What is the recommended dosage and treatment duration of Mupirocin for bacterial skin infections, such as impetigo, and MRSA (Methicillin-resistant Staphylococcus aureus) nasal decolonization?

Mupirocin Dosing and Treatment Duration

For bacterial skin infections like impetigo, apply mupirocin 2% ointment three times daily for 5-10 days, and for MRSA nasal decolonization, apply twice daily to the anterior nares for 5-10 days. 1, 2

Bacterial Skin Infections (Impetigo and Other Superficial Infections)

Standard Dosing Regimen

• Apply a small amount of mupirocin 2% ointment to the affected area three times daily 1
• Treatment duration: 5-10 days 3
• The treated area may be covered with gauze dressing if desired 1
• Re-evaluate patients who show no clinical response within 3-5 days 1

Clinical Context and Efficacy

• Mupirocin demonstrates excellent activity against Staphylococcus aureus (including MRSA) and Streptococcus species, the primary pathogens in impetigo 3
• Clinical trials show over 90% bacterial eradication and at least 80% clinical cure or marked improvement in primary skin infections 4
• The Infectious Diseases Society of America specifically recommends mupirocin 2% ointment for impetigo in children and secondarily infected skin lesions such as infected eczema, ulcers, or lacerations 3

Important Limitations

• Mupirocin is NOT appropriate for extensive infections requiring systemic therapy 3
• For abscesses, furuncles, and carbuncles, incision and drainage is the primary treatment—mupirocin serves only as adjunctive therapy 3
• Systemic antibiotics are required when fever or extensive surrounding cellulitis is present 3

MRSA Nasal Decolonization

Standard Decolonization Protocol

• Apply mupirocin 2% ointment to each nostril twice daily for 5-10 days 2, 3
• The 10-dose regimen (twice daily for 5 days) is superior to shorter 6-dose regimens, maintaining decolonization for at least 4 weeks post-treatment 5

Enhanced Decolonization for Recurrent Infections

When simple nasal decolonization fails or for outbreak control, combine multiple interventions: 2, 3

• Intranasal mupirocin 2% twice daily for 5-10 days PLUS
• Daily chlorhexidine body washes for 5-14 days OR dilute bleach baths (1/4-1/2 cup per full bath)
• Consider twice-daily chlorhexidine mouthwash for oropharyngeal decontamination 3

Recurrent Infection Prevention

• For recurrent furunculosis, apply mupirocin to the anterior nares twice daily for the first 5 days of each month—this reduces recurrences by approximately 50% 3
• This monthly prophylactic regimen is based on older trials showing efficacy 2

Surgical Prophylaxis

• For cardiac surgery patients, start mupirocin 2% to each nostril combined with chlorhexidine mouthwash at least 48 hours before surgery, continuing for a total of 5-7 days to significantly reduce postoperative MRSA infections 3

Critical Clinical Pitfalls

When Mupirocin is Insufficient

Switch to systemic antibiotics when: 3

• Systemic signs present (fever, extensive cellulitis)
• Deeper infections or lack of response within 5 days
• Immunocompromised patients with significant infections
• Severe infections with SIRS (Systemic Inflammatory Response Syndrome)

Resistance Concerns

• Avoid prolonged or indiscriminate use to prevent resistance development 3, 6
• High-level mupirocin resistance (MIC >512 µg/mL) has been identified in S. aureus and is associated with treatment failure 3
• Resistance rates vary geographically and are increasing, particularly among MRSA isolates with widespread use 6

Evidence Limitations for Decolonization

• One randomized trial in military personnel showed that twice-daily nasal mupirocin for 5 days did NOT reduce subsequent skin infections in MRSA carriers 2
• The efficacy of older decolonization regimens in the current era of community-acquired MRSA remains unclear 2
• Despite mixed evidence, decolonization may still be considered when recurrent infections persist despite optimizing wound care and hygiene measures 2