Dermatophyte and non-dermatophyte fungi

Dermatophyte (from the Greek words δέρμα, dérma, “skin”, and φυτόν, phytón, “plant”) is a fungus that causes parasitic infections on the skin, hair, or nails. There are about 300 dermatophyte species belonging to the genera Trichophyton, Microsporum, and Epidermophyton.

In humans, dermatophytes such as Trichophyton rubrum, T. tonsurans, T. mentagrophytes, and Microsporum canis cause superficial infections of the nails, skin and hair. Dermatophytes get their food from keratin material. The organisms colonize the keratin tissues and the inflammation is caused by a reaction to the fungi’s ‘excrement’.

Some of these skin infections are known as ringworm or tinea (which is the Latin word for “worm”), though infections are not caused by worms. It is thought that the word tinea (worm) is used to describe the snake-like appearance of the dermatophyte on the skin. A very well-known type of dermatophyte infection is tinea pedis, aka athlete’s foot.

Toenail and fingernail infections are referred to as onychomycosis (tinea unguium). Dermatophytes usually do not invade living tissues but colonize the outer layer of the skin.

Non-dermatophytes are also fungi, but these fungi come from the body. In addition to keratin, these also feed on sugars from the rest of the body.