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

Species of the genus Scedosporium (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 Scedosporium species distribution varies according to geographic region. To assess the diversity of Scedosporium 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 ß-tubulin gene (BT2) demonstrated that 92 % of the strains belonged to the species S. boydii, S. apiospermum and S. angustum, all them pertaining to S. apiospermum species complex. However, two strains (4%) were identified as S. aurantiacum, 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 S. apiospermum. In addition, the strain DMic 165285 was phylogenetically located far away from the rest of the species, so is proposed as the novel species Scedosporium americanum. On the other hand, from all seven antifungals tested, voriconazole and posaconazole were the most active drugs against Scedosporium spp.

National production of certified reference fungal cultures / Producción nacional de cultivos fúngicos de referencia certificados

Reference fungal cultures (RFCs) are essential for the internal quality control of laboratories. The production of these cultures requires standardized procedures (IRAM 14950:2016 and ISO 17034:2016 standards) carried out by a recognized and accredited laboratory. The aim of this work was to produce RFC in paper disks of autochthonous strains, characterized by two, homogeneous and stable reference methods traceable at species level. RFC were produced using 14 regional species (7 yeasts and 7 filamentous fungi) from the fungal culture collection (DMic). Paper disks were impregnated with a culture suspension, dried and packed. Homogeneity, viability, identity and purity were verified. Short-and long-term stability at different temperatures and storage times were studied. Characterization of each strain allowed to confirm its identity and to ensure its traceability at international level. Produced batches were homogeneous and stable at -20 ±5 °C for 30 months. This method of production was adequate to produce homogeneous and stable RFC with phenotypic and genotypic characteristics correctly defined and internationally traceable. Standardized procedures were developed for the production of certified RFC that could be transferred to other microorganisms. Providing RFC that represent regional strains allows laboratories to produce more reliable results with a favorable impact on medical diagnosis, the environment or the food industry.

Los cultivos microbianos de referencia (CR) son imprescindibles para el control de calidad interno de los laboratorios. Asegurar su producción requiere de procedimientos estandarizados (IRAM 14950:2016 e ISO 17034:2016) realizados en un laboratorio reconocido y acreditado. El objetivo de este estudio fue producir cultivos fúngicos de referencia en discos de papel, a partir de un panel de cultivos autóctonos caracterizados por dos métodos de referencia, trazables a nivel taxonómico de especie, homogéneos y estables. Se produjeron CR de 14 especies circulantes en Argentina (7 de levaduras y 7 de hongos miceliales), depositadas en la colección de hongos de interés médico (DMic). Los discos de papel fueron embebidos con una suspensión del cultivo por producir, secados y envasados. Se verificó la homogeneidad, viabilidad, identidad y pureza de cada lote. Se evaluó la estabilidad a corto y largo plazo a distintas temperaturas y tiempos de almacenamiento. La caracterización de cada CR nos permitió confirmar su identidad y asegurar su trazabilidad a nivel internacional. Los lotes producidos fueron homogéneos y estables durante 30 meses conservados a -20 ±5 °C. Este método resultó adecuado para producir CR homogéneos y estables, con características fenotípicas y genotípicas correctamente definidas y trazables a nivel internacional. Los procedimientos estandarizados desarrollados en este trabajo pueden ser transferidos para producir CR certificados de otros microorganismos. La provisión de CR que represente cepas regionales permite a los laboratorios producir resultados más confiables con un impacto favorable en el diagnóstico médico, los estudios ambientales y la industria alimenticia.

National production of certified reference fungal cultures.

Reference fungal cultures (RFCs) are essential for the internal quality control of laboratories. The production of these cultures requires standardized procedures (IRAM 14950:2016 and ISO 17034:2016 standards) carried out by a recognized and accredited laboratory. The aim of this work was to produce RFC in paper disks of autochthonous strains, characterized by two, homogeneous and stable reference methods traceable at species level. RFC were produced using 14 regional species (7 yeasts and 7 filamentous fungi) from the fungal culture collection (DMic). Paper disks were impregnated with a culture suspension, dried and packed. Homogeneity, viability, identity and purity were verified. Short- and long-term stability at different temperatures and storage times were studied. Characterization of each strain allowed to confirm its identity and to ensure its traceability at international level. Produced batches were homogeneous and stable at -20±5°C for 30 months. This method of production was adequate to produce homogeneous and stable RFC with phenotypic and genotypic characteristics correctly defined and internationally traceable. Standardized procedures were developed for the production of certified RFC that could be transferred to other microorganisms. Providing RFC that represent regional strains allows laboratories to produce more reliable results with a favorable impact on medical diagnosis, the environment or the food industry.