Staphylococcus aureus is a common bacterium (germ), which up to a third of the population carry on parts of their skin or in the nose without any problems or infections developing.
Some strains of staphylococcus aureus are resistant to some antibiotics, including meticillin, and these strains are referred to as meticillin-resistant Staphylococcus aureus (MRSA).
Both MRSA and staphylococcus aureus can be carried by patients both in their nose and on their skin.
MRSA can live harmlessly on the skin and in some chronic wounds such as leg ulcers but can cause problems if it does get into a skin break (e.g. a surgical wound) or parts of the body that are normally sterile, such as the bladder.
MRSA tends to be a problem in hospitals as people who are already unwell are more vulnerable to infection.
It can also be easily spread from person to person.
In general, healthy people are at a low risk of infection with MRSA.
Causes of MRSA
Like many bacteria, MRSA usually only becomes a problem if your immune system (which normally fights infection) is compromised due to illness, certain medications, surgery or injury.
It can cause more serious infections if it enters the body through wounds or tubes after surgery or serious illness.
It's worth remembering that:
- MRSA only affects a minority of people and not all people with MRSA will develop an infection
- The majority of patients that have MRSA are either colonised (presence of the MRSA on the skin and causing no harm) or have superficial infections that don't require specific treatment
- MRSA can be acquired in the community as well.
Importantly, MRSA does not pose a risk to healthy people (i.e. those without wounds or chronic illness).
Prevention and treatment
Please see MRSA: Prevention and treatment.
Please see the NHS website: MRSA infections.