Staphylococcus aureus

The staphylococcus aureus bacteria live in the nose, mouth and throat of humans as well as on the skin. It is responsible for producing several types of toxins which are known to cause food poisoning and other medical conditions.

Staphylococcal food poisoning is usually caused by a failure to store food properly although it can occur if food is undercooked or inadequately heated.

This type of bacteria has an appearance not unlike a bunch of grapes and is responsible for a range of diseases apart from food poisoning which include toxic shock syndrome, osteomyelitis (bone infection) and septicaemia (blood poisoning).

Staphylococcus aureus and staph infections

The staphylococcus aureus bacterium is the most common cause of staph related diseases. One such disease is the ‘hospital acquired’ infection MRSA (Methicillin Resistant Staphylococcus Aureus) which has been a major feature within the media over the last few years.

This infection is contracted by people who have undergone treatment in hospital and as a result of this, have a weakened immune system. This means that they are susceptible to disease and infection. Another possible cause is poor attention to hygiene and standards of cleanliness.

Theses bacteria are the cause of many infectious diseases which range from mild –such as pimples and abscesses through to serious even life threatening ones such as endocarditis (inflammation of the inner layer of the heart), pneumonia (lung infection) and meningitis (inflammation of the membranes that cover the brain).

The most common type of staph infection is a skin infection such as impetigo.

Staphylococcus toxins

It produces 7 varieties of toxins which can be categorised into the following three groups:

• Superantigens: this includes the ‘enterotoxins’which are known to cause food poisoning.
• Exfoliative: these affect the skin, for example, scalded skin syndrome.
• Others: this group includes toxins which cause MRSA

These toxins can be connected to specific diseases and infections.

Foods which contain staphylococcus aureus bacteria

The staphylococcus aureus bacteria are found within the following types of foods:

• Eggs
• Dairy products
• Ham
• Poultry, e.g. chicken
• Fish
• Bakery products, e.g. pastries

This bacterium is able to reproduce within these foods before causing an infectious disease.

Causes of staphylococcus aureus poisoning

This type of food poisoning is caused by the enterotoxins which form part of the superantigens group of toxins produced by the staph bacteria.

These bacteria are often found in foods which have been kept at room temperature or have been handled by someone who has a skin infection.

Another cause is food which has not been completely cooked through.

There is an incubation period of 1 to 6 hours after consumption of infected food.

Symptoms of staphylococcus aureus poisoning

These symptoms appear a short while after eating contaminated food and include:

• Nausea
• Vomiting
• Diarrhoea
• Abdominal cramps
• Loss of appetite
• Low grade fever

These develop in mild cases but severe cases will also include headaches, muscle cramps, joint pains and dehydration.

This type of food poisoning is not infectious and cannot be spread from one person to another.

Treatment for staphylococcus aureus poisoning

Most cases of this food poisoning are treatable at home. This means plenty of bed rest and fluids to replace those lost during this illness. Drink lots of water and include an electrolyte solution, e.g. sachet which can be purchased at a pharmacy. This will contain essential vitamins and minerals which need to be replaced to prevent the risk of dehydration.

A medication such as antibiotics is not usually prescribed as they have little or no effect on the staph bacteria.

People who fall into a high risk group such as children under 5 or the elderly may require treatment in hospital. This will involve intravenous fluids.

Recovery usually takes around 48 hours.

Complications of staphylococcus aureus poisoning

The main risk is dehydration. But contact your GP if you have severe diarrhoea which lasts more than 3 days, bloody diarrhoea or your entire symptoms worsen.

Preventing staphylococcus aureus poisoning

There are a few steps you can take to reduce the chance of you being the next staph food poisoning statistic. These include:

• Ensure that meat and any leftovers are stored in the food as soon as they are safe to do so.
• Keep any chopping boards, utensils etc which have been used with raw meat separate from other kitchen equipment. Wipe these down thoroughly after use.
• Avoid cross contamination (mixing raw and cooked food)
• Do not handle food if you have an open wound on your skin or a skin infection.

For more information visit our preventing food poisoning section.