection
Escherichia coli, or E. coli, is a type of bacteria that naturally lives in the digestive system of humans and animals. While most strains are harmless and even helpful, certain types can cause illnesses ranging from mild stomach upset to life-threatening complications.
Table of contents
- What is E. coli?
- Types of E. coli Infections
- Symptoms of E. coli Infection
- How Do People Get Infected?
- Who Is at Higher Risk?
- How Is E. coli Diagnosed?
- Treatment Options
- Serious Complications
- How to Prevent E. coli Infection
What is E. coli?
Escherichia coli (E. coli) is a type of bacteria that commonly lives in the intestines of healthy people and animals[1]. Most types of E. coli are harmless and are actually part of a healthy digestive system. These bacteria help digest food, produce vitamins, and protect the body from harmful germs[1].
The bacteria belong to a larger group of organisms that normally live in the lower intestine of warm-blooded animals[3]. In fact, E. coli makes up about 0.1% of the normal bacteria in your gut and usually doesn’t hurt you—it can even be beneficial to your health[6].
However, some types of E. coli can cause serious illness. These harmful strains produce toxins or have other features that allow them to cause disease when they enter your body[2]. The bacteria can be found in many places, including the environment, in foods, in water, and in the intestines of people and animals[1].
Types of E. coli Infections
E. coli can cause different types of infections depending on where in your body the bacteria end up. The most common types include infections in the digestive system and urinary tract[2].
Intestinal infections are the most well-known type of E. coli illness. Scientists have identified several different strains that cause diarrhea, and they categorize them by how they attach to your cells and the types of toxins they release[2]. The most serious type is Shiga toxin-producing E. coli (STEC), also called enterohemorrhagic E. coli (EHEC)[3]. There are about 265,000 STEC infections each year in the United States, making it the most common cause of E. coli outbreaks[2].
Other strains that cause intestinal illness include enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC), and diffusely adherent E. coli (DAEC)[2]. Each type causes similar symptoms but works in slightly different ways.
E. coli can also cause infections outside the intestines. When the bacteria that normally live in your gut get into places they shouldn’t be, such as your urinary tract, they can cause problems[2]. Other possible infections include bloodstream infections, lung infections (pneumonia), gallbladder infection, prostate infection, pelvic inflammatory disease, wound infections, and rarely, meningitis[2].
Symptoms of E. coli Infection
The symptoms you experience depend on where the infection occurs in your body. For intestinal infections, the most common symptoms include watery diarrhea that may become bloody, stomach cramps and pain, nausea, vomiting, loss of appetite, and a low fever[2][5].
Watery diarrhea is usually the first sign of an E. coli infection in your digestive system[2]. The illness often begins with stomach cramping and diarrhea that may range from mild and watery to severe and bloody[5]. Some people also experience nausea and vomiting[5].
Symptoms typically begin three to four days after you come into contact with the bacteria, but they can start as soon as one day or as late as ten days after exposure[5][3]. Most people recover within about one week, though the time can vary[7].
If E. coli infects your urinary tract, you might have different symptoms. These include pain in your abdomen or pelvis, a burning sensation when you urinate, an urgent need to urinate frequently, and cloudy or foul-smelling urine[2][13].
How Do People Get Infected?
People get E. coli infections when they swallow the bacteria. This usually happens through contaminated food or water, or through contact with animals, environments, or other people who are infected[1].
Contaminated food is the most common source of infection. It’s estimated that 85 percent of current E. coli infections come from food[20]. The bacteria can get onto the outer surface of meat during slaughter or processing, and this contamination can spread throughout the meat, especially in ground beef[3][7].
Eating undercooked meat, particularly ground beef, is a major risk factor. The bacteria can survive if the meat isn’t cooked thoroughly[7]. Raw or undercooked ground meat products are primary sources of STEC outbreaks[3].
