What is the recommended antibiotic regimen with dosing for acute diverticulitis?

Recommended Antibiotic Regimens for Acute Diverticulitis

For acute uncomplicated diverticulitis, antibiotics can be used selectively rather than routinely in immunocompetent patients, with specific regimens based on patient factors and severity when antibiotics are indicated. 1

Patient Stratification for Antibiotic Use

Uncomplicated Diverticulitis

• Antibiotics are not routinely required for immunocompetent patients with mild uncomplicated diverticulitis 1, 2
• Antibiotic therapy (up to 7 days) is recommended for uncomplicated diverticulitis in the following patients:
  • Immunocompromised patients 1
  • Elderly patients 1
  • Patients with comorbidities or frailty 1
  • Patients with refractory symptoms or vomiting 1
  • Patients with elevated inflammatory markers (CRP >140 mg/L or WBC >15 × 10^9/L) 1
  • Patients with fluid collection or longer segment of inflammation on CT 1

Complicated Diverticulitis

• Antibiotic therapy is mandatory for all cases of complicated diverticulitis (abscess, perforation, fistula, obstruction) 1, 3

Specific Antibiotic Regimens by Patient Category

Outpatient Management (Mild Uncomplicated Diverticulitis)

• First-line oral regimen: Amoxicillin-clavulanate OR ciprofloxacin plus metronidazole 3
  • Amoxicillin-clavulanate: Dosing not specified in guidelines
  • Ciprofloxacin: 500 mg PO q12h 4
  • Metronidazole: Typically 500 mg PO q8h (based on general knowledge)

Inpatient Management (Moderate-Severe or Complicated Diverticulitis)

Immunocompetent, Non-Critically Ill Patients with Adequate Source Control

• Duration: 4 days of antibiotic therapy 1
• Recommended regimens:
  • Piperacillin/tazobactam: 4 g/0.5 g q6h 1, 5
  • Ceftriaxone plus metronidazole 3
  • Ciprofloxacin 400 mg IV q12h plus metronidazole 5

Immunocompromised or Critically Ill Patients with Adequate Source Control

• Duration: Up to 7 days based on clinical condition and inflammatory markers 1
• Recommended regimens:
  • Piperacillin/tazobactam: 4 g/0.5 g q6h or 16 g/2 g by continuous infusion 1, 5
  • Eravacycline: 1 mg/kg q12h 1, 5

Patients with Inadequate/Delayed Source Control or High Risk for ESBL-producing Enterobacterales

• Ertapenem: 1 g q24h 1, 5
• Eravacycline: 1 mg/kg q12h 1, 5

Patients with Septic Shock

• One of the following:
  • Meropenem: 1 g q6h by extended or continuous infusion 1, 5
  • Doripenem: 500 mg q8h by extended or continuous infusion 1
  • Imipenem/cilastatin: 500 mg q6h by extended infusion 1
  • Eravacycline: 1 mg/kg q12h 1, 5

Patients with Documented Beta-lactam Allergy

• Eravacycline: 1 mg/kg q12h 1, 5
• Tigecycline: 100 mg loading dose, then 50 mg q12h 1, 5

Special Considerations

Diverticular Abscess Management

• Small abscesses: Antibiotic therapy alone for 7 days 1
• Large abscesses: Percutaneous drainage combined with antibiotic therapy for 4 days 1

Monitoring Response to Therapy

• Monitor white blood cell count, C-reactive protein, and procalcitonin 1, 5
• Patients with ongoing signs of infection beyond 7 days warrant further diagnostic investigation 1, 5

Diet Recommendations

• Clear liquid diet during acute phase 1
• Advance diet as symptoms improve 1

Common Pitfalls and Caveats

• Failure to recognize patients who need antibiotics despite having "uncomplicated" diverticulitis (immunocompromised, elderly, high inflammatory markers) 1
• Unnecessarily prolonged antibiotic courses beyond 7 days without clinical indication 1
• Failure to investigate persistent symptoms beyond 5-7 days of appropriate therapy 1
• Using antibiotics routinely for all cases of uncomplicated diverticulitis, contrary to current evidence 1, 2