FIG 4.

Inhibited S. aureus survival in nasal medium containing select species from the Gammaproteobacteria class. (A) Multiple unique strains of S. aureus were tested for their ability to proliferate in a physiological synthetic nasal medium supplemented with 0.1% human serum (SNM). Error bars represent the mean ± SEM. (B and C) Growth of putative nasal S. aureus competitor strains in SNM. Individual data points are shown as open circles. Bars and error bars indicate the mean ± SEM. Colored circles for A. haemolyticus indicate the unique strains tested. (D) To screen which resident nasal species compete with S. aureus, mixtures (50,000 S. aureus CFU + 50,000 CFU test strain) were incubated, and S. aureus recovery was calculated by comparing S. aureus CFU on selective agar when S. aureus was incubated alone versus with the indicated strain. Individual data points and box and whiskers representing the median, 25th to 75th percentiles, and min/max values are shown for at least 3 experiments using unique nasal strains of S. aureus. *, P < 0.05; **, P < 0.01 versus S. aureus incubated alone (100% recovery).