Land use drives drug resistance in an airborne human fungal pathogen

Area of Science:

• Environmental Science
• Mycology
• Public Health

Background:

• Humans inhale Aspergillus fumigatus, a mold causing infections resistant to triazole antifungals.
• The environmental sources and contribution of agricultural settings to triazole resistance in A. fumigatus are not fully understood.
• Genomic methods struggle to trace resistant isolates to specific environmental origins.

Purpose of the Study:

• To investigate the spatial distribution and environmental drivers of triazole resistance in airborne Aspergillus fumigatus.
• To quantify the prevalence of triazole resistance in A. fumigatus populations across the Netherlands.
• To determine the association between agricultural land use and antifungal resistance in airborne A. fumigatus.

Main Methods:

• A large-scale, unbiased air sampling was conducted across the Netherlands using a citizen science approach.
• Over 60,000 colonies of A. fumigatus were screened for resistance to clinical triazoles.
• Spatial modeling integrated resistance data with land-use data, and genotyping was performed on resistant isolates.

Main Results:

• Approximately 4% of screened A. fumigatus colonies exhibited resistance to clinical triazoles.
• Agricultural land use, specifically flower bulbs and greenhouses, was found to predict hotspots of antifungal resistance in airborne A. fumigatus.
• Genotyping revealed niche differentiation between resistance haplotypes, with one haplotype strongly associated with agricultural land use.

Conclusions:

• Agricultural practices, particularly those involving flower bulbs and greenhouses, contribute significantly to the prevalence of antifungal resistance in airborne A. fumigatus.
• Linking triazole resistance to specific land uses provides crucial information for policy development to mitigate human exposure.
• Similar spatial patterns of antifungal resistance may be present in other fungi associated with agricultural environments.