What is the antibiotic of choice for suspected skin infection or osteomyelitis (bone infection)?

Antibiotic Selection for Skin Infection and Osteomyelitis

For suspected skin infection or osteomyelitis, vancomycin is the first-line empiric antibiotic treatment, with alternatives including daptomycin or linezolid based on patient factors and suspected pathogens. 1

Empiric Therapy Selection Algorithm

For Skin Infections:

1. Mild skin infections (no systemic symptoms):

   • Clindamycin 300-450 mg orally four times daily (if local resistance <10%)
   • Alternative: TMP-SMX 1-2 double-strength tablets twice daily 2

2. Moderate to severe skin infections (with systemic symptoms):

   • First-line: Vancomycin 15-20 mg/kg IV every 12 hours 1
   • Alternatives:
     • Daptomycin 6-8 mg/kg IV daily
     • Linezolid 600 mg PO/IV twice daily 1

For Osteomyelitis:

1. First-line empiric therapy:

   • Vancomycin IV 15-20 mg/kg every 12 hours 1

2. Alternative options:

   • Daptomycin 6-8 mg/kg IV daily
   • Linezolid 600 mg PO/IV twice daily
   • TMP-SMX with rifampin 600 mg daily 1

Pathogen-Specific Treatment After Culture Results

Methicillin-Susceptible S. aureus (MSSA):

• First choice: Nafcillin or oxacillin 1.5-2 g IV every 4-6 hours
• Alternatives:
  • Cefazolin 1-2 g IV every 8 hours
  • Ceftriaxone 2 g IV daily 1

Methicillin-Resistant S. aureus (MRSA):

• First choice: Vancomycin IV 15-20 mg/kg every 12 hours
• Alternatives:
  • Daptomycin 6-8 mg/kg IV daily
  • Linezolid 600 mg PO/IV twice daily 1

Treatment Duration

• Skin infections: 5-10 days for uncomplicated; 7-14 days for complicated 2
• Osteomyelitis: Minimum 8-week course is recommended 1
  • Some experts suggest an additional 1-3 months of oral rifampin-based combination therapy for chronic infection 1

Important Considerations

• Surgical intervention: Debridement and drainage of associated soft-tissue abscesses is essential for osteomyelitis management and should be performed whenever feasible 1

• Route of administration: The optimal route (parenteral vs. oral) has not been definitively established. Initial parenteral therapy followed by oral therapy may be appropriate depending on individual circumstances 1

• Rifampin addition: Consider adding rifampin 600 mg daily or 300-450 mg twice daily to the primary antibiotic for osteomyelitis, but only after clearance of bacteremia if present 1

• Monitoring response:

  • MRI with gadolinium is the imaging modality of choice for detection of osteomyelitis
  • Erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP) levels help guide response to therapy 1

• Vancomycin considerations:

  • Target trough levels of 15-20 μg/mL for serious infections
  • Avoid in patients with renal impairment or when MRSA isolate shows MIC for vancomycin ≥1.5 mg/mL 1

Pediatric Considerations

• For children, IV vancomycin is recommended for osteomyelitis 1
• If the patient is stable without ongoing bacteremia, clindamycin 10-13 mg/kg/dose IV every 6-8 hours can be used as empirical therapy if local clindamycin resistance is low (<10%) 1
• Linezolid dosing: 600 mg PO/IV twice daily for children >12 years; 10 mg/kg/dose every 8 hours for children <12 years 1, 2

By following this evidence-based approach to antibiotic selection for skin infections and osteomyelitis, you can optimize patient outcomes while minimizing complications related to inappropriate antimicrobial therapy.