Dermatophyte infections

Tinea is a very common superficial fungal skin infection caused by dermatophytes (1). It causes athlete's foot, nail infections, tinea corporis (ringworm of the body) and scalp ringworm. Dermatophyte are fungi which invades keratinized tissue of the hair, skin, and nails but do not penetrate living tissue (1). The resultant inflammation is due to delayed hypersensitivity or due to metabolic products produced by the fungus.

Click here for example images of tinea corporis (ringworm of the body)

There are three types of general of dermatophyte infection (1):

• microsporum - skin and nail infections
• trichophyton - hair, skin, nail infections
• epidermophyton - skin and nail infection

A dermatophyte infection can be transmitted from:

• Direct contact with an infected person (Anthropophilic) or an infected animal (Zoophilic) e.g.- cats, dogs, or, more rarely, from cattle
• Contact with soil (Geophilic) - rare
• Indirect contact – through objects contaminated with the fungus (2)

The infection is associated with

• hot, humid environments
• sweating or maceration of the skin
• use of hair greases or oils
• occlusive footwear
• diabetes mellitus (1)

Key points (3):

• most cases:
  • use topical terbinafine as fungicidal, treatment time shorter and more effective than with fungistatic imidazoles or undecenoates.If candida possible, use topical imidazole
• if intractable, or scalp:
  • send skin scrapings, if infection confirmed:
    • use oral terbinafine or itraconazole
• scalp:
  • oral therapy, and discuss with specialist

Reference:

• (1) American Academy of Dermatology. Tinea (Dermatophyte) infection
• (2) Hainer BL. Dermatophyte infections. AFP 2003;67(1)
• (3) Public Health England (June 2021). Managing common infections: guidance for primary care