What antibiotic covers Gram-positive (Gram+) cocci?

Antibiotics for Gram-Positive Cocci

Vancomycin is the first-line antibiotic for treating serious infections caused by gram-positive cocci, particularly when methicillin resistance is suspected or confirmed. 1

First-Line Options for Gram-Positive Cocci

Vancomycin

• Gold standard for serious gram-positive infections
• Effective against:
  • Staphylococcus aureus (including MRSA)
  • Coagulase-negative staphylococci
  • Streptococci
  • Enterococci (except vancomycin-resistant enterococci)
• Dosing: 15-20 mg/kg IV every 8-12 hours (adjusted based on renal function)
• Requires therapeutic drug monitoring

Linezolid

• Alternative to vancomycin with excellent activity against gram-positive cocci
• Particularly effective for MRSA skin and soft tissue infections
• Has better clinical cure rates than vancomycin for MRSA skin infections (RR = 1.09,95% CI, 1.03-1.16) 2
• Available in both IV and oral formulations with 100% bioavailability
• Dosing: 600 mg IV/PO every 12 hours

Daptomycin

• Rapid bactericidal activity against gram-positive cocci
• Approved for complicated skin and soft tissue infections at 4 mg/kg/day IV 3
• Approved for S. aureus bacteremia and right-sided endocarditis at 6-10 mg/kg/day IV 2
• Cannot be used for pneumonia due to inactivation by pulmonary surfactant 2

Second-Line Options

Beta-lactams (for methicillin-susceptible isolates)

• Penicillinase-resistant semisynthetic penicillins (oxacillin, nafcillin)
• First-generation cephalosporins (cefazolin)
• Preferred for methicillin-susceptible S. aureus when applicable

Teicoplanin

• Glycopeptide similar to vancomycin
• Less nephrotoxicity than vancomycin
• Not available in the United States

Quinupristin/dalfopristin

• Effective against MRSA and vancomycin-resistant E. faecium
• No activity against E. faecalis 1
• Associated with severe arthralgias and myalgias

Special Situations

For Vancomycin-Resistant Enterococci (VRE)

• Linezolid is the drug of choice 1
• Daptomycin is an alternative option
• Quinupristin/dalfopristin for E. faecium only

For Community-Acquired MRSA

• Oral options include:
  • Trimethoprim-sulfamethoxazole
  • Clindamycin (if susceptible)
  • Doxycycline or minocycline
  • Linezolid (for serious infections)

Clinical Considerations

• For empiric coverage of gram-positive cocci in critically ill patients, vancomycin remains the first choice 1
• When treating neutropenic patients with suspected gram-positive infection, vancomycin should be considered if there is:
  • Hemodynamic instability
  • Pneumonia
  • Skin/soft tissue infection
  • Suspected catheter-related infection 1
• Vancomycin should be discontinued after 72-96 hours if cultures remain negative 1

Monitoring and Adverse Effects

• Vancomycin: Monitor trough levels, risk of nephrotoxicity and ototoxicity
• Linezolid: Risk of thrombocytopenia, especially with prolonged use (>2 weeks) 2
• Daptomycin: Monitor CPK levels weekly, risk of myopathy 3
• Quinupristin/dalfopristin: Severe arthralgias, infusion-related reactions

Treatment Duration

For uncomplicated skin and soft tissue infections caused by gram-positive cocci, 5-10 days of therapy is typically sufficient. For more complicated infections like bacteremia or endocarditis, longer durations (2-6 weeks) are required 2.

Remember that local antibiotic resistance patterns should guide empiric therapy choices, and therapy should be narrowed based on culture and susceptibility results when available.