Impetigo is a common contagious bacterial infection of the skin. The causative organisms are either Staphylococcus aureus or, less commonly, Streptococcus pyogenes. The infection can occur at any age, but it is particularly common in children, especially the pre-school and early school age years, and tends to be more frequent during the summer months. It may arise on previously normal skin or complicate a pre-existing dermatosis. The diagnosis is essentially a clinical one, but if in doubt a swab should be taken for bacteriological culture.