What are the best intravenous (IV) antibiotics for the treatment of diverticulitis?

From the Guidelines

For diverticulitis requiring intravenous antibiotics, the recommended first-line regimen is a combination of a beta-lactam antibiotic plus an anaerobic agent, such as ceftriaxone 1-2g IV once daily plus metronidazole 500mg IV every 8 hours, as supported by the most recent guidelines 1. This approach is based on the principle of targeting both gram-negative organisms and anaerobes commonly found in the colon, which are the primary pathogens in diverticulitis.

• The choice between regimens should consider local resistance patterns, patient factors such as renal function, and severity of infection.
• Patients with complicated diverticulitis (abscess, perforation) may require longer courses or additional interventions such as drainage procedures alongside antibiotic therapy.
• Treatment duration typically ranges from 4-7 days, with transition to oral antibiotics once clinical improvement occurs (usually after 2-4 days) 1.
• For patients with penicillin allergies, ciprofloxacin 400mg IV every 12 hours plus metronidazole is an appropriate alternative.
• Alternatively, piperacillin-tazobactam 3.375g IV every 6 hours or ertapenem 1g IV once daily can be used as single-agent therapy. The most recent and highest quality study 1 provides the best evidence for guiding the selection of intravenous antibiotics in the treatment of diverticulitis, emphasizing the importance of a tailored approach based on patient-specific factors and the severity of the infection.

From the Research

IV Antibiotics for Diverticulitis

• The following IV antibiotics have been used to treat diverticulitis:
  • Ampicillin, gentamicin, metronidazole, piperacillin, and tazobactam for severe and complicated diverticulitis 2
  • Ciprofloxacin, metronidazole, and rifaximin for uncomplicated diverticular disease 2
• A study comparing ceftriaxone and metronidazole to piperacillin/tazobactam found that ceftriaxone and metronidazole was non-inferior to piperacillin/tazobactam for treating complicated diverticulitis 3
• Another study found that amoxicillin-clavulanate may reduce the risk of fluoroquinolone-related harms without adversely affecting diverticulitis-specific outcomes in outpatient diverticulitis treatment 4

Considerations for Antibiotic Choice

• The use of ceftriaxone for more than 4 days may increase the incidence of intra-abdominal Enterococcus faecium detection 5
• Broad-spectrum antibiotics are recommended for patients with complicated diverticulitis, while outpatient management is considered the best strategy for uncomplicated patients 6
• The combination of mesalazine and an antibiotic may be more effective than antibiotics alone in improving symptoms and preventing recurrence of diverticulitis 2

Antibiotic Regimens

• Ceftriaxone and metronidazole: non-inferior to piperacillin/tazobactam for complicated diverticulitis 3
• Piperacillin/tazobactam: commonly used for severe and complicated diverticulitis 2, 3
• Amoxicillin-clavulanate: may be a suitable alternative to fluoroquinolone-based regimens for outpatient diverticulitis treatment 4