Can Doxycycline and Clindamycin be combined for the treatment of leg cellulitis non-responsive to Augmentin (Amoxicillin/Clavulanate) and Septrim (Co-trimoxazole)?

Combination of Doxycycline and Clindamycin for Non-Responsive Leg Cellulitis

Yes, doxycycline and clindamycin can be combined for the treatment of leg cellulitis that has not responded to Augmentin and Septrim, as this combination provides broad coverage against common pathogens including MRSA. 1

Rationale for Combination Therapy

When initial therapy with Augmentin (amoxicillin-clavulanate) and Septrim (co-trimoxazole) fails, this suggests either:

1. Resistant organisms (particularly MRSA)
2. Unusual pathogens not covered by initial therapy
3. Presence of anaerobic bacteria

The combination of doxycycline and clindamycin addresses these possibilities:

• Doxycycline: Effective against MRSA and many gram-positive and gram-negative organisms 2
• Clindamycin: Provides coverage against streptococci, staphylococci, and anaerobic bacteria 2, 3

Evidence-Based Approach

The Infectious Diseases Society of America (IDSA) guidelines support using combination therapy for non-responsive skin and soft tissue infections:

• For purulent skin infections (likely due to S. aureus), doxycycline is recommended 2
• For non-purulent infections, clindamycin is recommended 2
• For specific pathogens like Streptococcus, the combination of penicillin plus clindamycin is recommended 2

For cases that have failed first-line therapy, combination therapy with broader coverage is appropriate. The IDSA recommends combination therapy with amoxicillin-clavulanate and doxycycline for empiric treatment of moderate to severe infections 1.

Dosing Recommendations

• Doxycycline: 100 mg twice daily for 5-7 days 1
• Clindamycin: 300-450 mg three times daily for 5-7 days 1

Potential Concerns and Monitoring

1. Gastrointestinal side effects: Both antibiotics can cause diarrhea, with clindamycin carrying a higher risk of Clostridioides difficile infection 4

   • In one study, 22% of patients on clindamycin developed diarrhea compared to 9% on flucloxacillin alone 4

2. Resistance patterns: Consider local resistance patterns when selecting therapy

   • In areas with high MRSA prevalence, antibiotics with MRSA activity (like doxycycline and clindamycin) showed higher success rates than beta-lactams 5

3. Drug interactions: Monitor for potential interactions between these antibiotics and other medications

Follow-up and Reassessment

Patients should be reassessed within 48-72 hours to ensure clinical improvement 1. If no improvement is observed:

• Consider broadening antibiotic coverage
• Evaluate for possible abscess requiring drainage
• Consider underlying conditions affecting treatment response

Common Pitfalls to Avoid

1. Failing to consider local resistance patterns when selecting empiric therapy 1
2. Not providing adequate duration of therapy for deep-seated infections
3. Overlooking the possibility of an abscess requiring drainage in addition to antibiotics
4. Not considering doxycycline contraindications (pregnancy, children under 8 years) 1

This combination approach is supported by clinical evidence showing that antibiotics with activity against community-associated MRSA (such as doxycycline and clindamycin) are preferred empiric therapy for outpatients with cellulitis in settings where MRSA is prevalent 5, 3.