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SOURCE

Source: Fish DN. Skin and soft-tissue infections. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=146071658. Accessed March 23, 2017.

DEFINITION

  • Superficial skin infection.

ETIOLOGY

  • Staphylococcus aureus either alone or in combination with S. pyogenes has emerged as a principal cause of impetigo.

    • Bullous form caused by strains of S. aureus

    • As with other SSTIs, impetigo due to MRSA has increased.

PATHOPHYSIOLOGY

  • Minor trauma, such as scratches or insect bites, allows organisms to enter superficial layers of skin.

EPIDEMIOLOGY

  • Most common in children.

  • Highly communicable and spreads through close contact.

    • Hot, humid weather facilitates microbial colonization of skin.

PREVENTION

  • Improved hygiene, especially handwashing.

RISK FACTORS

  • Close contact at daycare centers and schools.

CLINICAL PRESENTATION

  • Exposed skin, especially the face is most common site of infection.

SIGNS AND SYMPTOMS

  • Systemic signs and symptoms are minimal.

  • Pruritus.

    • Scratching of lesions may further spread infection through excoriation of skin.

  • Nonbullous impetigo.

    • Manifests initially as small, fluid-filled vesicles.

    • Rapidly develop into pus-filled blisters that readily rupture.

    • Purulent discharge dries to form golden yellow crusts characteristic of impetigo.

  • Bullous impetigo.

    • Weakness, fever, and diarrhea may be seen.

    • Lesions begin as vesicles.

    • Lesions rapidly turn into bullae containing clear yellow fluid.

      • Bullae soon rupture, forming thin, light brown crusts.

DIAGNOSIS

MEANS OF CONFIRMATION AND DIAGNOSIS

  • Culture of lesions.

    • Crusted tops of lesions should be raised to obtain purulent material at the base for culture.

LABORATORY TESTS

  • Complete blood counts (CBC): leukocytosis common.

DIFFERENTIAL DIAGNOSIS

  • Chicken pox.

DESIRED OUTCOMES

  • Relief of symptoms and discomfort.

  • Improve cosmetic appearance of lesions.

  • Rapid eradication of infection.

  • Prevent further spread of infection.

  • Prevent formation of new lesions.

  • Prevent complications such as cellulitis.

  • Prevent recurrence.

TREATMENT: NONPHARMACOLOGIC THERAPY

  • Soaking lesions with warm, soapy water provide symptomatic relief and promotes removal of crusts on lesions.

TREATMENT: PHARMACOLOGIC THERAPY

  • Penicillinase-resistant penicillins (eg, dicloxacillin) are agents of first choice because of increased isolation of S. aureus (Tables 1 and 2).

  • First line therapy for mild impetigo not involving multiple lesions or the face: topical mupirocin or retapamulin ointment for 5 days.

  • Treat for 7 days.

TABLE 1.abRecommended Oral Drugs for Outpatient Treatment of Impetigo

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