What is the treatment for sepsis caused by a knee infection?

Treatment for Sepsis Caused by Knee Infection

Immediate treatment for sepsis from a knee infection requires aggressive fluid resuscitation, broad-spectrum intravenous antibiotics within one hour, and urgent surgical debridement of the infected knee joint. 1

Initial Assessment and Stabilization

• Assess for systemic signs of sepsis:

  • Measure serum lactate level (elevated lactate >4 mmol/L indicates tissue hypoperfusion)
  • Obtain at least 2 sets of blood cultures before starting antibiotics 1
  • Obtain joint fluid sample for culture and Gram stain 2

• Immediate resuscitation measures:

  • Administer crystalloid fluids (20-30 mL/kg) for hypotension or lactate >4 mmol/L 1
  • Target mean arterial pressure (MAP) ≥65 mmHg 2
  • If hypotension persists despite fluid resuscitation, start vasopressors (norepinephrine is first-line) 1

Antibiotic Therapy

• Initiate broad-spectrum IV antibiotics within 1 hour of sepsis recognition 1

• Initial empiric regimen should cover:

  • Methicillin-resistant Staphylococcus aureus (MRSA) - most common pathogen in knee infections 3
  • Gram-negative organisms
  • Anaerobic bacteria if clinically suspected

• Recommended initial antibiotic regimen:

  • Vancomycin (for MRSA coverage) PLUS
  • Piperacillin-tazobactam (for broad gram-negative and anaerobic coverage) 4

• Adjust antibiotics based on culture results and antibiotic susceptibility testing 1

• Duration of therapy: typically 4-6 weeks for bone/joint infections with S. aureus 1

Source Control

• Orthopedic surgical consultation for urgent source control within 12 hours 1

• Surgical options include:

  • Arthroscopic irrigation and debridement for early or less severe infections
  • Open arthrotomy with thorough debridement for more severe or established infections 5

• Important: MRSA infections have higher failure rates with arthroscopic treatment alone (62.5% vs. 12% for other pathogens) and may require open arthrotomy 3

• Remove any infected prosthetic material or foreign bodies if present 2

• Consider repeat surgical debridement if clinical improvement is not observed within 24-48 hours

Ongoing Management

• Monitor response to treatment:

  • Daily reassessment of antibiotic regimen for potential de-escalation 1
  • Track inflammatory markers (CRP, ESR) to assess response
  • Monitor renal function if using nephrotoxic antibiotics

• Supportive care:

  • Deep venous thrombosis (DVT) prophylaxis - septic knee infections have increased risk of DVT 6
  • Maintain blood glucose <150 mg/dL (8.3 mmol/L) 2
  • Provide adequate nutritional support once patient is stabilized 2

Complications to Monitor

• Osteomyelitis - may develop as a complication of septic arthritis 6
• Deep venous thrombosis and pulmonary emboli - increased risk with knee infections 6
• Septic shock - requires aggressive hemodynamic support and intensive care management
• Joint destruction - may lead to long-term disability and need for future joint replacement

Prognosis

The mortality rate for sepsis varies significantly based on severity: no sepsis 1.2%, sepsis only 4.4%, severe sepsis 27.8%, and septic shock 67.8% 2. Prompt recognition and treatment significantly improve outcomes.

Common Pitfalls to Avoid

1. Delaying antibiotic administration - must be given within 1 hour of sepsis recognition
2. Inadequate source control - surgical debridement is essential and should not be delayed
3. Underestimating MRSA infections - these have higher failure rates with arthroscopic treatment alone
4. Insufficient fluid resuscitation - monitor for signs of tissue hypoperfusion
5. Failing to reassess antibiotic therapy - daily review and adjustment based on culture results is essential

Remember that sepsis from a knee infection represents a medical emergency requiring immediate, coordinated care between emergency medicine, infectious disease, and orthopedic specialists.