What is the appropriate treatment for secondary impetigo arising from an eczematous fissure?

Treatment of Secondary Impetigo from Eczematous Fissures

For secondary impetigo arising from an eczematous fissure, treat the bacterial infection with topical mupirocin 2% ointment applied three times daily for 5-7 days while simultaneously managing the underlying eczema with topical corticosteroids and emollients. 1, 2

Dual Treatment Approach Required

This clinical scenario requires addressing both the bacterial superinfection and the underlying inflammatory dermatitis:

Antimicrobial Therapy for Impetiginization

For limited disease (localized to the fissure area):

• Apply mupirocin 2% ointment three times daily for 5-7 days as first-line treatment 1, 2
• Mupirocin is FDA-approved for impetigo caused by Staphylococcus aureus and Streptococcus pyogenes, the most common pathogens in secondary bacterial infections 2, 3
• Topical therapy achieves cure rates 6-fold higher than placebo for limited impetigo 4

Switch to oral antibiotics if:

• No improvement after 3-5 days of topical therapy 1
• Extensive disease beyond the localized fissure area 1
• Systemic symptoms present (fever, lymphangitis) 5
• Multiple scattered lesions develop 1

Oral antibiotic options when needed:

• Cephalexin 250-500 mg four times daily for 7 days (first-line for presumed MSSA) 1, 4
• Dicloxacillin 250 mg four times daily for 7 days (alternative for MSSA) 1, 4
• Clindamycin 300-450 mg three times daily for 7 days if MRSA suspected 1, 4
• Trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily for 7 days if MRSA suspected 1, 4

Management of the Underlying Eczematous Fissure

Simultaneously treat the inflammatory component:

• Apply topical corticosteroid (e.g., prednicarbate cream 0.02%) to the eczematous areas to reduce inflammation 5
• Use emollients liberally and frequently to restore the skin barrier 5
• Avoid alcohol-containing lotions; favor oil-in-water creams or ointments 5

Specific fissure management:

• Apply propylene glycol 50% in water for 30 minutes under plastic occlusion nightly, followed by hydrocolloid dressing 5
• Alternatively, use antiseptic baths (potassium permanganate 1:10,000) or topical silver nitrate solutions to accelerate wound closure 5
• Apply emollients to surrounding skin to prevent further fissuring 5

Critical Treatment Considerations

Do NOT use:

• Penicillin alone—it lacks adequate coverage against S. aureus 1, 4
• Topical clindamycin cream—it is FDA-approved only for acne, not impetigo, and has insufficient bioavailability for bacterial skin infections 1
• Bacitracin or neomycin—considerably less effective than mupirocin 1

Important pitfalls to avoid:

• Do not treat the infection without addressing the underlying eczema, as persistent inflammation and barrier dysfunction will predispose to recurrent impetiginization 5
• Topical steroids should only be used under appropriate supervision, as improper use can cause perioral dermatitis and skin atrophy 5
• Ensure 7-day duration for oral antibiotics (not the 5-day course used for topical agents) to prevent treatment failure 1, 4

Infection Control Measures

• Keep lesions covered with clean, dry bandages 1
• Maintain good hand hygiene with regular handwashing 1
• Avoid sharing personal items that contact the skin (towels, clothing) 1
• Exclude from work/school until 24 hours after starting effective antimicrobial therapy 4

When to Obtain Cultures

Consider bacterial culture with antibiotic susceptibility testing if: 5, 1

• Treatment failure after 3-5 days of appropriate therapy
• Recurrent infections
• MRSA suspected based on local epidemiology
• Immunocompromised patient

Special Populations

Penicillin-allergic patients:

• Use clindamycin as preferred alternative 1, 4
• Cephalosporins can be used unless type 1 hypersensitivity (anaphylaxis/hives) to β-lactams 4

Pregnant patients:

• Cephalexin is considered a safe alternative 1

Children under 8 years:

• Avoid tetracyclines (doxycycline) due to risk of permanent dental staining 1, 4