DEAR DOCTOR K: My son developed a large, red, swollen area on his arm. The doctor called it cellulitis. My son is better now, but I'd like to learn more about cellulitis and what can be done to prevent it.
DEAR READER: Cellulitis is a serious bacterial infection of the skin. Bacteria live on the surface of our skin, but the skin is built to keep the bacteria from getting inside us. If they get beneath the surface of the skin, and then into the tissues below the skin, they can make trouble. When our skin gets injured, bacteria can break through the skin's protective outer layer.