The proportion of Staphylococcus aureus that is methicillin resistant (MRSA) has been rising in UK hospitals over the past 10 years. In some individual hospitals this increase has been explosive. The propensity for MRSA to spread arises mainly from the following reasons: Antimicrobial selection increases the biomass of MRSA in a particular patient or patient population The organism is located on exposed body surfaces(for example, the skin and nasal mucosa) MRSA is easily transferred from patient to patient, for example via the hands of staff.