Fig. 5: Sustainable susceptibility of S. aureus to silver endows it with potency to overcome antibiotic resistance.

a Representative heat plot of microdilution checkerboard assay for the combination of antibiotics and Ag⁺ against S. aureus Newman (n = 3). b Isobolograms of the combination of ampicillin and Ag⁺ against S. aureus Newman (n = 3). c Time–killing curves for ampicillin and Ag⁺ mono- and combined-therapies against S. aureus Newman during 24 h incubation (n = 3). d Heat plot visualizing the mutation frequency of S. aureus Newman exposed to ampicillin in the presence of increasing concentration of Ag⁺. e Bar chart showing MPI values of ampicillin in the presence of increasing concentration of Ag⁺ against S. aureus Newman (n = 3). f Resistance acquisition curves during serial passage with the subinhibitory concentration of ampicillin or combination of ampicillin and Ag⁺ against S. aureus Newman (n = 3). MIC test was performed every two passages. g–i Ag⁺/AgNP synergize with antibiotics to kill MRSA 33591. g Representative heat plot of microdilution checkerboard assay for the combination of ampicillin and Ag⁺ against MRSA 33591 (n = 3). h Representative heat plot of microdilution checkerboard assay for the combination of ampicillin and AgNP against MRSA 33591 (n = 3). i Isobologram of the combination of ampicillin and Ag⁺/AgNP against MRSA 33591. All experiments were performed in three biological replicates. Mean value of three replicates is shown and error bars indicate ±SEM (b).