Select Gammaproteobacteria inhibit S. aureus survival on nasal cells. S. aureus competition assays were performed as described in Fig. 4 and 5 except that incubations occurred in the apical chamber of Transwells containing polarized primary human nasal epithelial cells. (A) Growth of 5 unique strains of S. aureus on polarized primary nasal epithelia, presented as input and output (24 h) CFU/well. (B and C) S. aureus recovery (%) for incubations of S. aureus mixed with an equivalent input of the indicated strain. *, P < 0.05; **, P < 0.01 versus S. aureus alone (100% recovery). (D) S. aureus recovery (%) for incubations containing 90% S. aureus + 10% indicated strain. **, P < 0.001; ***, P < 0.0001 versus S. aureus incubated alone (100% recovery). (E) Percent recovery of competitor strains from the 90% S. aureus/10% test strain mixtures presented in panel D. For all panels, bars and error bars represent the mean ± SEM.