SKINIPEDIA - Skin Encyclopedia: Impetigo Contagiosa
Impetigo Contagiosa Article by Medical Authors: Alan Rockoff, MD, and John Mersch, MD, FAAP
Medical Editor: William C. Shiel Jr., MD, FACP, FACR
What is impetigo? What causes impetigo?
Impetigo (pronounced im-puh-TIE-go) is a contagious, superficial infection of the skin caused by staphylococcus (Staph) and streptococcus (Strep) bacteria. Impetigo is more common in children (especially 2- to 5-year-olds) than in adults. Impetigo is most likely to occur in warm and humid environments and is most commonly spread by close contact (such as family members).
What are the types of impetigo, and what are impetigo symptoms and signs?
What does impetigo look like?
There are two kinds of impetigo:
- Non-bullous impetigo: This is the common form, caused by both Staph and Strep bacteria. This form initially presents as small red papules similar to insect bites. These lesions rapidly evolve to small blisters and then to pustules that finally scab over with a characteristic honey-colored crust. This entire process takes about one week. These lesions often start around the nose and on the face, but less frequently they may also affect the arms and legs. At times, there may be swollen but non-tender lymph nodes (glands) nearby.
- Bullous impetigo: This form of impetigo is caused only by Staph bacteria. These bacteria produce a toxin that reduces cell-to-cell stickiness (adhesion) causing separation between the top skin layer (epidermis) and the lower layer (dermis). This leads to the formation of a blister. (The medical term for blister is bulla.) Bullae can appear in various skin areas, especially the buttocks and trunk. These blisters are fragile and contain a clear yellow-colored fluid. The bullae are delicate and often break and leave red, raw skin with a ragged edge. A dark crust will commonly develop during the final stages of development. With healing, this crust will resolve.
IMPETIGO TRANSMITION
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.
SOURCE: National Institute of Allergy and Infectious Diseases, National Institutes of Health
Is impetigo contagious?
Impetigo is contagious, mostly from direct contact with someone who has it but sometimes from towels, toys, clothing, or household items. After starting, impetigo often spreads to other parts of the body. This is particularly common with impetigo in children. There may be mini epidemics in day-care centers. Bacteria that cause impetigo may enter through a break in the skin, such as that which comes from cuts and scrapes. A common toddler impetigo experience is an infection at the nasal openings with prominent nasal drainage associated with a cold. The skin integrity is often disrupted by the continuous covering of purulent nasal discharge. Adults often develop impetigo from close contact with infected children. Heat, humidity, and the presence of eczema predispose a person to developing impetigo. Sometimes bacteria live in the nose and spread from there to other parts of the skin.
Impetigo (Impetigo Contagiosa) Article Part II