What is the treatment for septic arthritis?

Treatment of Septic Arthritis

Septic arthritis requires immediate surgical debridement combined with IV vancomycin as first-line antibiotic therapy, followed by culture-directed treatment for 3-4 weeks in uncomplicated cases. 1

Immediate Management Algorithm

Step 1: Recognize the Emergency

• Septic arthritis is an orthopedic emergency—bacterial proliferation rapidly destroys cartilage and causes permanent joint dysfunction 1, 2
• Mortality ranges from 2-15% overall, with 90-day mortality reaching 7% in patients ≤79 years and 22-69% in those >79 years 3, 4
• Poor functional outcomes (amputation, arthrodesis, severe deterioration) occur in 24-33% of patients 3

Step 2: Obtain Diagnostic Samples BEFORE Antibiotics

• Perform joint aspiration immediately in non-emergency presentations 1
• Synovial fluid WBC ≥50,000 cells/mm³ is highly suggestive of septic arthritis 1, 2
• Culture is positive in approximately 80% of non-gonococcal cases 1, 2
• For surgical emergencies (severe sepsis, rapidly progressive joint destruction), proceed directly to surgical debridement with intraoperative cultures rather than waiting for aspiration results 1

Step 3: Surgical Intervention

Drainage of the joint space must always be performed—this is non-negotiable. 1

• Surgical debridement with arthrotomy, irrigation, and drainage is the standard approach 1, 2
• Medical treatment (arthrocentesis alone) may be as effective as surgery for select cases with shorter hospital stays (12 days shorter) and better functional outcomes, but 30% ultimately require surgery 3, 5
• For prosthetic joint infections, device removal is mandatory 2

Antibiotic Therapy

Empiric Treatment (Start Immediately After Cultures)

Adults:

• IV vancomycin 15 mg/kg every 6 hours (or 30-60 mg/kg/day in 2-4 divided doses) is first-line empiric therapy 1
• This covers MRSA, which is increasingly common and the most common pathogen overall 1, 6

Children:

• IV vancomycin 15 mg/kg/dose every 6 hours (40 mg/kg/day in 4 divided doses) 1
• Alternative: Clindamycin 10-13 mg/kg/dose IV every 6-8 hours if local clindamycin resistance is low 1, 2

Culture-Directed Definitive Therapy

For MRSA (confirmed):

• Continue IV vancomycin as primary treatment 1
• Consider adding rifampin 600 mg daily or 300-450 mg twice daily for enhanced bone and biofilm penetration 1, 2
• Monitor vancomycin trough levels to avoid toxicity 1

For MSSA (methicillin-sensitive S. aureus):

• Switch to nafcillin or oxacillin 1-2 g IV every 4 hours 1
• Alternative: Cefazolin 1 g IV every 8 hours 1
• If penicillin allergic: Clindamycin 600 mg IV every 8 hours 1

For Streptococcal infections:

• Penicillin G 20-24 million units IV daily (continuous or divided) 1
• Alternative: Ceftriaxone 1-2 g IV every 24 hours 1

For polymicrobial infections:

• Dual antibiotic coverage is mandatory (e.g., linezolid for MRSA plus ciprofloxacin for Pseudomonas) 1, 2

Transition to Oral Therapy

• Oral antibiotics are NOT inferior to IV therapy for most cases 1, 6
• Switch after 2-4 days if patient is clinically improving, afebrile, and tolerating oral intake 1
• Oral options for MRSA: Linezolid 600 mg PO every 12 hours, TMP-SMX (trimethoprim 4 mg/kg/dose) every 8-12 hours plus rifampin 600 mg daily 1

Duration of Treatment

Standard cases:

• 3-4 weeks total for uncomplicated bacterial arthritis 1, 2
• Recent evidence suggests 2 weeks may be adequate after surgical drainage in select cases (predominantly small joints) 1

Special circumstances requiring longer treatment:

• Concomitant osteomyelitis (occurs in up to 30% of pediatric cases): Requires extended therapy 1, 2
• Prosthetic joint infections with debridement and implant retention: 12 weeks is superior to 6 weeks 1, 2
• Hip prosthesis with one- or two-stage exchange: 3 months total 1
• Knee prosthesis with one- or two-stage exchange: 6 months total 1

Pathogen-Specific Considerations

• Children <4 years: Consider Kingella kingae as causative organism 1, 2
• Sickle cell disease: Consider Salmonella species 1, 2
• Gonococcal arthritis: Requires specific consideration based on sexual history 6
• Candida septic arthritis: Fluconazole 400 mg daily for 6 weeks OR echinocandin for 2 weeks followed by fluconazole 400 mg daily for ≥4 weeks 2

Critical Pitfalls to Avoid

• Never assume negative cultures exclude infection—consider percutaneous bone biopsy if clinical suspicion remains high despite negative joint aspirate 1, 2
• Never give intra-articular corticosteroids during active infection—this worsens outcomes 1
• Do not delay treatment—permanent cartilage damage occurs rapidly 1, 2
• Monitor for drug interactions and adverse effects in elderly patients 1
• Follow CRP and ESR to monitor treatment response 1

Management of Persistent Symptoms

If joint swelling persists or recurs after completing antibiotics:

• Re-treatment with another 4-week course of oral antibiotics OR 2-4 weeks of IV ceftriaxone 1, 2
• Arthroscopic synovectomy may reduce inflammation duration in cases with significant pain or functional limitation 1, 2
• If synovial fluid PCR is negative, treat symptomatically with NSAIDs or DMARDs 1