Scytalidium

Abstract: Phenotypic similarities between the root endophytes Scytalidium vaccinii, a hyphomycete, and Hymenoscyphus ericae, an ascomycete, led to speculation that S. vaccinii might be the anamorph of H. ericae. To test this hypothesis, we used the polymerase chain reaction to amplify portions of the ribosomal DNA from the ex-type cultures of each species and from cultures of several endophytes putatively identified as Scytalidium or H. ericae based on colonial and morphological similarities. An initial restriction fragment analysis of the amplified rDNA separated the H. ericae isolates from England from the ex-type culture of S. vaccinii and most isolates tentatively identified as H. ericae from North America. However, restriction mapping of the amplified fragment revealed that the apparent differences were an artifact resulting from the presence of one or two insertions in the small and large subunit ribosomal RNA genes of the North American isolates. Sequencing of homologous regions of the small subunit and the 5' internal transcribed spacer indicated that sequence divergence between pairs of isolates identified as Scytalidium and H. ericae was low, ranging from 1.2-3.5%, as compared to divergence of up to 24% with H. monotropae, another ericoid endophyte. Although there was variation among the isolates, molecular and morphological evidence suggests that S. vaccinii and H. ericae are anamorph and teleomorph states of a single taxon.

Abstract: We report on a case of subcutaneous infection of the arm caused by the coelomycetous fungus Nattrassia mangiferae (formerly Hendersonula toruloidea) in a steroid-dependent diabetic man with chronic obstructive lung disease. The man was a resident of Arizona, where the fungus is known to be endemic on Eucalyptus camaldulensis and on citrus trees. Diagnosis of fungal infection was made by observation of narrow hyphal filaments by histopathology of biopsy specimens and isolation of a fast-growing black mold which demonstrated hyphae and arthroconidia of varying widths typical of the Scytalidium synanamorph (S. dimidiatum). The formation of pycnidia, which at maturity expressed conidia with a central median dark band, allowed for the confirmation of the isolate as N. mangiferae. Remission of the lesions occurred following intravenous therapy with amphotericin B, followed by topical clotrimazole treatment. We use this patient's case report as an opportunity to review the literature on cases of deep infection caused by Scytalidium species, to evaluate the antifungal susceptibilities of a spectrum of Scytalidium isolates, and to review the taxonomy of Scytalidium species isolated from human infections.

Abstract: Eight cases of fungal infection are described in which an arthrosporic hyphomycete has been isolated from patients of Jamaican and West African origin. In most cases the organism was the only one isolated and in one case it was isolated 3 times over a 5 month period. The fungus is described as a new species of Scytalidium (S. hyalinum).