Escherichia coli, or E. coli for short, is a diverse group of bacteria found in the environment, food, and the intestines of people and animals. While most strains of E. coli are harmless, some can cause illnesses, ranging from mild to severe. The dangerous strains produce toxins that can lead to symptoms such as diarrhea, abdominal pain, and, in some cases, more severe complications like kidney failure.
The strains of greatest concern for food operations are Shiga toxin-producing E. coli, commonly referred to as STEC. The most well-known STEC strain is O157:H7, which the USDA declared an adulterant in raw ground beef in 1994. Six additional STEC serogroups (O26, O103, O111, O121, O145, and O104:H4) were added as adulterants in 2012. All STEC strains produce toxins that can cause severe illness, including hemolytic uremic syndrome (HUS), particularly in young children and older adults.
The true scale of E. coli illness is significantly larger than reported case counts suggest. The CDC estimates that for every confirmed E. coli outbreak patient, more than 26 additional cases go undetected. This means that even a seemingly small outbreak represents a much larger number of people affected, reinforcing the importance of proactive prevention rather than reactive response.
Therefore, it is paramount for food operations to understand the sources and implement effective E. coli prevention measures.
Join us as we explore in this article how food businesses can mitigate the risk of E. coli contamination.
Sources of E. coli in Food Operations
- Raw Materials: E. coli can often be present on the surface of raw meat, particularly ground beef. Food establishments must exercise extreme caution when handling and cooking meat to prevent cross-contamination. Raw fruits and vegetables can become contaminated with E. coli through contact with contaminated water, soil, or during the harvesting and processing stages. Three of the largest E. coli outbreaks in 2024 were traced to fresh produce: slivered onions, organic carrots, and romaine lettuce. Unlike meat, produce is often consumed raw, meaning there is no kill step to eliminate contamination. Food operations handling fresh fruits and vegetables must apply the same rigor to produce sourcing, washing, storage segregation, and environmental monitoring as they apply to raw meat.
- Cross-Contamination: Improper food handling practices can lead to the spread of E. coli. This includes using the same cutting boards or utensils for raw and ready-to-eat foods and not maintaining proper hand hygiene among food handlers.
- Water Sources: Contaminated water sources can contribute to an increased risk of E. coli presence at food operations.
- Personnel Hygiene: Improper personnel hygiene practices can lead to the spread of E. coli. People not washing their hands after using the restroom, lunch and breaks can lead to an increase potential of cross-contamination. In addition, people that do not report illness and remain in contact with the food can pose a risk for E. coli contamination of food contact surfaces and product.
Prevention and Control Measures
- Food Safety Training: Comprehensive training for all employees in food operations is essential. Ensure that staff understands the importance of food safety, including proper handwashing, hygiene practices, and avoiding cross-contamination.
- Temperature Control: Cook foods to the correct internal temperatures to destroy E. coli and other pathogens. The USDA recommends a minimum internal temperature of 160°F (71°C) for all ground beef and other ground meats, 165°F (74°C) for poultry, and 145°F (63°C) with a three-minute rest for whole cuts of beef, pork, lamb, and veal. Never rely on color alone to judge doneness. Ground beef can turn brown before reaching a safe temperature. Bacteria, including E. coli, multiply rapidly in the temperature danger zone which is between 40°F and 140°F (4°C and 60°C). Store ground beef at 40°F or below and use it within two days of purchase, or freeze it. Ensure hot foods are held above 140°F. Monitor refrigeration units regularly with calibrated thermometers to confirm they are maintaining safe temperatures.
- Sanitization Protocols: Implement strict cleaning and sanitization protocols for all food preparation and serving areas. Pay special attention to surfaces and equipment that come into contact with raw foods.
- Source Verification: Establish strong relationships with suppliers and verify the safety of the products you receive. Be vigilant about the quality of ingredients used in your food operations.
- HACCP Plans: Develop and implement Hazard Analysis and Critical Control Point (HACCP) plans specific to your food operations. This systematic approach identifies potential hazards and outlines preventive measures.
