LAUSR

BACKGROUND Aspergillus fumigatus, the causal agent of aspergillosis in humans, is commonly present as saprophyte in various organic substrates, such as spoiled silages. Aspergillosis is generally combated with demethylation inhibitor (DMI) fungicides, but the recent appearance of resistant medical and environmental strains made current treatment strategies less reliable. The goal of this study was to determine the evolution of A. fumigatus populations during the ensiling process of whole-crop corn, high moisture corn and wet grain corn, and to monitor the sensitivity of isolates from treated and untreated fields to one medical and one agricultural DMI fungicide. RESULTS A. fumigatus was isolated from fresh forage at harvest at rather low concentrations (102 cfu/g). The low frequency lingered during the silage process (at 60 and 160 days), whereas it significantly increased during air exposure (at 7 and 14 days of air exposure). Field treatment of corn with a mixture of prothioconazole and tebuconazole did not affect the sensitivity of A. fumigatus isolates. One isolate out of 29 coming from the untreated plot was resistant to voriconazole. A unique amino acid substitution (E427K) was detected in the cyp51A gene of 10 out of 12 sequenced isolates, but it was not associated to DMI resistance. CONCLUSION A. fumigatus significantly increased during aerobic deterioration of ensilaged corn after silo opening, compared to the low presence in fresh corn and during ensiling. Field treatment of corn with DMI fungicides did not affect the sensitivity of A. fumigatus isolates collected from fresh and ensiled corn. This article is protected by copyright. All rights reserved.