Trading Standards Institute Advice

Food borne illness and contamination: Clostridium perfringens

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 Clostridium perfringens?
Clostridium perfringens is a bacteria that is found in soil, sewage and animal manure as well as in the intestines of humans and animals.

Clostridium perfringens food poisoning is linked mainly with foods that are cooked slowly in large amounts and left to stand for a long time at room temperature. Outbreaks can affect a large number of people, so places such as canteens, schools and hospitals must take extra care.

How does food get contaminated?
Like other types of bacteria that cause food borne illness, you may not be able to protect food from Clostridium perfringens just by cooking. It tolerates heat fairly well and can multiply only when there is no air. So, if cooking temperatures are not high enough, it can multiply in foods such as in the middle of a meat pie, in a boned and rolled joint of meat or in the bottom of a large pot of casserole or stew.

Which foods are most at risk of contamination or infection?
Food poisoning often happens when food has been prepared too early and then kept warm for several hours before it's served. Clostridium perfringens food poisoning is commonly linked with:

  • meat
  • meat products such as stews
  • meat pies
  • gravy made from beef, turkey, or chicken

Food poisoning happens when these foods have been contaminated and then not properly refrigerated or if they are not thoroughly cooked or reheated right through. Soil on, or from, vegetables can also cause contamination in a food preparation area.

This bacteria will be killed by thorough cooking but it can produce spores. Spores are not a serious risk to an healthy adult but, as they can survive harsh conditions for a long time, they could be a problem. They can survive with no water or food and, not only can they tolerate high temperatures, they can use the heat to produce more bacteria.

When large amounts of food are cooked but not cooled straightaway, these spores could find the conditions they need to turn into bacteria, which then start to multiply. In the right conditions the number of bacteria can double every 10 to 12 minutes which, when eaten, may cause gastroenteritis.

What are the effects or symptoms of eating contaminated food?
Once in the small intestine, if there is enough of the bacteria present they release a toxin (poison). Symptoms start about six to 24 hours after the contaminated food is eaten. Although usually mild, some types of this bacteria cause serious gastroenteritis that can damage the small intestine and sometimes kill the very young, elderly, and those already ill. The most common symptoms are:

  • watery diarrhoea
  • abdominal pain

The illness can cause dehydration and lower the blood pressure. Symptoms may cause nausea (though not usually vomiting or fever) and normally last between 12 to 24 hours.

How do I control or prevent clostridium perfringens?

GENERAL:

  • buy meat from suppliers only with a good reputation
  • use an efficient labelling system to make sure you keep to a FIFO ('first in, first out') system for food-stock rotation

HAND WASHING: 

  • wash hands thoroughly with soap and water immediately:
    - before working with cooked foods
    - after you handle raw food
    - after you handle cooked food
    - after you get rid of waste
    - after you use the toilet
    - after you take a break

COOKING: 

  • you must completely defrost frozen food before you cook it, unless the manufacturer gives you different instructions - this will help to make sure it can be cooked thoroughly
  • thoroughly cook food to a minimum temperature of 75oC at the thickest part of the meat
  • serve meat dishes hot or keep them in the fridge until you serve them - once you've cooked the food, if you are going to serve it hot, keep it hot (above 63oC)

REHEATING: 

  • if you are going to reheat food, reheat it quickly to a minimum temperature of 75oC at the thickest part of the meat
  • only reheat food once and throw away any food that is not eaten
  • never partially cook meat or poultry and then reheat it 

COOLING: 

  • if you are going to cool the food, divide casseroles and similar dishes that may have been prepared in large numbers into smaller portions to allow them to cool quickly
  • allow the food to cool for no longer than 90 minutes before storing in a refrigerator at or below 5oC
  • keep foods refrigerated, ideally below 5oC
  • do not put hot food into the fridge, as this will raise the temperature of other food stored there

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.

© 2017 itsa Ltd.