In Vitro Activity of Two Nanoparticles on Clinical Isolates of Candida parapsilosis, Showing Resistance Against Antifungal Agents in Children

Resistance of pathogenic fungi to conventionally available antifungal agents has been increasing and has become a serious problem. On the other hand, nanoscience has emerged as a powerful tool capable of developing and designing new antimicrobial drugs.
The aim of this study was to test minimum inhibitory concentrations (MICs) of silver (Ag-NPs) and selenium (Se-NPs) nanoparticles, both alone and in combination with antifungal agents fluconazole (FLU), itraconazole (ITR), and amphotericin B (AMB) on resistant C. parapsilosis strains.
Eight C. parapsilosis strains resistant to antifungal agents (FLU, ITR, AMB) and the standard strain of C. parapsilosis (ATCC 22019) as a control were used in this study. The standard protocol of antifungal susceptibility testing for yeast was performed by the broth micro-dilution method described in the clinical and laboratory standards institute (CLSI) guidelines, document M 27-S4.
Results and MICs of standard and resistant strains were different against nano compounds, both alone and in combination with antifungal drugs. The growth of yeast was inhibited by Ag-NPs at concentrations as low as 2 µg /mL (against FLCR1 and FLCR3) and 0.25 µg /mL (against ITRR2 and AMBR2). Antifungal activity testing of Se-NPs revealed that it can inhibit the growth of yeasts at concentrations as low as 4 µg /mL (against FLCR1 and FLCR3) and 0.5 mg/mL (against ITRR2, ITRR3 and AMBR1). The results demonstrated that Se-NPs had lower activity than Ag-NPs, but both (Se-NPs and Ag-NPs) had higher activity than common antifungal agents. Further in vitro and in vivo studies are required for this.