FIG 2 .

Selection coefficients as a function of antibiotic and heavy metal concentrations during competition experiments between resistant strains carrying the pUUH239.2 plasmid and susceptible plasmid-free strains. (A) Competitions in the presence of combinations of trimethoprim and erythromycin. The total normalized concentration is the sum of the two normalized concentrations, where the concentration of each compound was first normalized to its respective MSC. Data can be found in Table S4 in the supplemental material. (B) Competitions in the presence of combinations of arsenic and tetracycline. These competitions were performed in LB medium, explaining why the selection coefficients of tetracycline in this experiment were different from the values in Fig. 1A, where Mueller-Hinton medium was used. Data can be found in Table S5. The differences in MSC with and without arsenic were significant (P value = 0.0001 in a paired t test). (C) Competitions in the presence of combinations of arsenic, tetracycline, and trimethoprim. The total normalized concentration is the sum of all normalized concentrations, where the concentration of each compound was first normalized to its respective MSC. Data can be found in Table S6. Standard deviations are indicated.