What is the treatment for septic arthritis?

Treatment of Septic Arthritis

Septic arthritis treatment requires immediate surgical drainage of the joint combined with appropriate antibiotic therapy based on culture results. 1

Diagnostic Approach

• Septic arthritis presents with acute atraumatic joint pain, swelling, and limited mobility
• Constitutional symptoms like fever may be present but are not reliable indicators 2
• Risk factors include age >80 years, diabetes mellitus, rheumatoid arthritis, recent joint surgery, prosthetic joints, and immunosuppression 3

Initial Management Algorithm

Step 1: Determine if Surgical Emergency

• Assess for signs of septic arthritis requiring immediate intervention:
  • Severe joint pain, swelling, erythema, limited range of motion
  • Elevated inflammatory markers (ESR, CRP)
  • Synovial fluid WBC count >50,000 cells/mm³ (non-prosthetic joints) 2

Step 2: Joint Drainage

• Surgical debridement and drainage should always be performed 1
• Method of drainage depends on clinical scenario:
  • Surgical arthrotomy/debridement: Preferred for most cases, especially hip and shoulder joints 4
  • Arthroscopic drainage: Effective for knee, shoulder, and ankle joints 5
  • Repeated needle aspiration: May be considered for less severe cases, but has higher failure rates (>40%) 4

Step 3: Obtain Cultures

• Joint fluid must be sent for:
  • Gram stain
  • Culture and sensitivity
  • Cell count with differential
  • Crystal analysis (to rule out concurrent crystal arthropathy) 2

Step 4: Empiric Antibiotic Therapy

• Start immediately after obtaining cultures

• For adults with suspected MRSA:

  • IV vancomycin (15-20 mg/kg every 8-12 hours) 1
  • Alternative: Daptomycin 6 mg/kg IV once daily 1

• For children:

  • IV vancomycin if MRSA suspected 1
  • Clindamycin 10-13 mg/kg/dose IV every 6-8 hours if clindamycin resistance is low 6
  • Alternative: Linezolid 600 mg PO/IV twice daily (>12 years) or 10 mg/kg/dose every 8 hours (<12 years) 6

Step 5: Targeted Antibiotic Therapy

• Adjust antibiotics based on culture results and susceptibilities
• Most common pathogens:
  • Staphylococcus aureus (40-60% of cases) 4, 5
  • Streptococcus species (15-20%)
  • Gram-negative organisms

Step 6: Duration of Therapy

• Standard duration: 3-4 weeks 6
• Extended duration (4-6 weeks) for:
  • Concurrent osteomyelitis
  • S. aureus infections
  • Prosthetic joint infections
  • Immunocompromised patients 6

Step 7: Transition to Oral Therapy

• Consider after:
  • Clinical improvement (decreased pain, swelling)
  • Normalization of inflammatory markers
  • At least 2-5 days of IV therapy 7
• Choose oral antibiotics with good bioavailability:
  • Fluoroquinolones (for susceptible gram-negative organisms)
  • Linezolid, clindamycin, or TMP-SMX (for susceptible gram-positive organisms) 6
  • Avoid oral β-lactams due to poor bioavailability 6

Special Considerations

Prosthetic Joint Infections

• Always remove prosthetic device when possible 1
• If device cannot be removed, chronic suppression with fluconazole 400 mg daily (for fungal infections) or appropriate antibiotics for bacterial infections 1

Fungal Septic Arthritis

• For fluconazole-susceptible Candida: Fluconazole 400 mg daily for 6 weeks 1
• Alternative: Echinocandin for 2 weeks followed by fluconazole for at least 4 weeks 1

Monitoring Response

• Track clinical improvement (pain, swelling, range of motion)
• Monitor inflammatory markers (ESR, CRP) weekly
• Consider repeat joint aspiration if clinical improvement is not observed
• Failure to improve may indicate:
  • Inadequate drainage
  • Resistant organism
  • Concurrent osteomyelitis
  • Prosthetic material requiring removal

Pitfalls to Avoid

• Delaying surgical drainage (increases risk of joint destruction)
• Inadequate antibiotic coverage for MRSA in high-risk patients
• Insufficient duration of therapy (less than 3 weeks)
• Failure to recognize concurrent osteomyelitis (present in up to 30% of cases) 6
• Premature transition to oral antibiotics with poor bioavailability

Remember that septic arthritis is an orthopedic emergency that requires prompt intervention to prevent permanent joint damage and potential mortality 1.