Impetigo is an infection of the top layers of the skin and is most common among children ages 2 to 6 years. It usually starts when bacteria get into a cut, scratch, or insect bite.
Impetigo is usually caused by staphylococcus (staph) bacteria, but it also can be caused by group A streptococcus bacteria. Skin infections are usually caused by different types (strains) of strep bacteria than those that cause strep throat. Therefore, the types of strep germs that cause impetigo are usually different from those that cause strep throat.
The infection is spread by direct contact with lesions (wounds or sores) or nasal discharge from an infected person. Scratching may spread the lesions. It usually takes 1 to 3 days from the time of infection until you show symptoms. If your skin doesn't have breaks in it, you can't be infected by dried strep bacteria in the air.
Symptoms start with red or pimple-like lesions surrounded by reddened skin. These sores can be anywhere on your body, but mostly on your face, arms, and legs. The sores fill with pus, then break open after a few days and form a thick crust. Itching is common.
Your healthcare provider can diagnose the infection by looking at the skin lesions.
If your impetigo is caused by strep bacteria, your healthcare provider will prescribe oral antibiotics, as with strep throat. This treatment may also include an antibiotic ointment to be used on your skin.