What antibiotics should be given for a ruptured appendix?

Antibiotic Treatment for Ruptured Appendix

For a ruptured appendix, piperacillin-tazobactam 4.5g IV every 6 hours is the preferred first-line antibiotic treatment for critically ill patients, while ceftriaxone 2g daily plus metronidazole 500mg every 6 hours is recommended for non-critically ill patients. 1

Treatment Algorithm Based on Patient Status

For Non-Critically Ill Patients:

• First-line options:

  • Ceftriaxone 2g IV every 24 hours + Metronidazole 500mg IV every 6 hours 1
  • Cefotaxime 2g IV every 8 hours + Metronidazole 500mg IV every 6 hours 1
  • Amoxicillin/clavulanate 1.2-2.2g IV every 6 hours 1

• For patients with beta-lactam allergy:

  • Ciprofloxacin 400mg IV every 8 hours + Metronidazole 500mg IV every 6 hours 1
  • Moxifloxacin 400mg IV every 24 hours 1

• For patients at risk for ESBL-producing Enterobacteriaceae:

  • Ertapenem 1g IV every 24 hours 1, 2
  • Tigecycline 100mg IV initial dose, then 50mg every 12 hours 1

For Critically Ill Patients:

• First-line options:

  • Piperacillin/Tazobactam 4.5g IV every 6 hours 1
  • Cefepime 2g IV every 8 hours + Metronidazole 500mg IV every 6 hours 1

• For patients at risk for ESBL-producing Enterobacteriaceae:

  • Meropenem 1g IV every 8 hours 1
  • Doripenem 500mg IV every 8 hours 1
  • Imipenem/Cilastatin 1g IV every 8 hours 1

• For patients at high risk for Enterococci:

  • Add Ampicillin 2g IV every 6 hours (if not using piperacillin-tazobactam or imipenem-cilastatin) 1

Duration of Therapy

• For adequately drained intra-abdominal infections: 3-5 days of antibiotic therapy is sufficient 1
• For complicated appendicitis with adequate source control: Do not prolong antibiotics beyond 3-5 days 1
• For pediatric patients: Early switch (after 48 hours) to oral antibiotics with total therapy duration less than 7 days 1

Special Considerations

• For pediatric patients with complicated intra-abdominal infection:

  • Acceptable regimens include aminoglycoside-based regimens, carbapenems, beta-lactam/beta-lactamase inhibitor combinations, or advanced-generation cephalosporins with metronidazole 1
  • Once-daily ceftriaxone plus metronidazole has shown to be cost-effective and efficacious for perforated appendicitis in children 3, 4

• For patients at high risk for invasive candidiasis:

  • Consider adding echinocandins (caspofungin: 70mg loading dose, then 50mg daily; anidulafungin: 200mg loading dose, then 100mg daily) 1

Important Clinical Pearls

• Avoid ampicillin-sulbactam due to high rates of resistance among community-acquired E. coli 1
• Avoid cefotetan and clindamycin due to increasing prevalence of resistance among Bacteroides fragilis group 1
• Empiric coverage of Enterococcus is not necessary in patients with community-acquired intra-abdominal infection unless they are immunocompromised 1
• Metronidazole dosing: 500mg IV every 8-12 hours or 1500mg IV every 24 hours for adults; 15mg/kg loading dose followed by 7.5mg/kg every 6 hours for anaerobic infections 5
• Monitor drug levels for aminoglycosides and vancomycin to optimize dosing and minimize toxicity 1

Antibiotic Selection Based on Local Resistance Patterns

• Consider local microbiology data when selecting antibiotics, particularly for quinolone-resistant E. coli and resistant B. fragilis isolates 1
• In areas with high ESBL prevalence, carbapenems may be preferred, though judicious use is recommended to prevent resistance development 1

Remember that early and effective source control (surgical drainage) remains the cornerstone of treatment for ruptured appendix, with antibiotics serving as an essential adjunct to surgery 1.