Figure 2.

Principal component analysis of 1,056 S. aureus strains reveals genetic clusters of hypervirulent clones (17). The different cubes, plotted here in a 3D space and colored according to their source, represent each S. aureus strain analyzed in the Melles et al. study. The 5 circles indicate the 3 major (I, II, and III) and 2 minor (IVa and IVb) different phylogenetic clusters identified by AFLP. While strains from each of the genetic clusters are essentially able to cause invasive disease, some clusters contain proportionally more invasive isolates.