An infection of the base of a hair follicle. Hot tub folliculitis occurs when a patients comes in contact with the bacteria Pseudomonas aeruginosa that can live in the water of some hot tubs. It is more common if the hot tub is made of wood or if the acidity and chlorine content of the water is not strictly controlled. The infection is sometimes worse underneath the swimsuit areas. The infection typically appears 2 days after swimming in the hot tub.