Candidiasis

Definition

Definition of Candidiasis
Candidiasis or thrush is a fungal infection (mycosis) of any of the Candida species (all yeasts), of which Candida albicans is the most common. Also commonly referred to as a yeast infection, candidiasis is also technically known as candidosis, moniliasis, and oidiomycosis.

Candidiasis 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 as well as non-trauma emergency surgery patients.

Symptoms

Symptoms of Candidiasis
Most candidial infections are treatable and result in minimal complications such as redness, itching and discomfort, though complication may be severe or fatal if left untreated in certain populations. In immunocompetent persons, candidiasis is usually a very localized infection of the skin or mucosal membranes, including the oral cavity (thrush), the pharynx or esophagus, the gastrointestinal tract, the urinary bladder, or the genitalia (vagina, penis).

Candidiasis is a very common cause of vaginal irritation, or vaginitis, and can also occur on the male genitals. In immunocompromised patients, Candida infections can affect the esophagus with the potential of becoming systemic, causing a much more serious condition, a fungemia called candidemia.

Causes

Causes of Candidiasis
Candida yeasts are commonly present in humans, and their growth is normally limited by the human immune system and by other microorganisms, such as bacteria occupying the same locations (niches) in the human body.

Candidiasis albicans was isolated from the vaginas of 19% of apparently healthy women, i.e., those that experienced few or no symptoms of infection. External use of detergents or douches or internal disturbances (hormonal or physiological) can perturb the normal vaginal flora, consisting of lactic acid bacteria, such as lactobacilli, and result in an overgrowth of Candida cells causing symptoms of infection, such as local inflammation. Pregnancy and the use of oral contraceptives have been reported as risk factors, while the roles of engaging in vaginal sex immediately and without cleansing after anal sex and using lubricants containing glycerin remain controversial. Diabetes mellitus and the use of anti-bacterial antibiotics are also linked to an increased incidence of yeast infections. Diet high in simple carbohydrates has been found to affect rates of oral candidiases, and hormone replacement therapy and infertility treatments may also be predisposing factors. Wearing wet swimwear for long periods of time is also believed to be a risk factor.

Diagnosis

Diagnosis of Candidiasis
Diagnosis of a yeast infection is done either via microscopic examination or culturing.

1. 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 Candida species.
2. 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 that is causing disease symptoms.

Treatment

Treatment of Candidiasis
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 (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 dosing. In severe infections 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 when used 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.

Chlorhexidine gluconate oral rinse is not recommended to treat candidiasis but is effective as prophylaxis; chlorine dioxide rinse was found to have similar in vitro effectiveness against candida.

Prognosis

Prognosis of Candidiasis
Typically, in otherwise healthy people with superficial candidiasis, a properly treated infection goes away without leaving permanent damage. Candidiasis is unlikely to return as long as the person remains healthy and well nourished. In people with chronic illnesses or weakened immune systems, episodes of candidiasis may be more resistant to treatment and may return after treatment ends. In people with deep candidiasis, those who are diagnosed quickly and treated effectively have the best prognosis, especially if their infection can be stopped before it spreads to major organs.

Prevention

Prevention of Candidiasis
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.