This is a very nice study that combines the power of core genome MLST with the analysis of the flexible genome components for the tracking of epidemiologically linked and geographically endemic clones.
The idea of 'low virulence' in S. aureus really goes well when compared with other seasoned pathogens such as Mycobacterium tuberculosis; in the latter case also 'low virulence' strains reportedly exist, particularly those rampant in South India and mostly belonging to the East African Indian (EAI) clades.
However, in my opinion such observations need to be substantiated by laboratory based evidence towards abrogation of virulence gene functions, animal studies involving grading of virulence and finally the field level data from contact studies.
