Objective: To determine the incidence of methicillin resistant and methicillin sensitive Staphylococcus aureus (MRSA and MSSA) bacteraemia in inpatients and associated mortality within 30 days after diagnosis.
Design: Anonymised record linkage study of data from hospital information systems and microbiology databases.
Setting: Teaching hospital and district general hospital in Oxfordshire.
Participants: Inpatients aged 18 or over admitted to a teaching hospital between 1 April 1997 and 31 March 2004 and to a district general hospital between 1 April 1999 and 31 March 2004. The main part of the study comprised 216 644 inpatients; patients admitted to haematology, nephrology, or oncology services were not included because most were managed as outpatients.
Outcome measures: Nosocomial MSSA and MRSA bacteraemia; death in hospital within 30 days after bacteraemia.
Results: Rates of S aureus bacteraemia rose between 1997 and 2003, and MRSA was responsible for this increase. Overall mortality 30 days after bacteraemia was 29%. The crude odds ratio for death after MRSA bacteraemia compared with MSSA bacteraemia was 1.49 (95% confidence interval 0.99 to 2.26).
Conclusion: The spread of MRSA has greatly increased the overall number of cases of S aureus bacteraemia and has contributed to short term mortality after S aureus bacteraemia.