 Microbial infections of joints are destructive. It typically takes 2-3 days to identify a causative organism and confirm diagnosis. Recent studies suggest low-level bacterial colonisation within joints. The investigators aim to analyse the joint fluid for any bacterial colonisation using enrichment and 16S Polymerase Chain Reaction PCR then correlate the results to the metabolic profile. In addition the investigators aim to seek metabolites indicative of the presence of a biofilm which, if present severely limits treatment options. 