Silver nanoparticles, a promising treatment against clinically important fluconazole‐resistant Candida glabrata

Resistance to azole antifungal agents is a challenging limitation in Candida glabrata treatment. It is associated with decreased intracellular concentrations of antifungal agents as a result of overexpression of efflux pumps on the cellular plasma membranes. This work evaluates the potential of silver nanoparticles (AgNPs) to reverse the resistance of fungal cells to fluconazole. Silver nanoparticles were prepared using wet chemical method and characterised by UV‐Vis spectrophotometry, dynamic light scattering, and zeta potential. Broth microdilution and pour plates methods were used to study the anticandidal activity using two C. glabrata fluconazole‐resistant strains (DSY565 and CBS138) known to overexpress active efflux pumps, and a standard fluconazole sensitive strain ATCC 22553. Silver nanoparticles–fluconazole combinations decreased concentrations of fluconazole substantially without compromising the activity. These findings suggest that AgNPs enhance the efficacy of fluconazole and offer a promising application in therapy of C. glabrata infections. Significance and Impact of the Study: This is the first study to use special Candida glabrata strains (DSY 565 and CBS 138 that possess efflux pumps proteins with low fluconazole sensitivity) to study the anticandidal effect of silver nanoparticle (AgNPs)–fluconazole combinations. The findings showed that AgNPs–fluconazole combinations demonstrated remarkable activity against strains known to express well‐characterised efflux pumps; thus, we speculate that the possible mechanism of increased sensitivity to fluconazole produced by AgNPs is the inhibition of the active efflux pumps.