MRSA is often referred to as a 'superbug'. MRSA stands for methicillin-resistant staphylococcus aureus. Staphylococcus aureus is a bacteria that normally lives on our skin and doesn't cause us any health problems. However some of these bacteria have become resistant to the antibiotic methicillin and other antibiotics such as penicillin. Infections like MRSA are known as hospital aquired infections because they occur mostly in healthcare environments. This is because when we have an open wound such as after surgery, or when our immune systems are weakened e.g. when we are suffering from another illness or the elderly or young children, we can get what are known as opportunistic infections. These infections occur when bugs that normally live in, on or around us without harming us, grow in number and cause illness in us. These bugs, like MRSA, may be resistant to antimicrobial treatment.