It is a parasitic fungi that attacks the skin. It includes three genera of fungi: Microsporum Trichophyton Epidermophyton, .
Dermatophytes cause infection of the hair, skin and nails due to their ability to feed on keratinized substances. These fungi form their colonies in the keratinized tissues, and then inflammation occurs as a reaction of the body to the secondary metabolites of the fungi. In general, the presence of these fungi is limited to the keratinized layer of the epidermis, due to its inability to penetrate the living tissues of the host with a healthy immune system. This infection elicits an immune response from the host body that ranges from moderate to severe. Protease, elastase, keratinase and other proteolytic enzymes also play a role in the virulence of these fungi, and the host's development of cellular immunity associated with delayed hypersensitivity would aid recovery in contrast to hosts who have problems with their cellular immunity. It predisposes to a chronic or recurrent fungal infection.