What is the most common cause of prosthetic graft infection?

Most Common Cause of Prosthetic Graft Infection

Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, are the most common cause of prosthetic graft infections. 1

Microbiology of Vascular Graft Infections

• The microbiology of vascular graft infections (VGIs) has evolved over time. While Staphylococcus aureus was historically the predominant organism, improvements in surgical technique and prophylactic antimicrobial therapy have changed the epidemiological landscape 1
• Gram-positive cocci account for at least two-thirds of all vascular graft infections 1
• Coagulase-negative staphylococci (particularly S. epidermidis) are now more commonly isolated than S. aureus in prosthetic graft infections 1
• Among S. aureus infections, methicillin-resistant S. aureus (MRSA) infections are increasing in frequency 1
• Pseudomonas aeruginosa is the most common gram-negative organism, accounting for approximately 10% of vascular graft infections 1

Pathogenesis and Risk Factors

• Intraoperative bacterial contamination is considered the most common cause of vascular graft infections 1
• S. epidermidis has a particular affinity for prosthetic materials and forms biofilms that significantly reduce antibiotic effectiveness 2
• Biofilm formation on prosthetic materials can increase the minimal bactericidal concentration of most antibiotics by 1000-fold 2
• Risk factors for prosthetic graft infection include:
  • Redo bypass procedures 3
  • Active infection at the time of bypass 3
  • Female gender 3
  • Diabetes mellitus 3
  • Emergency procedures 1

Clinical Presentation

• Prosthetic graft infections can present differently based on timing and location:
  • Early-onset infections (<2 months post-op) typically present with fever, chills, leukocytosis, and sepsis 1
  • Late-onset infections (>2 months post-op) often present with more indolent symptoms including local erythema, painful swelling, or sinus tract drainage 1
• Extracavitary infections (most commonly in the groin) are more readily apparent than intracavitary (abdominal or thoracic) infections 1
• The most obvious sign of graft infection is a draining sinus tract 1

Diagnostic and Treatment Considerations

• The frequency of vascular graft infection varies by anatomic location:
  • 1.5-2% for most extracavitary grafts 1
  • Up to 6% for vascular grafts in the groin 1
  • 1-5% for intracavitary grafts 1
• Treatment typically involves surgical removal of the infected graft followed by prolonged antibiotic therapy 4
• For S. epidermidis infections, vancomycin combined with rifampin, gentamicin, or both is often recommended for empiric therapy 5
• Removal of the prosthetic device is usually necessary for successful treatment 5

Important Clinical Implications

• Prosthetic graft infection is associated with significant morbidity and mortality:
  • 10-25% mortality within 30 days of diagnosis 4
  • Significantly increased risk of major limb amputation (HR 9.8) 3
• Early recognition and appropriate treatment are essential to improve outcomes
• When feasible in high-risk patients, autologous vein for lower extremity bypass or endovascular interventions should be considered instead of prosthetic grafts 3