What is the recommended dose of doxycycline (DOXY) for the treatment of Methicillin-resistant Staphylococcus aureus (MRSA)?

Doxycycline Dosing for MRSA Infections

For treatment of MRSA infections, doxycycline should be administered at a dose of 100 mg twice daily orally for adults. 1

Adult Dosing

• Doxycycline 100 mg orally twice daily for MRSA skin and soft tissue infections (SSTIs) 1
• For purulent cellulitis caused by MRSA, doxycycline 100 mg orally twice daily is recommended 1
• Duration of therapy is typically 7-10 days but should be adjusted based on clinical response 1
• For complicated MRSA infections requiring intravenous therapy, doxycycline can be administered at 100 mg every 12 hours intravenously 1

Pediatric Considerations

• Doxycycline is not recommended for children under 8 years of age due to risk of dental staining 1
• For children ≥8 years: 2 mg/kg/dose orally every 12 hours (not to exceed adult dose) 1
• For children >45 kg: use adult dosing of 100 mg twice daily 1

Clinical Efficacy

• Doxycycline is considered bacteriostatic against MRSA 1
• It is an effective alternative to trimethoprim-sulfamethoxazole (TMP-SMX) for outpatient treatment of MRSA SSTIs 1, 2
• In areas where tetracycline resistance is low, doxycycline has shown good clinical outcomes for community-acquired MRSA infections 2

Important Considerations

• Always check local susceptibility patterns before prescribing doxycycline for MRSA 2
• Tetracycline susceptibility testing can predict doxycycline susceptibility 2
• Doxycycline may be preferred over TMP-SMX in some cases due to better tolerability 3
• Resistance can emerge during therapy, particularly with monotherapy 4

Alternative Options for MRSA

• Clindamycin 300-450 mg orally three times daily (if susceptible) 1
• TMP-SMX 1-2 double-strength tablets twice daily 1
• Linezolid 600 mg orally twice daily (more expensive option) 1
• Minocycline 200 mg initially, then 100 mg orally twice daily (alternative tetracycline) 1, 3

Treatment Failures

• If treatment failure occurs with doxycycline, consider:
  • Performing incision and drainage if abscess is present 1
  • Checking for antimicrobial susceptibility 2
  • Switching to an alternative agent like linezolid or vancomycin for severe infections 1
  • Adding rifampin in select cases of persistent infection 5

Doxycycline remains a valuable oral option for MRSA infections, particularly for outpatient management of skin and soft tissue infections when the organism is susceptible.