What is the recommended treatment and dosage of Linezolid (oxazolidinone antibiotic) for complicated skin and skin structure infections, including those caused by Methicillin-resistant Staphylococcus aureus (MRSA)?

Linezolid Treatment for Complicated Skin and Skin Structure Infections

The recommended dosage of linezolid for complicated skin and skin structure infections (cSSSIs) caused by MRSA is 600 mg administered intravenously or orally every 12 hours for 10-14 days. 1, 2

Dosage and Administration

• Adults and adolescents (≥12 years): 600 mg IV or oral every 12 hours for 10-14 days 1, 2
• Children (<12 years):
  • Birth through 11 years: 10 mg/kg IV or oral every 8 hours 2
  • Children 5-11 years: 10 mg/kg oral every 12 hours for uncomplicated infections 2
  • Children <5 years: 10 mg/kg oral every 8 hours for uncomplicated infections 2

Efficacy for MRSA Skin Infections

Linezolid demonstrates superior efficacy compared to vancomycin for MRSA skin and soft tissue infections:

• Higher clinical cure rates for MRSA cSSSIs (88.6% for linezolid vs. 66.9% for vancomycin) 3
• Better treatment success for MRSA skin/soft tissue infections (OR 1.40; 95% CI 1.01-1.95) 1
• Superior microbiological success rates at end of treatment 4
• The Infectious Diseases Society of America recommends linezolid for skin and skin structure infections, including MRSA, with strong evidence (recommendation 1A) 1

Special Populations

Patients with Vascular Disease

• Linezolid shows significantly higher clinical success rates (80.4%) compared to vancomycin (66.7%) in patients with vascular disease and lower-extremity cSSSIs caused by MRSA 5

Pediatric Patients

• Linezolid is effective and well-tolerated in children with MRSA infections 6
• Clinical cure rates of 92.3% have been reported for pediatric MRSA skin infections 6

Monitoring and Safety Considerations

Important Monitoring

• Complete blood counts should be monitored weekly, particularly in patients receiving linezolid for longer than two weeks 2
• Monitor for signs of peripheral and optic neuropathy, especially for treatment durations approaching 28 days 2
• No dosage adjustment needed for renal impairment, making it advantageous over vancomycin in patients with kidney dysfunction 1

Key Adverse Effects

• Myelosuppression: Including anemia, leukopenia, pancytopenia, and thrombocytopenia 2
• Neurological effects: Peripheral neuropathy, optic neuropathy, and headache with prolonged use 1, 2
• Gastrointestinal effects: Diarrhea, nausea, and vomiting 1

Important Caveats and Limitations

• Linezolid is not indicated for Gram-negative infections; specific Gram-negative therapy must be initiated immediately if a concomitant Gram-negative pathogen is documented or suspected 2
• The safety and efficacy of linezolid given for longer than 28 days have not been evaluated in controlled clinical trials 2
• Avoid linezolid or use with caution when:
  • Treatment duration is expected to be >14 days
  • Patient is on serotonergic medications (due to risk of serotonin syndrome)
  • Pre-existing cytopenias are present 1
• Contraindicated in patients taking monoamine oxidase inhibitors or within two weeks of taking such medications 2

Treatment Algorithm for MRSA cSSSIs

1. First-line therapy: Linezolid 600 mg IV/oral every 12 hours for 10-14 days
2. Consider alternative therapy (vancomycin) if:
   • Patient has contraindications to linezolid (e.g., taking MAOIs)
   • Pre-existing myelosuppression
   • Concurrent serotonergic medications
3. Switch from IV to oral linezolid when clinically appropriate (same dosage) for outpatient completion of therapy
4. Extend treatment duration to 14 days for:
   • Deep or extensive infections
   • Slow clinical response
   • Immunocompromised patients

Linezolid's ability to be administered both intravenously and orally with 100% bioavailability makes it particularly valuable for step-down therapy from inpatient to outpatient settings, potentially reducing hospital length of stay compared to vancomycin 1, 4.