Bacteria

Bacteria are microscopic (can only be seen through a microscope) living cells which are found naturally in the air, in the soil, in the water, on work surfaces and on people, animals and insects. They are around us on us and in us every where and all the time. Most bacteria are harmless, indeed we need them to stay healthy. Bacteria help our guts to digest food, they are used to make many foods such as cheese, wine, beer, yoghurt and medicines such as penicillin. Many of our body's bacteria fight harmful bacteria and keep us healthy.

Some bacteria are what we call pathogenic, or disease causing. Some are what we call opportunistic - in the right place in the right numbers they are harmless or even beneficial, but in the wrong place or at the wrong numbers they can take advantage of the opportunity to become pathogenic. Many of the 'gut bugs' or intestinal bacteria are opportunistic - in the gut they help digest food, but once they get back into the food and are themselves being digested they become pathogenic and cause illness.

Bacteria need a warm, moist environment to survive in with a food source and they may or may not need oxygen from the air to survive. If we provide these things for them bacteria will not only survive but multiply in our food to levels where they are harmful to the person who eats that food. And they multiply incredibly rapidly. They can be in their billions within hours of colonising a site.

Some bacteria can survive cooking by forming spores, or protective shells around themselves like an insulating coat. After the heat is off they can then turn back into their normal form and begin multiplying again.

Some bacteria can also make toxins or poisons and release these into the food while they are multiplying, thus making the food very harmful to eat. Some bacteria do not make their toxins in the food but in the person who eats them. When the bacteria laden food gets into the person's stomach, which is acidic, they release toxins as they forms spores to protect themselves from the acid, thus making the person very sick indeed.

Salmonella

Salmonella may be already in any meat, eggs or shellfish or raw milk as it can get there from the skin or intestine of the animal at its slaughter (or at milking in the case of raw milk). It doesn't make spores or toxins so it should be easy to prevent by simply cooking the food properly. It will be destroyed at 75 - 80°c. It is also likely to get into any food from the food handler not washing their hands or utensils after handling raw meat or dairy products.

Symptoms of illness include fever, headache, abdominal pain, diarrhoea and vomiting. Illness is likely to begin 12 - 36 hours after eating the food and may last for 1 - 8 days.

Campylobacter

Campylobacter is very similar to Salmonella in that it is likely to be present in meats, shellfish, raw milk and foods contaminated by the food handler. It does not make spores or toxins and can be killed at temperatures of 75 - 85°c. The difference is that we need a large number of salmonella bacteria in the food to make most people ill, but we only need a small number of campylobacter bacteria to make most people ill. Because of this it is also possible to get campylobacter bacteria into us from hand to mouth contact with an infected person. For example: they have campylobacter and haven't washed their hands after going to the toilet, you shake their hand as you greet them, then put your finger in your mouth for some reason. Hey presto - now you have campylobacter too!

Symptoms of illness include fever, headache, nausea, vomiting, haemorrhagic diarrhoea and severe abdominal and muscular pain. Illness is likely to begin 1 - 10 days after eating the food and may last between 2-3 days but relapses can occur.

Listeria

Listeria is an extremely common bacteria found in water, soil, plants and faeces. Foods affected by listeria are most likely to be shellfish, vegetables, raw milk and highly processed foods such as soft cheese, hams, pate e.t.c. The trouble with listeria is that it can still multiply quite happily in the fridge (which would usually be too cold for most bacteria). However it is killed easily at temperatures of 75 - 80°c

Symptoms of illness in a healthy adult are very similar to the 'flu and many people may not even realise they have a food borne illness. However, the very young, very old or immunocompromised may develop the full symptoms of septicaemia or meningitis, which can kill. This also applies to unborn babies. Mum may not get much more than slight 'flu symptoms, but her baby may die before it's even born.

You may not be able to protect all your customers from Listeriosis, depending on the type of food you produce, but you should still be aware of its dangers, even if only for your own use.

Clostridium perfringens

This bacteria does form spores to survive heating and produces toxins in the gut of the consumer. It is commonly found in the intestines (gut) of animals and humans and can be assumed to be present on raw meat from contamination at slaughter. It is also commonly provided by the unwashed hands of a food handler. Flies can also contaminate food with clostridium perfringens by bringing it in on dust and soil.

The time spent in between hot and cold is the most vital time to be controlled to prevent this bacteria being harmful. The raw meat must be assumed to have the bacteria present. If it is cooked properly, most of them will have been killed but some must be assumed to have survived by forming spores. If the meat is then left at room temperature for too long, these surviving bacteria will begin to multiply again. If they are then eaten, as they meet the acidic contents of the stomach they form spores to protect themselves and release toxins as they do, thus making the person who ate them very sick. This could have been prevented by either eating the food as soon as it was cooked, keeping it hot at over 65°c until it was eaten, or cooling it rapidly and either eating it cold or reheating it to over 80°c. It is the time at room temperature which must be minimised to ensure the bacteria cannot begin again to multiply in the food.

