What is the treatment for septic arthritis?

Treatment of Septic Arthritis

Septic arthritis requires immediate surgical drainage combined with IV vancomycin as first-line empiric antibiotic therapy, followed by culture-directed treatment for 3-4 weeks in uncomplicated cases. 1, 2

Immediate Management Algorithm

Step 1: Surgical Drainage (Mandatory in All Cases)

• Surgical drainage must be performed immediately in all cases of septic arthritis - this is non-negotiable and takes priority over waiting for culture results 1, 2
• Three drainage options exist: arthrocentesis at bedside, arthroscopic drainage, or open arthrotomy with irrigation and debridement 1, 3
• Arthrotomy, irrigation, and debridement remain the standard surgical intervention 1, 2
• Obtain intraoperative cultures during surgical debridement 2

Common Pitfall: Do not delay surgical drainage while waiting for imaging or culture results - bacterial proliferation causes rapid irreversible cartilage damage within hours 1, 4

Step 2: Empiric Antibiotic Therapy (Start Immediately After Cultures Obtained)

Adults:

• IV vancomycin 15 mg/kg every 6 hours (or 30-60 mg/kg/day in 2-4 divided doses) is the mandatory first-line empiric therapy due to high MRSA prevalence 1, 2, 3
• Alternative options if MRSA is less likely: linezolid 600 mg IV/PO every 12 hours, daptomycin 6 mg/kg IV daily, or teicoplanin 6-12 mg/kg IV every 12 hours for 3 doses then daily 2

Children:

• IV vancomycin 15 mg/kg/dose every 6 hours (40 mg/kg/day in 4 divided doses) 2
• Alternative: clindamycin 10-13 mg/kg/dose IV every 6-8 hours if local clindamycin resistance is low 1, 2
• In children <4 years, ensure coverage includes Kingella kingae 1, 2, 4

Special Populations:

• Sickle cell disease patients: ensure coverage for Salmonella species 1, 2, 4
• Polymicrobial infections: dual antibiotic coverage is mandatory (e.g., linezolid for MRSA plus ciprofloxacin for Pseudomonas) 1, 2

Step 3: Culture-Directed Definitive Therapy

For Methicillin-Susceptible Staphylococcus aureus (MSSA):

• Switch from vancomycin to nafcillin or oxacillin 1-2 g IV every 4 hours 2
• Alternative: cefazolin 1 g IV every 8 hours 2
• Penicillin-allergic: clindamycin 600 mg IV every 8 hours 2

For Methicillin-Resistant Staphylococcus aureus (MRSA):

• Continue vancomycin as primary therapy 1, 2, 3
• Consider adding rifampin 600 mg PO daily or 300-450 mg PO twice daily for enhanced bone and biofilm penetration 1, 2

For Streptococcal Infections:

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

Step 4: Transition to Oral Therapy

• Oral antibiotics are not inferior to IV therapy and can be initiated after 2-4 days if the patient is clinically improving, afebrile, and tolerating oral intake 2, 5
• Oral options for MRSA (after initial IV therapy): linezolid 600 mg PO every 12 hours, TMP-SMX (trimethoprim 4 mg/kg/dose) PO every 8-12 hours plus rifampin 600 mg PO daily, or fusidic acid 500 mg PO every 8 hours plus rifampin 2

Treatment Duration

Uncomplicated Native Joint Septic Arthritis:

• Standard duration: 3-4 weeks total 1, 2, 3
• Recent evidence suggests 2 weeks may be adequate after surgical drainage in select cases (predominantly small joints) 2

Prosthetic Joint Infections:

• 12 weeks is superior to 6 weeks for debridement with implant retention 1, 2
• Hip prostheses with one-stage or two-stage exchange: 3 months total 2
• Knee prostheses with one-stage or two-stage exchange: 6 months total 2
• If prosthetic device cannot be removed: chronic suppression with fluconazole 400 mg daily (if susceptible) 1

With Concomitant Osteomyelitis:

• Extend treatment to 6 weeks if imaging confirms accompanying osteomyelitis 2, 3
• This occurs in up to 30% of children with septic arthritis 1, 2

Candida Septic Arthritis:

• Fluconazole 400 mg daily for 6 weeks OR echinocandin for 2 weeks followed by fluconazole 400 mg daily for at least 4 weeks 1
• All patients with candidemia require dilated retinal examination within the first week to rule out endophthalmitis 1

Management of Treatment Failure

• For persistent or recurrent joint swelling after oral antibiotics: re-treat with another 4-week course of oral antibiotics OR 2-4 weeks of IV ceftriaxone 1, 2
• For persistent synovitis with significant pain or functional limitation: arthroscopic synovectomy may reduce duration of joint inflammation 1, 2

Critical Caveats

• Negative joint aspirate culture does not rule out infection - consider percutaneous bone biopsy if clinical suspicion remains high 1, 2
• Monitor vancomycin trough levels and adjust dosing to avoid toxicity 2
• Be vigilant for drug interactions and adverse effects in elderly patients 2
• Follow CRP and ESR to monitor treatment response 2
• Medical treatment (arthrocentesis) appears as effective as surgical treatment with shorter hospital stays (12 days shorter) and better functional outcomes, though 30% ultimately require surgical intervention 6, 7
• The 90-day mortality rate is 7% in patients ≤79 years but increases to 22-69% in patients >79 years 6