Environmental screening for the Scedosporium apiospermum species complex in public parks in Bangkok, Thailand

Abstract

The Scedosporium apiospermum species complex, comprising filamentous fungal species S. apiospermum sensu stricto, S. boydii, S. aurantiacum, S. dehoogii and S. minutispora, are important pathogens that cause a wide variety of infections. Although some species (S. boydii and S. apiospermum) have been isolated from patients in Thailand, no environmental surveys of these fungi have been performed in Thailand or surrounding countries. In this study, we isolated and identified species of these fungi from 68 soil and 16 water samples randomly collected from 10 parks in Bangkok. After filtration and subsequent inoculation of samples on Scedo-Select III medium, colony morphological examinations and microscopic observations were performed. Scedosporium species were isolated from soil in 8 of the 10 parks, but were only detected in one water sample. Colony morphologies of isolates from 41 of 68 soil samples (60.29%) and 1 of 15 water samples (6.67%) were consistent with that of the S. apiospermum species complex. Each morphological type was selected for species identification based on DNA sequencing and phylogenetic analysis of the β-tubulin gene. Three species of the S. apiospermum species complex were identified: S. apiospermum (71 isolates), S. aurantiacum (6 isolates) and S. dehoogii (5 isolates). In addition, 16 sequences could not be assigned to an exact Scedosporium species. According to our environmental survey, the S. apiospermum species complex is widespread in soil in Bangkok, Thailand.