MRSA = methicillin-resistant staphylococcus aureus - think I spelled that right
It is a 'superbug' that is resistant to most antibiotics and is frequently picked up in hospitals with a very detrimental effect on the poor souls who acquire it. Often is is passed on by medical staff and visitors not washing their hands properly. It is causing a real problem in hopsitals over here. Many people carry it, and it is usually harmless - but not in hospital patients.
I have known of two people who died from this bug.