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Fungal Skin Infections: Types, Symptoms and Treatment

Fungi are a common cause of numerous skin infections. Some are naturally present in the human body (known as yeasts), while others (known as dermatophytes) grow on the body as foreign particles and promote infection. Fungi grow best in warm, moist and dark environments. In humans, they grow well on skin, especially in skin folds (e.g., groin, breast folds, armpits) and in mucous membranes (e.g., genitals, mouth).

Yeast Infections and their Symptoms

Candidiasis happens to be the most frequent form of yeast infection in humans. It may affect the skin, nails and mouth as well as many organs such as genitals or respiratory system. Common candidiasis infections include:

  • Yeast onychomycosis. Yeast infection affecting the nails. It is characterized by pain, redness, inflammation and warmth around and underneath the nail and nail bed, sometimes with a discharge of pus. A yellow opaque streak at the side of the nail, yellow spots in the half moon, or white, flaky patches on the top of the nail plate signal the presence of onychomycosis. The nails may be thickened, opaque and ridged and the end of the nail may lift-up. In the later stages of the disease, the entire nail may be lost.
  • Thrush. Yeast infection of the mouth, most commonly occurring in infants. Thrush is characterized by white patches that bear a resemblance to cottage cheese forming on the inside of the mouth (learn more).
  • Tinea versicolor (pityriasis versicolor). Common skin infection in adolescents and young adults typically affecting the neck, arms and torso. It is characterized by white, tan or red scaly patches.
  • Generalized cutaneous candidiasis. A rare form of yeast infection with a widespread, diffuse, itchy rash. Itching is most intense in the groin and anal region, armpits, feet and hands.

Furthermore, patients with intertrigo, a skin infection that causes inflammation in the body folds, can also be infected with yeast, which worsens this condition. When intertrigo is accompanied by a yeast infection, localized, bright-red rashes tend to develop in the skin folds. The border of the rash is usually scalloped with a white rim that may contain small bumps filled with pus. Scaling is common and may be accompanied by itching or burning. The rash may also spread to other regions.

Dermatophyte Infections and their Symptoms

Since dermatophytes digest the protein keratin, dermatophyte infections are found in areas where this protein is found, such as the skin, nails or hair. Most forms occur in adolescents after puberty and in adults. The dermatophyte infections are contagious and may be spread by direct contact with humans, animals or soil. They may or may not produce inflammation and may be acute or chronic in duration. Common dermatophyte infections include:

  • Athlete’s foot (tinea pedis). As the name suggests it is a fungal infection of the foot. Athlete’s foot is the most common form of dermatophyte infection in the westernized world, and is often accompanied by other fungal infections such as nail fungus, hand fungus or jock itch. It is uncommon in children before puberty. Athlete’s foot is most often chronic. Typical features include cracking and scaling of the skin between the toes, especially the fourth and fifth toe, with itching and possibly soreness. Tiny, fluid-filled blisters may also occur.
  • Ringworm (tinea corporis). Although ringworm may appear anywhere on the skin, it is most commonly found on exposed skin, such as the hands and arms. Ringworm often results from the spread of dermatophytes from other infections such as athlete’s foot or ringworm of the scalp. It is common among all age groups, but particularly common among children. Ringworm infection is best known for its red, flat or slightly raised circular sores that may be dry and scaly or crusted and moist and intensely itchy. Small blisters may also accompany the sores. Large sores tend to have a seemingly clear skin in the center surrounded by an infected edge, giving this infection its common name.
  • Dermatophyte onychomycosis (tinea unguium). This nail infection usually begins in a nail that has been injured and spreads to other nails, affecting the nail bed or the surface of the nail itself. It more often occurs on the toenails than the fingernails. Dermatophyte onychomycosis is frequently associated with other fungal infections such as athlete’s foot or ringworm. It is the most resistant dermatophyte infection. Onychomycosis is most common in men. The affected nail becomes discolored, thick, grooved, pitted and brittle and loses its shine. Dull white spots may also form on the nail. Affected portions of the nail often break away. The nail may eventually loosen and detach completely. Foul odor and pain in the toes or fingers may accompany the infection.
  • Jock itch (tinea cruris). This infection in the groin area is sometimes also referred to as gym itch. Jock itch is often caused by the spread of athlete’s foot through infected clothing and is most common in adult men. It is characterised by a raised, red, itchy rash with scaly, well-defined borders that normally appears at sites of skin-to-skin contact in the groin and anal areas. Blisters or pustules may also form in the rash area.
  • Ringworm of the scalp (tinea capitis). This infection, also known as herpes tonsurans, occurs almost exclusively in children and some forms can be nearly epidemic. Features include lesions on the scalp that may or may not be inflamed, swollen and filled with pus. Patchy baldness typically occurs which may eventually affect the entire scalp. Although baldness is usually reversible, it may become permanent, if the infection persists. Several species of dermatophytes are associated with tinea capitis, including:
  1. Black dot type. Found most often in children, this is the most common type of tinea capitis. This form appears as bald patches with multiple black dots. There is redness on the scalp but no itching. Hairs break off flush with the skin, appearing as characteristic black dots. Also, scars may form if the condition is left untreated.
  2. Gray patch type. This infection is usually acquired from animals and appears as fuzzy, grey patches of baldness, causing redness and scaling. Hairs break off above the scalp surface.
  • Tinea manuum. Infection of the palm of the hand and spaces between the fingers. It causes thickening of the skin. This condition is usually non-inflammatory. Tinea manuum is often chronic and associated with athlete’s foot or onychomycosis.
  • Pityriasis nigra (tinea nigra). Infection of the skin on the palm of the hand characterized by dark-pigmented, painless patches. Usually, only a single, no itching, non-inflammatory lesion is formed. In some cases, lesions also develop on the soles of the feet.
  • Barber’s itch (tinea barbae). Fungal infection in the bearded portions of the face and neck causing circular lesions with scaling. Severe inflammation may result in forming pus-filled follicles. Bald patches commonly develop and scarring may also occur.
  • Piedra. Fungal, stony growths form along the hair shaft, usually in the hair of the beard or mustache. Hair may break easily.

