<p>Impetigo is a skin infection caused by bacteria. It is usually caused by <a href="https://medlineplus.gov/staphylococcalinfections.html">staphylococcal</a> (staph) bacteria, but it can also be caused by <a href="https://medlineplus.gov/streptococcalinfections.html">streptococcal</a> (strep) bacteria. It is most common in children between the ages of two and six. It usually starts when bacteria get into a break in the skin, such as a cut, scratch, or insect bite. </p> <p>Symptoms start with red or pimple-like sores surrounded by red skin. These sores can be anywhere, but usually they occur on your face, arms and legs. The sores fill with pus, then break open after a few days and form a thick crust. They are often itchy, but scratching them can spread the sores. </p> <p>Impetigo can spread by contact with sores or nasal discharge from an infected person. You can treat impetigo with antibiotics. </p>