My favorite treatment is to clean the area twice daily with some gauze and very dilute Betadine (an iodine based soap, available at grocery and drug stores; also called something like povidone iodine--generic okay). Make sure it is *really* dilute (weak tea color) because Betadine can be very irritating to the skin, and with some cats, you may not get the chance to rinse it off.
Feline acne is very common in cats who eat or drink from plastic, because plastic is microscopically porous, and bacteria can colonize it. Even a dishwasher won't get them out. It's also common with dry food because the surface of the food is so oily. However, I've seen in cats who have neither plastic bowls nor dry food, so nothing's a sure bet.
I recommend glass or ceramic dishes. A flat plate rather than a bowl, or a straight-sided bowl (like a ramekin or casserole dish), will help prevent the skin coming in contact with the food and sides of the bowl.
I'm not crazy about steel or aluminum, even the shiny smooth ones, because the metal can hold static and shock the cat when he goes to eat. This is a big issue around here right now because it's extremely dry and very windy--just taking a couple of steps across the floor will build up enough static to give you a nasty jolt!