Nature Microbiology 2, 16257 (2017); published online 23 January 2017; corrected 13 March 2017

In the version of this Article originally published, the horizontal bars in Fig. 1a that indicate statistical differences were incorrectly placed. This has now been corrected in all versions of the Article, so that the horizontal bars indicate the statistical differences between strain 331865 and strains USA300, MW2 and 103.