Characteristics of Impetigo Rashes
Impetigo is characterized by two main types: nonbullous impetigo (70% of cases) with honey-colored crusted erosions, and bullous impetigo (30% of cases) with fragile, thin-roofed vesicopustules caused by toxin-producing strains of S. aureus. 1, 2
Nonbullous Impetigo (Impetigo Contagiosa)
- Caused by Staphylococcus aureus, Streptococcus pyogenes, or both in combination 1
- Begins as erythematous papules that rapidly evolve into vesicles and pustules 1
- Develops honey-colored crusts after pustules rupture, typically affecting the face and extremities 2
- May occur as primary infection through minor breaks in skin or secondary infection of existing dermatoses 3
- Most commonly affects children 2-5 years of age 2
Bullous Impetigo
- Caused exclusively by toxin-producing strains of S. aureus 1
- Characterized by fragile, thin-roofed vesicopustules that form when toxins cleave the dermal-epidermal junction 1
- Results in large, flaccid bullae that are more likely to affect intertriginous areas 2
- Represents the milder end of a spectrum that includes staphylococcal scalded skin syndrome 4
- Bacteria can be cultured from the blister contents 4
Ecthyma
- Deeper infection than impetigo, caused by S. aureus and/or streptococci 1
- Begins as vesicles that rupture, resulting in circular, erythematous ulcers with adherent crusts 1
- Penetrates through the epidermis into the dermis, unlike superficial impetigo 1
Clinical Course and Complications
- Both types usually resolve within 2-3 weeks without scarring 2
- Complications are rare, with the most serious being poststreptococcal glomerulonephritis 2
- Highly contagious, especially among children 3
Diagnostic Features
- Diagnosis is typically made clinically based on characteristic appearance 5
- Cultures of vesicle fluid, pus, erosions, or ulcers may be obtained to establish the cause, especially in cases of:
- Treatment failure
- Suspected MRSA
- Recurrent infections 1
Distribution Patterns
- Face and extremities are common sites for nonbullous impetigo 2
- Intertriginous areas are more commonly affected in bullous impetigo 2
- Can occur in specific locations such as scalp or nose with characteristic presentations 6, 7
Key Distinguishing Features
- Nonbullous: honey-colored crusts, primarily on exposed areas 2
- Bullous: fluid-filled vesicles and flaccid blisters 4
- Ecthyma: deeper ulcers with adherent crusts 1