Prospective survey of azole drug resistance among environmental and clinical isolates of Aspergillus fumigatus in a French University hospital during major demolition works.

OBJECTIVES: Recent studies have reported the emerging worldwide problem of azole drug resistance of A. fumigatus isolates. The aim of this study was to evaluate the antifungal susceptibilities of A. fumigatus isolates recovered from air and clinical samples collected in a French University hospital (Lyon), which underwent major deconstruction works over a one year-period.

METHODS: A daily surveillance of fungal contamination was implemented during 11-months. Environmental survey was realized by air samplings, outdoor and indoor, with an automatic agar sampler. In parallel, surveillance of IA infection cases was conducted by epidemiological investigation. Environmental and clinical isolates of A. fumigatus were identified by conventional methods and β-tubulin sequencing. Susceptibility testing of A. fumigatus isolates against Itraconazole (ITZ), Voriconazole (VCZ) was performed using Etest method.

RESULTS: A total of 3885 air samples (1744 outdoor samples and 2141 indoor samples) were collected. From the 3073 identified colonies of A. fumigatus, 400 A. fumigatus isolates were tested for their susceptibility to ITZ and VCZ, including 388 isolates coming from the environment (indoor n:157, outdoor n:231) and 12 isolates coming from clinical samples. All the 400 isolates were susceptible to azoles (≤1μg/mL).

CONCLUSIONS: No environmental reservoir of A. fumigatus azole resistant strains was found in our hospital which was undergoing major demolition works. Further studies with larger number of A. fumigatus clinical isolates and environmental isolates from agricultural areas and healthcare establishments are needed to better appreciate the occurrence and prevalence of azole resistance.