| Description | Candida albicans is a yeast-like fungus with cells that range from globose to elongate in shape, often organized in pseudohyphal arrangements. It reproduces primarily by budding, though under specific conditions it can sporulate to form ascospores. As a mesophilic organism, C. albicans grows optimally between 30–37 °C and is most commonly associated with the human mucosa, where it exists both as a harmless commensal and a potential pathogen. It is a facultative anaerobe, capable of growth in both oxygen-rich and oxygen-limited environments, and functions as a chemoheterotroph, deriving energy from a variety of organic carbon sources. Gram staining of C. albicans produces variable or ambiguous results. This variability stems from its cell wall composition, which lacks peptidoglycan and instead contains a thick polysaccharide matrix of β-glucans, mannans, and chitin. While the wall can trap dyes and appear Gram-positive, this is considered an artifact rather than a reliable diagnostic feature. The robust structure of the cell wall also contributes to its resistance against antifungal agents and host immune defenses. A hallmark of C. albicans biology is its morphological flexibility. It can transition between yeast, pseudohyphal, and true hyphal forms in response to environmental cues—a process known as dimorphism. This switch is central to its pathogenicity, as the filamentous forms facilitate tissue invasion, immune evasion, and persistent colonization. Additionally, C. albicans readily forms biofilms on both biotic and abiotic surfaces, including medical devices, where cells are shielded from antifungal treatments and immune clearance. Unlike many fungi, C. albicans does not undergo classical meiosis but instead exhibits a parasexual cycle that generates genetic diversity without a conventional sexual process [PMID: 26210747 ]. This mechanism enhances adaptability and may contribute to antifungal resistance. Its ability to sense environmental changes and modulate morphology accordingly underpins its success as both a commensal and a pathogen. Ecologically, C. albicans inhabits a broad spectrum of environments, including the gastrointestinal and urogenital tracts of humans, as well as abiotic surfaces such as hospital bedding and indwelling medical devices. This ecological versatility, combined with efficient strategies for adherence, immune evasion, and biofilm formation, underscores why C. albicans remains a major focus of research in fungal pathogenesis, antifungal drug resistance, and host–microbe interactions. |
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