Shiga toxin-producing E. coli (STEC) Infections Fact Sheet

Last Reviewed: March 2023

What is STEC?

E. coli are a diverse group of bacteria that normally live in the intestines of humans and animals. Although most strains of these bacteria are harmless, some produce toxins that can make you sick and cause diarrhea (loose stool/poop) such as Shiga toxin-producing E. coli (STEC).

Who gets STEC infections?

Anyone can get STEC infection. Young children and the elderly are more susceptible to develop serious infection, but healthy older children and young adults can also become seriously ill.

How does STEC spread?

People become infected with STEC when they eat any product contaminated with the bacteria. The bacteria live in the intestines of healthy cattle, and contamination of their meat may occur during the slaughtering process. Infection most typically occurs by eating contaminated food, particularly raw or undercooked meat. Infection can also occur after eating any product contaminated with STEC, including lettuce, alfalfa sprouts, salami, and raw (unpasteurized) milk, juice, or cider. Infected people can spread E. coli to other people if they do not wash their hands after using the toilet.

What are the symptoms of STEC infections and when do they appear?

Symptoms of STEC infections can vary, but most often include severe diarrhea (loose stool/poop), stomach cramps, and vomiting. Diarrhea is often bloody and usually little or no fever is present. Symptoms typically appear 3-4 days after eating (or having direct contact with) a contaminated product, but can range from 1-10 days.

What complications can result from infection with STEC?

In some people, particularly children under five years of age, infection can lead to the development of hemolytic uremic syndrome (HUS). HUS is a serious life-threatening disease that can cause kidney damage or failure and other serious problems. Hospitalization is often required because transfusions of blood, plasma exchange, or kidney dialysis may be necessary. Fortunately, most people with HUS recover completely within a few weeks, although for some it can be fatal.

How are STEC infections diagnosed?

STEC infections are most often diagnosed through laboratory testing of stool (poop) specimens.

What is the treatment for STEC infections?

There is no specific treatment for STEC infections. Since diarrhea can cause dehydration (loss of water in the body causing weakness or dizziness), drinking plenty of fluids to stay hydrated is important. Antibiotics should not be used for the treatment of STEC infection since there is no evidence that antibiotics are helpful with these infections and may increase the risk of developing hemolytic uremic syndrome (HUS).

What can be done to help prevent STEC infections?

1. Always handle raw meat, especially ground beef, according to these recommendations:

• Wrap fresh meats in plastic bags at the market to prevent blood and juices from dripping on to other foods. Refrigerate promptly; do not store at room temperature.
• Never place cooked food on an unwashed plate that previously held raw beef, poultry, pork, fish, or seafood.
• Cutting boards and counters used for beef, poultry, pork, fish, or seafood preparation should be washed immediately after use to prevent cross contamination with other foods.
• Avoid eating raw or undercooked meats. While the juice color will usually change from red to gray when the meat is fully cooked, it is not a reliable test to assure it is safe to eat.
• Always check the temperature of cooked foods with a meat thermometer. Foods that reach the temperatures listed below (or higher) are considered fully cooked.

























Food	Temperature
Chicken	165° F
Hamburger	160° F
Pork	150° F
Hot dogs	140° F
Leftovers	165° F
Eggs	145° F
Other foods	140° F

Avoid drinking raw (unpasteurized) milk, juices, and ciders.

Shiga toxin-producing Escherichia coli – Testing.com

At a Glance

Why Get Tested?

To determine if your gastrointestinal symptoms are due to an infection caused by Escherichia coli bacteria that produce Shiga toxin

When To Get Tested?

When you have acute diarrhea that is persistent, severe and/or bloody

Sample Required?

A fresh liquid or unformed stool sample that does not contain urine or water, collected in a clean dry container; a rectal swab may be collected from infants. The stool or rectal swab may be placed in transport media for delivery to the laboratory.

Test Preparation Needed?

None

What is being tested?

Escherichia coli (E. coli) bacteria commonly occur in nature and are a necessary component of the digestive process. Most strains of E. coli are harmless, but disease-causing (pathogenic) E. coli can cause inflammation of the stomach and intestines (gastroenteritis). Laboratory tests can detect the presence of pathogenic E. coli that produce Shiga toxins.

