Piper chaba mediated synthesis of silver nanoparticles to control multidrug-resistant diarrheagenic fecal pathogens

Plant-mediated biosynthesis of nanoparticles has gained significant attention in Biomedical fields. This study focused on the isolation of multidrug-resistant diarrheagenic fecal pathogens and their control by green-synthesized silver nanoparticles. Furthermore, we assessed the antioxidant and cytotoxic properties of <i>Piper chaba</i> leaf-synthesized nanoparticles. We isolated and identified multiple antibiotic-resistant fecal pathogens, including <i>Enterococcus gallinarum</i>, <i>Klebsiella pneumoniae</i>, and <i>Escherichia coli</i>, through biochemical assays and 16S rRNA gene sequencing. Then the synthesis of silver nanoparticles was visually confirmed by a color change in the sample solutions and further confirmed through UV-Vis spectroscopy, FTIR, TEM, DLS, and XRD analyses. UV-Vis spectroscopy revealed a surface plasmon resonance (SPR) peak at 440 nm. Meanwhile, FTIR analysis identified functional groups such as haloalkanes, alkenes, and alcohols contributing to the synthesis and stabilization of the nanoparticles. DLS showed the nanoparticles were 56.66 nm in size with monodispersity, and XRD confirmed the presence of face-centered cubic crystals with an average size of 16.06 nm. Furthermore, TEM images showed spherical-shaped nanoparticles at various resolutions. The DPPH (2, 2-diphenyl-1-picrylhydrazyl) assay indicated antioxidant activity, with a maximum radical scavenging activity (% RSA) of 69.28 %. In addition, the brine shrimp lethality assay (BSLA) demonstrated low cytotoxicity with an LC₅₀ value of 912.01 μg/mL. The nanoparticles effectively inhibited these multidrug-resistant pathogens at varying doses, with minimum inhibitory concentrations of 4 μg/mL against <i>Klebsiella pneumoniae</i> and <i>Escherichia coli</i>, and 16 μg/mL against <i>Enterococcus gallinarum</i>. These findings suggest that green-synthesized silver nanoparticles could be a promising therapeutic approach for controlling antibiotic-resistant fecal pathogens.