Pharmacists will often encounter patients looking for advice on fungal infections. Rod Tucker gives the latest guidance

 

Superficial fungal infections

There are at least three different forms of fungal skin infections that will be encountered by community pharmacists.

•Dermatophytes.

•Candida.

•Malassezia.

 

Dermatophyte infections

A dermatophyte fungus requires keratin or growth and invades the non-living keratinised layers of superficial skin, hair and nails. The most common dermatophyte is tinea and the fungus is spread by direct contact with infected individuals, animals, soil or through contact with infected clothing, towels and bedding. Under normal circumstances, the dryness of the epidermis and continual shedding of skin cells discourages organisms from establishing themselves. However, if the skin is damaged through trauma, irritated or macerated (which occurs when the skin is wet), then the barrier function of the skin is compromised, making infection more likely.

The growth of tinea is encouraged by a warm, damp environment and the most common form is tinea corporis, which normally occurs on the body. Once the infection takes hold, the organism spreads outwards in a circular pattern with a central clearing, hence the more common term, ringworm. The body responds to the infection by increased proliferation of epidermal cells that leads to scaling in an effort to shed the fungus. The scaling is most clearly visible around the border of the advancing lesion.

 

Treatment of tinea infections in the pharmacy

Tinea pedis (athlete’s foot), corporis, cruris and manuum can all be successfully managed with over-the-counter (OTC) products. Topical formulations include creams, sprays or powders, though the BNF cautions against the use of powders (particularly for tinea pedis), suggesting that these might cause irritation but could be of value at preventing re-infection. In most instances, treatment with a cream will be appropriate. Tinea capitis requires systemic therapy and if this is suspected patients should be referred to their GP.

There are two classes of topical anti-fungal agents: imidazoles (such as clotrimazole, miconazole and econazole) and allylamines, of which there is currently only one product, terbinafine. There is little difference in terms of cure rate, although imidazoles such as clotrimazole require treatment for up to four weeks. Terbinafine, while more expensive and not licensed for use in children, clears tinea corporis after two weeks and tinea pedis in seven days.

The reason for the difference in treatment duration is that allylamines are fungicidal, thus killing the fungus, whereas imidazoles are fungistatic and merely prevent further growth of the organism, relying on the normal process of skin shedding to remove any further living fungi.

Combination products such as Daktacort and Canesten HC include 1% hydrocortisone with the imidazole and may be used for up to seven days if the infection is associated with inflammation.

Other OTC treatments for athlete’s foot include zinc undecylenate/undecylenic acid (Mycota cream) and tolnaftate 1% (Scholl’s athlete’s foot spray), although these treatments are less effective than imidazoles or allylamines.

 

Tinea unguium (nail infections)

Two OTC topical agents specifically formulated for infected nails are:

•Urea 40% (Canespro) – applied to the nail daily and covered with a plaster for 24 hours. The urea softens the infected part of the nail and should cure the infection after two to three weeks, although the manufacturer suggests that a topical antifungal cream
is used as a follow-up for an extra two to
three weeks.

•Amorolfine 5% (Curanail) is applied once weekly but to no more than two infected nails. Treatment can take up to 12 months for toenails and six months for fingernails.

Patients with more than two infected nails should be referred to their GP.

 

Candida infections

This name refers to a group of common yeast infections on the skin. Though there are up to 20 different species, Candida albicans is the organism responsible for most infections.

 

Oral thrush

Although candida is a normal commensal organism in the digestive tract that rarely causes a problem, infection with candida can occur when the mucosal barriers are damaged or if the host defences are reduced. The most common oral candida infection is pseudomembranous candidiasis (or oral thrush). It can develop in those with a weakened immune system, dentures, diabetes, poor nutrition and patients using broad-spectrum antibiotics or inhaled corticosteroids. Classically, the condition presents with patches of white or yellowish plaques on the inner cheeks, gum or tongue. Oral miconazole gel (Daktarin) for a week is an effective OTC treatment.

Another candida infection is angular cheilitis, which is seen as the cracks in the corner of the mouth. However, there are other potential causes of angular cheilitis. For this reason, patients should be referred
to their GP.

 

Intertrigo

This appears as an inflamed, itchy, sore rash in the axillae (armpits), finger web spaces and sub-mammary (below the breast) regions, especially in those who are overweight.

Candida can be a cause of secondary infections in nappy rash and should be suspected where there are inflamed plaques and small satellite spots or pustules around the margins of a main red area.

If the infection is not widespread, both intertrigo and infected nappy rash can be managed with topical imidazoles or an allylamine. However, although terbinafine is effective, it does not have an OTC license for yeast infections.

 

Vulvovaginal candidiasis

Vaginal thrush is an inflammation of the vagina or vulva caused by infection with candida. Infection can occur during pregnancy and in women with diabetes or immunosuppressive conditions such as HIV infection. Common symptoms will include vulval itching, soreness and irritation combined with a white, cheese-like discharge.

Most simple cases can be easily managed with an intravaginal antifungal cream or pessary, which should be inserted high into the vagina (preferably with an applicator). Symptoms should resolve in a few days. Women aged between 16 and 60 who prefer an oral treatment can be given a single 150mg fluconazole capsule and advised that if symptoms do not resolve after 14 days, they should see their GP.

 

Malassezia folliculitis

This is an infection of the hair follicles caused by the overgrowth of malassezia, a commensal yeast. It is primarily seen in young males and adolescents living in humid climates and presents as itchy papules and pustules on the forehead, chin, neck, chest and back.

Risk factors for overgrowth of the organism include high sebum production, excessive sweating and immunosuppression. It can be managed with topical agents but is best treated with oral antifungals, so patients should be referred.

 

Pityriasis versicolor

A second malassezia infection that is common in young adults, slightly more in men than women, is pityriasis versicolor. The condition frequently occurs in hot and humid climates. Although it resolves during the winter months, it can recur during the summer. It is seen on the trunk and arms and in Caucasians appears as brown or fawn macules with fine scale. Generally it is asymptomatic, though it can be mildly itchy. In people with darker skin, the condition presents with hypopigmentation.

The imidazoles are licensed for the OTC management of pityriasis versicolor but often topical application of ketoconazole (or selenium sulphide) shampoo, lathered onto the skin and left in contact for 10 minutes and then washed off and repeated for five days, is used. Widespread cases should be referred to the GP. The condition can affect the skin for several months and often recurs.

 

Self-care for fungal infections

Since fungal infections thrive on warm, moist skin, the risk of infection can be reduced by washing and drying the skin thoroughly, avoiding sharing of towels and washing these items frequently.

It may also help to wear loose fitting clothing and underwear – for instance, cotton, which keeps moisture away from the skin.

Tinea pedis infection can be minimised if patients wear shoes that keep the feet cool and dry and wear cotton socks. The feet should also be dried thoroughly, particularly between the toes where the fungus is most likely to be present. In addition, the patient should avoid scratching the skin as this can allow transmission of the fungus to other parts of the body such as the groin or the hands.

Rod Tucker is a community pharmacist