Algorithm to assess the presence of Aspergillus fumigatus resistant strains: The case of Norwegian sawmills

Abstract

Association between selection pressure caused by the use of azole fungicides in sawmills and the development of fungal resistance has been described. The aim of this study was to implement an algorithm to assess the presence of Aspergillus section Fumigati resistant strains in sawmills.Eighty-six full-shift inhalable dust samples were collected from eleven industrial sawmills in Norway. Different culture media were used and molecular identification to species level in Aspergillus section Fumigati was done by calmodulin sequencing and TR 34 /L98H and TR 46 /Y121F/ T289A mutations were screened by real-time PCR assay and confirmed by cyp51A sequencing. Six Fumigati isolates were identified as A. fumigatus sensu stricto and two of these grew on azolesupplemented media and were further analyzed by real-time PCR. One was confirmed to be a TR 34 /L98H mutant.The obtained results reinforce the need to assess the presence of A. fumigatus sensu stricto resistant isolates at other workplaces with fungicide pressure.

Settleable Dust and Bioburden in Portuguese Dwellings

“…On the other hand, the fact that higher values on POS were related to higher values of Cq suggests that fungal species with some reduced susceptibility to posaconazole might be from Aspergillus sp., although not observed by culture-based methods. This aspect reinforces, once more, the importance of an algorithm of combined methods (molecular and culture-based) for an accurate fungal assessment in the environment, as the one suggested previously to be applied in occupational environments with azole pressure [31].…”

Azole-Resistant Aspergillus fumigatus Harboring the TR34/L98H Mutation: First Report in Portugal in Environmental Samples

“…The obtained results also validate a previously proposed algorithm aiming to support and provide guidance from fieldwork in assessed occupational environments (which sampling methods should be applied) to the bench work (what analysis should be performed) for exposure assessors [ 33 ]. Thus, in occupational environments where the azole pressure is high, such as vineyards, sawmills, and waste sorting plants, just to name a few, the frequency of cryptic species and of azole resistance of A. fumigatus sensu stricto should be assessed as routine to achieve an accurate risk characterization.…”

“…Thus, in occupational environments where the azole pressure is high, such as vineyards, sawmills, and waste sorting plants, just to name a few, the frequency of cryptic species and of azole resistance of A. fumigatus sensu stricto should be assessed as routine to achieve an accurate risk characterization. In high-load environments, such as in the waste sorting unit and the dairy farm assessed, results are most certainly underestimated; the recovery of the Aspergillus section Fumigati isolates is a challenging task due to overgrowth of other fungi isolates with fast growth rates, such as Mucorales and Chrysonilia sitophila [ 22 , 33 , 37 , 39 , 40 , 42 ]. Additionally, isolate recovery relies only on the viable component of the fungal contamination.…”

“…Aspergillus fumigatus isolates were selected for further characterization. These procedures followed the algorithm previously suggested to assess the presence of A. fumigatus resistant strains [ 33 ].…”

“…The selective pressure on A. fumigatus is particularly problematic in environments where the use of azoles is a requirement, such as in agriculture, in preservation industries, and sawmills, where an increased probability of emergence of specific occupational health problems has been observed [ 32 , 33 ]. After infection of azole-naïve individuals with these resistant strains, subsequent treatment failure with triazole therapy (the first choice for treatment and prophylaxis of aspergillosis) may occur [ 34 ].…”