Research Article: Genetic variation analysis and relationships among environmental strains of Scedosporium apiospermum sensu stricto in Bangkok, Thailand

Date Published: July 12, 2017

Publisher: Public Library of Science

Author(s): Thanwa Wongsuk, Potjaman Pumeesat, Natthanej Luplertlop, Craig Eliot Coleman.


The Scedosporium apiospermum species complex is an emerging filamentous fungi that has been isolated from environment. It can cause a wide range of infections in both immunocompetent and immunocompromised individuals. We aimed to study the genetic variation and relationships between 48 strains of S. apiospermum sensu stricto isolated from soil in Bangkok, Thailand. For PCR, sequencing and phylogenetic analysis, we used the following genes: actin; calmodulin exons 3 and 4; the second largest subunit of the RNA polymerase II; ß-tubulin exon 2–4; manganese superoxide dismutase; internal transcribed spacer; transcription elongation factor 1α; and beta-tubulin exons 5 and 6. The present study is the first phylogenetic analysis of relationships among S. apiospermum sensu stricto in Thailand and South-east Asia. This result provides useful information for future epidemiological study and may be correlated to clinical manifestation.

Partial Text

The Scedosporium apiospermum species complex is a group of filamentous fungi that have been reported in cystic fibrosis (CF) patients [1]. It can be isolated from the environment, especially in human-impacted areas such as playgrounds, industrial and agricultural zones [2]. In Thailand, S. apiospermum has been reported in brain abscesses of near-drowning and renal transplant patients [3,4], and S. boydii infections have also been reported in brain tissue of renal transplant patient [5]. Additionally, two Swiss tourists who nearly drowned in the tsunami disaster in Thailand were found to be infected with S. apiospermum [6].

PCR amplification of the eight genes was successful for all strains, with a single band investigated on gels after electrophoresis. The BLASTn algorithm was used for sequence similarity searching in the NCBI database. Sequence-based identities with a cutoff of ≥ 99% were considered significant [24,25].

The Scedosporium apiospermum species complex contains important opportunistic species. Giraud and Bouchara [8] and the European Confederation of Medical Mycology (ECMM)/International Society for Human and Animal Mycology (ISHAM) classify the novel nomenclature of the S. apiospermum species complex as comprising five species: S. apiospermum sensu stricto, S. boydii (= Pseudallescheria boydii), S. aurantiacum, S. dehoogii, and S. minutispora. In contrast, a recent study [7] defined the S. apiospermum species complex as only S. apiospermum, S. boydii, and S. angusta (= Pseudalleschelia angusta) because phylogenetic analysis of β-tubulin (BT2), γ-actin, transcriptional elongation factor 1α (TEF-1α), and internal transcribed spacer of the small ribosomal protein 60sS L10 (L1) distinguished S. minutispora, S. aurantiacum, and S. dehoogii from these three species. These days, there are numerous molecular techniques to determine genetic diversity that are robust and reproducible. MLST has been proposed as one of the best tools for genotypic and evolutionary studies.




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