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

[Background]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.[Objectives]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.[Methods]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 Conclusions]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 FLC_R1 and FLC_R3) and 0.25 µg /mL (against ITR_R2 and AMB_R2). Antifungal activity testing of Se-NPs revealed that it can inhibit the growth of yeasts at concentrations as low as 4 µg /mL (against FLC_R1 and FLC_R3) and 0.5 mg/mL (against ITR_R2, ITR_R3 and AMB_R1). 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.