Augmentin Does NOT Work for MRSA Skin Infections
Augmentin (amoxicillin-clavulanate) is completely ineffective against MRSA skin infections because MRSA is resistant to all beta-lactam antibiotics, including Augmentin. 1
Why Augmentin Fails Against MRSA
MRSA resistance is conferred by the mecA gene encoding penicillin-binding protein 2a (PBP2a), which has significantly lower affinity for beta-lactams, allowing cell-wall biosynthesis to continue even in the presence of typically inhibitory concentrations of antibiotic. 1 This means Augmentin cannot bind to its target in MRSA, rendering it useless regardless of dose.
Correct Antibiotics for MRSA Skin Infections
For Outpatient Treatment (Oral Options)
The Infectious Diseases Society of America recommends the following oral antibiotics for MRSA skin infections: 1
- Clindamycin 300-450 mg three times daily (A-II evidence) - covers both MRSA and streptococci, but only use if local resistance <10% 1
- Trimethoprim-sulfamethoxazole (TMP-SMX) 1-2 double-strength tablets twice daily (A-II evidence) - must combine with a beta-lactam like amoxicillin if streptococcal coverage is also needed 1
- Doxycycline 100 mg twice daily (A-II evidence) - must combine with a beta-lactam for streptococcal coverage 1
- Linezolid 600 mg twice daily (A-II evidence) - covers both MRSA and streptococci but expensive 1
For Hospitalized Patients (IV Options)
For complicated MRSA skin infections requiring hospitalization: 1
- Vancomycin 15-20 mg/kg IV every 8-12 hours (A-I evidence) - first-line agent 1
- Linezolid 600 mg IV twice daily (A-I evidence) 1
- Daptomycin 4 mg/kg IV once daily (A-I evidence) 1
- Telavancin 10 mg/kg IV once daily (A-I evidence) 1
Treatment Duration
Treat for 5-10 days based on clinical response - 5 days if improvement occurs, extending only if symptoms persist. 1, 2 For complicated infections requiring hospitalization, 7-14 days is recommended. 1
Critical Caveat: When Augmentin IS Appropriate
Augmentin is only appropriate for bite-associated cellulitis (animal or human bites) at 875/125 mg twice daily, where it provides coverage for polymicrobial oral flora. 2, 3 However, this is NOT for MRSA - it's for the mixed bacteria from bite wounds.
The Bottom Line
If you suspect or confirm MRSA, immediately switch from Augmentin to one of the MRSA-active agents listed above. 1 Continuing Augmentin for MRSA is guaranteed treatment failure because the organism is mechanistically resistant to all beta-lactams. 1