Impetigo
Impetigo: Excerpt from Professional Guide to Diseases (Eighth Edition)
A contagious, superficial skin infection, impetigo occurs in nonbullous and bullous forms. This vesiculopustular eruptive disorder spreads most easily among infants, young children, and elderly people. Predisposing factors, such as poor hygiene, anemia, malnutrition, and a warm climate, favor outbreaks of this infection, most of which occur during the late summer and early fall. Impetigo can complicate chickenpox, eczema, or other skin conditions marked by open lesions.
Causes and incidence
Coagulase-positive Staphylococcus aureus and, less commonly, group A beta-hemolytic streptococci usually produce nonbullous impetigo; S. aureus (especially phage type 71) generally causes bullous impetigo.
In the United States, impetigo occurs most often in southern states. It often causes deeper dermal inflammation in blacks than in whites and may result in postinflammatory hypopigmentation or hyperpigmentation.
Signs and symptoms
Common nonbullous impetigo typically begins with a small red macule that turns into a vesicle or pustule. When the vesicle breaks, a thick yellow crust forms from the exudate. (See Recognizing impetigo.) Autoinoculation may cause satellite lesions. Although it can occur anywhere, impetigo usually occurs on the face, around the mouth and nose. Other features include pruritus, burning, and regional lymphadenopathy.
A rare but serious complication of streptococcal impetigo is glomerulonephritis, which is more likely to occur when many members of the same family have impetigo. Infants and young children may develop aural impetigo or otitis externa; the lesions usually clear without treatment in 2 to 3 weeks, unless an underlying disorder such as eczema is present. Scarlet fever also may occur.
In bullous impetigo, a thin-walled vesicle opens, and a thin, clear crust forms from the exudate. The lesion consists of a central clearing, circumscribed by an outer rim — much like a ringworm lesion — and commonly appears on the face or other exposed areas. Both forms usually produce painless itching; they may appear simultaneously and be clinically indistinguishable.
Ecthyma is a skin infection that resembles impetigo but extends into the dermis and takes longer to resolve. These lesions are painful and more common on distal extremities. (See Ecthyma, page 1234.)
Diagnosis
Culture and sensitivity testing of fluid or denuded skin may indicate the most appropriate antibiotic, but therapy shouldn’t be delayed for laboratory results, which can take 3 days. White blood cell count may be elevated in the presence of infection.
Treatment
Topical mupirocin is the treatment of choice if the lesions aren’t too extensive. It’s highly effective against group A beta-hemolytic streptococcus and Staphylococcus aureus, including methicillin-resistant S. aureus. Mupirocin also eliminates nasal carriers of these organisms. Extensive or nonresolving lesions require systemic antibiotics.
Therapy may also include removal of the exudate by washing the lesions two or three times a day with soap and water (or antibacterial soap) or, for stubborn crusts, warm soaks or compresses of normal saline or a diluted soap solution.
Special considerations
❑ Urge the patient not to scratch, because this spreads impetigo. Advise parents to cut their child’s fingernails and cover his hands with socks or mittens to prevent scratching.
❑ Give medications as ordered. Remember to check for medication allergy. Stress the need to continue prescribed medications for 7 to 10 days, even after lesions have healed.
❑ Teach the patient or his family how to care for impetiginous lesions. To prevent further spread of this highly contagious infection, encourage frequent bathing using a bactericidal soap. Tell the patient not to share towels, washcloths, or bed linens with family members. Emphasize the importance of following proper hand-washing technique.
❑ Check family members for impetigo. If this infection is present in a school-age child, notify his school.
Pictures
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
More About Impetigo
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Medical Books Excerpts
- Impetigo
- "Professional Guide to Diseases (Eighth Edition)" (2005)
- [ read ]
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
» Next page: Streptococcal infections (Handbook of Diseases)
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