Why is rifaximin (antibiotic) stopped in post-operative arteriovenous fistula cases?

Rifaximin Discontinuation in Post-Operative Arteriovenous Fistula Cases

Rifaximin should be discontinued in post-operative arteriovenous fistula cases because it is a poorly absorbed antibiotic designed specifically for gastrointestinal infections and has no therapeutic role in vascular access procedures.

Rationale for Discontinuation

Rifaximin's Pharmacological Properties

• Rifaximin is a synthetic antibiotic specifically designed to have low gastrointestinal absorption while maintaining good antibacterial activity 1
• It is a nonsystemic antibiotic that remains primarily within the GI tract, making it ineffective for treating or preventing vascular access infections 1
• The drug's bioavailability is high only within the GI tract, with minimal systemic distribution 1

Appropriate Antibiotic Selection for Vascular Access Procedures

• For arteriovenous fistula (AVF) infections, which are rare but potentially serious, guidelines recommend systemic antibiotics that can reach adequate tissue concentrations at the vascular access site 2
• When antibiotic therapy is indicated for AVF infections, they should be treated as subacute bacterial endocarditis with 6 weeks of appropriate systemic antibiotic therapy 2
• The American Heart Association guidelines recommend parenteral antimicrobial therapy for 4-6 weeks for vascular graft infections, not poorly absorbed GI-specific antibiotics like rifaximin 2

Appropriate Antibiotic Management for AVF Infections

When Antibiotics Are Indicated

• Infections of primary AVFs are rare but require immediate intervention when they occur 2
• Treatment should include:
  • Initial broad-spectrum coverage with vancomycin plus an aminoglycoside 2
  • Adjustment based on culture and sensitivity results 2
  • Total treatment duration of 6 weeks 2

Specific Antibiotic Selection

• For empiric therapy: vancomycin plus an aminoglycoside is recommended initially 2
• For targeted therapy: antibiotics should be selected based on culture results and adjusted accordingly 2
• For long-term suppression (when indicated): oral antibiotics with good bioavailability should be selected 2

Clinical Considerations

Risk Factors for AVF Infections

• AVFs have the lowest infection risk among all vascular access types for hemodialysis 3
• Central venous dialysis catheters carry the highest risk of infection 3
• Prosthetic arteriovenous grafts have intermediate infection risk 3

Management of Infected AVFs

• Surgical intervention may be required for infected AVFs at the arteriovenous anastomosis, including resection of infected tissue 2
• For infections at cannulation sites, cannulation at that site must cease and the arm should be rested 2
• Metastatic complications can occur with any access-related bacteremia 2

Common Pitfalls to Avoid

1. Inappropriate antibiotic selection: Rifaximin is designed for GI infections and has minimal systemic absorption, making it ineffective for vascular access infections 1

2. Inadequate treatment duration: When systemic antibiotics are indicated for AVF infections, a full 6-week course is typically required 2

3. Delayed intervention: Any signs of infection in an AVF require prompt evaluation and treatment to prevent serious complications 2

4. Failure to obtain cultures: Proper cultures should guide antibiotic selection for targeted therapy 2

5. Overlooking surgical intervention needs: Some infections, particularly those at the AV anastomosis, require immediate surgical intervention in addition to antibiotics 2

In conclusion, rifaximin has no role in the management of post-operative arteriovenous fistula cases and should be discontinued. When antibiotics are needed for AVF infections, appropriate systemic agents with adequate tissue penetration should be selected based on culture results and continued for an adequate duration.