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Category: Fungi and Fungal Pathogenesis; Clinical Microbiology
An Introduction to the Medically Important Candida Species, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555817176/9781555815394_Chap02-1.gif /docserver/preview/fulltext/10.1128/9781555817176/9781555815394_Chap02-2.gifAbstract:
In recent years DNA sequence-based methods have helped to confirm taxonomic relationships within the genus and have been used to confirm that both sexual and nonsexual Candida species are ascomycetes. Molecular methods have shown that many of the medically important Candida species belong to a phylogenetic subgroup known as the CTG clade, a group of largely commensal yeast species that translate CTG as serine instead of leucine. Most women suffer from vulvovaginal candidiasis (VVC) at least once in life, with as many as 8% experiencing regular recurrent infections. VVC is primarily caused by Candida albicans, while C. glabrata is the second most common cause of this infection. Candida species are an important component of the normal flora of the human oral cavity, and if given the opportunity, these can overgrow and cause oropharyngeal candidiasis (OPC). The introduction of highly active antiretroviral therapy (HAART) in the mid-1990s has led to a marked decrease in the incidence of OPC in HIV-infected individuals. In general, the majority of C. albicans isolates are fully susceptible to all major classes of antifungal agents, including the azoles, echinocandins, and polyenes. Candida parapsilosis is frequently isolated from physical surfaces in the hospital environment, making it unique among Candida species. The remaining Candida species associated with human disease are only rarely detected, and therefore relatively little is known about the etiology or the epidemiology of the diseases they cause.
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Phylogenetic tree showing the relationships between Candida yeasts of the CTG clade and other pathogenic Candida species. The tree is based on alignment of the amino acid sequences of the genes encoding enolase (Eno1p) from each species. Alignments were generated using MUSCLE using the default settings. Phylogenetic relationships were inferred with PHYML. Numbers at each node represent bootstrap values and indicate the number of times the arrangement shown occurred in 100 replicate trees. The bar under the tree represents a genetic distance of 5%. doi:10.1128/9781555817176.ch2.f1
Photomicrographs showing the different growth morphologies of C. albicans yeast cells (A), pseudohyphae (B), hyphae (C), and chlamydospores (D; one example is indicated by an arrow). doi:10.1128/9781555817176.ch2.f2
Medically relevant Candida species
Major risk factors for mucosal Candida infections
Major risk factors for IC