Within and Beyond the MIC: Unveiling the Antifungal Potency of Green-Synthesized Silver Nanoparticles Against Clinical Isolates of Candida albicans

Biogenic silver nanoparticles (AgNPs) synthesized using aqueous extracts of Pyracantha koidzumii (AgNPs-P) and Schinus molle (AgNPs-S) were evaluated for antifungal activity against two clinical isolates (HCI-I and HCI-II) and an ATCC strain of Candida albicans. Synthesis was confirmed by UV–Vis, Fourier transform infrared spectrophotometry (FTIR), dynamic light scattering (DLS), electrophoretic light scattering (ELS), nanoparticle tracking analysis (NTA), and transmission electron microscopy (TEM) revealing stable, quasi-spherical particles averaging 15.13 nm (AgNPs-P) and 10.81 nm (AgNPs-S). Both types of AgNPs exhibited a minimum inhibitory concentration (MIC) of 1.56 µg/mL across all strains. However, AgNPs-P demonstrated superior efficacy against HCI-I, with the lowest minimum fungistatic (6.25 µg/mL) and fungicidal concentrations (12.5 µg/mL). Notably, AgNPs-P eliminated fungal cells at a lower particle concentration (1.76 × 10¹⁰ NPs/mL) yielding a lower particle efficiency index (2.8 × 10⁴ NPs/CFU), underscoring their enhanced antifungal efficacy. Mechanistically, the AgNPs compromised cell wall integrity, inhibited hyphal growth, and reduced proteolytic activity. These results highlight the need to evaluate antifungal performance beyond MIC values and suggest AgNPs-P as a promising therapeutic candidate.