When to prescribe bacitracin (topical antibiotic) versus mupirocin (topical antibiotic) for skin infections?

When to Prescribe Mupirocin vs Bacitracin

Mupirocin should be your first-line topical antibiotic for staphylococcal and streptococcal skin infections, while bacitracin should generally be avoided due to treatment failure rates and high sensitization risk. 1

Primary Recommendation: Choose Mupirocin

For impetigo and localized staphylococcal/streptococcal infections, prescribe mupirocin 2% ointment applied three times daily for 5 days. 2 This recommendation is based on:

• Superior efficacy: Mupirocin demonstrates significantly better outcomes than bacitracin-containing preparations in treating primary skin infections 3
• Lower resistance rates: Clinical resistance to mupirocin has remained low despite widespread use 1
• Better safety profile: Mupirocin causes fewer sensitization reactions compared to bacitracin 1

Clinical Scenarios for Mupirocin Use

Impetigo (Primary Indication)

• Apply mupirocin 2% ointment to affected areas three times daily for 5 days 2
• Appropriate for patients with limited number of lesions and localized infection 2
• Switch to oral antibiotics (cephalexin 25-50 mg/kg/day, dicloxacillin 25-50 mg/kg/day, or clindamycin 10-20 mg/kg/day for 7 days) if numerous lesions present, outbreak situation, or no response within 3-5 days 2

Other Primary Skin Infections

• Folliculitis, furunculosis, and other acute staphylococcal lesions respond well to mupirocin 1
• Mupirocin cream formulation shows similar or superior efficacy to oral flucloxacillin and significantly better outcomes than oral erythromycin 3

Secondary Infected Skin Lesions

• Mupirocin is effective for secondarily infected wounds, eczema, and other dermatoses 4
• Clinical cure or marked improvement achieved in 96.2% of patients in large trials 4

Why Bacitracin Should Be Avoided

Bacitracin has significant limitations that make it inferior to mupirocin:

• High sensitization risk: Topical bacitracin frequently produces allergic contact dermatitis 1
• Treatment failure: Clinical studies document higher failure rates with bacitracin 1
• Inferior efficacy: Mupirocin cream demonstrates superior bacterial reduction compared to neomycin-bacitracin combinations 3

Practical Algorithm

Step 1: Assess infection extent

• Limited lesions (≤5 sites) → Mupirocin topical 2
• Numerous lesions or outbreak → Oral antibiotics 2

Step 2: Apply mupirocin correctly

• 2% ointment formulation 5, 2
• Three times daily application 5, 2
• 5-day treatment duration for impetigo 2
• 7-day duration for other skin infections 5

Step 3: Reassess at 3-5 days

• No improvement → Switch to oral therapy 2
• MRSA suspected → Consider clindamycin (if local resistance <10%) or continue mupirocin for limited disease 2

Important Caveats

When Mupirocin May Not Be Appropriate

• Chronic or recurring dermatitis: Avoid prolonged topical antibiotic use due to resistance development risk 1
• Surgical wounds: Consider systemic therapy for deeper infections 1
• Extensive cellulitis: Requires systemic antibiotics; mupirocin is not indicated for diffuse spreading infections 5

Resistance Considerations

• While mupirocin resistance remains low, avoid using it for decolonization in outbreak settings as this may promote resistance 5
• For MRSA decolonization, intranasal mupirocin twice daily for 5 days combined with chlorhexidine or dilute bleach baths may be considered, though efficacy data are limited 5

Dosing Summary

Mupirocin (preferred):

• Adults and children: Apply to lesions 3 times daily 5
• Duration: 5 days for impetigo 2, 7 days for other infections 5

Bacitracin (not recommended):

• Should not be first-line due to sensitization and treatment failure 1