Recommended Antibiotics for MRSA Infections
Vancomycin is the first-line treatment for most MRSA infections, with a dosing regimen of 15-20 mg/kg/dose IV every 8-12 hours based on actual body weight, not to exceed 2 g per dose, with target trough concentrations of 15-20 μg/mL for serious infections. 1, 2
First-Line Treatment Options by Infection Type
Skin and Soft Tissue Infections (SSTIs)
- For simple abscesses or boils, incision and drainage may be adequate without antibiotics 1
- For purulent cellulitis:
- For complicated SSTIs requiring IV therapy:
Bacteremia and Endocarditis
- Vancomycin 15-20 mg/kg/dose IV every 8-12 hours 1, 2
- Daptomycin 6 mg/kg/dose IV daily (first-line alternative) 1
- For prosthetic valve endocarditis: Vancomycin plus gentamicin plus rifampin 1
- For persistent bacteremia: High-dose daptomycin (10 mg/kg/day) in combination with another agent (gentamicin, rifampin, linezolid, TMP-SMX, or a beta-lactam) 1, 2
Pneumonia
- Vancomycin 15-20 mg/kg/dose IV every 8-12 hours 1, 2
- Linezolid 600 mg PO/IV BID (may be superior to vancomycin) 1, 4
- Clindamycin 600 mg PO/IV TID (for susceptible strains) 1
Central Nervous System Infections
- For meningitis: Vancomycin IV for 2 weeks; some experts recommend adding rifampin 600 mg daily or 300-450 mg BID 1
- For brain abscess, subdural empyema, spinal epidural abscess: Vancomycin IV for 4-6 weeks; some experts recommend adding rifampin 1
- Alternatives include linezolid 600 mg PO/IV BID or TMP-SMX 5 mg/kg/dose IV every 8-12 hours 1
Vancomycin Dosing and Monitoring
- Initial dosing: 15-20 mg/kg/dose (actual body weight) every 8-12 hours, not to exceed 2 g per dose 1, 2
- For serious infections (bacteremia, endocarditis, osteomyelitis, meningitis, pneumonia, severe SSTI): Target trough concentrations of 15-20 μg/mL 1, 2
- For less severe SSTIs in patients with normal renal function: Traditional doses of 1 g every 12 hours may be adequate without trough monitoring 1
- Loading dose consideration: 25-30 mg/kg in seriously ill patients (sepsis, meningitis, pneumonia, endocarditis) 1, 5
- Trough monitoring: Obtain at steady state, prior to fourth or fifth dose 1, 6
- Monitoring is essential for serious infections, morbidly obese patients, those with renal dysfunction, or fluctuating volumes of distribution 1, 7
Alternative Agents for MRSA
- Linezolid: 600 mg PO/IV BID; particularly effective for pneumonia and skin infections 1, 3, 4
- Daptomycin: 4-6 mg/kg/dose IV daily (not for pneumonia due to inactivation by pulmonary surfactant) 1, 8
- Telavancin: 10 mg/kg/dose IV daily 1
- TMP-SMX: 5 mg/kg/dose IV every 8-12 hours or 1-2 double-strength tablets PO BID 1
- Clindamycin: 300-450 mg PO TID or 600 mg IV TID (only for susceptible strains) 1
- Tedizolid: Newer alternative to linezolid with similar efficacy 8, 4
Special Considerations
- For vancomycin MIC ≥2 μg/mL (VISA or VRSA), an alternative to vancomycin should be used 1
- For persistent MRSA bacteremia despite adequate vancomycin therapy, consider alternative agents regardless of MIC 1
- Combination therapy may be beneficial in difficult-to-treat cases, particularly with high-dose daptomycin plus another agent 1, 2
- Area under the curve (AUC) dosing strategies may reduce vancomycin total daily dose compared to trough-based dosing, particularly in obese patients 6, 7
Pediatric Considerations
- Vancomycin: 15 mg/kg/dose IV every 6 hours for serious infections 1, 2
- Clindamycin: 10-13 mg/kg/dose IV every 6-8 hours, not to exceed 40 mg/kg/day 1, 2
- Linezolid: 10 mg/kg/dose PO/IV every 8 hours, not to exceed 600 mg/dose 1, 9
- For neonatal pustulosis: Topical mupirocin for mild cases; IV vancomycin or clindamycin for premature infants or extensive disease 1