Mushroom-mediated silver nanoparticles from Pleurotus ostreatus as antimicrobial candidates against multidrug-resistant bacteria: Physicochemical, in-silico, cytotoxicity, and immunobiological evaluation.

The rise of antimicrobial resistance has heightened the demand for alternatives to traditional antibiotics, especially against multidrug-resistant (MDR) strains of Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniaei, and Pseudomonas aeruginosa. We examined whether silver nanoparticles (AgNPs) mediated by Pleurotus ostreatus exhibit improved antibacterial efficacy alongside acceptable levels of cytotoxicity and immunobiological effects. Silver nanoparticles (AgNPs) were synthesized from aqueous Pleurotus ostreatus extract and characterized by UV-visible spectroscopy, dynamic light scattering, transmission electron microscopy (TEM), zeta potential analysis, Fourier-transform infrared spectrometry (FTIR), and gas chromatography-mass spectrometry (GC-MS). The antibacterial activity was evaluated using broth microdilution, time-kill, and antibiofilm tests. Cytotoxicity and immunobiological effects were assessed in macrophages by MTT, cytokine, nitric oxide, and reactive oxygen species assays. AgNPs exhibited a plasmon resonance peak at 428 nm, a hydrodynamic diameter of 38.6 nm (SD 4.8), a core diameter of 22.4 nm (SD 6.1), and a zeta potential of -27.8 mV (SD 2.4). The minimum inhibitory values were 4 μg/mL for MRSA, 8 μg/mL for E. coli, and 16 μg/mL for both K. pneumoniae and P. aeruginosa. AgNPs diminished viable counts against MRSA from 6.2 to 1.2 log10 CFU/mL at 24 h. Biofilm inhibition varied between 68.4% and 86.5%. The CC50 of macrophages was 61.3 μg/mL. AgNPs decreased TNF-α from 384 to 149 μg/mL and elevated IL-10 from 35 to 69 pg/mL. P. ostreatus-mediated AgNPs demonstrated significant in vitro antibacterial, antibiofilm, and immunomodulatory effects, accompanied by a favorable cytotoxicity profile, warranting future preclinical exploration.