Author(s)

KENZA BOULOUIZ, NATHAN GOUNEL, ANTOINE GÉRY, VIRGINIE SÉGUIN, JULIE BONHOMME, DAVID GARON

Abstract

During routine farming activities, dairy workers and animals are exposed to bioaerosols containing airborne fungal contaminants. Among them, Aspergillus fumigatus, Fusarium spp., and Mucorales are considered priority fungal pathogens by the World Health Organization because of increasing antifungal resistance and the growing burden of invasive fungal infections. The widespread use of azole compounds in agriculture may contribute to the environmental emergence and dissemination of resistant isolates. This study aimed to investigate the occurrence of airborne priority fungal pathogens in dairy farms in Normandy, France, and to assess their susceptibility to clinical and agricultural azole antifungals. A total of 119 airborne isolates, including 74 A. fumigatus, 13 Fusarium spp. and 32 Mucorales isolates, were purified and identified using microscopy and molecular sequencing. Antifungal susceptibility phenotypes were evaluated using itraconazole (1 mg/L) and, for itraconazole-resistant isolates, enilconazole (0.1 mg/L). Among Mucorales, Lichtheimia ramosa (43.8%), L. corymbifera (28.1%), and Mucor circinelloides (12.5%) were the predominant airborne species. Within the Fusarium genus, Fusarium graminearum (53.8%) and F. culmorum (30.8%) were the most frequently identified species. Overall, 20.2% of isolates were resistant to itraconazole, and 83.3% of these resistant isolates also exhibited resistance to enilconazole. Resistance to itraconazole reached 9.5% for A. fumigatus, 25% for Mucorales, and 69.2% for Fusarium spp. Among itraconazole-resistant isolates, all A. fumigatus and Mucorales isolates and 55.6% of Fusarium spp., were also resistant to enilconazole. These findings demonstrate the presence of airborne azole cross-resistant moulds in Normandy dairy farms and suggest that agricultural bioaerosols may represent an environmental reservoir of antifungal resistance within a One Health context. Such exposure could contribute to difficult-to-treat infections in humans and animals, while the dynamics of airborne dissemination remain poorly understood.

Keywords

bioaerosols, airborne moulds, Aspergillus fumigatus, Fusarium spp., Mucorales, azole resistance, itraconazole, enilconazole (imazalil), One Health