What antibiotics are used to treat acute diverticulitis?

Antibiotic Treatment for Acute Diverticulitis

For acute diverticulitis, antibiotics should be used selectively rather than routinely, with oral amoxicillin-clavulanate or ciprofloxacin plus metronidazole being the preferred regimens when antibiotics are indicated. 1, 2

Patient Stratification for Antibiotic Treatment

Uncomplicated Diverticulitis

• Immunocompetent patients without systemic manifestations:

  • Symptomatic treatment alone (no antibiotics)
  • Clear liquid diet that advances as symptoms improve
  • Oral analgesics
  • Re-evaluation within 7 days 1, 2

• Antibiotics indicated for uncomplicated diverticulitis if:

  • Patient is immunocompromised
  • Elderly or has significant comorbidities
  • Presents with systemic manifestations of infection
  • Has refractory symptoms or vomiting
  • CRP >140 mg/L or WBC >15 × 10^9/L
  • Fluid collection or longer segment of inflammation on CT 1, 2

Complicated Diverticulitis

• Always requires antibiotic treatment
• Small abscesses: Antibiotics alone for 7 days
• Large abscesses: Percutaneous drainage plus antibiotics for 4 days 2
• Peritonitis: IV antibiotics with gram-negative and anaerobic coverage 2

Antibiotic Regimens

Outpatient Treatment (4-7 days)

• First choice: Amoxicillin-clavulanate (oral) 1, 2, 3
• Alternative: Ciprofloxacin plus metronidazole (oral) 1, 2, 3
  • Note: Recent evidence shows amoxicillin-clavulanate may reduce the risk of C. difficile infection compared to metronidazole-with-fluoroquinolone combinations 3

Inpatient Treatment

• IV antibiotics with gram-negative and anaerobic coverage
• Switch to oral antibiotics when clinically improved 2
• Common regimens include:
  • Amoxicillin-clavulanate IV
  • Ciprofloxacin plus metronidazole IV 1

Special Considerations

• Immunocompromised patients:

  • Lower threshold for imaging, antibiotic treatment, and surgical consultation
  • Extended antibiotic duration (10-14 days) 2
  • Higher risk for complicated disease 1

• Outpatient vs. Inpatient Management:

  • Outpatient management is appropriate for patients who:
    • Can tolerate oral intake
    • Have no significant comorbidities
    • Have adequate pain control with oral analgesics
    • Have appropriate home support
    • Have stable vital signs 2, 4
  • Outpatient treatment has shown similar safety and efficacy to inpatient treatment 4, 5

Important Clinical Pearls

• The shift away from routine antibiotics for uncomplicated diverticulitis is supported by multiple studies showing no difference in outcomes between antibiotic and non-antibiotic treatment in immunocompetent patients 1, 6
• Fluoroquinolones should be reserved for cases with no alternative treatment options due to potential adverse effects 3
• For patients requiring antibiotics, treatment duration is typically 4-7 days but may be extended based on clinical response 1, 2
• Closely monitor patients with risk factors for progression to complicated diverticulitis, including elevated inflammatory markers and longer segments of inflammation on CT 1