Skin Problems & Treatments Health Center

Understanding Impetigo -- the Basics

What Is Impetigo?

Impetigo is a highly contagious bacterial skin infection. It can appear anywhere on the body but usually attacks exposed areas. Children tend to get it on the face, especially around the nose and mouth, and sometimes on the arms or legs. The infected areas appear in plaques ranging from dime to quarter size, starting as tiny blisters that break and expose moist, red skin. After a few days, the infected area is covered with a grainy, golden crust that gradually spreads at the edges.

In extreme cases, the infection invades a deeper layer of skin and develops into ecthyma, a deeper form of the disease. Ecthyma forms small, pus-filled bumps with a crust much darker and thicker than that of ordinary impetigo. Ecthyma can be very itchy, and scratching the irritated area spreads the infection quickly. Left untreated, the sores may cause permanent scars and pigment changes.

The gravest potential complication of impetigo is post-streptococcal glomerulonephritis, a severe kidney disease that occurs following a strep infection in less than 1% of cases, mainly in children. The most common cause of impetigo is Staphylococcus aureus. However, another bacteria source is group A streptococcus. These bacteria lurk everywhere. It is easier for a child with an open wound or fresh scratch to contract impetigo. Other skin-related problems, such as eczema, body lice, insect bites, fungal infections, and various other forms of dermatitis can make a person susceptible to impetigo.

Most people get this highly infectious disease through physical contact with someone who has it or from sharing the same clothes, bedding, towels, or other objects. The very nature of childhood, which includes lots of physical contact and large-group activities, makes children the primary victims and carriers of impetigo.