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Impetigo

Impetigo1

Impetigo2


General Information

There are two forms of the disease. Bullous Impetigo: This form is caused by staph bacteria, which produce a toxin that causes a break between the epidermis and the lower levels of skin (“Bulla” means blister). Blisters can appear in various skin areas, especially the buttocks, though these blisters are fragile and often break while leaving red, raw skin with a ragged edge. Both non-bullous and bullous impetigo are caused by bacterial infections and are contagious from direct contact with someone who has it, day-to-day items including toys and household articles can hold the infection. At times, however, impetigo appears even if no one nearby has it and the skin seems unbroken. It is important to be aware that not all blisters or ooze from blisters means infection. At times, other infected and noninfected skin diseases produce blister-like skin inflammation with conditions including herpes cold sores, chickenpox, poison ivy, eczema, and insect bites. Mild cases can be handled by gentle cleansing, removing crusts, and applying the prescription-strength antibiotic ointment mupirocin (Bactroban). More severe or widespread cases, especially of bullous impetigo, may require oral antibiotic medication for impetigo. Non-bullous Impetigo: This is the common form caused by both staph and strep appearing as small blisters or scabs that form yellow or honey-colored crusts. Often starting around the nose and on the face.

Epidemiology
Common; Accounting for 10% of skin diseases treated in pediatric clinics

Etiology
Bacterial infection

Pathogenesis
Bullous impetigo – rapid onset of blisters that enlarge and rupture. Nonbullous – Single erythematous macule that rapidly evolves into a vesicle or pustule, ruptures leaving a crusted yellow exudates over erosion.

Clinical
One or all of these characteristics: blisterlike rash, reddish, “honey colored crust.

Histology
Bullous Impetigo – few or no inflammatory cells. A polymorphous infiltrate in the upper dermis, acantholysis noted in the granular layer. Non-bullous Impetigo – Vesicopustules present in the upper epidermis, usually within the stratum corneum. Neutrophils common within the vesicopustule. Gram-positive cocci are seen, epidermal spongiosis and a severe dermal infiltrate of neutrophils and lymphoid cells seen.

Bibliography
1. “Impetigo” (Online). October 2006. http://www.mayoclinic.com/health/impetigo/DS00464 (visited: March 20, 2008) 2. “Impetigo” (Online). January 2007. http://www.emedicine.com/derm/TOPIC195.HTM (visited: March 20, 2008)

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