The two main research projects focus on understanding mechanisms of staphylococcal (predominantly methicillin-resistant Staphylococcus aureus MRSA) disease pathogenesis and transmission in the hospital setting.

• Identification of a highly bacteraemic strain of MRSA. During 2003/2004 the Trust had high rates of MRSA bacteremia. The result of a detailed epidemiological study identified that a significant reason for this was an extended outbreak on the ICU with a novel variant of MRSA, designated TW. This strain had an enhanced capacity to bind vascular access devices leading to bloodstream invasion. A targeted introduction of basic infection control and a novel decolonisation strategy led to termination of the outbreak. We have performed microarray-based analysis of this strain and are performing full genomic sequencing (collaborators Dr Jodi Lindsay, St George's University of London and Dr Julian Parkhill, Sanger Insititute, Cambridge). We are currently investigating the mechanism of adhesion and invasion in vitro which combined with the awaited genome sequence will potentially provide insight into the basic mechanism of MRSA bacteraemia and identify novel approaches to prevention. It may also identify genetic markers for hyperinvasive strains that can be used to assess the distribution of such strains across the UK for targeted enhanced infection control strategies.
• MRSA transmission dynamics. Following the detailed ICU analysis it became apparent that our enhanced infection control efforts led to a sustained (more than 2 years) prevention of MRSA cluster outbreaks on the ICU and only a residuum of sporadic acquisitions. We are developing mathematical models of transmission dynamics through analysis of data from the ICU over the last 5 years to assess the reduction in risk of MRSA acquisition, assess the confidence with which the reduction can be ascribed to the enhanced interventions and to compare the transmissibility of different strains including TW in collaboration with Dr Ben Cooper, Health Protection Agency).