What is the recommended treatment for an infection susceptible to linezolid (Zyvox)?

Treatment of Linezolid-Susceptible Infections

For infections susceptible to linezolid, treat with linezolid 600 mg IV or oral every 12 hours, with treatment duration determined by the specific infection site and clinical response. 1, 2

Dosing and Administration

• Standard adult dose: 600 mg every 12 hours (IV or oral) for serious gram-positive infections 2
• Pediatric dosing (birth through 11 years): 10 mg/kg every 8 hours (IV or oral) 2
• Adolescents (≥12 years): 600 mg every 12 hours (same as adults) 2
• Route selection is clinically equivalent due to 100% oral bioavailability—choose IV for hemodynamic instability, inability to tolerate oral intake, or severe GI pathology; otherwise oral administration is equally effective 3

Infection-Specific Treatment Durations

Prosthetic Joint Infections

• 4-6 weeks of therapy for staphylococcal or enterococcal PJI 1
• Linezolid 600 mg PO/IV every 12 hours is listed as an alternative for both oxacillin-susceptible and oxacillin-resistant staphylococci 1

Diabetic Foot Infections

• Moderate infections: linezolid (with or without aztreonam) for 2-4 weeks 1
• Linezolid is specifically FDA-approved for diabetic foot infections without concomitant osteomyelitis 2

Vancomycin-Resistant Enterococcal (VRE) Infections

• Pneumonia: at least 7 days 1
• Bloodstream infections: 10-14 days 1
• Complicated intra-abdominal infections: 5-7 days 1
• Complicated UTI: 5-7 days 1
• Linezolid 600 mg IV/PO every 12 hours is the strong recommendation (1C) for VRE infections 1

MRSA Infections

• Pneumonia (nosocomial or community-acquired): 14-28 days 2
• Complicated skin/soft tissue infections: 10-14 days 2
• Uncomplicated skin infections: 10-14 days (adults: 400 mg every 12 hours; adolescents: 600 mg every 12 hours) 2

CNS Infections

• Meningitis: 2 weeks with linezolid 600 mg PO/IV twice daily as alternative to vancomycin 1
• Brain abscess, subdural empyema, spinal epidural abscess: 4-6 weeks 1
• Linezolid achieves CSF penetration of approximately 66% with concentrations of 7-10 μg/mL, superior to vancomycin's 1-5% penetration 1

Septic Arthritis

• 3-4 weeks, longer if contiguous osteomyelitis present 1

Critical Monitoring and Safety Considerations

Hematologic Toxicity

• Monitor CBC weekly for thrombocytopenia (occurs in 7.4% of patients) and anemia (4.1% of patients), particularly with treatment exceeding 2 weeks 4, 5
• Thrombocytopenia typically develops after prolonged administration (>2 weeks) and resolves after discontinuation 5

Neuropathy Risk

• Peripheral or optic neuropathy is associated with prolonged treatment (3-6 months) 5
• Avoid linezolid courses exceeding 28 days unless absolutely necessary, as safety beyond this duration has not been established in controlled trials 2, 6

Common Adverse Events

• Gastrointestinal disturbances (nausea, vomiting, diarrhea) occur in 9.8% of patients and are the most common reason for discontinuation 4, 7
• Other adverse events include headache, fungal infections, hypertension, serotonin syndrome (avoid concurrent serotonergic agents), and Clostridium difficile diarrhea 5

Clinical Efficacy Data

• Clinical cure rates: 73-92% in intent-to-treat populations with multidrug-resistant gram-positive infections 4, 7
• Microbiological success rates: 76-86% across various infection types 4, 7
• Linezolid demonstrates equivalent or superior efficacy compared to vancomycin for MRSA nosocomial pneumonia and complicated skin infections 8, 9, 5

Critical Limitations

• Linezolid is NOT indicated for gram-negative infections—if gram-negative pathogens are documented or suspected, specific gram-negative therapy must be initiated immediately 2, 6
• Not studied for decubitus ulcers or infections with concomitant osteomyelitis in diabetic foot infections 2
• For pediatric patients with pathogens having MIC of 4 μg/mL and suboptimal clinical response, consider lower systemic exposure and infection severity when assessing treatment adequacy 2