Impetigo is a staph infection of the skin. We have staph that lives on top of our skin normally and is kept under control by our immune systems. If the skin has an unusually high amount of staph (from being dirty, usually) it can enter in places where the top layers of skin have been compromised, like a scratch or pimple for example. Keep the infected area clean and DRY. Do NOT pick scabs or scratch at it because it will spread like wildfire. A very inexpensive ointment or cream called Bactroban (mupirocin is generic name) that is to be applied three times a day for 1-2 weeks is standard treatment.