Bullous impetigo rash on an infant's abdomen. Impetigo is a bacterial skin infection caused by Staphylococci or occasionally Streptococci. It is common among children & babies, beginning as a red patch, which develops into small pustules that join together, eventually forming crusty yellow blisters (bullae). Impetigo is especially contagious, spreading rapidly on contact & by shared towels & face cloths. It usually responds to treatment with topical antibiotics within seven to ten days. Impetigo of the newborn is rare today.