Candidiasis (yeast infection, moniliasis) is infection by the yeast Candida.
Candida yeast is a normal resident of the mouth, digestive tract, and vagina that usually causes no harm. Under certain conditions, however, Candida can overgrow on mucous membranes and moist areas of the skin. Typical areas affected are the lining of the mouth, the groin, the armpits, the skin under the breasts in women, and the skinfolds of the stomach. Conditions that enable Candida to infect the skin include the following:
People taking antibiotics may develop candidiasis because the antibiotics kill the bacteria that normally reside on the body, allowing Candida to grow unchecked. Corticosteroids or immunosuppressive therapy after organ transplantation can also lower the body's defenses against candidiasis. Inhaled corticosteroids, often used by people with asthma, sometimes produce candidiasis of the mouth. Pregnant women, people receiving cancer therapy drugs, obese people, and people with diabetes also are more likely to be infected by Candida.
In some people (usually people with a weakened immune system), Candida invades deeper tissues as well as the blood, causing life-threatening systemic candidiasis (see Fungal Infections: Candidiasis).
Symptoms vary, depending on the location of the infection.
Infections in skinfolds (intertriginous infections) or in the navel usually cause a bright red rash, sometimes with softening and breakdown of skin. Small pustules may appear, especially at the edges of the rash, and the rash may itch intensely or burn. A candidal rash around the anus may be raw, white or red, and itchy. Babies may develop a candidal rash in the diaper area (see Symptoms in Infants and Children: Rashes in Children).
Vaginal candidiasis (vulvovaginitis, yeast infection—see Vaginal Infections and Pelvic Inflammatory Disease: Overview of Vaginal Infections) is common, especially in women who are pregnant, have diabetes, or are taking antibiotics. Symptoms of these infections include a white or yellow cheeselike discharge from the vagina and burning, itching, and redness along the walls and external area of the vagina.
Penile candidiasis most often affects men with diabetes, uncircumcised men, or men whose female sex partners have vaginal candidiasis. Sometimes the rash may not cause any symptoms, but usually, the infection produces a red, raw, itching, burning or sometimes painful rash on the head of the penis and sometimes the scrotum.
Thrush is candidiasis inside the mouth (see also Periodontal Diseases: Gingivitis Due to Infections). The creamy white patches typical of thrush cling to the tongue and sides of the mouth and may be painful. The patches cannot be scraped off easily with a finger or blunt object. Thrush in otherwise healthy children is not unusual, but in adults it may signal a weakened immune system, possibly caused by cancer, diabetes, or AIDS. The use of antibiotics that kill off competing bacteria increases the chances of getting thrush.
Perlèche is candidiasis at the corners of the mouth, which causes cracks and tiny fissures. It may stem from chronic lip licking, thumb sucking, ill-fitting dentures, or other conditions that make the corners of the mouth moist enough that yeast can grow.
Candidal paronychia is candidiasis in the nail beds, which causes painful redness and swelling (see Nail Disorders: Onychomycosis). This disorder typically occurs in people with diabetes or a weakened immune system or in otherwise healthy people whose hands are subjected to frequent wetting or washing.
Diagnosis and Treatment
Usually, doctors can identify candidiasis by observing its distinctive rash or the thick, white, pasty residue it generates. To confirm the diagnosis, doctors may scrape off some of the skin or residue with a scalpel or tongue depressor. The sample is then examined under a microscope or placed in a culture medium (a substance that allows microorganisms to grow) to identify the specific fungus (see Diagnosis and Treatment of Skin Disorders: Diagnosis of Skin Disorders).
Generally, candidiasis of the skin is easily cured with creams containing miconazole, clotrimazole, oxiconazole, ketoconazole, econazole, ciclopirox, or nystatin. The cream is usually applied twice daily for 7 to 10 days. Corticosteroid creams are sometimes used with antifungal creams because they quickly reduce itching and pain (although they do not help cure the infection itself and, used alone, worsen the infection). Candidiasis that does not respond to antifungal creams and liquids may be treated with gentian violet, a purple dye that is painted on the infected area to kill the yeast.
Keeping the skin dry helps clear up the infection and prevents it from returning. Talcum powder helps keep the surface area dry, and talcum powder with nystatin may further help prevent a recurrence.
Different treatments are prescribed for vaginal yeast infections, thrush, and nail infections.
Last full review/revision August 2008 by A. Damian Dhar, MD, JD