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MRSA stands for methicillin (M) resistant (R) Staphylococcus (S) aureus (A).

It is a variety of a common germ called Staphylococcus aureus. This germ lives completely harmlessly on the skin and in the nose of about one third of people. It is more common on skin that is broken - if you have a cut, a sore, or a rash such as eczema.

People who have MRSA on their bodies or in their noses but who are unharmed by it are described as being colonised.

MRSA can cause problems when it gets the opportunity to enter the body. This is more likely to happen in people who are already unwell. MRSA causes abscesses, boils, and it can infect wounds - accidental wounds such as grazes and deliberate wounds such as those made for a drip or during surgery.

These are called local infections. It may then spread into the body and cause serious infections such as septicaemia (blood poisoning). MRSA is resistant to methicillin (a type of penicillin) and some of the other drugs that are commonly used to treat infections.


See the Welsh Government's information leaflet about MRSA for further details and answers to some frequently asked questions.

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