4.5. Time–Kill Assay

The kill kinetics of antimicrobial activity provides a more accurate description of antimicrobial agents, in contrast to the MIC assay [57]. In order to determine the synergistic effect from the survival curve of bacteria, the standard strain ATCC 33591 and clinical strain DPS-2 were used to conduct experiments, and three treatment modes (DMC alone, GEN alone and GEN combined with DMC) were designed to compare the antibacterial effects with the control (no drug). The inocula were diluted to 1.5 × 10⁶ CFU/mL and incubated at 37 °C. At five different time intervals (0, 4, 8, 16 and 24 h), the surviving bacteria were properly diluted and inoculated on the plate. After incubation at 37 °C for 24 h, counted the colonies on the plate. Then the number of viable bacteria was calculated according to the dilution ratio, and the growth curve was drawn.