Fig. 5: Transition metal treatment changed bacterial response to antibiotics.

a MIC₅₀ of M. abscessus, untreated or transition metal-treated, to clinically relevant antibiotics. Data are averaged from at least three biological replicates for each condition and expressed as mean ± standard deviation. Asterisks indicate levels of significance compared with untreated bacteria; the significance level of differences were determined by unpaired Student’s t tests, with *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001. b Time-killing curves of M. abscessus with different ion-antibiotic combinations. The growth of bacterial cultures was monitored for 7 days (168 hours) and numbers of viable cells (CFU/mL) were quantified by plating on 7H10 agar. Figures are averaged from two biological replicates, each with three technical replicates. Error bars represent standard deviation for each time point. The significance level of differences between antibiotic (blue) and ion-antibiotic combinations (red) for each group were calculated using a one-way ANOVA test and marked as **p < 0.01; ***p < 0.001; ****p < 0.0001. c Intracellular accumulation of clarithromycin (CLR), ciprofloxacin (CIP) and levofloxacin (LVF) in M. abscessus in the presence of Ni²⁺ or Co²⁺. The efflux pump inhibitors verapamil and reserpine were used in combination with ions and antibiotics. The statistical significance levels of differences between the treated and untreated groups for each condition were calculated by unpaired t tests, with levels of significance indicated on top of each condition as *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001. The data of each panel are averaged from two biological replicates, each with three technical replicates, and individual data points are shown for each replicate.