Abundance of Pseudallescheria/Scedosporium species in the Australian urban environment suggests a possible source for scedosporiosis including the colonization of airways in cystic fibrosis

Abstract

Members of the Pseudallescheria/Scedosporium species complex are emerging opportunistic fungal pathogens which have the capacity to colonize patients with damaged airways, including those with cystic fibrosis (CF). Assuming human infection is acquired via inhalation of fungal spores from the environment, we performed a qualitative environmental survey encompassing 25 urban, semirural and rural sites in the greater Sydney region to determine the prevalence of Pseudallescheria/Scedosporium species. Soil sampling revealed an abundance of Pseudallescheria/Scedosporium, particularly in locations associated with high human activity. No variation was noted during repeated sampling at different times of the year. Strains of Scedosporium aurantiacum were most frequently isolated (54.6%), followed by Scedosporium prolificans (43%), P. boydii (2.1%) and S. dehoogii (0.3%). The findings coincide with the relatively high prevalence of Scedosporium infections in Australia and their presence as colonizers in CF patients. They emphasize the importance of environmental studies to assess the clinical risk of infection.