Other foods can also be contaminated. Raw fruits and vegetables can pick up E. coli while growing in fields through improperly composted manure, contaminated water, or contact with wildlife[24]. Fresh leafy greens like spinach, lettuce, and alfalfa sprouts have been linked to infections[20]. Raw milk and unpasteurized dairy products can also carry the bacteria[3].
Water is another source of infection. You can get E. coli from drinking untreated water or swimming in contaminated water from lakes, ponds, or pools[7][18]. Water sources can become contaminated when exposed to human or animal waste[14].
Direct contact can also spread the infection. You can get E. coli through contact with infected people, especially if exposed to their vomit or stool[13]. Without good hygiene and regular handwashing, the bacteria can spread from person to person in homes, daycare centers, nursing homes, and hospitals[20]. Handling animals that carry the bacteria, such as farm animals or pets, can also lead to infection[13].
Who Is at Higher Risk?
While anyone can get an E. coli infection, some groups of people are more likely to become infected and more likely to develop serious complications[1].
Young children, especially those younger than five years old, are at increased risk[1]. Their immune systems are still developing, making it harder to fight off the infection. Children under five are also at higher risk of developing hemolytic uremic syndrome, a serious complication that can cause kidney failure[5][20].
Adults aged 65 and older are also at higher risk for both infection and serious illness[1]. Older adults are more likely to experience severe complications and have worse outcomes if they develop hemolytic uremic syndrome[16].
People with weakened immune systems have a greater risk of contracting E. coli and experiencing severe illness[1][14]. This includes people with certain medical conditions or those taking medications that suppress the immune system.
International travelers may be at increased risk, particularly when traveling to areas with different food safety standards or water treatment practices[1]. People taking antacids also face higher risk because stomach acid normally helps kill bacteria that are swallowed[14].
How Is E. coli Diagnosed?
To diagnose an E. coli infection, your doctor will need to test a sample of your stool in a laboratory[5][9]. The laboratory can identify whether E. coli bacteria are present in the sample and can determine which specific type of E. coli is causing the infection.
For patients with diarrheal illness, stool samples should be tested for E. coli O157 and simultaneously checked for non-O157 STEC using tests that detect Shiga toxins or the genes that produce them[16]. The bacteria may be grown in a laboratory culture to confirm the diagnosis and identify specific toxins, such as those produced by E. coli O157:H7[9].
Getting an accurate diagnosis quickly is important because early clinical decisions can affect how well patients recover, and early detection can help prevent the spread of infection to others[16].
If hemolytic uremic syndrome is suspected, doctors use standard blood chemistry tests and blood count tests to make the diagnosis[16]. These tests can show whether the infection has affected the blood and kidneys.
Treatment Options
Most people with E. coli infections recover on their own without needing antibiotics[10]. The main treatment focuses on making yourself comfortable and preventing dehydration, which means not having enough water in the body[10].
For most people, treatment includes rest and drinking plenty of fluids to help prevent dehydration and fatigue[9][10]. Diarrhea causes the body to lose more water than usual, which can be especially dangerous for babies and older adults[7]. Taking frequent, small sips of water throughout the day helps prevent dehydration[7].
It’s important to know that anti-diarrheal medications should be used carefully. You should talk to your healthcare provider before taking medications like Imodium[10]. These medications slow down your digestive system, which prevents your body from getting rid of the toxins[9]. They might help with diarrhea and cramps, but they can make your illness last longer[10].
Importantly, do not use anti-diarrheal medication if you have a high fever or bloody diarrhea[10]. With STEC infections, using these medications can increase the chance of developing hemolytic uremic syndrome[10]. Medications containing bismuth subsalicylate, such as Pepto-Bismol, should not be used in children younger than 12[10].
Antibiotics are generally not recommended for E. coli infections. Most people get better without antibiotics, and using them can actually increase the risk of serious complications[9][10]. With STEC infections specifically, antibiotics should not be used because they can increase the chance of developing hemolytic uremic syndrome[10][12]. Antibiotics may cause the bacteria to release more toxins, worsening the condition.
