What is toenail fungus? People can develop an infection of their toenails by from different types of fungus, mold, or yeast ( dermatophytes – trichophyton, candida) . The fungus can infect multiple parts of the nail unit including the nail bed and/or plate What are the types of toenail fungus? There are 4 main types of toenail fungus: distal subungual, …