Dynamics of in azole-fungicide-containing plant waste, the Netherlands, 2016-2017.

The treatment of patients suffering from Aspergillus diseases is hampered due to infections with Aspergillus fumigatus that are already resistant to medical azoles. Previous work has suggested that A. fumigatus likely gains resistance through environmental azole exposure in so-called hotspots. Here, we investigated A. fumigatus resistance dynamics over time, at three sites at which farmers used azole fungicides for crop protection. Over 16 months 114 samples were taken from stockpiles of decaying plant waste. A. fumigatus and azole fungicide residues were ubiquitously present in the plant waste. On average 105A. fumigatus CFU/g was recovered of which roughly half were itraconazole and tebuconazole resistant. Similar tandem repeat-mediated resistance mechanisms were found in colonies cultured from plant waste as reported in clinical azole-resistant isolates. Our results show a consistent high burden of azole-resistant A. fumigatus in azole-containing plant waste and underscores the need to further investigate resistance-reducing interventions and transmission routes.ImportanceAspergillus fumigatus is consistently present independently on season at a high abundance in plant-waste material throughout sampling period. Our study confirmed that long-term storage of azole-containing decaying plant material indeed be considered hotspots, which can sustain resistance development and maintenance in A. fumigatus Roughly half of individual isolates were azole-resistant and carry genetic mutations that are highly similar to those found in patients with azole-resistant invasive aspergillosis. Our work suggests that environmental sources of azole resistance in A. fumigatus might be important, underscoring the need for further studies on environment-to-patient transmission routes