Novel Taxa of the Systemic Dimorphic Fungal Pathogens in the Ajellomycetaceae (Onygenales)
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Session: P071 Epidemiology of fungal infections II Category: 6a. Fungal disease epidemiology & clinical trials 24 April 2017, 13:30 - 14:30 P1441 Novel taxa of the systemic dimorphic fungal pathogens in the Ajellomycetaceae (Onygenales) Karolina Dukik*1, Jose Munoz2, Yanping Jiang3, Benjamin Stielow4, Joanna Freeke5, Azadeh Jamalian6, Bert Gerrits van den Ende6, Ilan Schwartz7, Nelesh P. Govender8, Chris Kenyon9, Andrew Borman10, Sybren De Hoog6 1Westerdijk Fungal Biodiversity Institute 2Mit Broad Institute 3Cbs-Knaw Fungal Biodiversity Centre 4Thermo Fisher Scientific; Microbiology Mass Spectrometry 5Thermo Fisher Scientific 6Cbs-Knaw Fungal Biodiversity Center 7Epidemiology and Social Medicine, University of Antwerp 8National Institute for Communicable Diseases, Mycology Reference Unit 9Institute of Tropical Medicine, Antwerp; Clinical Sciences 10Public Health England; Mycology Reference Laboratory and National Collection of Pathogenic Fungi Background: Recent discoveries of novel systemic human-pathogens with thermally-dimorphic pathogenic phases that consist of budding cells have challenged current taxonomy of the family Ajellomycetaceae. For nearly 100 years only four genera of classical systemic pathogens, each containing just one or two species, were recognized in the order Onygenales, i.e. Coccidioides, Blastomyces, Histoplasma and Paracoccidioides. These are the most common causes of pulmonary fungal infections in healthy hosts worldwide and account for several million human infections each year. All these fungi exist in filamentous forms in soil or guano, and upon inhalation by mammals they undergo morphologically shifts to an invasive yeast-like phase in the host’s pulmonary system. Several of these novel taxa contain opportunistic pathogens of immunocompromised hosts, primarily persons infected with HIV. An important emerging species associated with disease in advanced HIV infection was found in South Africa with at least 56 cases reported since first being correctly identified in 2008. Material/methods: Strains were taken from the reference collection of the Centraalbureau voor Schimmelcultures (CBS) of CBS-KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands, of the University of Alberta Microfungus Collection and Herbarium (UAMH) of Devonian Botanic Garden, Edmonton, Canada and the National Collection of Pathogenic Fungi (NCPF) of Mycology Reference Laboratory, Bristol, U.K., supplemented by kind donations of individual researchers. The set comprised 117 strains in total, including 19 representing novel dimorphic species. Strains were analyzed by means of morphological characters, Sanger and next generation sequencing (NGS). Results: Our morphological, phylogenetic and phylogenomic analyses demonstrated species relationships and their specific phenotypes, clarified generic boundaries and provided the first annotated genome assemblies to support the description of two new species. A new genus, Emergomyces, accommodates Emmonsia pasteuriana as type species, in addition to the new species Emergomyces africanus, the etiological agent of case series of disseminated infections in South Africa. Both species produce small yeast cells that bud at a narrow base at 37 °C and lack adiaspores typically associated with the genus Emmonsia. Another dimorphic pathogenic species, producing broad-based budding cells at 37°C and occurring outside North America, proved to belong to the genus Blastomyces, and is described as B. percursus. Conclusions: Please A new type of systemic thermo-dimorphic fungal infections in humans has emerged over the past few decades. Initially, these fungi were referred to as ‘emmonsia-like’, based on the microscopic morphology of conidia, which cluster in florets on complex conidiophores. However, preliminary clinical, morphological and phylogenetic analyses suggested that most of the novel dimorphic human-associated fungi form a single, derived clade in the Ajellomycetaceae, challenging current taxonomy. .