What Vegetables Have E coli


E coli is a bacteria that can be found in plants and animals, including vegetables, undercooked beef and raw foods. Fecal and food contamination are the most common sources of E coli in the United States.

The Role of Pathogenic E. coli in Fresh Vegetables: Behavior, Contamination Factors, and Preventive Measures

Many raw vegetables, such as tomato, chili, onion, lettuce, arugula, spinach, and cilantro, are incorporated into fresh dishes including ready-to-eat salads and sauces. The consumption of these foods confers a high nutritional value to the human diet.

However, the number of foodborne outbreaks associated with fresh produce has been increasing, with Escherichia coli being the most common pathogen associated with them. In humans, pathogenic E. coli strains cause diarrhea, hemorrhagic colitis, hemolytic uremic syndrome, and other indications. Vegetables can be contaminated with E. coli at any point from pre- to postharvest.

This bacterium is able to survive in many environmental conditions due to a variety of mechanisms, such as adhesion to surfaces and internalization in fresh products, thereby limiting the usefulness of conventional processing and chemical sanitizing methods used by the food industry. The aim of this review is to provide a general description of the behavior and importance of pathogenic E. coli in ready-to-eat vegetable dishes. This information can contribute to the development of effective control measures for enhancing food safety.

1. Introduction

The consumption of fresh produce has increased notably in recent years due to multiple contributions of nutrients and functional properties . Over the last 30 years, there has been a 25% increase in the average amount of fresh produce consumed per person in the USA . A diet rich in fruit and vegetables has been shown to protect against various types of cancer and chronic illnesses, such as coronary heart disease . However, at the same time, consumption of fresh produce is associated with a growing number of foodborne outbreaks due to bacterial contamination of these products .

Leafy greens, such as lettuce, spinach, and fresh herbs, are some of the vegetables most frequently linked to bacterial infections . In the United States, from 1990 to 2005, the Food Safety Project reported that at least 713 produce-related outbreaks were associated with foodborne disease, of which 12% involved fresh fruits and vegetables . In 2011, the Advisory Committee on the Microbiological Safety of Food (ACMSF) reported that, in the UK, there were 531 cases of reported illness, including one death, related to the consumption of fruits and vegetables between 2008 and 2010 . In the same year, Germany reported an outbreak of Shiga toxin-producing E. coli (STEC) serotype O104 : H4; at the end of the outbreak, 3785 cases of illness were reported outside of Germany, identifying contaminated sprouted seeds as responsible for the foodborne outbreak .

It should be emphasized that the effect of foodborne diseases affects not only the sick person but also has considerable economic repercussions. On the one hand, there are costs related to the sick person, including medical care and absenteeism from work and school. On the other hand, there are the costs on society, including the decrease in worker productivity, expenses of research on the outbreak, the loss of income due to food companies closing, legal expenses for litigation related to diseases, and the expenses in public medical services .

It has been shown that how crops are harvested, processed, and distributed has enhanced both the supply and variety of products, which may also have increased the risk of more widespread outbreaks. The increase in illness associated with consumption of fresh produce reflects a documented increase in food contamination .

Foodborne illness may be the cause of fresh produce contamination by pathogenic bacteria, viruses, and protozoa . This contamination may originate from manure, soil, sewage, surface water, or wildlife ; it may also occur during washing, slicing, soaking, packing, and food preparation Among the bacteria associated with foodborne illnesses are Listeria monocytogenes , E. coli , Shigella soney , Salmonella , and Staphylococcus aureus .

Survival and growth of these microorganisms depend on several factors, including the specific features of the microorganism, fruit ripeness, environmental conditions, plant development, bacterial resistance to the plant metabolic processes, plus harvest, and postharvest processes . Particularly, some pathogenic microorganisms can internalize and adhere to the plant surface . Unfortunately, current industrial sanitizing and washing treatments of fruits and vegetables (e.g., triple washing of prepackaged leafy greens) do not guarantee the total elimination of pathogens . Therefore, this review considers the main E. coli pathotypes associated with foodborne outbreaks due to fresh produce consumption.

Furthermore, some recently introduced processes, considered to prevent the contamination of raw vegetables, are also described. They range from the production stages to the hygienic conditions during food preparation, from “the field to the table.” Reij and Den Aantrekker reported that important factors contributing to the presence of pathogens in prepared foods are insufficient hygiene (1.6%), cross contamination (3.6%), processing or storage in inadequate rooms (4.2%), contaminated equipment (5.7%), and contamination by personnel (9.2%).