Multiple subtypes of E. coli cause diarrheal illness, and they are classified by how they cause the disease. For example, some invade the lining of the intestines, causing inflammation, while others produce toxins.

E. coli that produce poisons called Shiga toxins are generally the only type of E. coli that are tested for in clinical settings from stool specimens. The Shiga toxins associated with these infections are so called because they are related to the toxins produced by another type of disease-causing bacteria, Shigella. Shiga toxin-producing E. coli (STEC) may also be called verocytotoxic E. coli (VTEC) or enterohemorrhagic E. coli (EHEC).

A strain of STEC called O157:H7 is the STEC strain responsible for most gastrointestinal illness outbreaks in the U.S. However, non-O157 strains of STEC are gaining recognition, in part due to increased testing for them by clinical laboratories. For example, a 2011 outbreak of E. coli O104:h5, a non-O157 STEC, was associated with travel to Germany and resulted in 32 deaths related to contaminated sprouts. According to the Centers for Disease Control and Prevention, STEC O157 causes about 36% of STEC infections in the U.S., while non-O157 STEC cause the rest.

Outbreaks have been linked to the consumption of contaminated food, including undercooked ground beef, unpasteurized juice, unpasteurized milk, and raw produce such as leafy greens and alfalfa sprouts. STEC may also be transmitted through contaminated water, contact with farm animals or their environment, and from person to person. Even ingesting small numbers of E. coli can cause an infection.

In addition to symptoms of nausea, severe abdominal cramps, watery diarrhea, fatigue, or possible vomiting and low-grade fever, STEC infections are often associated with bloody stools and, less commonly, can lead to serious complications, specifically hemolytic uremic syndrome (HUS). HUS is a result of the toxin entering the blood and destroying red blood cells (hemolysis). It can lead to kidney failure (uremia or the build up of nitrogen wastes in the blood) and can be life-threatening. Signs and symptoms include decreased frequency of urination (evidence of uremia), fatigue, and pale skin due to hemolytic anemia. HUS usually develops about a week after the onset of diarrhea.

About 5-10% of people who are diagnosed with an O157 STEC infection develop HUS. Children, the elderly, and persons with weakened immune systems are at greatest risk. However, most healthy persons recover from a STEC infection within a week and do not develop HUS. Non-O157 Shiga toxin-producing E. coli can cause the same symptoms and complications and likely account for 20-50% of STEC infections in the U.S. annually. Different testing techniques are required to identify O157 and non-O157 Shiga toxin-producing E. coli.

How is the sample collected for testing?

A fresh liquid or unformed stool sample is collected in a clean, dry container. The stool sample should not be contaminated with urine or water. Once it has been collected, the stool should be taken to the laboratory immediately or refrigerated and taken to the lab as soon as possible. Some laboratories provide transport media to support the survival of the organism from the time of collection until delivery to the laboratory. STEC becomes difficult to detect in the stool after one week of illness, so the timing of sample collection relative to the onset of illness is important.

Common Questions

How is it used?

These tests are used to detect the presence of Escherichia coli (E. coli) that produce Shiga toxin and to help diagnose an infection of the digestive tract due to these bacteria. E. coli bacteria are part of healthy digestive systems in humans and other mammals, but there are strains of E. coli that produce poisons, called Shiga toxins. In addition to severe diarrhea, Shiga toxin-producing E. coli (STEC) can cause hemolytic uremic syndrome (HUS), a serious illness that may lead to kidney failure and even death if not treated properly. Tests for STEC are used to make an accurate diagnosis and help guide treatment.

These tests may also be used to help recognize and track suspected outbreaks of STEC. Infections are often linked to the consumption of contaminated food or water, contact with farm animals or their environment, or person-to-person contact. E. coli O157:H7 is the strain that is most common in foodborne E. coli outbreaks in the U.S. However, there are non-O157 strains of STEC that can also cause severe diarrhea and HUS, such as E. coli O104:h5.

