E. coli – The Bacteria that Changed How We Look at Food Safety

In 1885, Theodore Escherich discovered Escherichia coli (E. coli) (1). Varieties of this bacteria are extremely important in modern food safety. They are addressed in Food Safety Plans and used in assessing the cleanliness of equipment, food, and processing facilities. There are over seven hundred types of E. coli and there are antigenic types – H, K, and O, within those types. The bacteria are very hardy and versatile, which allows them to adapt to harsh conditions, and they can thrive anaerobically in the environment. E. coli is easily found in the intestines of animals, birds, and humans, as well as in the soil and water, and can be found anywhere there is dirt or feces. During an outbreak of diarrhea in infants in 1935, E. coli was detected was determined as the cause of the illness (2). Since then, various strains, such as O157:H7, which causes HUS and was responsible for the illnesses in Oregon during an outbreak in 1982 (1).

The Bad Bug Book, which is available on the FDA website ( https://www.fda.gov/food/foodborne-pathogens/bad-bug-book-second-edition) states that there are six groups within the E. coli group, and four of them we will cover today. They are among the most common causes of related food-borne illness. They are Enterohemorrhagic E. coli (EHEC), Enteroinvasive E. coli (EIEC), Enteropathogenic E. coli (EPEC), and Enterotoxigenic E. coli (ETEC) (3). Let’s look at all four of these types of the E. coli bacteria so that we understand the cause and effect that they can have upon us if we are not careful.

Enterohemorrhagic E. coli

Let’s start with enterohemorrhagic E. coli (EHEC), which is the bad boy among the four groups. It is responsible for the most headlines and is the one group that most people think of when they hear the name E. coli. These bacteria produce Shiga toxin which can lead to various complications such as kidney failure, blood clotting issues and bloody diarrhea. These bacteria can lead to HUS (Hemolytic Uremic Syndrome) or other complications. The symptoms usually begin one to nine days after ingestion and immunocompromised, the elderly, and children are more at risk. Abdominal cramping, watery diarrhea and/or vomiting can occur. Severe symptoms should be reported to your doctor, as dehydration and complications can develop (3).

Ingestion can come from several routes, but usually it happens by ingesting fecal matter via soil, food, person-to-person contact, or contaminated water sources. Over the years, there have been many foods that have been implicated in EHEC outbreaks. Historically, ground beef and beef products have frequently been the cause of EHEC infections, however, produce can also be to blame. Lettuce, sprouts, spinach, and raw milk have also caused these illnesses. Interestingly, the bacteria can develop a resistance to acidic foods, causing yogurt, mayonnaise, and fermented sausages to become vehicles of transmission (3).

Enteroinvasive E. coli

Enteroinvasive E. coli (EIEC) is next on our list. Person-to-person contact usually causes this type of infection. If one does not wash their hands well after using the restroom, they can infect someone else by handling their food or drink. These type of infections usually manifests within 12-72 hours and lasts from five to seven days. Symptoms are milder than that of the EHEC bacteria, but it can cause abdominal cramps, diarrhea, vomiting, and fever. The disease usually resolves on its own, but if symptoms are severe or dehydration occurs, please make sure to see your physician. Past outbreaks were reported to be caused by Camembert cheese in 1971, tofu in 1988, and guacamole in 1994 (3).

Enteropathogenic E. coli (EPEC)

This form of E. coli is not as prevalent in the United States as it once was in the 1940s and 1950s. Enteropathogenic E. coli (EPEC) causes infantile diarrhea, and cases are more prone to occur in day-care and pediatric type settings. Developing countries with inadequate sanitation still see infections, and it had a mortality rate of 25% to 50% before better treatments were developed. When infants are exposed to EPEC, it does not take a high dosage of bacteria to make them ill, and it highly infective. Infants may show signs of infection as soon as four hours after ingestion, affecting bottle fed babies disproportionally, pointing to contaminated water as the culprit. Fecal to oral routes can also be paths of transmission. Symptoms of diarrhea, vomiting, and fever may be mild to severe but can last as long as 21-120 days and cause malabsorption issues (3).

