S. aureus is a spherical bacterium (coccus) which on microscopic examination appears in pairs, short chains, or bunched, grape-like clusters. These organisms are Gram-positive. Some strains are capable of producing a highly heat-stable protein toxin that causes illness in humans. Staphylococcus aureus is a bacterium which is carried on the skin of 10% or more of the population. In the majority of cases, this does not result in any harm. Occasionally, recurrent skin infections (boils) can occur. Rarely Staphylococcus aureus can cause a serious infection, such as pneumonia or a blood stream infection.

Contact with wounds and boils infected with Staphylococcus aureus can spread the infection.

Skin-to-skin contact with a person carrying the bacteria on their skin without symptoms and sharing towels or linen, or inadequate laundering, can spread the bacteria, particularly within families.

Lack of hand washing during food preparation can result in Staphylococcus aureus from hands contaminating food, which may lead to food poisoning.

Symptoms of infection range from pain, redness and swelling in an abscess, to a serious illness with fever, and occasionally shock, in a blood stream infection.

The diagnosis of Staphylococcus aureus infection is made by growing the bacteria from a sample of pus or blood.

In the majority of cases, the infection can be successfully treated with a range of antibiotics. In some cases, the bacteria are resistant to the commonly used antibiotics. These bacteria are known as MRSA (methicillin resistant Staphylococcus aureus). However, antibiotics are available which will work against MRSA.

Infections with MRSA are no more serious than infections with Staphylococcus aureus.

Infectious period

As long as the organism is carried on the skin.

Control of spread

  • Standard precautions in the form of strict hand washing by care givers and good personal hygiene in the person infected are the most effective means of control.
  • Clothing, sheets and towels of the infected person should be washed with detergent in hot water.
  • In hospital, there are some patients, such as those with wounds, where infection with MRSA could pose a special risk. Therefore, when a hospital patient is found to have an infection with MRSA, additional precautions may be taken to prevent transmission of MRSA. Use of a single room with ensuite facilities is recommended. Staff and visitors are requested to wash their hands thoroughly before leaving the room.
  • On returning home, it is appropriate to return to the use of standard precautions, such as hand washing and good personal hygiene.


Infections with Staphylococcus aureus (including MRSA) can be treated with appropriate antibiotics. People who carry the germ on their skin or in their nose will only require antibiotics under special circumstances.


Death from staphylococcal food poisoning is very rare, although such cases have occurred among the elderly, infants, and severely debilitated persons.

Target Population

All people are believed to be susceptible to this type of bacterial intoxication; however, intensity of symptoms may vary.