It is important that STEC infections be diagnosed quickly to prevent the bacteria from spreading throughout the community and so that interventions can be made, if necessary, to prevent HUS. Tests for STEC include:

• Stool culture: Cultures of stool samples use special nutrient media that selectively allow pathogens to grow while inhibiting growth of bacteria that are normally present in the digestive tract (normal flora). Once a pathogen grows in culture, other tests are performed to identify it. A stool sample may also be cultured for other pathogens, such as Salmonella, Shigella, and Campylobacter. O157:H7 STEC can be distinguished from other pathogens, including other types of E. coli, in culture because the bacteria have a distinct appearance when they are grown on a specific culture medium. Non-O157 STEC cannot be detected with the standard stool culture; they require special testing. Detection of non-O157 STEC is not usually performed at clinical laboratories but may be performed at public health laboratories. The Centers for Disease Control and Prevention (CDC) recommends that a culture for STEC be performed on all stools submitted for culture from people with acute, community-acquired diarrhea. Community-acquired diarrhea is in contrast to diarrhea acquired in a healthcare setting, such as a hospital.
• Toxin test: This test is used to detect the Shiga toxin directly using enzyme immunoassay (EIA). Stool cultures detect O157 STEC but do not detect non-O157 STEC. Therefore, the CDC recommends that EIA to detect Shiga toxins be used in conjunction with stool cultures. Detection of non-O157 STEC is important as it likely accounts for 20-50% of U.S. STEC infections annually. Enzyme immunoassay only identifies the presence of Shiga toxins and does not determine which strain of E. coli is producing the toxin.
• Genetic tests: PCR for Shiga toxin 1 gene (stx1) and Shiga toxin 2 gene (stx2) are rapid molecular tests that can be used to confirm the presence of Shiga toxin.
• Pulsed-field Gel Electrophoresis (PFGE): This method is used by public health laboratories to identify subtypes of E. coli that are suspected in an outbreak. It creates a DNA “fingerprint” of the bacteria detected that is entered into a national database to be compared to other fingerprints. If matches are made, it may indicate occurrences of disease caused by the same strain of bacteria. In this way, public health labs can quickly evaluate the cause of an outbreak even though the illnesses might occur in different geographic areas.

When is it ordered?

These tests may be ordered when a person has diarrhea and the healthcare practitioner suspects an infection of Shiga toxin-producing E. coli.

Some signs and symptoms include:

• Diarrhea that is severe or acute and persists for more than a few days
• Bloody stool
• Fever
• Severe abdominal pain, cramping and/or bloating

These tests are often ordered when a community-wide E. coli outbreak is suspected, for example, when several people who have eaten the same food from the same source have similar signs and symptoms.

What does the test result mean?

Stool culture
Stool culture results are frequently reported out with the name of the pathogenic bacteria that was detected. If Shiga toxin-producing Escherichia coli (STEC) is detected (positive culture), it means STEC is the cause of the person’s symptoms.

A negative stool culture for STEC means that Escherichia coli O157:H7 was not present or was not present in sufficient numbers to be detected. The culture results may indicate that a pathogen other than E. coli is causing the symptoms. These could include the bacterial pathogens Salmonella, Shigella, and Campylobacter, viral pathogens, or parasites.

Toxin test by EIA
A negative result for enzyme immunoassay (EIA) for Shiga toxin suggests that the toxin is not present.

A positive result for enzyme immunoassay (EIA) for Shiga toxins suggests that the toxins are present in the stool and that further testing should be done to grow and identify the E. coli producing the toxins.

Genetic tests
A negative result for a genetic test suggests that STEC was not present. A positive result suggests that STEC was present.

Is there anything else I should know?

Non-pathogenic E. coli are a normal part of a healthy human digestive system. However, E. coli infections in parts of the body other than the gastrointestinal system can cause illness. E. coli is responsible for the majority of urinary tract infections and can also cause neonatal meningitis, among other infections. These E.coli infections are detected by culturing a sample from the infected area.

How are Shiga toxin-producing E. coli infections of the digestive tract treated?

