Tinea: Fungal Skin Infections

Posted on 06 Jun 2012 14:01

Tinea refers a group of fungal skin infections (dermatomycosis) commonly called ringworm. The infection is caused by various dermatophytes (fungi which infect the skin) of the genera Microsprum, Trichophyton, and Epidermophyton. Dermatophytes invade the keratin layer of the skin, nails, and hair. They do not usually invade the living epidermis. As the fungus grows, it spreads out in a circle, often leaving normal looking skin in the middle, although not always. The skin along the circle edge is raised with vesicles, scaly, irritated and itchy.

Some of the common species of dermatophytes encountered include:

  • Microsporum audouni, M. canis
  • Trichopyton rubrum, T. mentagrophytes, T. violaceum, T. tonsurans, T. verrucosum, T. schoenleinii
  • Epidermophyton floccosum

These dermatophytes live on the stratum corneum of the skin, which is the uppermost layer consisting of dead skin cells. Sometimes they extend to the hair or nails. Deeper infections are very rare and usually present only in immune-deficient persons.

Tinea infections came to be called ringworm because the circle made by the fungus growth looks like a worm under the skin. However, not all tinea fit this description, referred to as classical ringworm.

Usually, a warm moist environment is affected. The common dermatophytes prefer temperatures in the high 80's and above, so those people living in tropical and subtropical areas are more affected and parts of the body that are routinely covered so that they stay warm and moist (through sweat) are most infected. Skin folds are also common sites so the obese are at risk. Other predisposing factors are poor nutrition, unhygienic conditions, frequent sweating, skin maceration, diabetes mellitus and other diseases, excessive corticosteroid intake, immunosupressive drugs, and contact with animals. It can affect various parts of the body and the infections are classified according to their anatomic location:

  • Feet and toes: tinea pedis (athlete's foot)
  • hands: tinea manumm
  • groin: tinea cruris (jock itch)
  • scalp: tinea capitis
  • fingernail and toenail: tinea ungulum
  • body: tinea corporis (ringworm of the body)
  • beard: tinea barbae (ringworm of the beard)
  • face: tinea faciale (ringworm of the face)

These fungal infections are communicable and can be spread from person to person by coming in contact with objects that have been used by infected persons. Athletic communal facilities or equipment can spread the infection, or it can be spread from person to person.1,3.

Although in some cases systemic anti-fungal therapy may be needed, such as griseofulvin or ketoconazole, many ringworm infections can be treated topically. Athlete's foot, jock itch, and tinea coporis can often be treated with over-the-counter products.

There are nonprescription topical products which claim to treat nail fungus, but creams or other topicals cannot penetrate the nail bed. Therefore, even if these products had activity against fungus, they would not work. Products such as Fungi Nail contain undecylenic acid, which, although it is used commonly to treat fungal infections of the skin, has no chance of actually reaching the nail bed when used on nail fungus infections. In fact, the product literature clearly states: "This product is not effective on the scalp or nails." The product's indications state that it "Eliminates fungal infections of the skin by inhibiting the growth and reproduction of fungal cells"making the name Fungi Nail misleading, to say the least (emphasis added).

Oral therapy is usually warranted so a physician should be seen for nail fungus, which if left untreated could destroy the nail plate permanently. Tinea capitis does not respond to nonprescription topicals for similar reasons. However, topical therapy, when appropriate, is preferred to avoid the common reactions to systemic medications.

Topical medications for fungal infections include creams, ointments, liquids, and powders, which are used depending on the area infected and the breadth of the infection.2 Your doctor will prescribe appropriate anti-fungal agents and both prescription and over-the-counter preparations are available. The following table 1 lists some antifungal agents available OTC that can be used to treat tinea infections.

OTC Topical Antifungal Agents Effective for Tinea Infections

Generic name Trade Name Form
clioquinol Clioquinol cream
clotrimazole( also RX) Lotrimin cream, lotion, solution
miconazole Micatin cream, powder, spray
terbinafine Lamasil AT cream
tolnaftate Tinactin cream, powder, spray, solution
undecylenic acid Desenex cream, foam, ointment, powder, spray, soap
1. Sehgal, Virendra N. Texbook of Clinical Dermatology. New Delhi: Jaypee, 2004.
2. Pray, W. Steven., and Richard Finkel. Nonprescription Product Therapeutics. Philadelphia, PA: Lippincott Williams & Wilkins, 2004.
3. O'Connor, Daniel P., and A. Louise Fincher. Clinical Pathology for Athletic Trainers: Recognizing Systemic Disease. Thorofare, NJ: SLACK, 2008.
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