Trading Standards Institute Advice

Food borne illness and contamination: E. coli O157

This leaflet is for all food businesses, including those involved in catering, food production, food preparation, retail premises, restaurants, pubs, cafes, and fast-food shops.

What is E. Coli O157?
E. Coli bacteria are carried in our bodies, and most strains of these bacteria do not cause us any harm. However, some types such as E. Coli O157 can produce toxins (poisons), and if these bacteria are eaten or absorbed by the body in some way, even in very small amounts, they can cause serious illness.

Those most vulnerable to the bacteria are children, elderly people or those who are already ill. Illness can start 10 hours after eating contaminated food, but it may take up to 10 days for the symptoms to show. Symptoms include abdominal pain, fever, diarrhoea and occasionally vomiting. There may be blood in the urine. The toxin can also cause kidney failure and can even kill.

What does E. Coli O157 come from?
E. Coli O157 may be found in the intestines of some cattle, sheep and goats. It can also come from sewage, contaminated water and raw or undercooked meat. Anything that has been contaminated can pass on the bacteria, including dairy products, fruit and vegetables.

Illness from E. Coli O157 has happened after trips to farm visitor centres where children have not washed their hands after touching infected farm animals. It can also spread from one person to another in families, nurseries or day-care centres through unwashed hands and by touching contaminated surfaces such as toilet flushes and door handles.

How does food get contaminated?
In catering, illness can be caused through raw or undercooked food such as:

  • minced beef, sausages and burgers that have been contaminated
  • foods such as unwashed vegetables that have been contaminated with animal faeces or soil
  • untreated water or unpasteurised milk.

The E. Coli bacteria can be killed by cooking, but because only small amounts of the bacteria are needed to cause illness it is important to prevent the bacteria cross-contaminating other foods.

You must keep raw meat away from cooked foods and other ready-to-eat foods such as salad, bread and cheese. You should never use a knife or a chopping board you have already used to prepare raw food to prepare cooked food or ready-to-eat food. For example, never use a plastic container or a roasting dish that has carried raw food to carry ready-to-eat food without thoroughly cleaning and disinfecting it first. After you have prepared raw food, you should also thoroughly clean cooking utensils and the work surface before moving to the next task.

How do I control or prevent E. Coli O157?
You must keep high standards of food hygiene at all times while preparing and serving food. To help keep the risk of contamination as low as possible, you can use colour-coded equipment such as chopping boards and knives. This equipment would only be used for one type of food or in one food-preparation area.

Here is an example of a colour-coded scheme.

Colour coding scheme

You must completely defrost frozen food before you start to cook it, unless the manufacturer gives you different instructions. This will help to make sure it can be cooked thoroughly.

You should wash fruit and vegetables thoroughly, especially if they are going to be eaten raw.

You should keep to the right cooking and storage temperatures:

  • frozen food should be kept at -18°C (or colder)
  • fridges should be set to a maximum of 8°C but preferably between 1°C to 5°C
  • cooking - core temperature should be a minimum of 75°C at the thickest part of the food
  • cooling - food should be cooled and put in the fridge within one and a half hours
  • reheating - core temperature should be a minimum of 75°C at the thickest part of the food
  • you can use a food thermometer or probe to check the temperature from time to time -you must clean and disinfect these every time you use them

Wash your hands thoroughly:

  • after you go to the toilet
  • after you've handled raw food
  • after you've touched pets and animals
  • before you prepare and eat food

It has been reported that E. Coli bacteria can survive for more than 60 days on stainless steel. You should make sure you thoroughly clean all food-preparation areas, equipment and work surfaces.

The way many businesses manage all their cleaning is to write a cleaning schedule which sets out what needs to be cleaned and when. The schedule must be followed each day and the standards of cleaning monitored by management.

You must disinfect anything that comes into contact with food. Always carefully follow the manufacturer's instructions when you use cleaning materials and disinfectants and make sure they are 'food safe' - colourless, odourless and not likely to taint the food.

You should keep pets out of the food preparation area and away from food-storage areas, equipment and worktops.

Protecting others
If anyone contracts E. Coli O157 and works in high-risk jobs, such as food handlers and health-care workers, they should not return to work until they have fully recovered and have had no symptoms for at least 48 hours.

More information
You will find further guidance in our other leaflets on this website. Information can also be found on the Food Standards Agency website.

Alternatively, contact your local environmental health service for advice.

Please note
This leaflet is not an authoritative interpretation of the law and is intended only for guidance.

© 2018 itsa Ltd.