Candida albicans is an opportunistic fungal pathogen that
is responsible for candidiasis in human hosts.
C. albicans grow in several different morphological forms,
ranging from unicellular budding yeast to true hyphae with
parallel-side wall .
Candida albicans is a unicellular, oval-shaped diploid
fungus (a form of yeast )
Typically, C. albicans live as harmless commensals in the
gastrointestinal and genitourinary tract and are found in
over 70% of the population. Overgrowth of these
organisms, however, will lead to disease
4. Candidiasis is a fungal infection that can affect areas
such as the:
Over 75% of women suffer from a C. albicans
infection, usually vulvovaginal candidiasis, in their
lifetimes, and 40-50% of them will have additional
Interestingly, C. albicans are the 4th leading cause for
nosocomial infections in patients’ bloodstreams.
This could result in an extremely life-threatening,
systemic infection in hospital patients with a mortality
rate of 30%
Several Candida species are commensal and colonize the
skin and mucosal surfaces of humans.
Who is at increased risk?
Babies with a nappy rash.
People with a metabolic disorder, including diabetics.
Pregnant women, and women who take high-dose
contraceptive pills, eg Ovran.
People who work in wet conditions.
People who are HIV-positive or suffer from another type of
7. There are several types of candidiasis:
If it is in the mouth or throat, it is called oral
candidiasis, oropharyngeal candidiasis, or thrush.
If it affects the genital area, it is called a yeast
infection. In women, it may be called a vulvovaginal
If yeast infects the skin on a baby's bottom area, it
causes a diaper rash.
If the infection enters your bloodstream, it is called
invasive candidiasis or candidemia
Candidiasis is caused by the abnormal growth in C.
albicans, which is usually due to an imbalance in the
Usually, this imbalance occurs in a woman’s vagina –
this infection less likely to occur for men.
Several events can spark an imbalance. For example,
antibiotic use can decrease the amount of lactobacillus
bacteria, which decreases the amount of acidic
products and the pH of the vagina. Other events are
pregnancy, uncontrolled diabetes, impaired immune
system, and irritation of the vagina.
C. albicans are able to take advantage of the conditions
and outcompete the normal microflora, resulting in
candidiasis or a yeast infection
Candida albicans is usually transmitted from mother
to infant through childbirth, and remains as part of a
normal human’s microflora.
The overgrowth of C. albicans leads to symptoms of
disease, and it occurs when there are imbalances – for
example, changes in the normal acidity of the vagina.
C. albicans infections very rarely spread through
sexual intercourse. The typical reservoir for C. albicans
is in the normal human microflora, and is not found
in animal vectors
10. Virulence FACTORS
C. albicans has several virulence factors which make it
harmful to its host; one of which is its use of cell wall
Adhesin proteins promote the binding of the
organism to host cells via hydrophobic interactions.
This reduces the level of yeast clearance from the body
under normal immune regulation
When C. albicans penetrates host mucosal surfaces
following morphogenesis into invasive filaments, the
polymorphic growing pattern helps the yeast invade host
tissue by secreting various degradative enzymes, including
various proteinases, aspartyl proteases, and
phenotypic switching also plays a role in altering the yeast's
adherence properties, antigen expression, and tissue
affinity. Switching might provide cells with a flexibility that
results in the adaptation of the organism to the hostile
conditions imposed not only by the host but also by the
physician treating the infection
12. DISEASES AND SYMPTOMS
A candida infection of the skin appears as a clearly
defined patch of red, itchy skin, often leaking
fluid. Scabs and pustules may be seen around the
edge of the rash.
It will usually be found in areas such as the groin, the
folds of the buttocks, between the breasts, toes, or
fingers, and in the navel.
A vaginal yeast infection may well result in a slow
leakage of a thick, white, cheese-like substance. The
vagina may itch or burn, especially during urination or
sex. Pain or discomfort during intercourse is common.
Candidal paronychia is candidiasis of the fingernails.
