In the United Kingdom reporting of bacteraemia due to methicillin resistant Staphylococcus aureus (MRSA) infections is mandatory, and reduction in bacteraemia rates is a performance target for NHS trusts. Rates of S aureus bacteraemia remain high around the world, so we need forms of surveillance that will allow better understanding of its causes.

In this week's BMJ Wyllie and colleagues describe the use of linked data in Oxfordshire hospitals to investigate secular trends in bacteraemia caused by S aureus.1 Using anonymised data on hospital admissions of patients and linking them to information on isolates of S aureus, Wyllie and colleagues found that about a third of patients with S aureus bacteraemia died within 30 days. The risk of death was similar for methicillin sensitive and methicillin resistant S aureus infections.

Between 1997 and 2003, rates of MRSA in these Oxfordshire hospitals increased while rates for methicillin sensitive S aureus (MSSA) strains remained constant. In other words, methicillin …