Isabel Iturrieta-González1, Isabel Pujol2, Simona Iftimie3, Dania García1, Vanesa Morente4, Rosana Queralt4, Marcela Guevara-Suarez5, Ana Alastruey-Izquierdo6, Frederic Ballester2, Margarita Hernández-Restrepo7, Josepa Gené1. 1. Unitat de Micologia, Facultat de Medicina i Ciències de la Salut i Institut d'Investigació Sanitària Pere Virgili (IISPV), Universitat Rovira i Virgili, Reus, Spain. 2. Laboratori de Referència Sud, Hospital Universitari Sant Joan, Reus, Spain. 3. Servei de Medicina Interna, Hospital Universitari Sant Joan, Reus, Spain. 4. Servei de Patologia, Hospital Universitari Sant Joan, Reus, Spain. 5. Laboratorio de Micología y Fitopatología, Facultad de Ingeniería, Universidad de los Andes, Bogotá, Colombia. 6. Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain. 7. Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands.
Abstract
BACKGROUND: Cutaneous phaeohyphomycosis is an emerging disease in immunocompromised patients, being Alternaria one of the most common genera reported as a causative agent. Species identification is not carried out mainly due to the complexity of the genus. Analysis of the ITS barcode has become standard for fungal identification, but in Alternaria it is only able to discriminate among species-groups or sections. METHODS: We present three cases of cutaneous infection caused by Alternaria isolates morphologically identified as belonging to section Infectoriae. They have been morphologically characterised and phylogenetically delineated with five molecular markers (ITS, ATPase, gapdh, rpb2 and tef1). RESULTS: Mycotic infections have been diagnosed by repeated cultures and histopathological examination in two of the cases. The polyphasic approach has allowed to delineate three new species of Alternaria section Infectoriae, that is A anthropophila, A atrobrunnea and A guarroi. ATPase has been the only locus able to discriminate most of the species (29 out of 31) currently sequenced in this section, including A infectoria the commonest reported species causing alternariosis. Susceptibility test showed different antifungal patterns for the three species, although terbinafine was the most active in vitro drug against these fungi. CONCLUSIONS: The ATPase gene is recommended as an alternative barcode locus to identify Alternaria clinical isolates in section Infectoriae. Our results reinforce the relevance of identification of Alternaria isolates at the species level and the necessity to carry out antifungal susceptibility testing to determine the most adequate drug for treatment.
BACKGROUND:Cutaneous phaeohyphomycosis is an emerging disease in immunocompromised patients, being Alternaria one of the most common genera reported as a causative agent. Species identification is not carried out mainly due to the complexity of the genus. Analysis of the ITS barcode has become standard for fungal identification, but in Alternaria it is only able to discriminate among species-groups or sections. METHODS: We present three cases of cutaneous infection caused by Alternaria isolates morphologically identified as belonging to section Infectoriae. They have been morphologically characterised and phylogenetically delineated with five molecular markers (ITS, ATPase, gapdh, rpb2 and tef1). RESULTS:Mycotic infections have been diagnosed by repeated cultures and histopathological examination in two of the cases. The polyphasic approach has allowed to delineate three new species of Alternaria section Infectoriae, that is A anthropophila, A atrobrunnea and A guarroi. ATPase has been the only locus able to discriminate most of the species (29 out of 31) currently sequenced in this section, including A infectoria the commonest reported species causing alternariosis. Susceptibility test showed different antifungal patterns for the three species, although terbinafine was the most active in vitro drug against these fungi. CONCLUSIONS: The ATPase gene is recommended as an alternative barcode locus to identify Alternaria clinical isolates in section Infectoriae. Our results reinforce the relevance of identification of Alternaria isolates at the species level and the necessity to carry out antifungal susceptibility testing to determine the most adequate drug for treatment.