What are the recommended antibiotics (Abx) for diverticulitis?

Antibiotic Recommendations for Diverticulitis

For uncomplicated diverticulitis in immunocompetent patients without systemic manifestations, antibiotics may be avoided altogether, with management focusing on observation, pain control, and dietary modification. 1, 2

Antibiotic Treatment Algorithm Based on Patient Factors

Uncomplicated Diverticulitis

Patients who do NOT require antibiotics:

• Immunocompetent patients without systemic manifestations
• CT-confirmed uncomplicated diverticulitis
• No high-risk factors

Patients who DO require antibiotics (for 7 days maximum):

• Immunocompromised patients
• Elderly patients
• Patients with persistent fever or chills
• Patients with increasing leukocytosis
• Pregnant patients
• Patients with chronic medical conditions (cirrhosis, CKD, heart failure, poorly controlled diabetes)

First-line oral antibiotic options:

• Amoxicillin/clavulanic acid
• Cefalexin + metronidazole
• Ciprofloxacin + metronidazole 2, 3

Small Diverticular Abscesses (<4 cm)

• Antibiotic therapy alone for 7 days 1, 2

Large Diverticular Abscesses (>4 cm)

• Percutaneous drainage combined with antibiotic therapy for 4 days 1, 2

Complicated Diverticulitis or Patients Requiring IV Therapy

Immunocompetent, non-critically ill patients (4 days if source control adequate):

• Piperacillin/tazobactam 4 g/0.5 g q6h
• Ceftriaxone + metronidazole
• Ampicillin/sulbactam 1, 3

Immunocompromised or critically ill patients (up to 7 days):

• Piperacillin/tazobactam 6 g/0.75 g LD then 4 g/0.5 g q6h or 16 g/2 g by continuous infusion
• Eravacycline 1 mg/kg q12h 1

Patients with beta-lactam allergy:

• Eravacycline 1 mg/kg q12h
• Tigecycline 100 mg LD then 50 mg q12h 1

Patients with inadequate/delayed source control or at risk for ESBL-producing organisms:

• Ertapenem 1 g q24h
• Eravacycline 1 mg/kg q12h 1

Septic shock:

• Meropenem 1 g q6h by extended/continuous infusion
• Doripenem 500 mg q8h by extended/continuous infusion
• Imipenem/cilastatin 500 mg q6h by extended infusion
• Eravacycline 1 mg/kg q12h 1

Important Clinical Considerations

Oral vs. IV Administration

• Oral antibiotics are as effective as IV antibiotics for uncomplicated diverticulitis that requires antibiotic treatment 2, 4
• Outpatient management with oral antibiotics is safe and cost-effective, saving approximately €1,600 per patient compared to inpatient IV treatment 5

Duration of Therapy

• 4 days for immunocompetent, non-critically ill patients with adequate source control
• Up to 7 days for immunocompromised or critically ill patients with adequate source control 1
• Patients with ongoing signs of infection beyond 7 days warrant further diagnostic investigation 1

Monitoring Treatment Response

• Monitor inflammatory markers (WBC, CRP, procalcitonin)
• Decreasing procalcitonin ratio (day 1 to day 2) indicates successful treatment
• Rising procalcitonin despite treatment suggests treatment failure requiring surgical intervention 2

Pitfalls and Caveats

1. Avoid unnecessary antibiotics: Recent evidence suggests uncomplicated diverticulitis may be inflammatory rather than infectious, and antibiotics may not affect outcomes in uncomplicated cases 6

2. Recognize high-risk patients: Immunocompromised patients have higher failure rates with standard non-operative treatment and may require more aggressive management 2

3. Consider source control: Antibiotics alone are insufficient for complicated diverticulitis with large abscesses, perforation, or peritonitis

4. Obtain cultures when possible: When draining abscesses, obtain cultures to guide targeted antibiotic therapy 2

5. Plan for follow-up: Schedule colonic evaluation 4-6 weeks after resolution of diverticular abscess to rule out malignancy 2