The recommended treatment for O157 Shiga toxin-producing E. coli (STEC) infection that has not progressed to hemolytic uremic syndrome (HUS) is supportive care (rest and rehydration). Those who are at an increased risk of developing HUS, such as children or the elderly, will be monitored closely. If they develop HUS, hospitalization will be required.

Infections of non-O157 Shiga toxin-producing E. coli are also treated with rest and rehydration, and they are often resolved without any additional intervention.

Why aren’t antibiotics a recommended treatment for an infection with Shiga toxin-producing E. coli ?

If you are infected with Shiga toxin-producing E. coli, antibiotics may increase your risk for developing hemolytic uremic syndrome (HUS).

Why shouldn’t I take anti-diarrheal medication if I have a Shiga toxin-producing E.coli infection of the gastrointestinal system?

Anti-diarrheal medicines may worsen or prolong your illness because they delay the removal of E. coli from your gastrointestinal tract by inhibiting the normal movement of food and fluids through the GI tract.

What else can cause acute diarrhea?

Other bacteria that can cause acute diarrhea include:

• Salmonella, often found in raw eggs, raw poultry, and in pet reptiles
• Shigella, from fecally-contaminated food and water
• Campylobacter, from raw or undercooked poultry
• Clostridium difficile, may become overgrown in the gut after antibiotic use

Parasites can also cause diarrhea. They are found in lakes and streams throughout the world and may also contaminate swimming pools, hot tubs, and community water supplies. The most common single-celled parasites responsible for gastrointestinal illness in the U.S. are Giardia lamblia (giardia), Entamoeba histolytica (E. histolytica), and Cryptosporidium parvum (crypto).

Rotavirus is the most common cause of severe diarrhea among children. Other viruses that cause diarrhea include Norwalk, noroviruses (also called Norwalk-like viruses), adenoviruses, calciviruses, cytomegalovirus (CMV), and HIV.

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Resources

• Mayo Clinic: E. coli
• Centers for Disease Control and Prevention: E.coli (Escherichia coli)
• National Institute for Allergy and Infectious Diseases: E. coli
• National National Institute of Diabetes and Digestive and Kidney Diseases: Hemolytic Uremic Syndrome in Children

Sources

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what it is and whether it can poison you

Recently Rospotrebnadzor reported that it had found E. coli in many Philadelphia rolls from different manufacturers. I eat rolls regularly and have never been poisoned.

In addition, I read that E. coli constantly lives in the human body and therefore is not dangerous. How reasonable is it to pay attention to reports that bacteria have been found somewhere?

Svetlana Belitskaya

medical journalist

Author profile

There are several varieties of E. coli. Some are safe and live in the human intestines, while others are toxic.

When the health services report that they have found E. coli somewhere, this does not mean that you can get poisoned. Some variants of E. coli are used only as a marker of contamination – these bacteria themselves are usually harmless. But if they were found in a product or water, then there may be other microbes, including pathogenic E. coli that cause severe infections.

See a doctor

Our articles are written with love for evidence-based medicine. We refer to authoritative sources and go to doctors with a good reputation for comments. But remember: the responsibility for your health lies with you and your doctor. We don’t write prescriptions, we give recommendations. Relying on our point of view or not is up to you.

What is E. coli

Escherichia coli, E. coli, or E. coli, is a group of bacteria most of which are harmless. Many strains of E. coli, that is, individual varieties of bacteria within the same species, constantly live in the human intestine. They are part of his healthy microflora. But some strains are pathogens.

E. coli – US Centers for Disease Control and Prevention, CDC

If pathogenic E. coli enters the body, it can cause urinary tract infection, respiratory disease, pneumonia. But more often they cause gastrointestinal infections, which are accompanied by diarrhea.

Pathogenic strains of E. coli are subdivided into pathotypes. Six known as diarrheagenic E. coli are associated with diarrhea. Most of them cause only mild stomach upset.

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The most dangerous strains are those that produce toxins that damage the mucous membrane of the small intestine. These strains are commonly referred to as STEC – Shiga toxin-producing E. coli. Other names are less common: VTEC – verotoxin-producing E. coli, EHEC – enterohemorrhagic E. coli. It is about them that they talk about in the news when mass food intoxications are reported.

