What causes impetigo?
Impetigo can be caused by the Staphylococcus aureus (staph) or group A Streptococci (strep) bacteria. Bullous impetigo is usually caused by the staph bacteria and can occur at any age, while impetigo caused by strep is more likely to appear between the ages of two and five. Impetigo is extremely contagious. It can be spread by direct contact with the infected skin
or through contact with an item used by the infected person. Epidemic impetigo spreads quickly among children and is aided by poor hygiene, overcrowded living conditions, and heat. Staph and strep bacteria can get through the skin’s natural defenses if the skin is broken, such as by a cut, bite, or chickenpox sores.
Epidemic impetigo can be caused by staph or strep bacteria, and (as the name implies) is very easily passed between children. Certain factors, such as heat and humidity, crowded conditions, and poor hygiene increase the chance that this type of impetigo will spread rapidly among large groups of children. This type of impetigo involves the formation of a small vesicle surrounded by a circle of reddened skin. The vesicles appear first on the face and legs. When a child has several of these vesicles close together, they may spread to each other. The skin surface may become eaten away (ulcerated), leaving irritated pits. When there are many of these deep, pitting ulcers, with pus in the center and brownish-black scabs, the condition is called ecthyma. If left untreated, the type of bacteria causing this type of impetigo has the potential to cause a serious kidney disease, called glomerulonephritis. Even when impetigo is initially caused by strep bacteria, the vesicles are frequently secondarily infected with staph bacteria.