LAUSR

BACKGROUND Triazole resistance in human fungal pathogen Aspergillus fumigatus has been a growing challenge in clinic treatment with triazole drugs such as itraconazole. The fast evolvement of triazole-resistance in Aspergillus fumigatus in the ecosystem has drawn great attention, and there has been a possible link between the application of triazole fungicides in agriculture and triazole resistance in A. fumigatus. The change in susceptibility of A. fumigatus exposed to the new chiral triazole fungicide mefentrifluconazole was investigated in this study. RESULTS The results indicated that triazole resistance in A. fumigatus was acquired with exposure to mefentrifluconazole at level of greater than or equal to 2 mg/L in liquid medium and soil (not at 0.4 mg/L nor 1 mg/L). Interestingly, stereoselectivity was found in the acquisition of triazole resistance in A. fumigatus when exposed to mefentrifluconazole. R-mefentrifluconazole, which is very active on plant pathogens, exhibited stronger possibility in the development of the resistance in A. fumigatus than its antipode. Overexpression of cyp51A, AtrF, AfuMDR1, and AfuMDR4 were associated with the acquired resistance in A. fumigatus with hereditary stability. CONCLUSION The results suggest that triazole-resistance in A. fumigatus could be resulted from the selection of mefentrifluconazole at level of larger than 2 mg/L. Mefentrifluconazole should be applied within the dosage recommended by good agricultural practice to avoid the resistance in A. fumigatus in soil. This may also be applicable to other triazole fungicides. This article is protected by copyright. All rights reserved.