Fig. 3. Ag⁺ potentiates bactericidal antibiotics in vitro.

(A) Log change in cfu/mL, from time zero, of wildtype E. coli after treatment for 3 h with 15 μM AgNO₃, 0.25 μg/mL gentamicin, 0.03 μg/mL ofloxacin, 1 μg/mL ampicillin, and combinations of AgNO₃ with the respective antibiotics. (B) Changes in HPF fluorescence after 1 h of administering the treatments described in (A). (C) Log change in cfu/mL, from time zero, of wildtype E. coli after treatment for 3 h with the indicated concentrations of AgNO₃ and 30 μg/mL vancomycin. (D) Changes in PI fluorescence after 1 h of administering different concentrations of AgNO₃. Error bars represent mean ± SEM for at least 6 biological replicates. 10 mice per treatment group were used for the survival studies. (E) Treatment of a drug-resistant E. coli strain with Ag⁺ restores antibiotic susceptibility back to wildtype levels. Tetracycline MIC of wildtype E. coli (AG100) and that of an E. coli drug-resistant strain (AG112) with and without Ag⁺ treatment. *** indicates a p-value of <0.001 and ** indicates a p-value of <0.05 as determined by a student t-test, indicating a significant difference from the wildtype strain or untreated control, unless otherwise specified. Error bars represent mean ± SEM for at least 3 biological replicates.