#470MBI Medical Mycology assignment by Ghaida Alrumaizan - Microbiology King Saud University

1. Ghaida Alrumaizan
Najla Alshaikh
470 Medical Mycology
March 6, 2021
Candidiasis Infections
History of Candidiasis
Over the past 200s, Candida species have come to be considered as important
agents of nosocomial infection. Langenbeck the
fi
rst who discovered the yeast in
scrapings of thrush from a patient has typhus as primary infection. The name Candida
was accepted in 1954. Several studies have documented that 60-70 % of patients in
the intensive care units (ICUs) are colonized with Candida species.
Candidiasis Infections
Candidiasis infections are type of infections caused by certain type of fungus,
speci
fi
cally yeast, Candida. These infections varies from its virulence to their site of in-
ections. There are several types of candidiasis: If it is in the mouth or throat, it is called
oral candidiasis, oropharyngeal candidiasis (OPC), or thrush. If it a
ff
ects the genital
area, it is called a yeast infection. In women, it may be called a vulvovaginal Candidia-
sis (VVC). If yeast infects the skin of a baby's bottom area, it causes a diaper rash. If
the infection enters the bloodstream, it is called invasive Candidiasis or Candidemia.
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2. Invasive fungal infections, such as candidemia, have been increasing. Can-
didemia is not only associated with a high mortality 30% - 40% but also lengthen the
period of hospital stay. Candidiasis is caused by the abnormal over growth in C. albi-
cans, which is usually due to an imbalance in the environment. Usually, this imbalance
occurs in a woman’s vagina. Several events can spark an imbalance. One important
factor, antibiotic use decreases the amount of lactobacillus bacteria, which resultsin
decreasing the amount of acidic products and the pH of the vagina. Other conditions
are pregnancy, uncontrolled diabetes, impaired immune system, and irritation of the
vagina. C. albicans are able to take advantage of the conditions and compete the nor-
mal micro
fl
ora, resulting in candidiasis or a yeast infection.
C. albicans has so many virulence factors which make it harmful to the host; one
of them is the adhesion of the cell wall. Adhesion proteins (antigenes) promote the
binding of the organism to host cells.
Cutaneous candidiasis can be generalized or restricted to the outer layer on lim-
ited body surfaces. Interdigital candidiasis between the
fi
ngers and toes is a common
manifestation of candidal skin infection. Candida spp., like most of fungi, prefer a dark,
warm, and a moist environment, which explains why it develops between skin surfaces
close to each another. Vesicles, pustules, maceration, and
fi
ssuring are often seen on
intertriginous skin areas. Cutaneous symptoms vary depending on body location, but
include the following:
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3. • rashes.
• red or purple patches.
• white,
fl
aky substance over a
ff
ected areas.
• scaling, or shedding of the skin with
fl
akes.
• erythema, which results in areas of redness.
Oral Candidiasis is often known as thrush. Although candida is present in 50%
of the normal
fl
ora of healthy mouths, it might causes candidiasis when very high num-
bers of yeast cells invade the mucosa.
Oral Candidiasis symptoms include:
• White patches on the inner cheeks, tongue, roof of the mouth, and throat.
• Redness or soreness, and cotton-like feeling in the mouth.
• Taste loss, and pain while eating or swallowing.
Causative agent
Candida albicans is an opportunistic
pathogen fungus. It inhabits the mammalian GI tract
and other mucosal surfaces. It posses a reversible
alteration of yeast cell morphology and dimorphism,
which is the ability to produce eaither seprated
yeast cells (blastospores) or
fi
lamentous form (hy-
phae and pseudohyphae). Candida is the causative
agent and the most common cause of fungal infec-
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4. tions worldwide, it has a few types which are responsible for the di
ff
erent types of in-
fections.
Macroscopic Features
The colonies of Candida spp. are yellowish cream colored, grow quickly and
mature in 3 days. The texture of the colony might be pasty, smooth, or dry, wrinkled
and dull, depending on the species.
Microscopic Features
All Candida species produce single blastoconidia small clusters. Blastoconidia
can be round or elongated. Most of the species produce a pseudohyphae which might
be long, branched or curved.
Taxonomic classi
fi
cation:
Kingdom: Fungi
Phylum: Ascomycota
Subphylum: Ascomycotina
Class: Ascomycetes
Order: Saccharomycetales
Family: Saccharomycetaceae
Genus: Candida
Diagnosis:
Diagnosis of Candidiasis is done by microscopic examination or culturing. For
identi
fi
cation by the light microscope, a scraping or swab of the a
ff
ected area is placed
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5. on a microscope slide. Single drop of 10% potassium hydroxide (KOH) solution is
added to the sample. KOH dissolves the skin cells, but leaves the Candida cells intact,
permits visualization of pseudohyphae/budding yeast cells. About the culturing
method, a sterile swab is being rubbed on the infected skin surface. Then swap is
streaked on a culture medium. Culture is incubated at 37 °C for couple of days, to al-
low the growing of Candida colonies. The characteristics of the colonies might give an
initial diagnosis of the organism causing disease symptoms.
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Pseudohyphae of candida with budding
yeasts are present on this potassium hy-
droxide preparation. Pseudohyphae are
chains of elongated yeast cells that fail to
detach after budding.
Candida albicans on Chromagar
Candida albicans Spiking on chocolate agar

6. Treatment:
The treatments depend on the underlying disease (diabetes, heart disease,
etc.) , and immune status, the speci
fi
c type of species of Candida, and in some cases,
the susceptibility of the species to a speci
fi
c antifungal drugs.
Most localized cutaneal candidiasis infections are often treated with any topical
antifungal agents (clotrimazole, econazole). Oropharyngeal candidiasis (OPC) are often
treated with either topical antifungal agents (eg, nystatin, amphotericin B oral sus-
pension) or systemic oral azoles (
fl
uconazole, itraconazole). Vulvovaginal candidiasis
(VVC) might be managed with either topical antifungal agents or a one dose of oral
fl
u-
conazole.
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7. REFERENCES:
- Aaron P, (1998). Dimorphism and virulence in Candida albicans, Current Opinion in Microbi-
ology. 1(6):687-692.
- https://drfungus.org/knowledge-base/candida-species/
- Sengar, K. Et al. (2012). Historical background, epidemiology and pathogenicity of Candida
species. Biochemical and Cellular Archives. 12. 89-94.
- https://emedicine.medscape.com/article/213853-clinical
- Oliveira S. Giselle C et al. (2018 ) Candida Infections and Therapeutic Strategies: Mecha-
nisms of Action for Traditional and Alternative Agents. Frontiers in microbiology vol. 9 1351.
- Brock M. (2009) . Fungal metabolism in host niches. Current Opinion in Microbiology.
12(4):371-6.
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