Impetigo refers to a very localized bacterial infection of the skin. It tends to afflict primarily children. Impetigo caused by the bacteria Staphylococcus aureus (or staph) affects children of all ages, while impetigo caused by the bacteria called group A. streptococci (or strep) are most common in children ages two to five.

The bacteria that cause impetigo are very contagious. They can be spread by scratching, or contact with a towel, clothing, or stuffed animal.

Impetigo tends to develop in areas of the skin that have already been damaged through some other mechanism (a cut, scrape, burn, insect bite, or pock from chicken pox).

There are two types of impetigo, bullous and epidemic. The first sign of bullous impetigo is a large bump on the skin, with a clear, fluid-filled top (called a vesicle). The bump develops a scab-like, honey-colored crust. There is usually no redness or pain...