High airborne level of Aspergillus fumigatus and presence of azole-resistant TR34/L98H isolates in the home of a cystic fibrosis patient harbouring chronic colonisation with azole-resistant H285Y A. fumigatus.

Azole-resistant Aspergillus fumigatus (ARAF) has been reported in the domestic environment of patients at risk for aspergillosis. Here, we assessed the mother's and father's homes of an 18-year-old cystic fibrosis patient harbouring chronic colonisation with H285Y CYP51A azole-resistant isolate, in order to explore the link between environmental exposure and ARAF infection. In one dwelling, a very high overall contamination level was found (710-7.240 CFU/m3), with a predominance of A. fumigatus (640-6.490 CFU/m3), and ARAF showing the TR34/L98H mutation was isolated. Mycological follow-up of the patient showed the persistence of H285Y isolates, but no acquisition of TR34/L98H isolates was observed. This could be due to the low proportion of TR34/L98H isolates (<3%), or the establishment of preventative measures and dwelling remediation taken after the environmental investigation. Our data underlines the value of an environmental assessment to establish preventative measures and limit the risk of A. fumigatus exposure and ARAF acquisition.