What Causes Impetigo

Impetigo is a skin infection caused by one or both of the following bacteria: group A Streptococcus and Staphylococcus aureus. This page focuses on impetigo caused by group A Streptococcus (group A strep). In addition to impetigo, group A strep cause many other types of infections.

What is the most common cause of impetigo?

It’s usually caused by one of two bacteria: Staphylococcus aureus or Streptococcus pyogenes (also called group A streptococcus, which also causes strep throat). Methicillin-resistant Staphylococcus aureus (MRSA) is also becoming an important cause of impetigo.

Why do adults get impetigo?

Impetigo is an infection caused by strains of staph or strep bacteria. These bacteria can get into your body through a break in the skin from a cut, scratch, insect bite, or rash. Then they can invade and colonize.