- Environmental Monitoring: Conduct routine testing for E. coli in food production environments. This proactive approach can help identify and address potential sources of contamination before they lead to outbreaks.
What Recent E. coli Outbreaks Reveal for Food Operations
The 2024 outbreak landscape was a significant reminder that E. coli risk is not confined to ground beef. Three of the year’s most serious outbreaks involved fresh produce, challenging food operations to broaden how they think about contamination sources and preventive controls.
The McDonald’s Quarter Pounder outbreak. In October 2024, an outbreak of E. coli O157:H7 was traced to fresh slivered onions served on McDonald’s Quarter Pounder sandwiches. A total of 104 people became ill across 14 states, 34 were hospitalized, four developed hemolytic uremic syndrome, and one person died. The onions were supplied by Taylor Farms. This outbreak highlighted that fresh produce used as a topping or condiment carries the same contamination risk as any other raw ingredient, even when the final product involves a cooked component. Supplier verification, lot traceability, and incoming material controls are essential for every ingredient category, not just primary proteins.
The Grimmway Farms organic carrot outbreak. Also in late 2024, an outbreak of STEC O121:H19 was traced to organic carrots produced by Grimmway Farms. There were 48 confirmed patients across 19 states, 20 were hospitalized, and one person died. This was the first time this pathogen and commodity combination had ever been confirmed in an outbreak investigation. One recall affected 20 brands with international distribution implications. The outbreak underscores that organic designation provides no protection against microbial hazards and that environmental monitoring programs must account for root vegetables and other produce categories.
The romaine lettuce outbreak. Entering 2025, an outbreak of E. coli O157:H7 linked to romaine lettuce had sickened 88 people across 12 states, with illnesses beginning in mid-November 2024. Romaine continues to be a recurring vehicle for E. coli contamination, reinforcing the importance of agricultural water testing and grower verification for leafy green suppliers.
The collective takeaway for food manufacturers: produce is now a primary, not secondary, E. coli risk category. Environmental monitoring programs, supplier verification protocols, and lot traceability systems must be designed to cover the full range of ingredients a facility handles. Relying on a kill step in a final product does not protect a facility if cross-contamination from a raw produce ingredient reaches a ready-to-eat product or a food contact surface. Both HACCP plans and food safety plans under FSMA Preventive Controls should reflect this expanded risk picture.
It’s crucial to remember that not all E. coli strains are harmful, and many are a natural part of the gut microbiome. However, in food operations, the focus must remain on preventing and controlling the pathogenic strains that can cause illnesses.
By prioritizing food safety, adopting rigorous prevention and control measures, and staying up-to-date with industry best practices, food operations can significantly reduce the risk of E. coli contamination and provide safer, healthier food to consumers.
FAQs
Small-scale operations can prioritize high-risk areas and ingredients for periodic testing, utilize affordable rapid testing kits, and participate in cooperative testing programs with local health departments or industry groups to share costs.
Advancements include biosensors for real-time detection of E. coli, UV and ozone treatments for disinfecting water and surfaces, and bacteriophage therapy as a natural, targeted approach to eliminate pathogenic E. coli strains without harming beneficial bacteria.
Probiotics, particularly those strains known to inhibit pathogenic bacteria, can be applied in food production environments to outcompete harmful pathogens like E. coli, potentially reducing contamination risks in a natural and safe manner.
Educating consumers about proper cooking temperatures, especially for meats, and the importance of kitchen hygiene can significantly reduce the risk of E. coli infection, underscoring the need for food operations to provide clear handling and cooking instructions.
In 2024, major E. coli outbreaks were traced to fresh onions, organic carrots, romaine lettuce, and ground beef — affecting hundreds across multiple states. The pattern confirms that fresh produce is now as high a priority for E. coli control as raw meat. Food manufacturers should ensure that supplier verification, environmental monitoring, and lot traceability cover all ingredient categories, not just proteins.
