Bacterial acne appears in different sizes, bumps, nodules, cysts, blackheads and whiteheads. It is caused when excess sebum clogs the hair follicles on your skin. When bacteria begin to grow in these follicles, it ends up creating blackheads or whiteheads on the surface of your skin. You usually experience bacterial acne on your face, particularly the T-zone and the neck. To treat these, you can include topical application of actives like retinol, benzoyl peroxide and salicylic acid.