Landscape-scale exposure to multiazole-resistantAspergillus fumigatusbioaerosols

Abstract

We demonstrate country-wide exposures to aerosolized spores of a human fungal pathogen, Aspergillus fumigatus, that has acquired resistance to first line azole clinical antifungal drugs. Assisted by a network of citizen scientists across the United Kingdom, we show that 1 in 20 viable aerosolized spores of this mold are resistant to the agricultural fungicide tebuconazole and 1 in 140 spores are resistant to the four most used azoles for treating clinical aspergillosis infections. Season and proximity to industrial composters were associated with growth of A. fumigatus from air samples, but not with the presence of azole resistance, and hotspots were not stable between sampling periods suggesting a high degree of atmospheric mixing. Genomic analysis shows no distinction between those resistant genotypes found in the environment and in patients, indicating that ~40% (58/150 sequenced genomes) of azole-resistant A. fumigatus infections are acquired from environmental exposures. Due to the ubiquity of this measured exposure, it is crucial that we determine source(s) of azole-resistant A. fumigatus, who is at greatest risk of exposure and how to mitigate these exposures, in order to minimize treatment failure in patients with aspergillosis.

Most azole antifungal resistance mutations in the drug target provide cross-resistance and carry no intrinsic fitness cost

“…In the future, it will be important to further investigate the different determinants of azole resistance mutations between ERG11 orthologues and all azole drugs. For instance, azoles are also used in agriculture and evidence shows that azole-resistant A. fumigatus from the environment can infect patients leading to an increase in treatment failures 14,16,60 . This is alarming as it implies the presence of cross-resistance between agricultural and medical azoles 15,61,62 .…”

“…Resistance to azoles is not restricted to yeast infections as these drugs are also used to treat other fungal infections such as the ones caused by Aspergillus spp. The fact that azoles are also used in agriculture may further exacerbate the resistance problem as resistance mutations are selected in nature, even before fungi infect humans [14][15][16] .…”

The human fungal pathogen Aspergillus fumigatus can produce the highest known number of meiotic crossovers

“…This purified DNA was incubated for 1 h at 37°C to digest RNA, and then frozen for storage. Meanwhile, for the crosses AfIR974 x 47–55 and C78 x 47–55 DNA were extracted as described [ 62 ].…”

“…For each offspring and parental strain from the crosses AfIR964 x AfIR974 and 88C19 X 46A23, an aliquot of DNA was processed for Illumina 150 bp paired-end sequencing (Novogene). DNA from offspring from crosses of AfIR974 x 47–55 and C78 x 47–55 were processed as previously described [ 62 ]. For each of the parental strains, an additional DNA aliquot was then processed for the Oxford Nanopore platform by first using the Circulomics SRE kit according to manufacturer’s instruction to remove short DNA fragments, followed by the SQK-LSK-109 Genomic DNA by Ligation kit.…”

Loss of a conserved C-terminal region of theAspergillus fumigatusAtrR transcriptional regulator leads to a gene-specific defect in target gene expression

“…Further complicating the control of aspergillosis is the common appearance of azole resistant A. fumigatus isolates that can be found in the environment (2)(3)(4). Detailed analyses of these environmental isolates argues that development of azole resistance does not appear to result in any fitness cost, thereby allowing azole resistant isolates to persist and spread via this environmental route (5,6).…”