In some cases, antibiotics are used to treat severe intestinal illness or for people at risk for severe illness[10]. For certain types of E. coli infections, such as those causing traveler’s diarrhea, antibiotics like azithromycin, fluoroquinolones, and rifaximin can shorten the duration of diarrhea by 24 to 36 hours[12].
Serious Complications
While most people recover completely from E. coli infections, some can develop serious health problems. The most concerning complication is hemolytic uremic syndrome (HUS), which can be life-threatening[1][3].
HUS is characterized by three main problems: red blood cells are destroyed (hemolytic anemia), the kidneys fail (acute renal failure), and blood platelet counts drop very low (thrombocytopenia)[3][16]. It’s estimated that up to 10% of patients with STEC infection may develop HUS[3].
HUS can lead to kidney failure, permanent health problems, and even death[1]. In the United States, E. coli-related HUS is the main cause of kidney failure among children[20]. The death rate for HUS is 3 to 5 percent[20].
Young children and older adults are particularly at risk for developing HUS[3][5]. The condition usually occurs in these vulnerable groups after a STEC infection, particularly in young children and the elderly[3].
If HUS develops, patients usually need intensive care treatment. This may include management of fluids and electrolytes, dialysis to help the kidneys, and transfusions of red blood cells or platelets[16][9]. With good supportive care, most people with HUS recover completely, though outcomes are typically better for children than adults[16].
Evidence from studies of children with STEC O157 infection shows that giving intravenous fluids early—within the first four days after diarrhea starts—may decrease the risk of developing kidney failure[16].
How to Prevent E. coli Infection
The good news is that you can take several steps to help keep yourself and your family safe from E. coli infection[1]. Prevention focuses on good hygiene, safe food handling, and avoiding contaminated water.
Hand Hygiene: Washing your hands is one of the best ways to protect yourself and others from getting sick[18]. Wash your hands thoroughly with hot, soapy water, especially after using the bathroom, changing diapers, handling raw meat, and before handling or eating food[7][18]. It’s especially important that people with diarrhea, particularly children, wash their hands thoroughly after using the bathroom to prevent spreading infection[7].
Safe Food Handling: Follow four simple steps when preparing food at home: clean, separate, cook, and chill[18]. Never eat raw or undercooked ground beef or pork. Cook ground meat to a temperature of at least 71°C (160°F) and always use a meat thermometer[7]. Ground beef should be cooked until all pink color is gone[7].
Cut open hamburgers to make sure they have been completely cooked. The juices should be clear or yellowish, with no trace of pink[7]. Always wash cooking tools, cutting boards, dishes, countertops, and utensils with hot, soapy water right after they touch raw meat[7]. Do not put cooked meat back on a plate that held raw meat unless you have thoroughly washed the plate[7].
Use separate cutting boards for raw meat and other food items[7]. Keep raw meat, poultry, and seafood separate from vegetables, fruits, breads, and other foods that are ready to eat[21].
Wash raw fruits and vegetables under running water before eating them[21]. Only use pasteurized milk, dairy, and juice products—look for the word “pasteurized” on the label[7][18]. Juice made from concentrate is the same as pasteurized[21].
Water Safety: At home, having safe drinking water may be as simple as turning on the tap, but sometimes extra steps are needed[18]. When camping, hiking, or traveling, always use safe water for drinking, cooking, and brushing your teeth[18]. Don’t swallow water when swimming or playing in lakes, ponds, streams, swimming pools, and backyard pools[18].
Animal Contact: Wash your hands after contact with farm animals, animal feces, and being in farm environments[18]. Be especially careful at petting zoos and fairs where you might come into contact with cattle or other farm animals[24].
Preventing Spread: If you are sick with diarrhea, don’t swim or let others swim[18]. Dispose of soiled diapers and stools carefully[7]. Ask your doctor when it will be okay to handle food or work in a daycare center or other institution if you’ve been infected[21].
