Azole-resistant Aspergillus fumigatus in sawmills of Eastern France.

AIMS: Emergence of azole-resistant Aspergillus fumigatus complicates management of Aspergillus diseases.Currently, selection pressure caused by azole fungicide use in farming is strongly suspected of creating resistance. As sawmills also use azole fungicides, we investigated the presence of azole-resistant strains in this environment and studied the relationship between azole fungicide use and development of resistance.

METHODS: Air (n = 200) and substrate (n = 600) samples were taken in 20 sawmills. Azole-resistant strains (Etest and EUCAST methods) were confirmed by sequencing the cyp51A gene and its promoters. Dosage of propiconazole and tebuconazole was performed by gas chromatography coupled with mass spectrometry.

RESULTS: Twenty four azole-resistant A. fumigatus strains were collected among 20 of the 600 substrate samples (3%). Eighty-three percent of theses strains had TR34 /L98H mutation. A significantly higher number of resistant strains was collected in sawmills using fungicide products made with propiconazole mixed with a high concentration of tebuconazole (P = 0.009). The presence of resistant strains was significantly linked to propiconazole quantities in substrates (P = 0.03).

CONCLUSION: The outcome of azole-resistant A. fumigatus carrying TR34 /L98H mutation seems to greatly depends on the azole fungicide formulation and quantities of azole. These preliminary results are valuable to propose new approaches limiting the emergence of azole-resistant strains. This article is protected by copyright. All rights reserved.