Silver Nanoantibiotics Display Strong Antifungal Activity Against the Emergent Multidrug-Resistant Yeast Candida auris Under Both Planktonic and Biofilm Growing Conditions

Abstract

Candida auris is an emergent multidrug-resistant pathogenic yeast with an unprecedented ability for a fungal organism to easily spread between patients in clinical settings, leading to major outbreaks in healthcare facilities. The formation of biofilms by C. auris contributes to infection and its environmental persistence. Most antifungals and sanitizing procedures are not effective against C. auris, but antimicrobial nanomaterials could represent a viable alternative to combat the infections caused by this emerging pathogen. We have previously described an easy and inexpensive method to synthesize silver nanoparticles (AgNPs) in non-specialized laboratories. Here, we have assessed the antimicrobial activity of the resulting AgNPs on C. auris planktonic and biofilm growth phases. AgNPs displayed a strong antimicrobial activity against all the stages of all C. auris strains tested, representative of four different clades. Under planktonic conditions, minimal inhibitory concentration (MIC) values of AgNPs against the different strains were <0.5 μg ml −1 ; whereas calculated IC 50 values for inhibition of biofilms formation were <2 μg ml −1 for all, but one of the C. auris strains tested. AgNPs were also active against preformed biofilms formed by all different C. auris strains, with IC 50 values ranging from 1.2 to 6.2 μg ml −1. Overall, our results indicate potent activity of AgNPs against strains of C. auris, both under planktonic and biofilm growing conditions, and indicate that AgNPs may contribute to the control of infections caused by this emerging nosocomial threat.

Bismuth Nanoantibiotics Display Anticandidal Activity and Disrupt the Biofilm and Cell Morphology of the Emergent Pathogenic Yeast Candida auris

“…We observed that the untreated samples from the different C. auris strains display variations on their phenotypes. This diversity of size and shapes has been described in other works [17,47]. In this work, we expand the current knowledge as we associate the observed specific phenotypes to particular clades.…”

“…We noted that the antibiofilm activity of BiNPs was close to the activity reported for other anticandidal agents during the biofilm formation stage. BiNPs displayed lower antibiofilm potency than that of AgNPs against C. auris biofilms [29,47]. However, the fact that BiNPs display antibiofilm activity should be considered for further research.…”

Eradication of Candida albicans Biofilm Viability: In Vitro Combination Therapy of Cationic Carbosilane Dendrons Derived from 4-Phenylbutyric Acid with AgNO3 and EDTA

“…In addition, we observed that yeast cells continue to attach to each other forming small groups of cells. This observation has been also reported [54]. In their study, they observed that biofilms treated with nanoparticles showed small multibranched groups of cells, usually formed by less than 10 cells.…”

“…In our previous studies, this effect was observed by SEM, including the formation of pores in the membrane of C. albicans [9]. These concurrent damages cause Candida cells to have decreased viability and reduce their ability to withstand the effects produced by treatments [54]. In contrast, the mode of action of antifungals is by targeting specific molecules or cell structures.…”

The Neosartorya fischeri Antifungal Protein 2 (NFAP2): A New Potential Weapon against Multidrug-Resistant Candida auris Biofilms

“…Therefore, certain non-antifungal agents alone or in combination with traditional antifungals have been investigated as a potential approach to overcome C. auris -related catheter-associated infections. These include ebselen [ 24 ], miltefosine [ 25 ], farnesol [ 26 ], and silver or bismuth nanoantibiotics [ 27 , 28 ]. To date, three conventional potential line lock solutions have been tested against C. auris biofilms.…”