Utility and limitations of Spa-typing in understanding the epidemiology of staphylococcus aureus bacteraemia isolates in a single University Hospital

Background: Staphylococcus aureus (SA) is a recognized cause of nosocomial infections with 8,767 SA bacteraemia (SAB) cases reported in England only in 2012. Different typing methods have been developed but they are not generally performed as a routine investigation in hospital laboratories. Findings. We collected epidemiological data and spa-typed all SAB isolates over a 12 months period. Spa-typing was useful to detect two potential outbreaks of methicillin-sensitive SA (MSSA). In addition, the analysis of spa-types from individuals with multiple bacteriaemias helped to distinguish between relapse and re-infection. Conclusions: Spa-typing could be used as a rapid tool to understand the epidemiology of SAB, in particular the detection of hospital clusters and to distinguish relapse from re-infection, but clinicians should be aware of its possible limitations.