FIG. 3.

Determination of SMX resistance by agar drug diffusion assay. SMX was solubilized in DMSO (100 mg/ml), and 25 μl was applied to the centers of agar plates. Additional plates were supplemented with increasing concentrations of PABA. Transformants were harvested in log-phase growth, washed in PBS, and normalized to 6 × 10⁶ CFU/ml. Each strain was then streaked radially from the center of the plate. The plates were grown for 3 to 5 days, and the zones of inhibition for each isolate, TRP, VRS, ARS, TRS, and ARP, were then scored. The results are averages of triplicate experiments; error bars represent the standard deviations of the means.