What antibiotics are used to treat diverticulitis?

From the Guidelines

Antibiotics should be used selectively in patients with diverticulitis, and the decision to use them should be based on the presence of complications, comorbidities, or high-risk features, as evidenced by the most recent guidelines and studies 1. When antibiotic treatment is necessary, the regimen usually includes broad-spectrum agents with gram-negative and anaerobic coverage.

• For outpatient treatment, combinations of metronidazole (Flagyl) 500 mg three times daily plus either ciprofloxacin (Cipro) 500 mg twice daily or trimethoprim-sulfamethoxazole (Bactrim) 160/800 mg twice daily are commonly used.
• For more severe cases requiring hospitalization, intravenous options include piperacillin-tazobactam (Zosyn) 3.375 g every 6 hours, ceftriaxone 1-2 g daily plus metronidazole, or meropenem 1 g every 8 hours. The duration of treatment is usually 4–7 days but can be longer, depending on the patient's general health status, immune status, severity of presentation, CT findings, and patient expectations, as suggested by the guidelines 1. It is essential to note that recent evidence suggests that antibiotics may not be necessary in immunocompetent patients with mild acute uncomplicated diverticulitis, and their use should be reserved for patients with complicated diverticulitis or those with high-risk features, as supported by studies 1.
• Patients with penicillin allergies may require alternative regimens, such as levofloxacin plus metronidazole.
• Alongside antibiotics, patients should follow a clear liquid diet initially, gradually advancing to low-fiber foods as symptoms improve. The most recent and highest-quality study, published in 2022, suggests that antibiotic therapy can be avoided in immunocompetent elderly patients with uncomplicated left colonic diverticulitis without sepsis-related organ failures, but the evidence is still limited, and further studies are needed to confirm this recommendation 1.

From the Research

Antibiotics Used to Treat Diverticulitis

• The following antibiotics are used to treat diverticulitis:
  • Metronidazole and Ciprofloxacin 2, 3
  • Ampicillin, Gentamicin, Metronidazole, Piperacillin, and Tazobactam for severe and complicated diverticulitis 3
  • Amoxicillin plus Clavulanic acid 4, 5
  • Rifaximin for uncomplicated diverticular disease 3
• These antibiotics can be administered orally or intravenously, depending on the severity of the condition and the patient's overall health.

Treatment Protocols

• Outpatient treatment with oral antibiotics is a viable option for patients with uncomplicated acute diverticulitis 2, 5, 6
• Inpatient treatment with intravenous antibiotics may be necessary for patients with severe or complicated diverticulitis, or for those who are unable to tolerate oral intake 2, 4
• The choice of treatment protocol depends on the individual patient's needs and medical history.

Efficacy and Safety

• Studies have shown that outpatient treatment with oral antibiotics is safe and effective for patients with uncomplicated acute diverticulitis 2, 5, 6
• Treatment failure rates are lower for outpatient treatment compared to inpatient treatment 6
• Predictive factors for treatment failure include admission/CT time, Ambrosetti score, and free air around the colon 6