The Role of Plant Agricultural Practices on Development of Antimicrobial Resistant Fungi Affecting Human Health Proceedings of a Workshop Series (2023) / Chapter Skim
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4 Fungicide Resistance in Plant Protection Use
4 Fungicide Resistance in Plant Protection Use
Pages 43-56
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From page 43... ...
Kevin Doughty, senior stewardship manager at Bayer AG Crop Science division, outlined the conditions capable of promoting the selection and amplification of resistant isolates of A fumigatus, as well as the role these settings can play in the distribution and frequency of azole-resistant fungal strains.
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From page 44... ...
A large and comprehensive literature review found that fungi develop resistance to all classes of drugs used against plant and animal fungal infections (Fisher et al., 2018) (see Figure 4-1)
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FIGURE 4-1 Resistance occurs to all classes of drugs used against plant and animal fungal infections. SOURCE: From Fisher et al., 2018.
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From page 46... ...
. As these plant pathogens evolve resistance, farmers must respond by shifting to new formulations of azoles or modifying the crop through trait breeding or genetic modification to increase its resilience to the evolved fungal pathogens.
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From page 47... ...
fumigatus spores across an 8-hour period. New Antifungal Drug Development The prevalence of resistant fungi requires new antifungals, and phase II and phase III trials are currently testing promising clinical antifungals with novel modes of action, Fisher noted (Fisher et al., 2022)
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From page 48... ...
AZOLE-RESISTANT ASPERGILLUS FUMIGATUS IN AGRONOMIC SETTINGS: HOTSPOTS AND COLDSPOTS Doughty discussed the agricultural uses of azoles, the processes and ideal conditions for the development of ARAf, the features of agronomic settings that can contribute to ARAf selection and amplification, in particular the importance of plant waste management in addressing ARAf. Representing CropLife International, the industry association of the major crop protection research and development companies, Doughty described the agronomic context as including broad acre crops, horticultural crops, and plantation crops.
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From page 49... ...
According to current understanding of the process, this mass release of predominantly resistant spores is a precondition for the link between the hotspot and the patient. Patterns of ARAf Distribution and Frequency in Agronomic Settings Doughty and colleagues conducted a literature review to examine which agronomic settings might contribute to ARAf selection and amplification (Doughty et al., 2021)
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From page 50... ...
fumigatus, plant waste piles also provide the conditions for sexual reproduction of the fungus, making them an ideal environment for the generation of new genotypes. Doughty noted that wide variety of cyp51A mutations of ARAf isolates have been identified in flower bulb waste piles, representing genetic variability (Zhang et al., 2021b)
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From page 51... ...
He added that the integrated disease management approach taken in addressing fungicide resistance for target pathogens in the crop itself is unlikely to address hotspots in agricultural waste. For example, the alternation of using fungicides with different modes of action against target pathogens in crops will not necessarily extend to effective management of resistance in waste piles of non-target organisms.
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From page 52... ...
Fisher acknowledged that he does not have an explanation, but that it is too soon to say that no tandem repeats are occurring in plant pathogens afflicting crops. Far more genome sequencing has been performed on human fungal pathogens than on agricultural ones, thus tandem repeats may exist in crops but have not yet been discovered.
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From page 53... ...
Brewer asked about the routes of transmission of ARAf to humans, whether these routes include sporulation occurring on food, and whether azole-resistant isolates are associated with different types of food. Fisher stated that since agricultural waste piles have been identified as hotspots, he is curious about whether small countertop compost bins in household k itchens could also become hotspots.
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From page 54... ...
With regard to whether no-till strategy was used with straw crops, Doughty was uncertain. Factors Promoting Azole Resistance Brewer asked whether some azoles are more inclined to promote resistance than others, given that agricultural azole use began in the 1970s, but ARAf has increased significantly in the past two decades.
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From page 55... ...
Edward Herbert School of Medicine at the Uniformed Services University of the Health Sciences, Bethesda, and Jeff LeJeune, food safety officer in the Food Systems and Food Safety Division of the Food and Agriculture Organization of the United Nations, offered reflections on the first day of the workshop. The workshop began with an overview of fungal diseases within humans and the effect of rising environmental temperatures -- in conjunction with lower human temperatures -- as a natu ral driver of the increasingly adapted fungal pathogens with the potential to wreak havoc.
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From page 56... ...
Fungal pathogens are ubiquitous in nature and commonly develop resistance -- driven by both environmental factors as well as the frequent use of azoles -- with implica tions for both food security and human health. The fungal pathogen trans fer from plants to humans may not be as uncommon as previously thought, further fueling the need to coordinate and develop surveillance, detection, diagnosis, risk assessment, mitigation, and therapeutics efforts.
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