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Thursday, March 27, 2008

Candidiasis

Candidiasis, commonly called yeast infection or thrush, is a fungal infection (mycosis) of any of the Candida species, of which Candida albicans is the most common. Candidiasis thereby encompasses infections that range from superficial, such as oral thrush and vaginitis, to systemic and potentially life-threatening diseases. Candida infections of the latter category are also referred to as candidemia and are usually confined to severely immunocompromised persons, such as cancer, transplant, and AIDS patients, whereas superficial infections of skin and mucosal membranes by Candida causing local inflammation and discomfort is common in many human populations. While clearly attributable to the presence of the opportunistic pathogens of the genus Candida, candidiasis describes a number of different disease syndromes that often differ in their causes and outcomes.


Causes:
Candida yeasts are usually present in most people, but uncontrolled multiplication resulting in disease symptoms is kept in check by other naturally occurring microorganisms, e.g., bacteria co-existing with the yeasts in the same locations, and by the human immune system.
A weakened or undeveloped immune system or metabolic illnesses, such as diabetes may predispose individuals to Candidiasis. Diseases or conditions linked to candidiasis include HIV/AIDS, mononucleosis, cancer treatments, steroids, stress and nutrient deficiency, among many others. Almost 15% of people with weakened immune systems develop a systemic illness caused by Candida species. In extreme cases, these superficial infections of the skin or mucous membranes may enter into the bloodstream and cause systemic Candida infections.
Pregnancy, the use of oral contraceptives, engaging in vaginal sex immediately and without cleansing after anal sex and using lubricants containing glycerin have been found to be causally related to yeast infections.
Diet has been found to be the cause in some animals. Hormone Replacement Therapy and infertility treatments may also be predisposing factors.

Symptoms:
Symptoms include severe itching, burning, and soreness, irritation of the vagina and/or vulva, and a whitish or whitish-gray discharge, often with a curd-like appearance.
In men, symptoms include red patchy sores near the head of the penis or on the foreskin, severe itching and/or a burning sensation. Candidiasis of the penis can also have a white discharge, although uncommon. However, having no symptoms at all is common and usually, a more severe form of the symptoms may emerge later.

Diagnosis:
Medical professionals use two primary methods to diagnose yeast infections: microscopic examination, and culturing.

For the microscope method, 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 also placed on the slide. The KOH dissolves the skin cells but leaves the Candida untouched, so that when the slide is viewed under a microscope, the hyphae and pseudo spores of Candida are visible. Their presence in large numbers strongly suggests a yeast infection.

For the culturing method, a sterile swab is rubbed on the infected skin surface. The swab is then rubbed across a culture medium. The medium is incubated for several days, during which time colonies of yeast and/or bacteria develop. The characteristics of the colonies provide a presumptive diagnosis of the organism causing symptoms.

Treatment:
In clinical settings, candidiasis is commonly treated with antimycotics—the antifungal drugs commonly used to treat candidiasis are topical clotrimazole, topical nystatin, fluconazole, and topical ketoconazole. For example, a one-time dose of fluconazole (as Diflucan 150-mg tablet taken orally) has been reported as being 90% effective in treating a vaginal yeast infection. This dose is only effective for vaginal yeast infections, and other types of yeast infections may require different treatments. In severe infections (generally in hospitalized patients), amphotericin B, caspofungin, or voriconazole may be used. Local treatment may include vaginal suppositories or medicated douches. Gentian violet can be used for breastfeeding thrush, but pediatrician William Sears recommends using it sparingly, since in large quantities it can cause mouth and throat ulcerations in nursing babies, and has been linked to mouth cancer in humans and to cancer in the digestive tract of other animals.

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