Silver Nanoantibiotics Display Strong Antifungal Activity Against the Emergent Multidrug-Resistant YeastCandida aurisUnder Both Planktonic and Biofilm Growing Conditions

Candida aurisis 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 byC. auriscontributes to infection and its environmental persistence. Most antifungals and sanitizing procedures are not effective againstC. 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 onC. aurisplanktonic and biofilm growth phases. AgNPs displayed a strong antimicrobial activity against all the stages of allC. aurisstrains tested, representative of four different clades. Under planktonic conditions, minimal inhibitory concentration (MIC) values of AgNPs against the different strains were <0.5 mu g ml(-1); whereas calculated IC(50)values for inhibition of biofilms formation were <2 mu g ml(-1)for all, but one of theC. aurisstrains tested. AgNPs were also active against preformed biofilms formed by all differentC. aurisstrains, with IC(50)values ranging from 1.2 to 6.2 mu g ml(-1). Overall, our results indicate potent activity of AgNPs against strains ofC. 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.