Investigations for environmental hotspots and application practices for azole-resistant Aspergillus fumigatus (ARAf)

Azole resistance in Aspergillus fumigatus has increased over 25 years, with evidence suggesting that selection of azole-resistant A. fumigatus (ARAf) occurs in the environment. The increased risk of resistance in patients with aspergillosis may be due to widespread use of fungicide azoles, particularly in the agricultural environment. A study in Denmark found ARAf in 20% of 366 tested samples and 4.2% of 4538 A. fumigatus isolates, with highest proportions in flower and compost-related samples. Genotyping showed clustering of TR-related ARAf and overlap with Danish clinical isolates. A. fumigatus grew poorly in field experiments, but sustained inhibition against wild-type A. fumigatus from some tested azoles suggests azole-fungicides may favor ARAf growth in soil.