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Abstract Candida species especially Candida albicans are one of the leading causes of invasive fungal infections world-wide (Shaw and Ibrahim, 2020; Cannon et al., 2009; Pfaller et al., 2007) Candidiasis or oral candidiasis, is an opportunistic yeast disease caused by Candida species (C. albicans, C. glabrata, C. guillermondii, C. krusei, C. parapsilosis, C. pseudotropicalis, C. stellatoidea and C. tropicalis) but C. albicans is the most frequent mucocutaneous mycosis of the oral cavity (Al Uobody, 2023; Singh et al., 2014) Candida is found in the oral cavity of 53% of the general population as a common commensal organism. One hundred and fifty species of this genus have been isolated in the oral cavity, and 80% of the isolates correspond to C. albicans, which can colonize the cavity alone or in combination C. glabrata or C. tropicalis (AL-kahfaji, 2022; Coronado-Castellote and Jiménez-Soriano, 2013). Candida spp. account for 70–90% of all invasive yeast infections, and are a frequent cause of hospital-acquired systemic infections with crude mortality rates of up to 50%. Candida albicans in the first order of Candida spp. in isolation frequency and the most common yeast pathogen in most clinical setting. The morphological flexibility of C. albicans plays a crucial role in several aspects of infection and host recognition (Swidergall, 2019). Candida albicans is a rounded and oval-shaped yeast measuring 3- 30 µm in diameter. It grows on ordinary media over a wide range of pH and temperature. It reproduces asexually through a budding process in which protoplasmic protrusions or buds (blastoconidia) emerge from the mother cell and grow until they finally detach to form a new cell. The daughter cells occasionally do not detach and form chains of cells called pseudohyphae, which can be mistaken for hyphae. The hyphae are composed of a row of elongated cells enveloped by a cell wall; they globally conform the mycelium (septate and ramified hyphae) (Navabi et al., 2021). In solid culture media, the yeast grows, giving rise to compact colonies that are macroscopically visible after 24-48 hours of incubation. Candida must be in the saprophytic phase in order to produce clinical lesions, though over time nutritional and environmental variations modulate its conversion to the mycelial or invasive form. In this phase the yeast keeps its previous virulence intact, and is able to evade macrophage phagocytic action. It can utilize ammonia but not nitrate; nitrogen and most strains need growth factor biotin to be supplemented for their growth (Di Cosola et al., 2021). Pathogenesis of invasive candidiasis is facilitated by a number of factors, including the ability to adhere to medical devices and/or host cells and to form biofilms. It is also important to highlight the ability of some Candida species to switch from yeast to filamentous growth forms, with the latter thought to increase the ability of the organism to invade host tissues (Silva et al., 2012). Moreover, reports clarified that pathogenesis of invasive C. albicans is facilitated by a number of factors, C. albicans has developed several virulence tools for evading and colonize the host immune system including the expression of adhesins and invasins which relate to the cell wall, polymorphism, the formation of biofilms, phenotypic switching and the secretion of hydrolytic enzymes as neuraminidase, proteases, chitin, mannoprotein and lipids are considered virulence factors (Abirami et al., 2020; Dhama et al., 2013). The antifungal resistance has represented a major challenge for the clinic, by the difficulty to treat candidiasis. The increase of the antifungal resistance may be due to the use of selective therapies with inadequate doses or to the drug’s frequent use in the fungal infection prophylaxis, both in human and animals, which may affect the selective clinical resistance (Gómez-López, 2020; Wiederhold, 2017) Despite the introduction of newer antifungal drugs for the treatment of infections by Candida species, the occurrence of invasive fungal infections and resistance to antifungal therapy is on the rise (von Lilienfeld-Toal et al., 2019). Hence, in vitro antifungal drug susceptibility testing for Candida species has become important in the detection of resistance as well as in effective patient management (Giri and Kindo, 2014; Pfaller and Diekema, 2012). The identification of Candida species phenotypically by traditional microscopic, cultural using chromogenic medium and metabolic characteristics as carbohydrate assimilation remains commonly used, that are laborious, time-consuming (may take days to weeks), require significant technological expertise and sometimes unsuccessful because of the atypical features of some isolates (Habib et al., 2023; Moron et al., 2017). Therefore, Molecular approaches have been developed to provide more rapid and accurate identification of pathogenic Candida species comparing to traditional phenotypic methods (Magalhães et al., 2022). The internal transcribed spaces 1 and 2 regions (ITS1 and ITS2) have been used extensively for molecular analysis of Candida . The methods used are PCR, ITS fragment length polymorphism, restriction fragment length polymorphism, DNA probe hypridization and DNA sequences (Morovati et al., 2023; Rafat et al.,2020) In Egypt, studies on Candida spp. are limited. A literature search showed that there is a lack of recent studies on clinical C. albicans in Egypt. However, clinical Candida spp. especially C. albicans are still among the poorly studied fungal groups in the country. This gap implies the need for isolating and identifying C. albicans in milk samples and buccal cavity swabs of candidiasis patients, which presently are not part of the routine protocols in the country’s hospital setting and diagnostic laboratories. |