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Introduction
Impetigo is the most common bacterial infection of the
skin. It is contagious and can happen at any age, but
is most common in young children.
Impetigo caused by the bacterium Staphylococcus aureus
affects children of all ages. Impetigo caused by the
bacteria called group A streptococci are most common
in children ages two to five.
Causes
The streptococcus bacteria exist on the skin and in
the throats of large numbers of people without any ill
effects. However, when the bacteria penetrate the
protective barrier of the skin, they can cause serious
disease. Streptococci make proteins called enzymes
that break down the skin and allow bacteria to spread.
They also produce toxins that cause the body to start
a protective response, leading to more inflammation.
Impetigo can complicate chicken pox, eczema, or other
skin conditions marked by open lesions.
Symptoms
Impetigo
usually occurs on the face, neck, arms, and limbs, but
the lesions may appear on any part of the body.
Impetigo starts as a small vesicle, or fluid-filled
lesion. The lesion then ruptures and the fluid drains
leaving areas that are covered with the honey-colored
crusts. The lesions may all look different, with
different sizes and shapes.
The common form of impetigo begins with a small
reddened, flat area of skin that rapidly forms either
a clear or pus-filled blister (vesicle or pustule).
These blisters are fragile and rupture easily,
releasing a fluid that dries into a golden crust. The
sores itch, and scratching them causes the infection
to spread to other areas. In the bullous form of the
disease, which is less common, the blisters are
larger, tense, and filled with a clear fluid.
Treatment
Generally, treatment consists of systemic
antibiotics (usually penicillin, or erythromycin for
patients who are allergic to penicillin), which also
help prevent glomerulonephritis (inflammation of the
kidney that can have serious complications).
Therapy also includes removal of the exudate by
washing the lesions two to three times a day with soap
and water, or for stubborn crusts, warm soaks or
compresses of normal saline or a diluted soap solution
before application of topical antibiotics.
Topical antibiotics are less effective than systemic
antibiotics. The patient is urged not to scratch since
this exacerbates the impetigo.
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