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Dyer, P. S.

Publications and source records attributed to Dyer, P. S..

2 recordsLinked to original sources
bioRxiv2021

Citizen-science surveillance of triazole-resistant Aspergillus fumigatus in UK residential garden soils

Compost is an ecological niche for Aspergillus fumigatus due to its role as a decomposer of organic matter and its ability to survive the high temperatures associated with the composting process. Subsequently, composting facilities are associated with high levels of A. fumigatus spores that are aerosolised from compost and cause respiratory illness in workers. In the UK, gardening is an activity enjoyed by individuals of all ages and it is likely that they are being exposed to A. fumigatus spores when handling commercial compost or compost they have produced themselves. In this study, 246 citizen scientists collected 509 soil samples from locations in their garden in the UK, from which were cultured 5,174 A. fumigatus isolates. Of these isolates, 736 (14%) were resistant to tebuconazole: the third most-sprayed triazole fungicide in the UK, which confers cross-resistance to the medical triazoles used to treat A. fumigatus lung infections in humans. These isolates were found to contain the common resistance mechanisms in the A. fumigatus cyp51A gene TR34/L98H or TR46/Y121F/T289A, and less common resistance mechanisms TR34, TR53, TR46/Y121F/T289A/S363P/I364V/G448S and (TR46)2/Y121F/M172I/T289A/G448S. Regression analyses found that soil samples containing compost were significantly more likely to grow susceptible and tebuconazole-resistant A. fumigatus than those that did not, and that compost samples grew significantly higher numbers of A. fumigatus than other samples. ImportanceThese findings highlight compost as a potential health hazard to individuals with pre-disposing factors to A. fumigatus lung infections, and a potential health hazard to immunocompetent individuals who could be exposed to sufficiently high numbers of spores to develop infection. This raises the question of whether compost bags should carry additional health warnings regarding inhalation of A. fumigatus spores, whether individuals should be advised to wear facemasks whilst handling compost or whether commercial producers should be responsible for sterilising compost before shipping. The findings support increasing public awareness of the hazard posed by compost and investigating measures that can be taken to reduce the exposure risk.

microbiology↗
bioRxiv2021

Tracing patterns of evolution and acquisition of drug resistant Aspergillus fumigatus infection from the environment using population genomics

Infections caused by opportunistic fungal pathogens are increasingly resistant to first-line azole antifungal drugs. However, despite its clinical importance, little is known about the extent to which susceptible patients acquire infection from drug resistant genotypes in the environment. Here, we present a population genomic analysis of the mould Aspergillus fumigatus from across the United Kingdom and Republic of Ireland. First, we show occurrences where azole resistant isolates of near identical genotypes were obtained from both environmental and clinical sources, indicating with high confidence the infection of patients with resistant isolates transmitted from the environment. Second, we find that the fungus is structured into two clades ( A and B) with little interclade recombination and the majority of environmental azole resistance genetically clustered inside Clade A. Genome-scans show the impact of selective sweeps across multiple regions of the genome. These signatures of positive selection are seen in regions containing canonical genes encoding fungicide resistance in the ergosterol biosynthetic pathway, whilst other regions under selection have no defined function. Phenotyping identified genes in these regions that could act as modifiers of resistance showing the utility of reverse genetic approaches to dissect the complex genomic architecture of fungal drug resistance. Understanding the environmental drivers and genetic basis of evolving fungal drug resistance needs urgent attention, especially in light of increasing numbers of patients with severe viral respiratory tract infections who are susceptible to opportunistic fungal superinfections.

genomics↗