Impetigo is a skin disorder caused by bacterial infection and characterized by crusting skin lesions.

Impetigo is a common skin infection. It is most common in children, particularly children in unhealthy living conditions. In adults, it may follow other skin disorders. Impetigo may follow a recent upper respiratory infection such as a cold or other viral infection. It is similar to cellulitis, but is more superficial, involving infection of the top layers of the skin with streptococcus (strep), staphylococcus (staph), or both.

The skin normally has many types of bacteria on it, but intact skin is an effective barrier that keeps bacteria from entering and growing within the body. When there is a break in the skin, bacteria can enter the body and grow there, causing inflammation and infection. Breaks in the skin may occur with insect bites, animal bites, or human bites, or other injury or trauma to the skin. Impetigo may occur on skin where there is no visible break.

Impetigo begins as an itchy, red sore that blisters, oozes and finally becomes covered with a tightly adherent crust. It tends to grow and spread. Impetigo is contagious. The infection is carried in the fluid that oozes from the blisters. Rarely, impetigo may form deeper skin ulcers.

• Skin lesion on the face or lips, or on the arms or legs, spreading to other areas. Typically this lesion begins as a cluster of tiny blisters which burst, followed by oozing and the formation of a thick honey- or brown-colored crust that is firmly stuck to the skin.
• Itching blister:
  • Filled with yellow or honey-colored fluid
  • Oozing and crusting over
• Rash (may begin as a single spot, but if person scratches it, it may spread to other areas).
• In infants, a single or possibly multiple blisters filled with pus, easy to pop and -- when broken -- leave a reddish raw-looking base.
• Lymphadenopathy -- local lymph nodes near the infection may be swollen.

Diagnosis is based primarily on the appearance of the skin lesion. A culture of the skin or mucosal lesion usually grows streptococcus or staphylococcus.