Fact sheet on STEC / VTEC / EHEC

General
Certain strains of Escherichia coli (E. coli), such as STEC (Shiga toxin–producing E. coli) or VTEC (verotoxin-producing E. coli), can cause foodborne illness. These can lead to EHEC infections. EHEC infections are particularly severe.
These dangerous bacteria frequently occur in the intestines of ruminants (especially cattle, but also sheep and goats, for example). They can be transmitted to humans via food, but also by direct contact, e.g. in petting zoos.

Characteristics

• Rod-shaped bacteria (belong to the family Enterobacteriaceae)
• Gram-negative
• Oxidase-negative
• Catalase-positive

Origin / Occurrence

• Natural inhabitant of the intestinal tract of ruminants (e.g. cattle, sheep, goats)
• Because they can survive for a long time in the environment, they are also found in soil, on plants and in surface water
• Primarily in animal-based but also in plant-based foods

Significance

• The presence of these pathogenic E. coli strains in ready-to-eat foods is undesirable and is generally considered a potential health hazard by food monitoring authorities in Germany. Because these bacterial infections can sometimes lead to severe, life-threatening outcomes up to and including death, these pathogens are feared in foods. Appropriate measures must be taken upon detection of viable STEC / VTEC in ready-to-eat foods.
• Fecal contamination is often the cause of contamination; however, because of their longer survival in the environment, different contamination sources must be considered depending on the situation
• The infectious dose is very low, so smear infection is also possible (from animal to human or from person to person)

Clinical picture

• Incubation period: on average 3 to 4 days
• Duration of illness: up to one week if no complications occur
• Symptoms of an EHEC infection: mild diarrhea up to haemorrhagic colitis (bloody inflammation of the large intestine) with severe bloody diarrhoea, often accompanied by abdominal cramps, nausea, vomiting and fever (EHEC infection).
• As a complication, especially in children, a hemolytic-uremic syndrome (HUS) can develop. This is often associated with chronic kidney damage and can be fatal

Examples of affected foods

• Beef products (e.g. hamburgers, ground beef, raw sausage)
• Raw milk and raw milk products
• Salad, vegetables and sprouts
• Flours
• Contaminated bathing and surface water

Growth conditions

• Temperature:
  • Optimum: +30 °C to +37 °C
  • Minimum: +8 °C
  • No growth above +50 °C
• pH: Growth at 4.4 to 9.0
• a_w value: Growth at high water activity of at least 0.95
• Oxygen requirement: growth with and without oxygen (facultative anaerobe)

Inactivation by heating

• At +72 °C for a minimum exposure time of 2 minutes (Note: monitor core temperature)

1. Check products at incoming goods for e.g. incoming or transport temperature, shelf life, packaging, deviations or abnormalities
2. This also applies to the goods before they are used in production. If in doubt, do not use the food and ask supervisors
3. Check microbiological specifications. If necessary, arrange laboratory testing of suspicious products or request results from the supplier
4. Verification by follow-up testing

1. Review work organization in the facility
   1. Separate work areas, equipment and utensils for raw and processed foods
   2. Separation of “clean” and “unclean” areas and activities
2. Train staff regarding potential errors and corrective measures
3. Verification by visual on-site inspections and follow-up testing

1. Review the execution of cleaning and disinfection:
   1. Hygiene plan
   2. Execution of cleaning and disinfection, e.g. dosing of the disinfectant, contact time, use of appropriate and clean materials and cleaning cloths
2. Avoid moisture residues and biofilms. Ensure good drying of equipment, devices and surfaces
3. Train staff regarding potential errors and corrective measures
4. Repeat cleaning and disinfection
5. Verification by visual on-site inspections, environmental testing and follow-up testing

1. Train staff regarding potential errors and corrective measures
2. Regular cleaning and disinfection of hands and regular glove changes
3. Regular changing of work clothing. Ensure work clothing is clean
4. Train employees regarding the requirements for infection protection
5. Verification by visual on-site inspections and follow-up testing

Deficiencies in infection protection:
This creates the risk of transmission of pathogenic microorganisms from humans to product-contact surfaces or directly to foods

Examples:

Salmonella from excretors or ill employees

Staphylococcus aureus from employees with infected or purulent wounds or with colonization of the nasopharynx

1. Employees who are ill with or suspected of infections by Salmonella, EHEC/STEC, Shigella, cholera vibrios, hepatitis A or E viruses or other infectious gastroenteritis, or who excrete the above bacterial pathogens, must not work in food establishments handling perishable foods and kitchens according to the German Infection Protection Act (IfSG) (see IfSG § 42)
2. The same applies to employees who suffer from infected or purulent wounds. Non-infected wounds must be hygienically properly covered
3. Regular training/instruction of employees regarding the required infection protection measures
4. Verification by visual on-site inspections, checks of training records and follow-up testing

1. Check processes, production protocols and documentation
2. Inactivation of most bacteria at a core temperature of +72 °C for at least 2 minutes. Exceptions include heat-stable spores and toxins. In these cases significantly higher temperatures and exposure times are required. Further information can be found, for example, in the respective information sheets (fact sheets)
3. Check the correctness of processes and temperatures
   1. In general, hot-holding temperatures above +60 °C are required
   2. Rapid cooling: after 3 hours a core temperature of at least +7 °C must be reached (special caution is required for large quantities)
4. Verification by follow-up testing

1. Check processes, environmental conditions, production protocols and documentation
2. Verification by follow-up testing

1. Request traceability of the cold chain during transport or from the supplier
2. Check incoming and storage temperatures
3. Control refrigeration temperatures and cold chains during processing, transport and sale
4. If over-age (or excessively long shelf life) is suspected, carry out appropriate shelf-life tests
5. Verification by follow-up testing

1. Maintain distance to fields with animal husbandry; keep wildlife away from fields using, for example, fences or nets
2. Water hygiene: contaminated water must not be used for irrigation. Irrigation and drainage systems must be suitable. Regular monitoring of microbiological water quality
3. Do not use microbiologically contaminated fertilizers in crop production
4. Personnel and work hygiene during harvest and post-harvest steps
5. Remove soil and contaminations by washing
6. Verification by follow-up testing