الفهرس 
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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.