Why Intranasal Mupirocin for Foot Furunculosis?
Intranasal mupirocin is given to patients with foot furunculosis because the nose serves as a reservoir for Staphylococcus aureus colonization, which drives recurrent skin infections at distant body sites—decolonizing the nasal reservoir breaks the cycle of reinfection. 1, 2
The Rationale: Breaking the Colonization-Infection Cycle
The anterior nares harbor S. aureus in up to 40% of the general population, and this rate increases in patients with recurrent skin infections 3. When you have furunculosis on your foot, the causative bacteria often originate from nasal colonization—patients continuously auto-inoculate themselves through hand contact, leading to recurrent infections at any body site, including the feet 4, 5.
When to Use Nasal Decolonization
According to IDSA guidelines, decolonization with intranasal mupirocin should be considered when 2:
- A patient develops recurrent SSTI despite optimizing wound care and hygiene measures
- Ongoing transmission is occurring among household members despite standard hygiene
The recommended regimen is mupirocin twice daily for 5-10 days combined with topical body decolonization (chlorhexidine or dilute bleach baths) 2.
The Evidence Base
Guideline Recommendations
The 2014 IDSA guidelines acknowledge that older trials showed intranasal mupirocin (5 days monthly) reduced recurrent infections 1. However, they note uncertainty about effectiveness in the current MRSA era, citing one negative military trial 1. Despite this, the 2011 IDSA MRSA guidelines still recommend nasal decolonization as part of a comprehensive strategy for recurrent infections 2.
Clinical Evidence
A 2013 study demonstrated the "CMC regimen" (chlorhexidine skin disinfection, mupirocin nasal ointment, and clindamycin) achieved 87% remission beyond 9 months in patients with recurrent furunculosis 4. This combined approach addresses both the nasal reservoir and active infection simultaneously.
Critical Implementation Points
The decolonization strategy must include 2, 4:
- Nasal mupirocin (twice daily × 5-10 days)
- Topical body antisepsis with chlorhexidine or dilute bleach baths (¼ cup per ¼ tub, 15 minutes twice weekly × 3 months)
- Household contact screening and treatment if transmission is suspected
- Ongoing hygiene reinforcement (keep wounds covered, hand hygiene, clean high-touch surfaces)
Common Pitfalls to Avoid
- Don't use topical mupirocin ointment intranasally—the FDA label explicitly warns against this 6. A separate intranasal formulation exists specifically for nasal use
- Don't rely on mupirocin alone—monotherapy is less effective than combined decolonization strategies 1, 2
- Don't skip household contacts—one study showed treating patient plus household contacts resulted in significantly fewer recurrences than treating the patient alone 1
- Don't perform routine surveillance cultures after decolonization in the absence of active infection 2
The Bottom Line
While the foot is the site of active infection requiring incision and drainage, the nose is often the source perpetuating the problem. Treating only the foot addresses the symptom but not the cause. Nasal decolonization combined with body antisepsis and hygiene measures targets the reservoir, reducing recurrence risk and improving long-term outcomes 1, 2, 4.