What is the management for a patient with recurrent toe infections who responds to doxycycline (Doxycycline) but then recurs, with a history of Methicillin-resistant Staphylococcus aureus (MRSA) but no current growth on wound culture?

Management of Recurrent Toe Infection with MRSA History

For this patient with recurrent toe infection and MRSA history, implement a comprehensive decolonization protocol combining nasal mupirocin with topical chlorhexidine body washes (or dilute bleach baths), while addressing underlying predisposing factors such as tinea pedis, trauma, or venous insufficiency. 1

Immediate Assessment Priorities

Evaluate for underlying osteomyelitis, as any chronic toe ulcer that fails to heal after 6 weeks of appropriate care should raise suspicion for bone involvement, particularly if bone is visible or palpable with a sterile probe. 1 This is critical because osteomyelitis acts as a focus for recurrent infection and requires prolonged therapy (4-6 weeks minimum). 1

Assess for predisposing local factors including:

• Tinea pedis or other toe web abnormalities (most common modifiable risk factor) 1
• Lymphedema or venous insufficiency 1
• Prior trauma or surgery to the area 1
• Obesity, diabetes, or immunosuppressive conditions 2

Why Doxycycline Alone Is Insufficient

While doxycycline has activity against MRSA, the recurrence pattern suggests either persistent colonization or inadequate source control rather than antibiotic failure. 1 The IDSA guidelines note that for recurrent MRSA skin infections, antibiotic therapy alone without addressing colonization and predisposing factors has limited long-term efficacy. 1

Recommended Decolonization Strategy

Implement a multi-component decolonization regimen (this is where the evidence is strongest for preventing recurrence):

• Nasal mupirocin 2% ointment applied twice daily for 5-10 days 1
• PLUS topical body decolonization with either:
  • Chlorhexidine gluconate solution daily for 5-14 days 1, OR
  • Dilute bleach baths (¼ cup per ¼ tub of water) for 15 minutes twice weekly for 3 months 1

Evidence supporting systemic antibiotics during decolonization: A randomized trial showed that adding oral rifampin and doxycycline to standard topical decolonization (chlorhexidine + mupirocin) achieved significantly higher initial MRSA clearance (79% vs 52%, p=0.01), though long-term sustained clearance was similar. 3, 4 Given this patient's recurrent pattern, consider adding rifampin 300mg twice daily plus doxycycline 100mg twice daily for 7 days to the topical regimen. 4

Critical Pitfall to Avoid

Do not treat based on culture results alone if there are no clinical signs of active infection. 5 The negative recent culture does not exclude MRSA colonization (which occurs in nares, perineum, and skin folds, not just the wound). 1, 4 The history of MRSA is the most reliable predictor for MRSA involvement in recurrent infections. 1

Address Predisposing Factors Aggressively

Treatment of tinea pedis is essential - this is one of the most common and modifiable risk factors for recurrent lower extremity cellulitis and toe infections. 1 Prescribe topical antifungal therapy and ensure compliance.

Optimize wound care and off-loading:

• Keep any draining wounds covered with clean, dry bandages 1
• Ensure proper foot hygiene with daily washing 1
• Address any mechanical trauma or pressure points 1

Environmental and Hygiene Measures

Implement household decontamination (often overlooked but evidence-based):

• Clean high-touch surfaces (counters, doorknobs, bathtubs, toilet seats) with commercial cleaners 1
• Avoid sharing personal items (razors, towels, linens) 1
• Wash hands with soap and water or alcohol-based sanitizer after touching infected areas 1

Evaluate household contacts for MRSA infection or colonization, as ongoing transmission may explain recurrences. 1 Symptomatic contacts should be treated; asymptomatic contacts may benefit from decolonization if transmission is suspected. 1

Antimicrobial Prophylaxis Consideration

If recurrences continue despite decolonization and addressing predisposing factors, consider long-term antimicrobial prophylaxis. Two randomized trials demonstrated that twice-daily oral penicillin or erythromycin substantially reduced recurrence rates in patients with recurrent cellulitis. 1 However, for MRSA-associated recurrences, prophylactic options include doxycycline, trimethoprim-sulfamethoxazole, or clindamycin (if local resistance rates are low). 1

When to Obtain Repeat Cultures

Screening cultures prior to decolonization are not routinely recommended if at least one prior infection was documented as MRSA. 1 However, obtain wound cultures if the infection recurs during or after decolonization to assess for:

• Emergence of mupirocin resistance (occurs in ~5% of cases) 4
• Alternative pathogens (Pseudomonas, Gram-negatives, polymicrobial infection) 1
• Need for targeted antibiotic adjustment 1

Monitoring and Follow-up

Reassess at 48-72 hours for clinical improvement (reduced erythema, decreased drainage, defervescence). 5 If no improvement occurs, consider imaging (MRI preferred) to exclude osteomyelitis, which would require 4-6 weeks of therapy. 1

The key to success is combining decolonization with aggressive management of predisposing factors - neither approach alone is sufficient for preventing recurrences in MRSA carriers. 1, 2