Fig. 1.

Maximum-likelihood phylogeny of 224 ST8 S. aureus isolates based on 12,403 core genome single nucleotide polymorphisms. The colors represent the region of origin of each sample. Phylogenetic positions of the included NCBI RefSeq genomes (two USA300 and one USA500) are highlighted with asterisks. Information about the complete presence (black squares), partial presence (gray squares), or absence (white squares) of USA300-specific genetic features is given for each sample. Major genetic introduction events are indicated on the respective phylogenetic branches. (Scale bar: substitution per site.)