Scedosporium spp. from Clinical Setting in Argentina, with the Proposal of the New Pathogenic Species Scedosporium americanum

Species of the genus (family Microascaceae, phylum Ascomycota) are responsible for a wide range of opportunistic human infections, and have a low susceptibility to most antifungal drugs. It is well known that the pattern of species distribution varies according to geographic region. To assess the diversity of species in Argentina involved in human infections, we carried out a retrospective study reviewing 49 strains from clinical samples sent for diagnosis to the National Clinical Mycology Reference Laboratory between 1985 and 2019. Then, a phenotypic characterization, a phylogenetic study and and in vitro susceptibility test to antifungals were carried out. An analysis of combined nucleotide sequences dataset of the internal transcribed spacer of the ribosomal DNA (ITS) and of a fragment of the β-tubulin gene ( ) demonstrated that 92 % of the strains belonged to the species , and all them pertaining to species complex. However, two strains (4%) were identified as , a species never reported in clinical settings in the Americas'. Surprisingly, one of them displayed a polycytella-like conidiogenesis, up to date only reported for . In addition, the strain DMic 165285 was phylogenetically located far away from the rest of the species, so is proposed as the novel species . On the other hand, from all seven antifungals tested, voriconazole and posaconazole were the most active drugs against spp.