Azole Resistance Mechanisms in Pathogenic Malassezia furfur

Abstract

<i>Malassezia</i> are emerging fungal pathogens causing opportunistic skin and severe systemic infection. Nosocomial outbreaks are associated with azole resistance and understanding of the underlying mechanisms are limited to knowledge from other fungal species. Herein, we identified distinct antifungal susceptibility patterns in 26 <i>Malassezia furfur</i> isolates derived from healthy and diseased individuals. A Y67F <i>CYP51</i> mutation was identified in five isolates of <i>M. furfur</i> However, this mutation alone was insufficient to induce reduce azole susceptibility in the wild type strain. RNA-seq and differential gene analysis of healthy and disease derived strains exposed to clotrimazole <i>in vitro</i> identified several key metabolic pathways and transporter proteins which are involved in reduce azole susceptibility. The pleiotropic drug transporter <i>PDR10</i> was the single most highly upregulated transporter gene in multiple strains of <i>M. furfur</i> after azole treatment and increased expression of <i>PDR10</i> is associated with reduced azole susceptibility in some systemic disease isolates of <i>M. furfur</i> Deletion of <i>PDR10</i> in a pathogenic <i>M. furfur</i> strain with reduced susceptibility reduced MIC values to the level of that in susceptible isolates. The current dearth of antifungal technologies, globally emerging multi-azole resistance, and broad agriculture and consumer care use of azoles means improved understanding of the mechanisms underlying intrinsic and acquired azole resistance in <i>Malassezia</i> is crucial for development of antibiotic stewardship and antifungal treatment strategies.