STEC strains have additional subspecies. The best studied is E. coli O157, which was first identified in 1982 and is now considered the most dangerous.

E. coli O157 – NHS, NHS (available from VPN)

3D rendering of an Escherichia coli cell. Source: Kateryna Kon / Shutterstock

How to get E. coli

Pathogenic E. coli enters the body through the mouth. Most often lead to infection:

1. Meat products that have not been fully cooked and remain raw.
2. Unpasteurized milk and soft cheeses.
3. Fresh vegetables and fruits, especially greens, grown in fields near livestock farms.

E. coli – Mayo Clinic

But any product can be dangerous if prepared by a person who did not wash their hands after using the toilet.

You can also get infected:

1. When swimming in any open water body, including running water, as well as in poorly disinfected pools.
2. Working with cattle and interacting with animals in petting zoos and at home.
3. Care of infected people.

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Who is most at risk of contracting E. coli

Pathogenic strains of E. coli have different virulence—the ability to cause disease. Some, such as E. coli O157, cause infection even in healthy adults, simply by entering the body in small quantities. Others are not as active and mainly affect those prone to intestinal infections.

E. coli infection – Cleveland Clinic (available with VPN)

E. coli infection risk groups include:

1. Small children.
2. Elderly people.
3. Those who are immunocompromised due to certain medications or immunodeficiency.
4. People who constantly take drugs that reduce stomach acid: Esomeprazole, Pantoprazole, Lansoprazole, Omeprazole and others.

How E. coli infection manifests

Signs of E. coli infection appear three to four days after it enters the body. Sometimes the disease makes itself felt after a few hours, sometimes after ten days.

Most pathogenic E. coli cause mild, watery diarrhea that resolves without treatment within three to four days. But infection with STEC strains gives acute symptoms:

1. Rise in temperature to 38.5 °C, sometimes higher.
2. Severe diarrhea, sometimes with blood in the stool.
3. Pain and cramps in the abdomen.
4. Sometimes nausea and vomiting.

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Symptoms of STEC infection do not appear immediately. The disease begins with a slight pain in the abdomen and watery diarrhea, but gradually the condition worsens.

Despite the severity of the symptoms, most people do not need special treatment in this case either. The disease also goes away on its own, but lasts a little longer – five to seven days. If it doesn’t get better after a week, you need to make an appointment with a doctor. And with severe diarrhea and signs of dehydration, especially in children, it is worth seeking help earlier.

If the poisoning was severe and was accompanied by a rise in temperature, debilitating diarrhea and vomiting, one must be attentive to the condition of the ill person even after the symptoms disappear.

Approximately one week after infection with pathogenic strains of E. coli, when diarrhea is already over, 5-10% of people develop a life-threatening complication, hemolytic uremic syndrome, HUS. With it, small blood vessels in different organs are clogged with blood clots, the kidneys are especially affected.

Hemolytic Uremic Syndrome, HUS – MSD Handbook

Main Symptoms of Hemolytic Uremic Syndrome:

1. Less frequent or no urination.
2. Great fatigue, confusion.
3. Blood in urine.
4. Pale skin.

Since HUS can lead to kidney failure and death, an ambulance should be called immediately if symptoms appear.

How E. coli poisoning is treated

As I said, most people don’t need special treatment to deal with an E. coli infection. The disease resolves on its own if the following rules are observed:

1. Rest and plenty of fluids are needed to avoid dehydration. Its risk is high because a lot of fluid is excreted due to diarrhea and vomiting. The ideal option is to drink not ordinary water, but with the addition of an oral rehydration agent, such as Regidron.
2. It is undesirable to use antidiarrheal drugs, such as Loperamide, as they slow down the removal of toxins from the intestines. As a result, the disease may last longer. These drugs can be used for mild diarrhea, but they are strictly prohibited for high fever and blood in the stool.
3. Do not take antibiotics: they increase the risk of developing hemolytic uremic syndrome.
4. No need to starve and eat only broths. Caffeinated drinks and sugary sodas, dairy products, and fatty foods can make diarrhea worse. Everything else can be safely eaten.
5. Do not take activated charcoal: it does not help with poisoning.