2. Incidence of E. coli

The most common vegetables associated with E. coli STEC are sprouts and green leafy vegetables. The possible source of the contamination of sprouts is the seed that is used (it was possible to see that there were many contaminated seed lots). In the case of leafy greens, it appears that contaminated water (drag water from cattle lots or water contaminated by other sources) is the most common source of contamination. Many outbreaks reported around 30 cases, with the ratio of hospitalizations to cases ranging from 18 to 67%.

3. Contamination Factors in Fresh Vegetables

There are three types of factors that affect microbiota present in fresh products: physical, chemical, and biological. Physical factors, such as pH, temperature, and moisture, affect the growth and some metabolic activities of microbiota. Chemical factors include the availability and nutrients in vegetables that may be used by microorganisms. Finally, biological factors include the presence of competitive microbiota and bacterial-plant interactions . Fresh produce may be contaminated at any point in the production chain between farm and table. It has been shown that produce contamination is high during three periods: in the field, during initial processing, and in the kitchen.

3.1. Preharvest Factors

Soil and improperly composted animal manure are considered to be the main preharvest contamination factors. Soil is a natural reservoir for a large variety of human pathogens, including pathogenic E. coli, due to the addition of animal waste . E. coli O157 : H7 may survive in the soil from 7 to 25 weeks depending on soil types, humidity level, and temperature. This bacterium can also survive during crop storage or distribution, the presence of STEC O157 in potatoes represents a risk because it may cause cross contamination with other foods that are consumed raw.

Furthermore, in organic food production, the use of animal manure is a common practice; several reports relate this type of crop system to the presence of fecal contamination, particularly during the leafy vegetable harvest . According to the Centers for Disease Control and Prevention (CDC) , several US states were affected by the consumption of organic spinach contaminated with STEC O157.

Domestic animals and wildlife also represent a potential source of pathogenic bacteria, particularly for lettuce and leafy greens at preharvest stages along the coast of California and in Yuma, AZ . Berger et al. showed that the feces of wildlife are involved in vegetable contamination and may cause E. coli O157 : H7 outbreaks. Jay-Russell et al. studied a potential reservoir for pathogenic E. coli in feces from coyotes and dogs. Insects could also be a source of plant contamination. Contaminated flies have been shown to transfer E. coli to plant leaves or fruits .

In addition, Lynch et al. found that intensive agricultural practices have forced crop fields to be too close to animal production areas. The ecological consequences of this proximity have increased the likelihood of contamination by E. coli O157 : H7 in wildlife: the percentages tested positive in unspecified duck was 5% (1/20 total samples) in Washington, USA; in large mammals including deer, such as the black-tailed deer (Odocoileus hemionus columbianus), it was 11.1% (1/9 total samples); in California, USA, in unspecified deer, it was 25% (1/4 total samples); in Ireland, in feral pig (Sus scrofa), it was 14.9% (13/87 total samples); in California and in small mammals in England, such as the rabbit (Oryctolagus cuniculus), it was 48.8% (20/41 total samples). All sample types were feces, anal and cloacal swabs, or gastrointestinal contents from individual animals, unless otherwise noted .

Seasons are another important environmental condition that affects the prevalence of E. coli in vegetables. For example, E. coli contamination in cilantro and parsley significantly increased in fall compared to that found in spring and winter . The finding of E. coli in irrigation water has been associated with the presence of feces from cattle and other animals, especially during heavy rainfall.

There are current reports on outbreaks caused by the consumption of lettuce irrigated with water contaminated with E. coli O157 : H7 . However, the risk associated with the use of contaminated water for irrigation depends on the irrigation system used. There is a lower probability risk of spreading pathogens from contaminated water through drip irrigation versus overhead sprinkler systems.

Another study shows that well water used for irrigation may be contaminated with E. coli O157 : H7 from feces of cattle or other animals, which can be observed especially during heavy rainfall. Also, karst formations occur when acidic water begins to break down bedrock surfaces, allowing surface water to enter fractures in limestone, contaminating the groundwater, which then favors the survival of E. coli in karst streams for long periods

An additional factor during the handling and harvesting of crops are the workers’ hands. They can become a vehicle for contamination during preharvest due to the lack of access to latrines or handwashing stations .

4 Foods Most Likely To Cause E. Coli

All foods have the potential to make you ill from the bacteria Escherichia coli. Some food sources increase your risk of E. coli, such as the four listed below.

1. Ground Beef

One of the most common foods that can become contaminated with E. coli is ground beef. E. coli from inside of the cow’s intestines can contaminate the meat meant for consumption.

It is also worth noting that ground beef does not only contain meat from cows. Many different animals are used in ground beef production, which increases the risk of E. coli contamination.

