The body normally hosts a variety of germs, including bacteria and fungi. Some of these are useful to the body, some produce no harm or benefit, and some can cause harmful infections.
Some fungal infections are caused by fungi that live on the hair, nails, and outer skin layers. They include mold-like fungi (dermatophytes, which cause tinea infections) and yeast-like fungi (such as Candida).
In cutaneous candidiasis, the skin is infected with Candida fungi. It is fairly common. Infection can involve almost any skin on the body, but most often it occurs in warm, moist, creased areas such as the armpits and groin. The fungus that most often causes cutaneous candidiasis is Candida albicans.
Candida is the most common cause of diaper rash in infants. The fungi take advantage of the warm, moist conditions inside the diaper. Candida infection is particularly common in people with diabetes and in people who are obese. Antibiotics, steroid therapy, and chemotherapy increase the risk of cutaneous candidiasis. Candida can also cause infections of the nails (onychomycosis), at the edge of the nails (paronychia), and at the corners of the mouth (angular cheilitis).
Oral thrush, a form of Candida infection of the moist lining (mucous membranes) of the mouth, is usually associated with taking antibiotics. It may also be a sign of HIV infection or other immunodeficiency disorders when it occurs in adults. Individuals with Candida infections are not usually contagious, though in some settings immunocompromised people can catch the infection.
People with seriously weakened immune systems and cutaneous candidiasis may go on to develop more serious internal Candida infections.