Caracterización fenotípica y molecular de hongos filamentosos oportunistas: scedosporium, acremonium, phialemonium, lecythophora y paecilomyces

Se estudiaron los géneros Scedosporium, Acremonium, Phialemonium, Lecythophora y Paecilomyces. En Scedosporium se seleccionó la mejor herramienta para la tipificación de S. aurantiacum y S. prolificans. En los otros géneros se estudiaron la identificación morfológica y molecular para establecer el espectro de especies y sus relaciones filogenéticas. Los resultados indican que el sistema basado en la secuenciación multilocus es la mejor metodología para la tipificación de Scedosporium. Se ha establecido el espectro de las especies asociadas a muestras clínicas de los Estados Unidos, siendo Acremonium kiliense, el complejo Acremonium sclerotigenum-Acremonium egyptiacum, Acremonium implicatum, Phialemonium obovatum, Phialemonium curvatum, Lecythophora hoffmannii, Cephalotheca foveolata y Lecythophora mutabilis las especies más encontradas. Se propone el nuevo género Phialemoniopsis. Se transfiere Sarcopodium oculorum y Phialemonium curvatum a Phialemoniopsis, y Acremonium atrogriseum y Taifanglania inflata a Phialemonium. Se proponen las nuevas especies: Phialemoniopsis cornearis, Phialemoniopsis pluriloculosa, Phialemonium globosum, Lecythophora luteo-rubra, Lecythophora cateniformis y Paecilomyces lavendulus.Scedosporium, Acremonium, Phialemonium, Lecythophora and Paecilomyces were studied. In Scedosporium, the study has focussed on choosing the best tool for the characterization of S. aurantiacum and S. prolificans. As for the other genera, studies have focussed on morphological and molecular identification. The results showed that the system based on multilocus sequencing is the best methodology for the characterization of Scedosporium. By correlating the results obtained by morphological and molecular techniques, we have been able to establish the species associated with clinical samples from the United States, Acremonium kiliense, complex Acremonium sclerotigenum-Acremonium egyptiacum, Acremonium implicatum, Phialemonium obovatum, Phialemonium curvatum, Lecythophora hoffmannii, Cephalotheca foveolata and Lecythophora mutabilis being the most found species. We proposed Phialemoniopsis as a new genus. We transferred Sarcopodium oculorum and Phialemonium curvatum to Phialemoniopsis, and Acremonium atrogriseum and Taifanglania inflata to Phialemonium. We proposed the new species: Phialemoniopsis cornearis, Phialemoniopsis pluriloculosa, Phialemonium globosum, Lecythophora luteo-rubra, Lecythophora cateniformis and Paecilomyces lavendulus

Multilocus Sequence Typing Reveals Extensive Genetic Diversity of the Emerging Fungal Pathogen Scedosporium aurantiacum

Scedosporium spp. are the second most prevalent filamentous fungi after Aspergillus spp. recovered from cystic fibrosis (CF) patients in various regions of the world. Although invasive infection is uncommon prior to lung transplantation, fungal colonization may be a risk factor for invasive disease with attendant high mortality post-transplantation. Abundant in the environment, Scedosporium aurantiacum has emerged as an important fungal pathogen in a range of clinical settings. To investigate the population genetic structure of S. aurantiacum, a MultiLocus Sequence Typing (MLST) scheme was developed, screening 24 genetic loci for polymorphisms on a tester strain set. The six most polymorphic loci were selected to form the S. aurantiacum MLST scheme: actin (ACT), calmodulin (CAL), elongation factor-1α (EF1α), RNA polymerase subunit II (RPB2), manganese superoxide dismutase (SOD2), and β-tubulin (TUB). Among 188 global clinical, veterinary, and environmental strains, 5 to 18 variable sites per locus were revealed, resulting in 8 to 23 alleles per locus. MLST analysis observed a markedly high genetic diversity, reflected by 159 unique sequence types. Network analysis revealed a separation between Australian and non-Australian strains. Phylogenetic analysis showed two major clusters, indicating correlation with geographic origin. Linkage disequilibrium analysis revealed evidence of recombination. There was no clustering according to the source of the strains: clinical, veterinary, or environmental. The high diversity, especially amongst the Australian strains, suggests that S. aurantiacum may have originated within the Australian continent and was subsequently dispersed to other regions, as shown by the close phylogenetic relationships between some of the Australian sequence types and those found in other parts of the world. The MLST data are accessible at http://mlst.mycologylab.org. This is a joined publication of the ISHAM/ECMM working groups on “Scedosporium/Pseudallescheria Infections” and “Fungal Respiratory Infections in Cystic Fibrosis”.Peer Reviewe