strains from persistent and intermittent nasal carriers are genetically related to nosocomial epidemic strains. (A) Bayesian MCMC analysis of persistent carrier strains (colored in blue), intermittent carrier strains (colored in black) and nosocomial epidemic strains (colored in red). Numbers at each node indicate posterior probability support and grey-filled circles represent 100% posterior probability. (B) eBURST analysis of the MLST data clusters STs from intermittent and persistent carriers into same clonal complexes and into groups that are represented by numbers in grey. STs colored in black are nasal carrier strains, STs colored in red are epidemic strains and those in green contain both carrier and epidemic strains. Circle sizes in each cluster are proportional to the number of isolates and blue circles are founders of that particular cluster.