FIG 2.

Ex vivo competition assays of S. aureus reveal the selective advantage of topical antibiotic resistance gene carriage in clinically relevant environments. S. aureus strains NZ14132 (orange), NZ14487 (aqua), and NZAK3 (green) wild-type or complemented strains paired with their respective isogenic mutants were grown on porcine skin under nonselective conditions and exposure to a single dose of 20 to 25 mg 2% Fucidin or 2% Bactroban ointment for 24 h. (A to D) Percentages of wild-type or complemented isolates within mixed cultures of wild-type and fusC mutant (A), fusC complemented and fusC mutant (B), wild-type and mupA mutant (C), and mupA complemented and mupA mutant (D) strains were determined at the conclusion of the assays. Five biological replicates were used to calculate the mean percentages and the SEM (black error bars) for each condition tested. Statistically significant differences are indicated by asterisks (**, P < 0.01; ***, P < 0.001, paired t test).