what cause fungus nail
Fungal Nail Infections-Cause. Fungal nail infections can be caused by three different types of fungus, alone or in combination. 1  Dermatophytes are a type of fungus that can grow on the skin, hair, and nails. 2  They don't invade the deeper tissues of the body. 3  The most common dermatophyte, Trichophyton rubrum, causes most cases of athlete's foot.