Recent Outbreaks

One of the most recent E. coli outbreaks related to ground beef occurred in 2019 across ten states. More than 209 people became ill, and 29 were hospitalized.

Ground Beef Food Safety Tips

  • When preparing ground beef at home, always defrost in the refrigerator.
  • Use a meat thermometer to ensure a safe internal temperature of 160 degrees Fahrenheit.
  • When eating in a restaurant, avoid ground beef that is still pink or red in the middle.

2. Fresh Produce

Eating fresh produce offers many health benefits, but not when you unknowingly ingest E. coli. Produce grown in areas near cattle or other meat production facilities can be contaminated with waste runoff.

Even certain types of vegetables are more likely to become contaminated with E. coli. These veggies include romaine and spinach because they can be more challenging to wash correctly and clean.

Recent Outbreaks

E. coli in fresh produce resulted in two recent outbreaks. In 2019, contaminated romaine lettuce caused 167 illnesses and 85 hospitalizations across 27 states. In 2020, a leafy greens outbreak caused 40 illnesses and 20 hospitalizations in 19 states.

Fresh Produce Food Safety Tips

  • Wash or scrub fruits and vegetables even if you do not plan to eat the peel. You could contaminate the interior when slicing.
  • Keep pre-cut fruits and veggies cold.
  • Cooked produce is the safest way to eat them.

3. Unpasteurized Milk

Although unpasteurized milk is not consumed as often as fresh produce or ground beef, it remains a severe threat to those who continue to drink it. According to the CDC, people who drink unpasteurized milk are 840 times more likely to develop a foodborne illness such as E. coli.

According to the FDA, pasteurization is a process that kills harmful bacteria by heating milk to a specific temperature, followed by rapid cooling. Unpasteurized milk does not have any unique health benefits. The CDC does not recommend drinking or consuming dairy products that contain unpasteurized milk.

4. Water

Some water sources may produce E. coli, including groundwater contaminated by human or animal waste. Private wells and municipal water supplies can become infected with E. coli. Fortunately, there have not been any significant outbreaks related to E. coli contaminated water since 2006.

How Serious Is E. Coli?

E. coli is ordinarily harmless to most humans and animals and might cause only mild and brief symptoms, if any. However, multiple strains of E. coli can be severe and painful, resulting in kidney failure or death.

How Can You Get An E. Coli Infection?

The most common way to get an E. coli infection is by eating or drinking contaminated food. Symptoms typically appear within three to four days. They include diarrhea, severe stomach cramping, nausea, vomiting, and tenderness or pain in your abdomen.

When Does An E. Coli Infection Become An Outbreak?

When one or more people are sickened by an E. coli infection, it is called an outbreak. According to the Centers for Disease Control and Prevention, there have already been two outbreaks of E. coli in 2021.

One outbreak was related to an unknown food source that caused twenty-two illnesses and eleven hospitalizations. The other was linked to a contaminated cake mix that made seventeen people sick across twelve states.

Escherichia coli (E. coli)

Escherichia coli (E. coli)

E. coli are mostly harmless bacteria that live in the intestines of people and animals and contribute to intestinal health. However, eating or drinking food or water contaminated with certain types of E. coli can cause mild to severe gastrointestinal illness. Some types of pathogenic (illness-causing) E. coli, such as Shiga toxin-producing E. coli (STEC), can be life-threatening.

Some wildlife, livestock, and humans are occasional carriers of pathogenic E. coli and can contaminate meats and food crops. Contamination is typically spread when feces come into contact with food or water.  Human carriers can spread infections when food handlers do not use proper hand washing hygiene after using the restroom. Pets and petting zoos can also cause infections if the animals are contaminated with pathogenic E. coli.


People infected with pathogenic E. coli can start to notice symptoms anywhere from a few days after consuming contaminated food or as much as nine days later. Generally, the symptoms include severe stomach cramps, diarrhea, fever, nausea, and/or vomiting.

The severity or presence of certain symptoms may depend on the type of pathogenic E. coli causing the infection. Some infections can cause severe bloody diarrhea and lead to life-threatening conditions, such as a type of kidney failure called hemolytic uremic syndrome (HUS), or the development of high blood pressure, chronic kidney disease, and neurologic problems. Other infections may have no symptoms or may resolve without medical treatment within five to seven days.

Due to the range in severity of illness, people should consult their health care provider if they suspect that they have developed symptoms that resemble a(n) E. coli infection.

At-Risk Groups

People of any age can become infected with pathogenic E. coli. Children under the age of 5 years, adults older than 65, and people with weakened immune systems are more likely to develop severe illness as a result of an E. coli infection. However, even healthy older children and young adults can become seriously ill. Learn more about People at Risk of Foodborne Illness.

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