The mouth is a place where a lot of things can go wrong. From cancers to canker sores, everything likes to live in our mouths, including fungus, but few people know about this last nasty little visitor. Oral fungal infections are usually caused by candida albicans. This fungus can be found in slight doses in everyone, and is present in small amount in the mouth and intestines and helps us digest food. Certain conditions can make the fungus proliferate out of control, making us sick.