What are the recommended antibiotics (Abx) for post-operative orthopedic infections?

Recommended Antibiotics for Post-Operative Orthopedic Infections

For post-operative orthopedic infections, first-line treatment should be cefazolin 2g IV for most cases, with specific modifications based on the type of infection, presence of hardware, and suspected pathogens. 1

Antibiotic Selection Algorithm by Infection Type

Standard Post-Operative Orthopedic Infections

• First-line: Cefazolin 2g IV slow infusion (reinject 1g if procedure >4h)
• Alternative first-line options:
  • Cefuroxime 1.5g IV slow (reinject 0.75g if procedure >2h)
  • Cefamandole 1.5g IV slow (reinject 0.75g if procedure >2h)
• For beta-lactam allergies:
  • Clindamycin 900mg IV slow
  • Vancomycin 30mg/kg/120min (for severe allergies or MRSA risk)

Prosthetic Joint Infections

• First-line: Cefazolin 2g IV slow (reinject 1g if procedure >4h)
• Duration: Limited to operative period (24 hours maximum)
• For MRSA risk factors: Add vancomycin 30mg/kg (maximum 2g)
• For beta-lactam allergies: Clindamycin 900mg IV slow or vancomycin 30mg/kg/120min

Open Fractures

• Type I & II: Cefazolin 2g IV or clindamycin 900mg IV (for allergies) 2
• Type III: Cefazolin plus gram-negative coverage with an aminoglycoside 2
  • Gentamicin 5mg/kg/day (avoid with renal dysfunction)
  • Alternative: Piperacillin-tazobactam

Special Considerations

MRSA Coverage

Indications for vancomycin (30mg/kg/120min) include:

• Beta-lactam allergies
• Suspected or proven colonization with MRSA
• Reoperation in a patient hospitalized in a unit with MRSA ecology
• Previous antibiotic therapy 1

Multidrug-Resistant Gram-Negative Bacteria

For patients colonized with extended-spectrum cephalosporin-resistant Enterobacterales:

• Ampicillin/sulbactam 3g IV (reinjection every 2-4 hours)
• Alternatives: Ertapenem 1g IV, piperacillin/tazobactam 3.375-4.5g IV 1

Duration of Therapy

• Prophylaxis: Limited to the operative period (24 hours maximum) 1, 3
• Established infection:
  • For infections with retained hardware: At least 3 months of suppressive antibiotics improves outcomes 4
  • For infections requiring debridement: Antibiotics should be continued based on culture results

Pathogen-Specific Considerations

• Staphylococci (account for ~70% of orthopedic prosthetic infections) 5:

  • For methicillin-sensitive strains: Cefazolin
  • For methicillin-resistant strains: Vancomycin or daptomycin
  • For biofilm-producing strains: Consider combination therapy with rifampin 6, 3

• MRSA infections: Higher failure rates compared to other pathogens 4

  • Consider daptomycin as an alternative to vancomycin (similar efficacy but fewer adverse events) 7

• Gram-negative infections: Associated with lower success rates 4

  • Require targeted therapy based on susceptibility testing

Common Pitfalls and Caveats

1. Inadequate duration: While prophylaxis should be limited to 24 hours, established infections require longer courses (at least 3 months for retained hardware) 4

2. Monotherapy for biofilm infections: Biofilm-associated infections (especially with retained hardware) respond poorly to monotherapy; combination therapy with rifampin should be considered for staphylococcal infections 6, 3

3. Ignoring local resistance patterns: Local hospital antibiograms should guide empiric therapy, especially regarding MRSA prevalence

4. Adverse events: Vancomycin has a higher rate of treatment discontinuation due to adverse events compared to alternatives like daptomycin 7

5. Inadequate surgical management: Antibiotics alone are often insufficient without appropriate surgical debridement or hardware management

Remember that while antibiotics are crucial, surgical intervention (debridement, hardware removal when possible) remains a cornerstone of treatment for post-operative orthopedic infections.