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Chapter 111 : Taxonomy and Classification of Fungi
Fungal identification can be challenging and sometimes frustrating because of the importance placed on the morphological characteristics of the organisms, and the need to become familiar with a range of different structures and terms. Investing time to learn the basic structures and principles of taxonomy, classification, and nomenclature can result in the ability to recognize and identify correctly many medically important fungi. The taxonomy and nomenclature of fungi that have both asexual and sexual stages are challenging. A simplified taxonomic scheme illustrating the major groups of medically important fungi is described in this chapter. Identification of yeast relies on a combination of morphological, physiological, and biochemical characteristics. Two artificial form classes of anamorphic or “mitosporic” molds are currently recognized, based on the mode of conidium formation. The Hyphomycetes produce their conidia directly on the hyphae or on specialized conidiophores, while the Coelomycetes have more elaborate reproductive structures, termed conidiomata. Most molds can be identified after growth in culture, but the criteria for recognition often differ from the fundamental characteristics that are used as a basis for classification. Many clinical laboratories today employ DNA sequencing as part of their routine protocol for fungal identification.