Morphological and Molecular Characterization of Exophiala polymorpha sp. nov. Isolated from Sporotrichoid Lymphocutaneous Lesions in a Patient with Myasthenia Gravis

Abstract

Exophialaspecies are capable of causing cutaneous and subcutaneous infections in immunocompromised patients. AnExophialaisolate was cultured from a biopsy specimen of a lesion on the forearm of a patient with myasthenia gravis. The patient also had lesions on the palm and distal aspects of the hand, which were successfully treated with a long-term course of itraconazole. A detailed morphological and molecular characterization of the isolate was undertaken. Phylogenetic analysis of the internal transcribed spacer region and portions of the β-tubulin and translation elongation factor 1-alpha genes indicated that the isolate was a novel species closely related to but genetically distinct from species within theExophiala spiniferaclade; the nameExophiala polymorphasp. nov. is proposed. Morphologically,E. polymorphamost closely resemblesE. xenobioticabut it differs in possessing phialides bearing prominent, wide collarettes, and it does not produce chlamydospores.