How to evaluate and manage a patient on dialysis with an Arteriovenous (AV) fistula presenting with fever of unknown origin?

Evaluation and Management of Fever in a Dialysis Patient with AV Fistula

For a 60-year-old male on dialysis with an AV fistula experiencing continuous fever spikes (PUO), the AV fistula should be considered a primary source of infection and requires prompt evaluation with blood cultures drawn from both the fistula and peripherally to determine differential time to positivity. 1

Initial Diagnostic Approach

Blood Culture Collection

• Obtain two sets of blood cultures (at least 20ml total volume): one from the AV fistula and one from a peripheral vein to allow calculation of differential time to positivity 1
• For multilumen access, sample from all lumens as colonization can occur in a single lumen 1
• Collect cultures before initiating antimicrobial therapy to maximize diagnostic yield 1

Clinical Assessment

• Assess for severity of illness (presence of hypotension, organ dysfunction) to guide management decisions 1
• Examine the AV fistula site for signs of infection including erythema, tenderness, purulence, or drainage 1
• Perform ultrasound imaging along the fistula with high resolution (≥7.5 MHz) if tunnel infection is suspected 1

Additional Diagnostic Tests

• Perform chest radiograph to evaluate for pulmonary sources of infection 1
• Consider CT imaging if recent abdominal surgery or if abdominal symptoms are present 1
• Evaluate for other potential sources of infection in dialysis patients (failed kidney transplants, urinary tract infections) 2

Management Algorithm

For Mild to Moderate Illness (no hypotension or organ failure):

• If no obvious signs of infection at the AV fistula site, do not immediately remove the access 1
• Consider empiric antimicrobial therapy while awaiting culture results 1
• If fever persists with no other source identified, consider removal and culture of the vascular access 1

For Severe Illness (hypotension, signs of organ failure):

• Remove the vascular access, culture the tip, and insert a new access at a different site 1
• Initiate broad-spectrum antimicrobial therapy immediately 1
• Perform thorough evaluation for metastatic infections (endocarditis, osteomyelitis) 1

For Confirmed AV Fistula Infection:

• For exit site infections without systemic symptoms:

  • Apply topical antimicrobial agents based on culture results (e.g., mupirocin for S. aureus, antifungal agents for Candida) 1
  • If not responding to topical therapy, initiate systemic antibiotics 1

• For tunnel infections or access site abscess:

  • Remove the infected access 1
  • Provide 7-10 days of antimicrobial therapy 1
  • Consider incision and drainage if indicated 1

Pathogen-Specific Considerations

For Staphylococcal Infections:

• S. aureus and coagulase-negative staphylococci are the most common pathogens in vascular access infections 1
• S. aureus colonization of vascular access has 25% risk of developing bacteremia if not treated promptly 1
• Consider nasal culture for S. aureus and treatment of carriers with mupirocin ointment (2%) 1

For Candida Infections:

• Candida infections of AV fistulas are rare but serious, typically presenting with drainage at the fistula site 3
• Complete removal of the infected access is often necessary for cure 3
• Systemic antifungal therapy is required 3

For Other Unusual Pathogens:

• Consider rare infections such as Brucella in patients with relevant exposure history (e.g., unpasteurized dairy products) 4
• Evaluate for mycobacterial infections in immunocompromised patients 1

Important Caveats

• Fever in dialysis patients may be absent or atypical, especially in older or immunocompromised patients 5
• Unnecessary removal of vascular access should be avoided as most catheters from patients with suspected infection are sterile (71% in one series) 1
• If vascular access must be removed in a patient at high risk for mechanical complications, consider guidewire exchange, but replace again if the tip culture is positive 1
• Thrombolytic agents (e.g., urokinase) should not be used as adjunctive therapy for vascular access infections 1
• Empiric antimicrobial therapy has not shown to be effective for fever of unknown origin and should be avoided except in critically ill patients 6