Trichosporon asahii has recently been recognized as an emergent fungal pathogen able to cause invasive
infections in neutropenic
cancer patients as well as in
critically ill patients submitted to invasive medical procedures and broad-spectrum
antibiotic therapy. T. asahii is the main pathogen associated with
invasive trichosporonosis worldwide. Treatment of patients with
invasive trichosporonosis remains a controversial issue, but
triazoles are mentioned by most authors as the best first-line antifungal
therapy. There is mounting evidence supporting the claim that
fluconazole (FLC) resistance in T. asahii is emerging worldwide. Since 2000, 15 publications involving large collections of T. asahii isolates described non-wild type isolates for FLC and/or
voriconazole. However, very few papers have addressed the epidemiology and molecular mechanism of antifungal resistance in Trichosporon spp. Data available suggest that continuous exposure to
azoles can induce mutations in the ERG11 gene, resulting in resistance to this class of antifungal drugs. A recent report characterizing T. asahii
azole-resistant strains found several genes differentially expressed and highly mutated, including genes related to the Target of
Rapamycin (TOR) pathway, indicating that evolutionary modifications on this pathway induced by FLC stress may be involved in developing
azole resistance. Finally, we provided new data suggesting that hyperactive efflux pumps may play a role as
drug transporters in FLC resistant T. asahii strains.