Coelomycetous fungi in the clinical setting: Morphological convergence and cryptic diversity

Abstract

Human infections by coelomycetous fungi are becoming more frequent and range from superficial to systemic dissemination. Traumatic implantation of contaminated plant material is the most common cause. The typical morphological feature of these fungi is the production of asexual spores (conidia) within fruiting bodies called conidiomata. This study aimed to determine the distribution of the coelomycetes in clinical samples by a phenotypic and molecular study of a large set of isolates received from a U.S. Reference mycological institution and by obtaining the in vitro antifungal susceptibility pattern of nine antifungals against a selected group of isolates. A total of 230 isolates were identified by sequencing the D1 and D2 domains of the large subunit (LSU) nuclear ribosomal RNA (nrRNA) gene and by morphological characterization. Eleven orders of the phylum Ascomycota were identified: Pleosporales (the largest group; 66.1%), Botryosphaeriales (19.57%), Glomerellales (4.35%), Diaporthales (3.48%), Xylariales (2.17%), Hysteriales and Valsariales (0.87%), and Capnodiales, Helotiales, Hypocreales and Magnaporthales (0.43% each). The most prevalent species were Neoscytalidium dimidiatum, Paraconiothyrium spp., Phoma herbarum, Didymella heteroderae, and Epicoccum sorghinum. The most common anatomical site of isolation was superficial tissue (66.5%), followed by the respiratory tract (17.4%). Most of the isolates tested were susceptible to the majority of antifungals, and only flucytosine showed poor antifungal activity.