Impetigo is a highly contagious superficial bacterial skin infection, most commonly affecting children. Nonbullous impetigo presents with honey-colored crusts on an erythematous base, typically caused by Staphylococcus aureus and/or Streptococcus pyogenes. Bullous impetigo, due to toxin-producing S. aureus, shows fragile flaccid bullae and collarettes of scale. Diagnosis is clinical; cultures are recommended in outbreaks, treatment failures, or suspected MRSA. Management includes gentle debridement, topical antibiotics for limited disease, and systemic antibiotics for extensive disease, bullous forms, or when topical therapy is impractical. Hygiene and decolonization strategies reduce recurrence.
Epidemiology and Risk Factors
- Peak in ages 2–5 years; outbreaks in schools/daycare; higher incidence in warm, humid climates.
- Risk factors: minor trauma/insect bites, atopic dermatitis, scabies, contact sports, poor hygiene, overcrowding.
Clinical Features
- Nonbullous: vesicles/pustules rupture to form honey-colored crusts; face (perinasal/perioral), extremities; mild pruritus.
- Bullous: larger fragile bullae (intertriginous areas, trunk) from exfoliative toxins; no systemic toxicity in most; neonates/infants commonly affected.
- Ecthyma: ulcerative form penetrating into dermis with “punched-out” ulcers and thick crusts (often on legs) in neglected or immunocompromised cases.
Differential Diagnosis
- Herpes simplex, allergic contact dermatitis with impetiginization, eczema herpeticum, varicella, scabies with secondary infection, insect-bite reactions.
Diagnosis
- Clinical. Obtain bacterial culture when:
- Recurrent/clustered cases, treatment failure, severe infection, concern for MRSA, or outbreaks.
- Consider swabbing nares for S. aureus carriage in recurrent disease.
Management
- Local care
- Gently remove crusts with warm soaks; cleanse with mild soap.
- Avoid picking; keep nails short; cover lesions when feasible.
- Topical therapy (limited nonbullous impetigo)
- Mupirocin 2% ointment or retapamulin 1% ointment twice daily for 5 days.
- Ozenoxacin 1% cream (where available) for 5 days.
- Avoid neomycin/bacitracin combinations due to allergy risk and lower efficacy.
- Systemic therapy (extensive lesions, bullous impetigo, ecthyma, outbreaks, or when topical impractical)
- First-line (MSSA and streptococci): cephalexin, dicloxacillin, amoxicillin-clavulanate.
- Suspected/confirmed MRSA: doxycycline (≥8 years), clindamycin, or TMP-SMX (add beta-hemolytic streptococcal coverage if needed).
- Duration: typically 5–7 days; ecthyma may require 7–10 days.
- Decolonization (recurrent S. aureus)
- Intranasal mupirocin twice daily for 5–10 days plus antiseptic body washes (chlorhexidine or dilute bleach baths) for patient and sometimes household members.
- Address coexistent tinea pedis, scabies, or eczema to prevent recurrence.
- Public health and return-to-activity
- Exclude from school/daycare until 24 hours after starting effective antibiotics and lesions are covered.
- Emphasize hand hygiene; avoid sharing towels, clothing, sports equipment.
Complications
- Post-streptococcal glomerulonephritis (PSGN) can follow streptococcal impetigo; antibiotics do not clearly prevent PSGN but are indicated to reduce spread and speed healing.
- Cellulitis, lymphangitis, and, rarely, invasive infections.
References (recent guidelines and key reviews)
- Pediatric impetigo treatment guidelines and MRSA considerations, 2021–2024.
- Trials comparing topical vs oral therapy and ozenoxacin/retapamulin efficacy, 2021–2024.
- Decolonization strategies for recurrent S. aureus, 2022–2024.