impetigo, contagious skin infection affecting mainly infants and children. The causative organisms are either hemolytic streptococci or staphylococci. The eruption consists of small red spots or blisters that rupture, discharge, and become encrusted. The infection is easily spread over the skin by fingernails because of its symptomatic itching; it can also be spread by contaminated linen, clothing, or other objects. Effective treatment with antibiotic ointments usually relieves the infection within 10 days. Systemic treatment with antibiotics is sometimes necessary to prevent the nephritis that occasionally develops.

Bacterial inflammatory skin disease, the most common skin infection in children. Initial blisters rupture, drying to a crust. Caused by staphylococcus or streptococcus, it is very contagious in newborns, becoming less so with age. Poor hygiene, crowding, and humid, hot weather may promote its spread. A broad-spectrum antibiotic applied to the blisters can treat simple impetigo; more extensive cases, especially in infants, may require a systemic antibiotic.

Learn more about impetigo with a free trial on Britannica.com.