Restoration of Antibacterial Activity of Inactive Antibiotics via Combined Treatment with AgNPs.

Antimicrobial resistance poses a huge threat to human health around the world and calls for novel treatments. Combined formulations of NPs and antibiotics have emerged as a viable nanoplatform for combating bacterial resistance. The present research work was performed to investigate the effect of combined formulations of AgNPs with streptomycin, cefaclor, ciprofloxacin, and trimethoprim against multidrug-resistant (MDR) isolates of and . AgNPs have been synthesized by using the seed extract, and their characteristics were analyzed. AgNPs depicted concentration-dependent antibacterial effects, as the highest concentration of AgNPs showed the strongest antibacterial activity. Interestingly, AgNPs in conjugation with antibiotics showed an enhanced antibacterial potential against both and , which suggested synergism between the AgNPs and antibiotics. Against , streptomycin and trimethoprim in conjugation with AgNPs presented a synergistic effect, while cefaclor and ciprofloxacin in combination with AgNPs showed an additive effect. However, all of the tested antibiotics depicted a synergistic effect against . The lowest value of MIC (0.78 μg/mL) was shown by AgNPs-Stp against , whereas AgNPs-Tmp showed the lowest value of MIC (1.56 μg/mL) against . The most important point of the present study is that both organisms ( and ) showed resistance to antibiotics but turned out to be highly susceptible when the same antibiotic was used in combination with AgNPs. These findings highlight the potential of nanoconjugates (the AgNPs-antibiotic complex) to mitigate the present-day crisis of antibiotic resistance and to combat antimicrobial infections efficiently.