Genomic investigation of an environmental antifungal-resistant Aspergillus fumigatus outbreak in a French hospital

spergillus fumigatus, a common filamentous fungus, is the predominant airborne fungal pathogen associated with various invasive, chronic, and allergic fungal diseases. The emergence of antifungal resistant strains complicates the treatment of these infections and can be responsible for epidemics. Although whole-genome sequencing (WGS) is widely used to study bacterial and viral outbreaks, its use in fungal infections is limited. We used nine microsatellites and WGS to characterize an environmental azole-resistant TR34/L98H A. fumigatus outbreak in a French hospital between November 2021 and October 2022. The outbreak involved nine patients, all of whom had attended the respiratory functional exploration or interventional bronchoscopy services. Eight of the nine TR34/L98H strains were genetically close. The results suggest that at least eight patients were exposed to a common environmental source, although the exact origin of the source could not be determined. The presence of antifungal-resistant strains in healthcare settings underscores the need for immediate, coordinated efforts to improve preventive measures and protect vulnerable patient populations.