Effect of proton pump inhibitors on susceptibility and melanogenesis of Sporothrix species

<b>Introduction.</b> Sporotrichosis is a subcutaneous infection caused by dimorphic <i>Sporothrix</i> species embedded in the clinical clade. Fungi have virulence factors, such as biofilm and melanin production, which contribute to their survival and are related to the increase in the number of cases of therapeutic failure, making it necessary to search for new options.<b>Gap statement.</b> Proton pump inhibitors (PPIs) have already been shown to inhibit the growth and melanogenesis of other fungi.<b>Aim.</b> Therefore, this study aimed to evaluate the effect of the PPIs omeprazole (OMP), rabeprazole (RBP), esomeprazole, pantoprazole and lansoprazole on the susceptibility and melanogenesis of <i>Sporothrix</i> species, and their interactions with itraconazole, terbinafine and amphotericin B.<b>Methodology.</b> The antifungal activity of PPIs was evaluated using the microdilution method, and the combination of PPIs with itraconazole, terbinafine and amphotericin B was assessed using the checkerboard method. The assessment of melanogenesis inhibition was assessed using grey scale.<b>Results.</b> The OMP and RBP showed significant MIC results ranging from 32 to 256 µg ml^-1 and 32 to 128 µg ml^-1, respectively. Biofilms were sensitive, with a significant reduction (<i>P</i><0.05) in metabolic activity of 52% for OMP and 50% for RBP at a concentration of 512 µg ml^-1 and of biomass by 53% for OMP and 51% for RBP at concentrations of 512 µg ml^-1. As for the inhibition of melanogenesis, only OMP showed inhibition, with a 54% reduction.<b>Conclusion.</b> It concludes that the PPIs OMP and RBP have antifungal activity <i>in vitro</i> against planktonic cells and biofilms of <i>Sporothrix</i> species and that, in addition, OMP can inhibit the melanization process in <i>Sporothrix</i> species.