Impetigo is caused by streptococcus (strep) or staphylococcus (staph) bacteria. Methicillin-resistant staph aureus (MRSA) is becoming a common cause.
The skin normally has many types of bacteria on it. When there is a break in the skin, bacteria can enter the body and grow there. This causes inflammation and infection. Breaks in the skin may occur with:
Injury or trauma to the skin
Impetigo may also occur on skin where there is no visible break.
It is most common in children who live in unhealthy conditions.
In adults, it may occur following another skin problem. It may also develop after a cold or other virus.
Impetigo can spread to others. You can catch the infection if the fluid that oozes from the blisters touches an open area on your skin.
Symptoms of impetigo are:
One or many blisters filled with pus that are easy to pop. In infants, the skin is reddish or raw-looking where a blister has broken.
Blisters that itch:
Filled with yellow or honey-colored fluid
Oozing and crusting over
Rash that may begin as a single spot, but spreads to other areas with scratching
Skin sores on the face, lips, arms, or legs, that spread to other areas
Swollen lymph nodes near the infection
Exams and Tests
Your health care provider will look at your skin to determine if you have impetigo.
The health care provider may take a sample of bacteria from your skin to grow in the lab.This can help determine if MRSA is the cause. Specific antibiotics are needed to treat this type of bacteria.
The goal is to cure the infection and relieve the symptoms.
Your doctor will prescribe an antibacterial cream. You may need to take antibiotics by mouth if the infection is severe.
Wash (do not scrub) the skin several times a day with an antibacterial soap to remove crusts and drainage.
The sores of impetigo heal slowly. Scars are rare. The cure rate is very high, but the problem often comes back in young children.
Pasternack MS, Swartz MN. Cellulitis, necrotizing fasciitis, and subcutaneous tissue infections. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 90.
Morelli JG. Cutaneous Bacterial Infections. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 657.
Kevin Berman, MD, PhD, Atlanta Center for Dermatologic Disease, Atlanta, GA. Review provided by VeriMed Healthcare Network. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.