Impetigo is a contagious bacterial infection of the superficial skin that is caused by Streptococcus pyogenes (group A β-hemolytic Streptococcus) and S aureus. It most commonly affects children 2 to 5 years of age and usually involves the face and extremities. It begins as small vesicles or pustules with very thin roofs that rupture easily with the release of a cloudy fluid and subsequent formation of honey-colored crusts. Variants include bullous and the ulcerative forms. The lesions may spread rapidly by autoinoculation secondary to scratching and coalesce to form larger areas of infection. The differential diagnosis includes second-degree burns, varicella, herpes simplex infections, nummular dermatitis, superinfected eczema, and scabies.
Management and Disposition
These lesions are highly contagious and spread by direct contact. Hand washing and personal hygiene should be emphasized to the patient and family. Application of topical antibacterials, such as mupirocin ointment, has proven to be as effective as oral antibiotics if there are a limited number of lesions and no bullae. Over-the-counter triple antibiotic ointments (bacitracin-neomycin-polymyxin B) may not be as effective. If lesions are extensive and/or bullous, oral antibiotic coverage is indicated.
Inflicted cigarette burns may resemble the lesions of impetigo.
Poststreptococcal glomerulonephritis and rheumatic fever can be complications of impetigo caused by group A β-hemolytic Streptococcus.
Impetigo. Infant with perioral erosions oozing discharge forming honey-colored crusts. (Photo contributor: Lawrence B. Stack, MD.)
Impetigo. Chest wall and axillary erosions oozing discharge forming honey-colored crusts. (Photo contributor: Lawrence B. Stack, MD.)
Bullous Impetigo. A child with impetiginous lesions on the face. Note the formation of bullae. (Photo contributor Anne W. Lucky, MD.)
Bullous Impetigo. Bullae with honey-colored exudate in a neonate with fever. (Photo contributor: Lawrence B. Stack, MD.)