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What is Impetigo?

Impetigo is a common type of skin infection. Picking at sores or scratching itchy bites may allow the bacteria which cause impetigo to enter the skin.

  • Bacteria may enter through a break in the skin. Typically the break in the skin is obvious (such as a skinned knee or a cut or even an insect bite), but even very small, microscopic breaks may allow for bacteria to enter.
  • Once the bacteria get into the inner layers of the skin, they grow and multiply, creating a blister. Usually, this blister becomes filled with pus and then bursts, leaving a crust. It is this blistering and crusting which is typical of impetigo.
  • There are two common forms of impetigo, referred to as bullous and nonbullous.
    • Bullous impetigo is less common and is only caused by staphylococci. Typically this form results in the formation of larger blisters.
    • Nonbullous impetigo is most common and is generally caused by a mild traumatic break in the skin and can be caused by two types of bacteria, streptococci or staphylococci. It results in the formation of smaller blisters.

Impetigo Causes

As mentioned above, two main types of bacteria cause impetigo: Streptococcus and Staphylococcus organisms. Both are commonly found in the environment and on the surface of many people's skin. Group A Streptococcus is the most common cause of impetigo. This is the same organism that causes strep throat and can be spread directly from person to person or through contact with contaminated objects.

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Read What Your Physician is Reading on Medscape

Impetigo »

Impetigo is a highly contagious gram-positive bacterial infection of the superficial layers of the epidermis.

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