Enterotoxigenic E. coli (ETEC)

The last of the group is ETEC, or enterotoxigenic E. coli, the cause of traveler’s diarrhea. Infants, the immunocompromised, the elderly, and travelers are most susceptible to this E. coli group. It starts with diarrhea, malaise, low grade fever, and nausea within eight to forty-four hours after ingestion, but usually within twenty-six hours is the most common. Symptoms can be mild to severe, with cholera-like symptoms in the severe form. Food and water-borne, this bacterium is transmitted by the fecal-oral route. Once again, I can not stress washing your hands too much! Humans are the most likely source, according to the Bad Bug Book, with contaminated water or insanitary conditions being the predominant factor. When contaminated water, utensils or hands are used to prepare foods, ice, or drinks, they can lead to those infamous vacation ruining scenarios. While humans may be carriers and remain asymptomatic, person to person contact does not usually cause transmission (3).

So now that we understand E. coli a little better, lets discuss how monitoring for its presence is important in the food industry. Obviously, we do not want E. coli present in the foods that we produce or eat. However, the larger family of coliforms, of which E. coli is a member, is very useful in monitoring sanitary conditions within processing facilities. E. coli can be carried in on produce when it is harvested, since the produce was grown in or has touched soil where the bacteria can be found.  The bacteria also live in the intestines of animals and birds, and by testing for them in the processing facilities, they can be useful in monitoring cleanliness after sanitation cycles. Once the sanitation crews have finished, someone, usually Quality Assurance or Food Safety personnel inspect and swab various production areas and equipment. There are a few other tests that can be performed, but testing for coliforms and specifically E. coli, is one way to ensure that the facility does not have an area that looks clean but is still harboring traces of these bacteria. Areas of specific focus include cracks and crevices that are hard to clean, biofilm which builds up on equipment, and places where the cleaning or sanitizing agents did not reach. Testing for coliforms or E. coli is also useful to ensure that the water that the facility is using meets or exceeds the state or federal guidelines. When looking at Food Safety Programs, a risk assessment should be performed for E. coli. Risk assessments that are used as guidelines for ensuring proper precautions by industry can be found here: https://www.fsis.usda.gov/science-data/risk-assessments, if you are interested in more ways facilities control bacterial hazards (4).

We still need to do our part when preparing foods to feed our families. Make sure that produce is washed or cooked thoroughly. Wash produce prior to slicing, dicing, and peeling. Animal, poultry, and fish products must be cooked thoroughly, by using a food thermometer, and the temperatures recommended by USDA. They can be found at https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/safe-temperature-chart ) (5).

As we approach the dawn of the New Year I want to mention a special tradition that gives rise to E. coli concerns, Raw Ground Beef! As I have discussed in previous posts, I know that some people in the Great Lakes region prepare this traditional item around New Year’s as “Cannibal Sandwiches”, Steak Tartar or “Tiger Meat Sandwiches” that consist of raw hamburger, raw onion, raw eggs, salt and pepper on rye bread or crackers. Please stay healthy and skip these dishes this season. Raw ground beef and raw eggs are not safe to eat, and E. coli is just one of the bugs that you can catch from these recipes.

As we can see, sanitary preparation, thorough cooking, washing one’s hands and temperature control are all part of making sure that we stay safe from food-borne illness. Manufacturing controls are just one part of making sure that we stay safe, but being responsible for keeping surfaces clean, washing our hands, cooking temperatures, and refrigerating items properly are our responsibilities.

As always, wash your hands, stay safe, and we at Food Safety Basics, wish you a Happy and Prosperous New Year!

1. Lim, J. Y., Yoon, J., & Hovde, C. J. (2010). A brief overview of Escherichia coli O157:H7 and its plasmid O157. Journal of Microbiology and Biotechnology, 20(1), 5–14.
2. Todar, K., Madison, & WI. (n.d.). [No title]. Retrieved July 9, 2021, from http://textbookofbacteriology.net/e.coli_2.html
3. Toxins, N. (n.d.). Bad Bug Book. Retrieved August 1, 2021, from https://www.fda.gov/media/83271/download 68:81
4. https://www.fsis.usda.gov/science-data/risk-assessments
5. Safe Minimum Internal Temperature Chart. (n.d.). Retrieved December 29, 2021, from https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/safe-temperature-chart