The microbiota of n = 20 randomly selected S. aureus carriers (red) and n = 20 non-carriers (blue) were analysed in faecal samples. a–c, Rarefaction (species-richness) curves based on 16S rRNA gene sequences. Data are mean ± s.d. a, Shannon index. b, Observed species. c, Chao1 index. d, Comparison of relative taxa abundance between S. aureus carriers (red) and non-carriers (blue). e, f, Beta diversity, represented by a principal coordinate analysis plot based on unweighted UniFrac (e) and weighted UniFrac (f) metrics for samples from S. aureus carriers (red) and non-carriers (blue).