Meticillin-sensitive Staphylococcus aureus is a type of bacteria (germ) which lives harmlessly on the skin and in the noses, in about one third of people. People who have MSSA on their bodies or in their noses are said to be colonised. However MSSA colonistation usually causes them no problems, but can cause an infection when it gets the opportunity to enter the body. This is more likely to happen in people who are already unwell. MSSA can cause local infections such as abscesses or boils and it can infect any wound that has caused a break in the skin e.g. grazes, surgical wounds.
MSSA can cause serious infections called septicaemia (blood poisoning) where it gets into the bloodstream.
MSSA is found when swabs from skin, nose or wounds or other specimens such as urine or sputum which are examined in the hospital
Simple guide to MSSA
Link to PHE website