Symptoms of illness include abdominal pain and diarrhoea and may begin 6-24 hours after the food is eaten and last 12-24 hours.

Clostridium botulinum

This bacteria is another member of the clostridium family but is much more dangerous. This one releases its particularly poisonous toxin in the food if it is allowed to begin multiplying again at room temperature after surviving cooking by forming spores. As it is commonly found in soils, foods likely to be affected are those which have come in contact with the soil - vegetables and filter feeding shellfish. It has been previously associated with incorrectly preserved meats, seafood and vegetables.

Symptoms of illness include diarrhoea, then vision, breathing and speech difficulties. Fatigue, dizziness, double vision and paralysis may result with death within 1-8 days likely unless the antitoxin is given. This is one of the most toxic toxins on the planet - only a very small amount is needed to cause life threatening illness. Symptoms are likely to appear 24 - 72 hours after the food is eaten. Again it is the time at room temperature which allows the toxins to be produced. Also, growth can be prevented by ensuring the preserves are sugary, salty or acidic enough (see later under high risk and low risk foods).

Staphylococcus aureas

This bacteria can only get into the food from unsafe handling by the food preparer. It is commonly found in the nose, throat and sinuses of humans and in pimples, boils, and infected cuts and burns of the skin. It gets into the food from sneezing, coughing, dribbling or unwashed hands and skin. It then releases its toxin as it multiplies in the food at room temperature.

Symptoms of illness include severe vomiting, abdominal pain, diarrhoea and collapse; usually starting 2 - 6 hours after eating the food and lasting for 6-24 hours.

Bacillus cereus

This bacteria is another spore forming bacteria that releases its toxin into the food as it multiplies at room temperature. It is commonly found in soils and dusts, thus the most likely foods affected are rice, grains, vegetables and reheated meat dishes. Again, prevention is simply a matter of ensuring that if the food is not to be eaten straight after cooking, it is either kept hot at over 65°c or cooled down rapidly and chilled at below 4O°c until eaten or thoroughly reheated to over 80°c.

Symptoms of illness include vomiting for 1 - 5 hours and / or diarrhoea for 6 - 15 hours, likely to start 1 - 15 hours after eating the food and lasting 1 - 2 days.

Yersinia

Yersinia is a non-spore forming bacteria which causes illness merely by its presence, similar to salmonella and campylobacter. It is commonly found in meats, seafood and water. Prevention is mostly a matter of personal hygiene of the food preparer and prevention of cross-contamination between food types.

Symptoms of illness include watery diarrhoea, intense abdominal pain, headaches, fever and vomiting. Illness is likely to begin between 24 and 36 hours after consuming the food or water, and last or 1 - 3 days.

E.coli

Escherischia coli is also a non-spore forming and non toxin producing opportunistic bacteria. It is commonly found in the gut, but if it gets into food causes a food infection illness. There are many different types of E. coli, causing slightly different symptoms, but they are typically of a vomiting and diarrhoea with abdominal cramps type illness. Prevention is mainly by control of personal hygiene of the handler and cross-contamination between food types. It is most commonly found in meats – especially highly processed selections, fish, vegetables and dairy products.

Symptoms are likely to begin around 18 hours after consumption of the contaminated food and last for an average of 2 days, longer for some of the nastier versions of the bacteria.

These illnesses can kill. In severe cases, especially in children, the elderly or immunocompromised, death by dehydration can occur. There is no excuse for illness caused by these bacteria. The required preventative measures include:

• Thorough cooking properly thawed food to at least 80°c
• Minimising time at room temperature (to less than ½ -1 hour) before putting the food in a chiller, if not being eaten immediately or kept hot until it is.
• Not handling food if you are ill with a cold, 'flu or any vomiting or diarrhoea
• Washing hands thoroughly and frequently (see the personal hygiene section later for details).
• Washing and sanitising all utensils and equipment according to the risk of the food being prepared (see cleaning section later for details).
• Preventing cross-contamination between food types
• Pest control
• Wash fruit and vegetables before using them
• Once preserved foods have been opened, keep them in the fridge

Giardia

Giardia (pronounced gee-ah-dee-ah) is a parasite found in the gut of humans and animals such as cattle, sheep, cats, dogs, rats and possums.

It is passed on in the faeces of infected animals and humans. Giardia is widespread in New Zealand and the parasites can live in the environment for long periods, especially in lake, river, stream and roof water.

People become infected when they swallow the parasites. This may be from contaminated water and food, or from contact with infected animals or humans.

Cryptosporidium

Cryptosporidium (pronounced crip-toe-spor-idium) is a parasite found in the gut of birds fish, reptiles (eg geckos and turtles), humans and animals such as cattle, sheep, cats and dogs.

It is passed on in the faeces of infected birds, animals and humans. Cryptosporidium is widespread in New Zealand and the parasites can live in the environment for long periods, especially in lake, river, stream and roof water.

People become infected when they swallow the parasites. This may be from contaminated water and food, or from contact with infected animals or humans.