Causes of Fungal Skin Infections

  • Compromised immune system can disturb the natural balance of skin organisms and allow one type to overgrow.
  • Tropical climate creates an ideal environment for fungi as they grow best in regions that are warm and humid.
  • Antibiotic use may promote yeast infections by killing the natural bacteria that keep the yeast growth under control.
  • Genetic predisposition for fungal skin infections
  • Obesity may increase the risk of fungal infections because overweight people have many skin folds that encourage fungal growth.
  • Pre-existing skin injury, nail injury or infection
  • Poor hygiene
  • Direct contact with people, animals, soil or other objects contaminated with dermatophytes
  • Continuous exposure to water

Treatment of Fungal Skin Infections

If treated early, most types of fungal skin infections can be cured quickly and easily. However, some infections may come back after treatment and some stubborn, chronic infections may be very difficult to treat at all. A number of factors must be considered when determining the best course of action. These include the extent and location of the infection, the patient’s age, overall health and medical history.

Topical antifungal medications are usually the first course of treatment for localized fungal skin infections regardless of their cause (dermatophyte or yeast). The azole and allylamine antifungals can be particularly useful. Many effective antifungal creams and lotions are available without a doctor’s prescription. For minor infections, a doctor may recommend a combination of topical corticosteroids and topical antifungals. Topical medications are applied directly to the affected skin area once or twice a day. Oral antifungal drugs, such as fluconazole, itraconazole, ketoconazole, terbinafine and griseofulvin, may be required for the treatment of genital or oral yeast infections and persistent chronic infections. Depending on the form, severity and location of the infection, antifungal medication may need to be used for weeks, months or even longer.

However, certain fungal skin infections require specific treatment:

  • Onychomycosis is the most difficult fungal infection to treat. Most topical treatments are not effective and oral antifungal medications may need to be taken for several months. Infection can recur, especially in people who have an inherited tendency to get it. Once oral medications are stopped, an antifungal nail lacquer that contains ciclopirox olamine should be used for another couple of months. It may take up to a year for a new, clear, healthy nail to grow and replace the old one.
  • Tinea capitis may be particularly resistant and impossible to cure with topical antifungals. Therefore, oral antifungals will be required.
  • Piedra. Treatment consists in clipping affected hairs and washing the area with an antifungal shampoo.

In addition, antibiotics may be prescribed to treat secondary bacterial infections that develop in areas affected by fungi. Since fungi can remain on the skin long after symptoms disappear, patients need to continue treatment exactly as recommended by the doctor.

Preventing Fungal Skin Infections

Fungal skin infections can usually be prevented by maintaining good hygiene and healthy weight. It is important to keep the skin clean and dry, to wash hands after touching an infected nail or skin area, to keep fingernails and toenails short, to wear clean, comfortable clothing every day, to alternate shoes daily to let them air out, to avoid using other people’s personal items (e.g., clothes, towels, toiletries), to clean showers and bathtubs frequently and to avoid walking barefoot in public places.

Where to Get More Information: DermNet NZ