Agricultural practices and biological characteristics as determinants of the prevalence of human pathogens A. fumigatus sensu stricto and A. udagawae.

Abstract

Aspergillus section Fumigati (ASF) comprises saprophytic moulds that naturally inhabit a wide range of biomes including cultivated soils where climatic factors and agricultural practices can influence the composition of fungal communities. Aspergillus fumigatus sensu stricto is the leading cause of invasive aspergillosis in immunocompromised individuals, but closely related species have also emerged as important pathogens. We analyzed 29 soil samples (13 from orchards and 16 from conventional agricultural soils) collected at different times and seasons. Interestingly, the 48 ASF strains isolated matched to only two species, typified as A. fumigatus sensu stricto (28) and A. udagawae (20). Significant differences in the prevalence of both species were observed. A higher recovery of A. fumigatus sensu stricto was obtained in spring and A. udagawae in summer and winter. Considering the agricultural production system, A. fumigatus sensu stricto was more prevalent in agroecological orchards and A. udagawae in conventional agricultural soils. Our results suggest that the presence of only these two species may be attributed to their distinctive biological characteristics and the climatic conditions prevailing in the study area. While the prevalence of A. fumigatus sensu stricto in agroecological orchards and A. udagawae in conventional agriculture, may be a result of the ecological impact of agricultural production systems. Our study provides empirical evidence in support of a potential model whereby the presence and distribution of ASF species in agricultural soils may be driven by two key factors: their biological characteristics and the use of agrochemical compounds for crop production.