Antifungal Efficacy of Chitosan-Stabilized Biogenic Silver Nanoparticles against Pathogenic Candida spp. Isolated from Human

Abstract

Biogenic silver nanoparticles (Bio-AgNPs) have been recognized to play a major role in the fight against multi-drug-resistant pathogens. The present study evaluates antifungal efficacy of biogenic AgNPs conjugated with a natural polymer chitosan (derived from shrimp (Penaeus monodon) shells). Bio-AgNPs used for conjugation were produced by a mycoendophyte Colletotrichum gloeosporioides (KX881911) isolated from the medicinal plant Withania somnifera (L.). During the last decade, although numerous reports on Bio-AgNPs with antimicrobial activity have been reported, insights on the usage of conjugates of Bio-AgNPs have been scarce. Candida species are responsible for severe nosocomial infections and which has developed resistance against many antifungal agents. The current study aims to evaluate the antifungal activity of Bio-AgNPs conjugated with chitosan (Ch Bio-AgNPs) on various Candida species isolated from patients. The fungicidal activity was screened by well diffusion assay and TTC assay. Antibiofilm activity against Candida species was well elucidated by Congo red agar and Crystal Violet assay. Ch Bio-AgNPs showed the potent antifungal effect at 50 μg/ml concentration on all the selected Candida species, and the disruption and distortion of cells were documented well with transmission electron microscopy (TEM). The TEM images showed adhesion and entry of Ch Bio-AgNPs into the cells and release of cellular inclusions along with cell damage and distorted cell morphology. To conclude, the study suggests that Ch Bio-AgNP is a potential antifungal agent to treat drug-resistant pathogenic Candida species.