What are the recommended antibiotics for diverticulitis (inflammation of the diverticula)?

From the Guidelines

Antibiotics should be used selectively in patients with acute uncomplicated diverticulitis, and are recommended for those with comorbidities, frailty, refractory symptoms, vomiting, CRP >140 mg/L, or baseline white blood cell count > 15 × 10^9 cells per liter, as well as for patients with complicated diverticulitis or uncomplicated diverticulitis with a fluid collection or longer segment of inflammation on CT scan 1.

Key Considerations

• The decision to use antibiotics in diverticulitis should be based on the severity of the disease and the presence of complications or high-risk factors.
• For mild cases treated as outpatients, oral antibiotics such as amoxicillin-clavulanate or the combination of metronidazole plus either ciprofloxacin or trimethoprim-sulfamethoxazole may be prescribed for 7-10 days.
• For more severe cases requiring hospitalization, intravenous antibiotics such as ceftriaxone plus metronidazole or piperacillin-tazobactam may be used until improvement occurs, followed by oral antibiotics to complete the course.

Patient Selection for Antibiotics

• Immunocompromised patients are at high risk for complications and should be treated with antibiotics.
• Patients with evidence of systemic inflammation, abscess, perforation, or obstruction should also receive antibiotics.
• The presence of a fluid collection or longer segment of inflammation on baseline CT is associated with an increased risk of progression to complicated diverticulitis and should be treated with antibiotics.

Antibiotic Regimens

• Oral antibiotics such as amoxicillin-clavulanate (875/125 mg twice daily) or the combination of metronidazole (500 mg three times daily) plus either ciprofloxacin (500 mg twice daily) or trimethoprim-sulfamethoxazole (160/800 mg twice daily) are commonly used for outpatient treatment.
• Intravenous antibiotics such as ceftriaxone (1-2 g daily) plus metronidazole (500 mg every 8 hours) or piperacillin-tazobactam (3.375 g every 6 hours) may be used for inpatient treatment.

Duration of Treatment

• The duration of antibiotic treatment is usually 4-7 days, but can be longer based on the patient's general health status, immune status, severity of presentation, CT findings, and patient expectations 1.

Supporting Evidence

• A systematic review and meta-analysis of 9 studies found no difference in time to resolution or risk of readmission, progression to a complication, or need for surgery among patients treated with antibiotics compared to those not treated with antibiotics in immunocompetent patients with mild acute uncomplicated diverticulitis 1.
• The 2020 update of the WSES guidelines for the management of acute colonic diverticulitis in the emergency setting recommends against routine antibiotic therapy in immunocompetent patients with uncomplicated diverticulitis, but suggests that antibiotics may be necessary in patients with high-risk factors or complications 1.

From the Research

Diverticulitis Antibiotics

• The use of antibiotics in treating diverticulitis is a topic of ongoing debate, with some studies suggesting that antibiotics may not be necessary for uncomplicated cases 2.
• A study published in 2010 found that outpatient treatment with oral antibiotics was safe and effective for patients with uncomplicated acute diverticulitis, with only 3% of patients requiring admission to the hospital 3.
• Another study published in 1999 found that the majority of colon and rectal surgeons used antibiotics to treat uncomplicated diverticulitis, with ciprofloxacin and metronidazole being common choices 4.
• A 2022 systematic review found that the evidence on antibiotic treatment for uncomplicated acute diverticulitis is limited, and the effect of antibiotics on complications, emergency surgery, and recurrence is uncertain 2.
• A 2017 study found that outpatient treatment with antibiotics was feasible and safe for patients with uncomplicated or mild complicated diverticulitis, with a lower failure rate compared to inpatient treatment 5.
• A 2021 study compared the effectiveness and harms of metronidazole-with-fluoroquinolone versus amoxicillin-clavulanate for outpatient diverticulitis, and found no differences in admission risk, urgent surgery risk, or elective surgery risk, but a higher risk of Clostridioides difficile infection with metronidazole-with-fluoroquinolone 6.

Antibiotic Regimens

• Common antibiotic regimens used to treat diverticulitis include:
  • Amoxicillin-clavulanic acid
  • Ciprofloxacin and metronidazole
  • Metronidazole-with-fluoroquinolone
• The choice of antibiotic regimen may depend on the severity of the disease, patient comorbidities, and local resistance patterns.

Treatment Outcomes

• Studies have shown that outpatient treatment with antibiotics can be effective in managing uncomplicated diverticulitis, with low failure rates and few complications 3, 5.
• However, the use of antibiotics may also be associated with harms, such as Clostridioides difficile infection, and the risk of antibiotic resistance 2, 6.