Xyvox (Linezolid) Antimicrobial Coverage
Xyvox covers Gram-positive bacteria exclusively, with particular strength against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and multidrug-resistant Streptococcus pneumoniae, but has NO clinically useful activity against Gram-negative organisms or atypical pathogens. 1
Primary Gram-Positive Coverage
Staphylococcus aureus
- Methicillin-resistant S. aureus (MRSA): The Infectious Diseases Society of America recommends linezolid as first-line therapy for MRSA skin and soft-tissue infections (Grade 1A recommendation) and as an alternative to vancomycin for nosocomial pneumonia caused by MRSA 1
- Vancomycin-intermediate S. aureus (VISA) and Vancomycin-resistant S. aureus (VRSA): Linezolid maintains in vitro activity against these highly resistant strains 1
- Methicillin-sensitive S. aureus (MSSA): Fully covered 2
Streptococcus Species
- All strains of Streptococcus pneumoniae, including multidrug-resistant isolates (MDRSP) resistant to penicillin, second-generation cephalosporins, macrolides, tetracycline, and trimethoprim/sulfamethoxazole 1
- Streptococcus pyogenes (Group A Strep) 2
- Streptococcus agalactiae (Group B Strep) 2
Enterococcus Species
- Vancomycin-resistant Enterococcus faecium (VRE): Linezolid demonstrates efficacy against VRE infections 2, 3
- Enterococcus faecalis including vancomycin-resistant strains 3
Select Anaerobes
- Clostridium perfringens, C. difficile, Peptostreptococcus species, and Bacteroides fragilis 3
Critical Coverage Gaps
Linezolid lacks clinically useful activity against:
- Aerobic Gram-negative organisms: Pseudomonas aeruginosa, Enterobacteriaceae, and Haemophilus influenzae 1
- Atypical pathogens: Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella species 1
This means patients with polymicrobial infections or suspected Gram-negative involvement require additional antimicrobial coverage (e.g., aztreonam was permitted in clinical trials for Gram-negative coverage) 2.
FDA-Approved Indications
Nosocomial Pneumonia
- Cure rates for MRSA nosocomial pneumonia: 59% (13/22 patients) 2
- Effective against S. aureus and S. pneumoniae causing hospital-acquired pneumonia 2
Community-Acquired Pneumonia
- Particularly effective for multidrug-resistant S. pneumoniae (MDRSP): 92% cure rate (33/36 patients) in microbiologically evaluable population 2
- Clinical cure rates of 73% in intent-to-treat population with CAP due to MDRSP 2
Complicated Skin and Skin Structure Infections
- 88% cure rate (73/83 patients) for S. aureus infections 2
- 79% cure rate (26/33 patients) for MRSA skin infections, compared to 73% with vancomycin 2
- Effective for diabetic foot infections with Gram-positive pathogens 2
Uncomplicated Skin and Skin Structure Infections
- Approved for MSSA and S. pyogenes 2
Clinical Advantages
Tissue Penetration
- Excellent tissue penetration into biofilms and poorly vascularized tissues such as the prostate 1
- Superior penetration properties compared to vancomycin 4
Oral Bioavailability
- 100% oral bioavailability, allowing seamless IV-to-oral transition when patients can tolerate oral medications 1
- This unique feature enables early hospital discharge and outpatient parenteral antimicrobial therapy (OPAT) alternatives 4
Important Safety Considerations
Thrombocytopenia Risk
- Associated with thrombocytopenia with prolonged use 4
- Approximately 2% of patients develop thrombocytopenia 3
- Monitor platelet counts, especially with treatment courses exceeding 10-14 days