Impetigo

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.