What is the treatment for septic arthritis?

Treatment of Septic Arthritis

The treatment of septic arthritis requires immediate surgical debridement combined with appropriate antibiotic therapy, with duration typically 3-4 weeks for uncomplicated cases. 1

Diagnostic Approach

• Septic arthritis is considered an orthopedic emergency as bacterial proliferation can rapidly cause cartilage damage 1
• Initial evaluation should determine if the case is a surgical emergency based on clinical presentation 1
• Joint aspiration is the definitive diagnostic procedure for non-emergency cases 1
  • Synovial fluid white blood cell count ≥50,000 cells/mm³ is suggestive of septic arthritis 1
  • Synovial fluid culture is positive in approximately 80% of non-gonococcal septic arthritis cases 1

Treatment Algorithm

Step 1: Determine Surgical Urgency

• Surgical Emergency: Proceed directly to surgical debridement with intraoperative cultures 1
• Non-Emergency: Perform joint aspiration for culture and cell count 1

Step 2: Drainage Approach

• Surgical debridement is the preferred method for:
  • Hip infections (always recommended) 2
  • Shoulder infections 2
  • Symptoms lasting >7 days 2
  • Patients with severe sepsis 2
  • Cases with extensive joint destruction 3
• Arthroscopic irrigation and debridement is effective in 91% of cases and allows for staging of infection 3
• Repeated joint aspiration may be sufficient for early-stage infections with minimal inflammation 3

Step 3: Antimicrobial Therapy

Initial Empiric Therapy

• Adults: IV vancomycin is recommended as first-line therapy 1
• Children:
  • IV vancomycin is recommended for MRSA coverage 1
  • Clindamycin 10-13 mg/kg/dose IV every 6-8 hours can be used if clindamycin resistance is low (<10%) 1

Alternative Agents

• Daptomycin 6 mg/kg/day IV once daily 1
• Linezolid 600 mg PO/IV twice daily (for adults and children >12 years) 1
• Linezolid 10 mg/kg/dose every 8 hours (for children <12 years) 1

Step 4: Duration of Therapy

• Septic arthritis: 3-4 weeks of antibiotics 1
• Concomitant osteomyelitis: 4-6 weeks of antibiotics 1
• Transition to oral therapy can occur when clinical improvement is observed 1
  • Switching to oral therapy at 7 days has shown similar outcomes to longer IV courses 1

Pathogen Considerations

• Staphylococcus aureus is the most common causative organism (42-56% of cases) 2, 3
• Other common pathogens include:
  • Streptococci (15-18%) 2, 3
  • Pneumococci (6%) 3
  • Gram-negative bacilli 4
• In children <4 years, consider Kingella kingae 1
• In patients with sickle cell disease, consider Salmonella species 1

Special Considerations

• For MRSA infections, vancomycin remains the primary treatment despite concerns about poor bone penetration 1
• Adding rifampin to the regimen may be beneficial due to its excellent penetration into bone and biofilm 1
• In cases of polymicrobial infection (e.g., MRSA and Pseudomonas), dual antibiotic coverage is necessary 1
• For prosthetic joint infections, longer antibiotic courses (12 weeks) show better outcomes than shorter courses (6 weeks) 1

Pitfalls and Caveats

• Delayed diagnosis and treatment can lead to permanent joint damage or even death (mortality rate 2-15%) 4
• Medical treatment alone (antibiotics with repeated aspirations) is insufficient in approximately 61% of cases 2
• Higher mortality is associated with medical treatment without adequate surgical drainage 2
• Negative joint aspirate culture does not rule out infection; consider percutaneous bone biopsy if clinical suspicion remains high 1
• Concomitant osteomyelitis occurs in up to 30% of children with septic arthritis and requires longer treatment 1