Silver Nanoparticles as Antibacterials: Synthesis, Characterization, and Molecular Simulations Against β-Lactamase-Producing Enterobacter and Salmonella spp.

Multidrug resistance poses a threat to public health all over the world. Evidences suggest that third-generation antibiotic resistance mediated by extended-spectrum beta-lactamases (ESBLs) in all Enterobacteriaceae species, especially in Enterobacter and Salmonella. In this study, silver nanoparticles (AgNPs) were synthesized and characterized using sol-gel synthesis and powder X-ray diffraction. It was shown that clinical isolates were sensitive to AgNPs. The MIC and MBC, time-dependent growth inhibition test as well as well diffusion agar techniques. ESBL generation was examined using these approaches. There was a low MIC value of 500 μg/ml for Enterobacter and Salmonella. 1000 μg/ml of AgNPs inhibited the development of microorganisms. The antibacterial effect of AgNPs was slow but dependent on concentration and duration. At a concentration of 100 μg/ml, the inhibition zone for Enterobacter was 22 mm, whereas that for Salmonella was 20 mm. Further, molecular docking employed to explore the binding affinity between AgNPs and the active site of beta-lactamase and compare it with reference. Results revealed a very strong score (- 26.79 kcal/mol). Next, MD simulation was performed. The MD simulation results showed a stable interaction between beta-lactamase-nanocluster. Experimental and computational results elucidate the molecular mechanism of anti-bacterial activity of AgNPs to fight against bacterial infections.