Candida albicans, a yeast that is a normal commensal in the microbial flora of the skin, the oral cavity and the vagina, commonly becomes pathogenic when immunological defences are suppressed by treatment or disease. In mild degree, oral candidosis is common among infants and persons who wear dentures, while vulvovaginitis may occur in otherwise healthy women, particularly those who are either pregnant or taking oral antibiotics or oral contraceptives. Cutaneous lesions tend to occur in patients with diabetes and other chronic debilitating conditions, including hypoparathyroidism and various congenital disorders of the immune system. C. albicans is also a cause of secondary infection in some primary skin diseases, including diaper dermatitis, intertrigo and chronic paronychia.

Treatment

Localized lesions in the mouth generally respond to topical preparations such as miconazole gel or oral suspensions of nystatin or amphotericin B. Oral antiseptics with a broader spectrum of action including polyvidone iodine and chlorhexidine also have useful anticandidal action, but they should not be swallowed, as they are toxic, particularly for infants. In patients with AIDS, it may be necessary to use oral ketoconazole or fluconazole for treatment-resistant cases; therapy needs to be maintained indefinitely, or prompt relapse is almost inevitable.

Most cases of vaginal candidosis are cured by nystatin pessaries, 100 000 International Units (IU). Two inserted nightly for 2 weeks are usually effective, but in some areas nightly doses as high as 1 000 000 IU are required. More rapid cures can be obtained with a more expensive imidazole preparation such as miconazole cream, 200 mg applied intravaginally daily for 3 days, or a single dose of clotrimazole cream 50 mg or a 500-mg pessary inserted high into the vagina. Vulval irritation may be relieved by local application of nystatin or clotrimazole cream. A relapse shortly after initial therapy should be treated with a longer course of imidazole therapy, for example clotrimazole, 100 mg daily for 12 days. Both acute and recurrent infections can now be cured most rapidly and reliably with a single oral dose of fluconazole 150 mg or with two doses of itraconazole 200 mg taken on the same day, but these treatments are expensive. Topically applied gentian violet may also be effective, but may not be acceptable to patients because it stains the skin.

The risk of reinfection can be reduced by the use of barrier contraceptives, antifungal creams and attention to hygiene. Should candidosis recur, sexual partners should also be treated since men may be infected asymptomatically, and other possible predisposing factors, including use of an oral contraceptive and tight or insulating clothing, should be discussed with the patient.

Any underlying skin condition such as diaper dermatitis or flexural eczema must be treated at the same time as secondary candidosis. Diaper dermatitis is most simply and effectively treated by removing occlusive clothing. Resistant cases usually respond to twice daily applications of an imidazole cream, such as clotrimazole. This treatment is also effective in intertrigo. Cutaneous candidosis, as seen in people with diabetes, usually responds to twice daily applications of nystatin ointment or cream (100 000 IU/g) or an imidazole cream.

Chronic Candida paronychia, which can result ultimately in nail dystrophy, is less responsive to treatment. If there are underlying causative factors, such as wet work or other pro- longed exposure to soap and water, these factors should be eliminated. Creams containing clotrimazole or other imidazoles massaged daily into the cuticles for several months are sometimes effective.