The dematiaceous fungal genus Bipolaris and its role in human disease

摘要: Introduction Bipolaris is one of several genera dematiaceous (darkly pigmented) fungi causing phaeohyphomycosis in animals as well humans (1-3). Species this genus have only recently been recognized having major clinical roles and allergic bronchopulmonary disease humans. Contributing to delay their recognition, even when they were isolated culture, was the original misclassification members either Helminthosporium or Drechslera. McGinnis colleagues demonstrated that isolates previously reported literature us these two latter actually its relative Exserohilum. A second delaying factor histopathologic practice basing fungal identification on microscopic findings alone. Hyphae seen histologic sections did not resemble coenocytic (nonseptate) hyphae zygomycetes darkly pigmented commonly "aspergiUus" without confirmarion by culture. Thus, it within past decade spectrum extent association certain species with human become appreciated. Mycology Originally, Drechslera, Exserohilum, lumped Helminthosporium, which traditionally considered an environmental contaminant (1). However, group can be separated characteristic development conidiophores (spore-bearing hyphae) morphology conidia (asexual spores). Initially, those ceasing grow after terminal conidial formation (determinate conidiophores) retained while whose continued increasing length through new growing points under each conidium (sympodial growth, indeterminate development) all segregated Drechslera (1,4). Because sympodial manner are frequently characterized a geniculate ("zig-zag" "bent-knee") appearance (Fig. la b). It later could further into additional genera, based (shape, size, position, nature septal divisions, position size hilum, scar marks latter's attachment point conidiophore) Early growth Curvularia spp. may also app. Although slide cultures performed, differential readily observed using adhesive tape preparations tease mounts. If necessary, germination direct examination before removing cover slip. Alternatively, aqueous suspension incubated at ambient temperature for 8 24 h aliquots microscopically intervals The egg-shaped ellipsoidal-to-fusoid, multicelled la'uncate hilum. cells divided distosepta (pseudosepta), polar germinate axially from both ends typically hilar end