Causes. Hair follicles become infected when bacteria are given the chance to get inside of them. Staphylococcus Aureus (commonly referred to as Staph) is a bacteria that occurs naturally on the surface of the skin, but can enter hair follicles when the skin is injured or blocked. Common activities that can injure skin are shaving, waxing, plucking, wearing tight clothing, and the use of bandages with an adhesive that can rip and irritate the skin. Once inside the follicle, bacteria cause inflammation that presents as pimple-like red bumps with or without white heads or blisters that may ooze pus and crust over. Another cause of folliculitis is from bacteria that can live in hot tubs that are not well maintained. Skin products, especially those with a lot of oils, can also cause folliculitis by physically blocking the pore.