|T. rubrum infection|
Trichophyton rubrum is a fungus that is the most common cause of athlete's foot, jock itch, and ringworm. This fungus was first described by Malmsten in 1845. The growth rate of Trichophyton colonies in the lab can be slow to rather quick. Their texture is waxy, smooth and even to cottony. From the top, the color is white to bright yellowish beige or red violet. Reverse is pale, yellowish, brown, or reddish-brown. Although Trichophyton rubrum is the most common of the dermatophytes causing fingernail fungus infections, there are others. Trichophyton interdigitale is the second most common source of fungal nail infections from the dermatophyte group. (Used to be called Trichophyton mentagrophytes var interdigitale - new guidelines now state that a fungus can only be called T mentagrophytes if it is isolated from an animal - the human variant is T. interdigitale)
Common skin diseases
- Ringworm properly known as dermatophytosis
- Athlete's foot properly known as Tinea pedis
- Jock itch properly known as Tinea cruris
- Fungal folliculitis of the scalp properly known as Tinea capitis
- Fungal folliculitis of the beard properly known as Tinea barbae
- Fungal folliculitis of the legs properly known as Majocchi granuloma often occurs in females who shave their legs.
- Onychomycosis (nail infection)
Positive, selective diagnosis of T. rubrum is difficult as many members of the genus react similarly with test reagents. The Mycology Unit at the Adelaide Women's and Children's Hospital uses a dermatophyte identification scheme comprising 6 different media to help identify and differentiate the various species and strains of Trichophyton. The media in this scheme are Littman Oxgall agar, Lactritmel agar, Sabouraud's agar with 5% NaCl, 1% Peptone agar, Trichophyton agar No. 1, and hydrolysis of urea.
- William Williams, The Principles and Practice of Veterinary Surgery, p.734, W.R. Jenkins, 1894, from the collection of the University of California.