Antifungal Activity of a Medical-Grade Honey Formulation against <i>Candida auris</i>

<i>Candida auris</i> is a pathogenic yeast causing outbreaks in intensive care units with high mortality rates. The treatment of <i>C. auris</i> colonization is challenging due to high resistance rates. A potential alternative antifungal treatment is medical-grade honey. In this study the susceptibility of <i>C. auris</i> and other <i>Candida</i> species to the medical-grade honey-based formulation L-Mesitran^® Soft was investigated. The medical-grade honey formulation reduced the growth of <i>C. auris</i> and other <i>Candida</i> species in a dose-dependent manner. This inhibition was not only due to the honey component, as treatment with an identical concentration of this component only was less effective and even stimulated the growth of <i>C. albicans</i> and <i>C. glabrata</i>, supporting the interpretation that supplements in the medical-grade honey formulation enhanced the antimicrobial activity. Increasing the concentration of the honey component to 40%, as is also present in an undiluted medical-grade honey formulation, lead to a 1- to 4-log inhibition of all <i>Candida</i> species. Unprocessed local honey reduced the growth of nearly all <i>Candida</i> species more strongly than medical-grade honey. <i>C. auris</i>’ susceptibility to the medical-grade honey formulation did not depend on geographic origin or resistance profile, although the multiresistant isolates tended to be more susceptible. Altogether, medical-grade honey formulation has a strong antifungal activity against <i>C. auris</i> and other <i>Candida</i> species. Future studies should demonstrate whether the treatment of open wounds or skin colonized with <i>C. auris</i> is feasible and effective in the clinical setting.