It often strikes people whose hands are in water a lot.
Sometimes it presents as a painful, red, swollen area
around the fingernail. In worse cases, the fingernail
may separate, revealing a discoloured white or yellow
Oral thrush causes curd-like white patches inside
the mouth, on the tongue and palate and around
the lips. It may also cause cracked, red, moist areas of
skin at the corners of the mouth. Thrush patches may
or may not be painful.
The diagnosis is most commonly made on the basis of
the skin's appearance and occasionally a skin scrape
sample is taken to confirm the clinical findings
For oral thrush, a suspension of antifungal medication
can be swished in the mouth and swallowed.
vaginal mucosa are examined under the microscope; a
potassium hydroxide smear, Gram stain, or methylene
blue is useful for direct demonstration of fungal cells
Diagnosis of a yeast infection is done either via microscopic
examination or culturing. For identification by light
microscopy, a scraping or swab of the affected area is
placed on a microscope slide. A single drop of 10%
potassium hydroxide (KOH) solution is then added to the
specimen. The KOH dissolves the skin cells, but leaves the
Candida cells intact, permitting visualization of
pseudohyphae and budding yeast cells typical of many
For the culturing method, a sterile swab is rubbed on the
infected skin surface. The swab is then streaked on a
culture medium. The culture is incubated at 37 °C for
several days, to allow development of yeast or bacterial
colonies. The characteristics (such as morphology and
colour) of the colonies may allow initial diagnosis of the
organism causing disease symptoms.
For infection of the skin, you can get an antifungal
cream or powder or prescription of antifungal drug.
For vaginal yeast infections, treatment consists of
antifungal medications that are administered directly
into the vagina as tablets, creams, ointments, or
suppositories, or administered by mouth (e.g.,
Cutaneous candidiasis — This skin infection can be
effectively treated with a variety of antifungal powders
and creams. The affected area must be kept clean and
dry and protected from chafing.
Deep candidiasis — This infection is usually treated
with intravenous fluconazole. People with very low
white blood cell counts may need an alternative
intravenous anti-fungal drug, such as caspofungin or
20. •Amphotericin B binds with ergosterol, a component of
fungal cell membranes, forming a transmembrane channel
that leads to monovalent ion (K+, Na+, H+ and Cl−) leakage,
which is the primary effect leading to fungal cell death.
• fluconazole inhibits the fungal cytochrome P450 enzyme
14α-demethylase. This inhibition prevents the conversion of
lanosterol to ergosterol, an essential component of the
fungal cytoplasmic membrane, and subsequent
accumulation of 14α-methyl sterols.
• Fluconazole is primarily fungistatic; however, it may be
fungicidal against certain organisms in a dose-dependent
manner, specifically Cryptococcus.
Clotrimazole works to kill individual Candida or
fungal cells by altering the permeability of the fungal
It binds to phospholipids in the cell membrane and
inhibits the biosynthesis of ergosterol and other sterols
required for cell membrane production. This leads to
the cell's death via loss of intracellular elements
interferes with the fungal synthesis of ergosterol, a
constituent of fungal cell membranes, as well as
As with all azole antifungal agents, ketoconazole
works principally by inhibiting the enzyme
cytochrome P450 14-alpha-demethylase (P45014DM).
This enzyme participates in the sterol biosynthesis
pathway that leads from lanosterol to ergosterol.
Lower doses of fluconazole and itraconazole are
required to kill fungi compared to ketoconazole, as
they have been found to have a greater affinity for
fungal cell membranes.
In general, you can prevent most Candida infections by
keeping your skin clean and dry, by using antibiotics
only as your doctor directs, and by following a healthy
lifestyle, including proper nutrition.
People with diabetes should try to keep their blood
sugar under tight control.
If you have HIV or another cause of recurrent episodes
of thrush, then antifungal drugs such as clotrimazole
(Lotrimin, Mycelex) can help to minimize flare-ups