Do’s and Don’ts for food poisoning

If the condition does not improve within a week or the symptoms of the disease are too severe, you should consult a doctor. Hemolytic uremic syndrome requires hospitalization: blood transfusion and hemodialysis may be needed, which temporarily replaces kidney function.

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Rehydration solutions cope better with dehydration. Ordinary water will not help in this case. Source: rilsnet.ru

How to avoid E. coli infection

Roast or boil meat well . E. coli was found in cattle meat, pork, rabbit meat, and poultry. Therefore, any meat products must be heated to at least 71 °C.

E. coli – WHO

If a piece of meat is thick, you should measure the temperature inside it with a special thermometer, and not judge the readiness of the meat by how well it is cooked on the outside.

This cooking thermometer can measure the temperature of meat and other food. Source: ozon.ru

Refuse products that have not been thermally processed. For example, from unpasteurized milk, juice, cider and products made from them, let’s say soft cheeses from raw milk.

Thoroughly wash anything that cannot be cooked, i.e. fruits and vegetables, especially leafy greens. If possible, it is worth peeling fruits and vegetables, especially if they will be eaten by small children or the elderly.

Keep the kitchen clean. Wash countertops and cutting boards that have come into contact with any raw food, including fruit, with hot soapy water.

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Maintain good hygiene. Be sure to wash your hands after going to the toilet, handling raw food, and contact with animals. If it is not possible to wash your hands, you can use alcohol-based disinfectants with an alcohol concentration of at least 60%.

It is also important to practice good personal hygiene when caring for young children and the elderly, including washing your hands after changing diapers.

Be careful when swimming. Do not swallow water when swimming in any body of water, especially fresh water.

Listen to messages from the health authorities. It is best to avoid foods that have been found to contain E. coli. And also not to sneak onto the beaches that were closed due to non-compliance with epidemiological standards.

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in Germany, they proposed ways to treat intestinal infection

1847

24 April

Doctors in Germany have prepared recommendations for the treatment of patients with an intestinal infection, which has killed more than 20 people in Europe, the Rospotrebnadzor said on Friday.

In Germany, 28 people died from the infection, on Wednesday the media reported 3 thousand cases. According to the World Health Organization, cases of infection have been recorded in 13 European countries. Rospotrebnadzor last week banned the import of vegetables from the EU into Russia – likely sources of the disease.

The infection is caused by a mutated strain of the bacterium Escherichia coli (E. coli). This strain – O104:h5 – has not been previously known and is reported to be resistant to many antibiotics. Earlier, the chief state sanitary doctor of Russia, Gennady Onishchenko, suggested that the standards that are used for the content of antibiotics in meat, milk, that is, in agricultural products in the EU, are very high. “This strain is resistant to all antibiotics used by the German healthcare system. And this means that medicine is disarmed, it cannot treat the sick,” he said.

The recommendations that Rospotrebnadzor sends to the territorial offices were prepared by experts from the German Society for Infectious Diseases (DGI) in cooperation with delegates from the German Society for Hygiene and Microbiology (DGHM) and representatives of the German Society for Nephrology (DGfN).

Rospotrebnadzor specialists report that the infectious agent produces Shiga toxin, which causes the clinical manifestations of the disease. In 25-30% of patients with acute intestinal infection, hemolytic uremic syndrome (HUS) develops – toxicosis with acute renal failure. “E.coliO104:h5 strains isolated from patients were characterized by resistance to beta-lactam antibiotics due to the production of extended-spectrum beta-lactamase, but remained sensitive to the aminoglycoside group (gentamicin) and fluoroquinolones,” the Rospotrebnadzor document says.

German specialists from the group of preclinical and clinical studies do not recommend the use of these drugs for the treatment of patients. According to German doctors, patients with acute intestinal infection can be prescribed a number of antibiotics. However, if patients are clinically indicated to be treated with antibiotics, then antibiotics such as carbapenems should be used. E. coli is often present in the intestines of humans and warm-blooded animals.