Exposure to Tebuconazole Drives Cross-Resistance to Clinical Triazoles in <i>Aspergillus fumigatus</i>

Multiazole-resistant <i>Aspergillus fumigatus</i> threatens antifungal therapy. This study investigated the impact of prolonged exposure to the agricultural triazole tebuconazole (TEB) on the susceptibility of <i>A. fumigatus</i> to clinical triazoles and its resistance mechanisms. After 28 days, resistant strains emerged with substantial increases in minimum inhibitory concentrations (MICs): up to 128× for itraconazole, 64× for posaconazole, and 16× for voriconazole. In the absence of TEB, resistance was maintained and associated with maintenance of CYP51A activity, with stable ergosterol levels and efflux pump activity. Among the 193 upregulated proteins identified in proteomics, 14 were related to resistance, 5 to the ergosterol biosynthesis pathway, 7 to the efflux pump activity, and 2 to the heat shock response pathway. These results demonstrate that agricultural triazoles can induce stable and multidrug-resistant phenotypes, emphasizing the need for surveillance of antifungal resistance in environmental and clinical settings.