Does Doxycycline Cover MRSA?
Yes, doxycycline is effective against MRSA and is recommended as a first-line oral antibiotic option for community-acquired MRSA skin and soft tissue infections.
Guideline-Based Recommendations
The Infectious Diseases Society of America (IDSA) explicitly recommends doxycycline as empirical oral therapy for CA-MRSA skin infections, alongside TMP-SMX, clindamycin, and linezolid. 1 The American Academy of Pediatrics and IDSA further endorse doxycycline 100 mg PO BID as an effective alternative for MRSA skin infections, with documented clinical cure rates of 83-100%. 2
Clinical Effectiveness Evidence
Doxycycline demonstrates excellent in vitro activity against MRSA, with observational studies showing 100% susceptibility of MRSA isolates to doxycycline in community settings. 3
Clinical cure rates are high, with one case series of 24 patients with serious tetracycline-susceptible MRSA infections achieving 83% clinical cure when treated with doxycycline or minocycline. 4
Both drugs are well-tolerated with minimal adverse effects in clinical practice. 4
Important Caveats and Limitations
Streptococcal Coverage Gap
Doxycycline has poorly defined activity against β-hemolytic streptococci, which limits its use as monotherapy for nonpurulent cellulitis where streptococcal coverage is needed. 1, 2
For mixed infections or cellulitis without purulent drainage, consider clindamycin (if local resistance rates are low) or add beta-lactam coverage. 1
Bacteriostatic vs. Bactericidal Activity
Doxycycline is bacteriostatic rather than bactericidal against MRSA, showing no bactericidal activity in time-kill studies and demonstrating regrowth after 24 hours at MIC levels. 5
This makes doxycycline less suitable for serious invasive infections (bacteremia, endocarditis, osteomyelitis) where bactericidal activity is preferred. 5
Pediatric Restrictions
- Doxycycline is contraindicated in children under 8 years of age due to risk of permanent tooth discoloration. 6
Minocycline as Superior Alternative
Minocycline may be preferred over doxycycline for CA-MRSA infections, as it is "reliably effective" in situations where doxycycline or TMP-SMX fails. 7
Minocycline dosing is 200 mg initially, then 100 mg PO BID. 2
Practical Algorithm for Use
Use doxycycline for MRSA when:
- Purulent skin and soft tissue infection (abscess, furuncle, carbuncle) after incision and drainage 1, 2
- Patient is ≥8 years old 6
- No signs of systemic illness or invasive infection 1
- Local clindamycin resistance rates are high (making clindamycin less desirable) 2
Avoid doxycycline for MRSA when:
- Nonpurulent cellulitis requiring streptococcal coverage 1, 2
- Invasive infections requiring bactericidal therapy (bacteremia, endocarditis, osteomyelitis) 5
- Children <8 years of age 6
- Severe/extensive disease with systemic toxicity 1
Treatment Duration
- Standard duration is 5-10 days for uncomplicated MRSA skin infections, with extension to 7-14 days for more severe or complicated cases based on clinical response. 2