Farnesol inhibits planktonic cells and antifungal-tolerant biofilms of Trichosporon asahii and Trichosporon inkin

Trichosporon species have been considered important agents of opportunistic systemic infections, mainly among immunocompromised patients. Infections by Trichosporon spp. are generally associated with biofilm formation in invasive medical devices. These communities are resistant to therapeutic antifungals, and therefore the search for anti-biofilm molecules is necessary. This study evaluated the inhibitory effect of farnesol against planktonic and sessile cells of clinical Trichosporon asahii (n = 3) andTrichosporon inkin (n = 7) strains. Biofilms were evaluated during adhesion, development stages and after maturation for metabolic activity, biomass and protease activity, as well as regarding morphology and ultrastructure by optical microscopy, confocal laser scanning microscopy, and scanning electron microscopy. Farnesol inhibited Trichosporon planktonic growth by 80% at concentrations ranging from 600 to 1200 mu M for T. asahii and from 75 to 600 mu M for T. inkin. Farnesol was able to reduce cell adhesion by 80% at 300 mu M for T. asahii and T. inkin at 600 mu M, while biofilm development of both species was inhibited by 80% at concentration of 150 mu M, altering their structure. After biofilm maturation, farnesol decreased T. asahii biofilm formation by 50% at 600 mu M concentration and T. inkin formation at 300 mu M. Farnesol inhibited gradual filamentation in a concentration range between 600 and 1200 mu M. Farnesol caused reduction of filament structures of Trichosporon spp. at every stage of biofilm development analyzed. These data show the potential of farnesol as an anti-biofilm molecule.