There are many types of "Impetigo." The most common is called "erythema chronicum migrans," or "chronic erythema migrans." This is a skin infection caused by the bacterium Staphylococcus aureus. It is most commonly seen in people who are exposed to the bacteria, such as those who work in hospitals or who are in close contact with people who have the infection. "Impetigo contagiosum" is a milder form of the infection that is caused by the bacterium Streptococcus pyogenes. "Impetigo simplex" is a less common form of the infection that is caused by the bacterium Corynebacterium diphtheriae.