Abstract
Several Scedosporium species are clinically important emerging pathogens. Scedosporium prolificans is reported to be the most virulent of the species, while the recently described species Scedosporium aurantiacum, which accounts for a substantial proportion of Australian clinical isolates is capable of causing a range of serious infections. In addition, environmental surveys have revealed a high prevalence of S. aurantiacum in the urban Sydney region. This study was conducted to assess the virulence of selected S. aurantiacum strains recovered from patients who are colonized or have invasive disease, as well as those from environmental sources, in comparison with S. prolificans. PCR fingerprinting with the primer M13 revealed high genetic variation among the S. aurantiacum strains. We evaluated the virulence of eight S. aurantiacum and two S. prolificans strains in a murine model using an infectious dose of 2 × 105 conidia. S. aurantiacum was noted to be as virulent as S. prolificans, causing death in 60–100% of mice (P > 0.05). There were significant strain-specific virulence differences (P < 0.005), indicating a possible link between genotype and virulence in S. aurantiacum.
Acknowledgements
We thank all members of the Australian Scedosporium (AUSCEDO) Study Group and Prof. Josep Guarro (Universitat Rovira i Virgili, Reus, Spain) for supplying clinical strains for this study. This work was supported by an NH&MRC project grant #352303 to WM and research funding by Merck, Sharp & Dohme, Australia to WM and SC. Azian Harun was supported by the Academic Staff Higher Education Scheme scholarship from the Universiti Sains Malaysia.
Declaration of interest: The authors have no conflict of interest in relation to this work. SC is a member of the antifungal advisory Board of Pfizer, Australia and Gilead Sciences Inc.