Mycoleptodiscus indicus: a new etiologic agent of phaeohyphomycosis

Abstract

Mycoleptodiscus indicus, a dematiaceous hyphomycete, was identified as the causal agent of subcutaneous infection in the knee of a 72-year-old male gardener residing in coastal South Carolina. The patient had Wegener's granulomatosis and immunodeficiency. Synovial fluid and biopsy tissue sections from the prepatellar bursa stained with hematoxylin and eosin, periodic acid-Schiff, and Gomori methenamine silver stains revealed branched, septate hyphae and many moniliform hyphal elements. When tissue sections were stained by the Fontana-Masson procedure, melanin pigment in the hyphal cell walls and at the septa was evident. A velvety, dematiaceous mold was isolated from both synovial fluid and the biopsy tissue. Sporulation was induced by exposure of slide cultures on potato dextrose agar to UV light for 12 h at 25 degrees C followed by incubation of the slide cultures at 25 degrees C in the dark for 4 weeks. Clypeate sporodochia consisting of ampulliform, compressed, phialidic conidiogenous cells produced curved, hyaline, one-celled conidia with setulae at one or both ends. Initial treatment with fluconazole for 7 days was not effective, and cultures were positive after treatment. Treatment with amphotericin B with concomitant irrigation and debridement of the affected area followed by treatment with itraconazole resulted in resolution of the infection.