Harmful bacteria spoils food and causes illness.

You can’t see, taste, feel or smell bacteria, making it difficult to detect on any food products, kitchen surfaces or cooking utensils. It can contaminate food without making its presence known. Bacteria are very small living things that can be found everywhere, in water, soil, animals, food and even people. Everyone has bacteria on their bodies.
What are bacteria
Bacteria are single celled organisms that reproduce through multiplication, and which can grow and divide every 20 minutes. It reproduces by dividing itself, so one bacterium will become two and then two will become four and so on. In ideal conditions one can become several million in just 8 hours.

Avoid food poisoning bacteria by; 

  • Not eating high-risk foods like raw or lightly cooked eggs, undercooked meat or poultry, and unpasteurized milk.
  • Always cooking food thoroughly.
  • Not handling ready-to-eat foods with your bare hands.
  • Washing and drying your hands properly after; touching raw foods, going to the toilet, touching bins, sneezing, coughing, washing dishes, touching pets etc. (Remember that even healthy people can spread bacteria by simply touching food with their hands).
  • Keeping worktops, chopping boards and utensils clean.
  • Keeping foods at the correct hot or cold temperatures.
  • Cleaning mealtime surfaces.
  • Using separate cutting boards for poultry, meat and vegetables.
  • Examining food closely whilst preparing it and looking for telltale signs of contamination.
  • Not handling food if you are ill, or have open sores or cuts etc.

How does bacteria grow
The bacteria that causes food poisoning needs warmth and moisture to grow. Pathogenic bacteria grows best when there is a rich food supply of high protein food, and will multiply rapidly between 4°C and 60°C. This is why it’s vital to keep food out of this “danger zone,” by keeping cold food cold and hot food hot.
Bacteria multiply with;

  • Warmth
  • Moisture
  • Food
  • Time

Bacteria spreads through;

  • Cross contamination
  • Improperly cooked food
  • Poor food handler hygiene
  • Pests infecting food

Can you see bacteria?
They are so small that it takes one million to cover a pinhead, meaning you need to look at them through a microscope.

What food does bacteria grow on?
Bacteria can grow in just about any food, but it is particularly fond of protein foods like meat, poultry, seafood, beans, grains, eggs, and dairy products.

Harmful bacteria
The bacteria that specifically causes disease and food-borne illnesses are called ‘pathogens.’ There are over two hundred different types of bacteria, parasites and viruses that can cause food borne diseases. However it is estimated that the vast majority of food poisoning (over 90 per cent) is caused by just a handful of bacteria (listed below);

  • Staphylococcus aureus
  • Salmonella
  • Clostridium perfringens
  • Campylobacter
  • Listeria monocytogenes
  • Vibrio parahaemolyticus
  • Bacillus cereus
  • Entero-pathogenic Escherichia coli.

In extreme cases when certain pathogens enter the food supply they can cause death, especially in babies, older people, and those with chronic diseases or weakened immune systems. Food-borne illness that has been caused by bacteria can manifest itself as flu-like symptoms such as fever, nausea, abdominal cramps, vomiting or diarrhoea.

  • Many cases of food poisoning by bacteria go undiagnosed or unreported.

After eating contaminated food a person will not normally become ill straight away. This is because most bacteria needs an incubation period in which to multiply in a person’s intestine. The delay before when symptoms start can be anything from a few hours to a few days, and depends on the type of bacteria and a person’s general health.
Bacteria can be found on:

  • Appliances
  • Kitchen utensils
  • Clothes
  • Equipment
  • Food
  • Hands

Some common types of bacteria

  • Aeromonas hydrophila
  • Bacillus cereu
  • Campylobacter
  • Campylobacter jejuni
  • Clostridium botulinum
  • Clostridium perfringens
  • E. coli
  • Escherichia coli O157:H7
  • Listeria monocytogenes
  • Norovirus (Norwalk Virus)
  • Salmonella
  • Shigella spp
  • Staphylococcus aureus
  • Vibrio cholerae

From a bacterial point of view this is one of the most common causes of food poisoning and diarrhoea in the UK.  It causes an infectious disease called Campylobacteriosis, and there were an estimated 371,000 cases in England and Wales in 2009. Typical symptoms are fever, diarrhoea, cramping, and abdominal pain, all of which usually start within two to five days of a person becoming infected.

Campylobacter is mostly found in:

  • Poultry
  • Red meat
  • Unpasteurised milk
  •  Untreated water

This name is used to describe a group of bacteria that is one of the most common causes of food poisoning in the population. Salmonella is usually transmitted through contaminated animal faeces. It’s therefore vital that you wash your hands after coming into contact with any animals, their food, or their habitat.

It can cause an infection called Salmonellosis, and is usually found in;

  • Poultry
  • Eggs
  • Unpasteurised milk
  • Meat
  • Juice
  • Cheese
  • Raw fruits
  • Vegetables
  • Spices
  • Nuts

Typical symptoms can last for between 4 – 7 days and can include stomach pain, diarrhoea, nausea, chills, fever, and headaches.

Escherichia Coli 0157 (E. coli)E. coli O157
This is found in the gut of farm animals, and can cause food poisoning through eating undercooked meat, unpasteurised dairy products and from contact with farm animals

Listeria monocytogenes
This bacteria can be found in soil or water, and can turn up in uncooked meats, vegetables, cold cuts, unpasteurized milk and soft cheeses. Typical symptoms include: chills, fever, headache, backache, sometimes abdominal pain and diarrhoea.
Prevent the spread of bacteria by focusing on;

  • Preventing existing bacteria from multiplying.
  • Destroying any existing bacteria by proper cooking.
  • Taking steps to avoid contaminating or re-contaminating food and surfaces.

Useful bacteria
Some bacteria are useful to human beings. They are used in the manufacture of sour cream, vinegar, buttermilk, yogurt, cheese, sauerkraut and even medicines.
Bacteria helps us to digest our food.


Related links
Food hygiene course online