Skin Disorders Guide

What is this condition?

Impetigo is a contagious, superficial skin infection marked by patches of tiny blisters that erupt, exposing the skin beneath. It can occur almost anywhere but usually appears in the area around the nose and mouth.

This disorder, which usually occurs in the late summer or early fall, spreads most easily among infants, young children, and the elderly. Certain risk factors - such as poor hygiene, anemia, malnutrition, and a warm climate - may increase the likelihood of an outbreak of this infection. Impetigo can complicate chickenpox, eczema, or other skin conditions marked by open lesions.

What causes Impetigo?

Impetigo is caused by bacterial infection. Types of bacteria that produce this disorder include Staphylococcus aureus and, less commonly, group A beta-hemolytic streptococci.

What are its symptoms?

Common nonbullous impetigo typically begins with a small red macule that turns into a pus-filled vesicle. When the vesicle breaks, a thick yellow crust forms from the discharge. Smaller lesions may appear around the original lesion. Other features include itching, burning, and swollen lymph nodes in the affected region.

A rare but serious complication of streptococcal impetigo is a kidney infection called glomerulonephritis. Infants and young children may develop impetigo in the ear or an external ear infection; the lesions usually clear without treatment in 2 to 3 weeks, unless an underlying disorder such as eczema is present.

In bullous impetigo, a thin-walled vesicle opens, and a thin, clear crust forms from the discharge. The lesion consists of a central clearing surrounded by an outer rim. It commonly appears on the face or other exposed areas.

Both forms usually produce painless itching; they may appear simultaneouslyand be clinically indistinguishable.

How is it diagnosed?

When diagnosing impetigo, the doctor looks for characteristic lesions. In the lab, microscopic examination of the causative organism usually confirms bacterial infection and justifies antibiotic therapy. Culture and sensitivity testing of fluid or denuded skin may indicate the most appropriate antibiotic. Lab studies may also reveal that the person’s white blood cell count is elevated.

How is it treated?

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Generally, the doctor will prescribe systemic antibiotics (usually penicillin, a cephalosporin, or E-Mycin) for 10 days. A topical antibiotic such as Bactroban ointment may be used for minor infections. Therapy also includes removal of the discharge by washing the lesions two or three times a day with soap and water or, for stubborn crusts, warm soaks or compresses of a salt water or diluted soap solution.