What is the antibiotic of choice for biliary peritonitis?

Antibiotic of Choice for Biliary Peritonitis

For biliary peritonitis, piperacillin/tazobactam is the antibiotic of choice and should be started immediately (within 1 hour) to reduce morbidity and mortality. 1

First-Line Treatment

Biliary peritonitis requires prompt antibiotic therapy along with source control measures. The 2021 World Society of Emergency Surgery guidelines provide clear recommendations:

• Piperacillin/tazobactam: First-line agent with excellent coverage against common biliary pathogens 1, 2
• Alternative options (if piperacillin/tazobactam unavailable):
  • Imipenem/cilastatin
  • Meropenem
  • Ertapenem
  • Aztreonam (with additional coverage if needed) 1

Special Considerations

• For patients in shock: Add amikacin to the regimen 1
• For fragile patients or delayed diagnosis: Consider adding fluconazole for antifungal coverage 1
• For patients with previous biliary infection/stenting: Consider 4th-generation cephalosporins with adjustments based on culture results 1

Microbiology Rationale

Biliary peritonitis typically involves polymicrobial infection with:

• Gram-negative bacteria (E. coli, Klebsiella, Pseudomonas)
• Anaerobes (Bacteroides species)
• Gram-positive organisms (Enterococci, Streptococci) 1

Piperacillin/tazobactam provides excellent coverage against this spectrum of organisms and has FDA approval specifically for intra-abdominal infections including peritonitis 2.

Treatment Duration

• For biloma and generalized peritonitis: 5-7 days of antibiotic therapy 1
• Treatment should be continued for 2 weeks if Enterococcus or Streptococcus is isolated to prevent endocarditis 1

Source Control

Antibiotics alone are insufficient. Source control is the first priority in biliary peritonitis:

• Percutaneous drainage for biloma
• Surgical intervention for generalized peritonitis 1
• In severe complicated intra-abdominal sepsis, open abdomen may be considered for patients with organ failure and gross contamination 1, 3

Common Pitfalls to Avoid

1. Delayed antibiotic administration: In severe sepsis or shock, antibiotics must be started within 1 hour 1
2. Inadequate source control: Antibiotics alone won't resolve the infection without addressing the underlying biliary leak 1
3. Failure to adjust therapy based on culture results: Initial empiric therapy should be modified based on bile culture findings 1
4. Overlooking fungal infection: Consider antifungal therapy in fragile patients or cases with delayed diagnosis 1
5. Aminoglycoside toxicity: Elderly patients with biliary disease have higher risk of renal problems; monitor closely when using amikacin 4

Monitoring Response

• Clinical improvement should be seen within 48-72 hours
• If a large cholangiolytic abscess doesn't respond to antibiotics within this timeframe, consider percutaneous drainage 1
• For patients with persistent biliary candidiasis, be aware of markedly reduced transplant-free survival and higher risk of cholangiocarcinoma 1

Piperacillin/tazobactam remains the cornerstone of antibiotic therapy for biliary peritonitis, providing broad-spectrum coverage while minimizing nephrotoxicity compared to aminoglycoside-containing regimens 4, 5.