Linezolid Dosing for MRSA Pneumonia and Cellulitis
For both MRSA pneumonia and cellulitis, administer linezolid 600 mg IV or PO every 12 hours in adults, with treatment duration of 7-14 days for pneumonia and 10-14 days for uncomplicated cellulitis. 1, 2
Adult Dosing
Standard Regimen
- 600 mg IV or PO every 12 hours for both pneumonia and complicated skin/soft tissue infections 1, 2
- The oral and IV formulations are interchangeable without dose adjustment 2
- No dose adjustment needed for renal impairment, including dialysis patients 3
Treatment Duration
- Pneumonia: 7-21 days, with most cases requiring 10-14 days 1, 4, 2
- Uncomplicated cellulitis: 10-14 days 1, 4, 2
- Complicated skin/soft tissue infections: 14-28 days 2
Pediatric Dosing
Age-Based Regimens
- Children <12 years: 10 mg/kg IV or PO every 8 hours (maximum 600 mg per dose) 1, 2
- Children ≥12 years: 600 mg IV or PO every 12 hours (adult dosing) 1, 2
- Neonates <7 days old: Start with 10 mg/kg every 12 hours, then increase to every 8 hours by day 7 of life 2
Critical Monitoring Requirements
Hematologic Surveillance
- Obtain complete blood counts weekly, particularly for treatment exceeding 2 weeks 4, 2
- Monitor for thrombocytopenia, anemia, and leukopenia—myelosuppression risk increases significantly beyond 2 weeks of therapy 4, 2
- Thrombocytopenia occurs more frequently in patients with severe renal impairment or moderate-to-severe hepatic impairment 2
Neurologic Monitoring
- Perform monthly visual acuity and color discrimination testing for patients receiving extended therapy (>2 weeks) 4
- Consider prophylactic pyridoxine (vitamin B6) in patients with diabetes, alcohol abuse, or malnutrition to reduce peripheral neuropathy risk 4
Important Clinical Considerations
Efficacy Evidence
- Linezolid demonstrated superior clinical cure rates compared to vancomycin for MRSA nosocomial pneumonia (57.6% vs 46.6%, P=0.042) in a prospective randomized trial, though 60-day mortality was similar 5
- Both linezolid and vancomycin show comparable efficacy for MRSA infections overall, with clinical cure rates of approximately 73% 6
Safety Profile
- Nephrotoxicity is significantly lower with linezolid (8.4%) compared to vancomycin (18.2%) 5
- Linezolid is particularly advantageous in patients with renal impairment, showing better clinical outcomes than dose-optimized vancomycin in this population 7
- Avoid concomitant use with monoamine oxidase inhibitors or within 2 weeks of discontinuing such medications 4, 2
Common Pitfalls
- Never reduce dosing frequency to every 24 hours—this fails to maintain adequate bactericidal drug exposure 4
- Do not extend therapy beyond 28 days without compelling indication, as safety data beyond this duration are limited 2
- Linezolid is bacteriostatic (not bactericidal) against staphylococci, but this is acceptable for most infections with adequate source control 8
- Ensure Gram-negative coverage is addressed separately, as linezolid has no activity against Gram-negative pathogens 2