What are the best antibiotics to treat diverticulitis?

From the Guidelines

The best approach for treating diverticulitis involves selective use of antibiotics, reserving them for patients with complicated diverticulitis, those who are immunocompromised, or have signs of systemic inflammation, with recommended regimens including metronidazole plus a fluoroquinolone or amoxicillin-clavulanate for 7-10 days. When considering the treatment of diverticulitis, it's crucial to differentiate between uncomplicated and complicated cases, as well as the patient's immune status and presence of systemic inflammation 1. For uncomplicated diverticulitis, recent evidence suggests that antibiotics may not be necessary in immunocompetent patients without signs of systemic inflammation, as the condition can be self-limiting and managed by local host defenses 1.

Key factors that guide the decision to use antibiotics include the presence of comorbidities, frailty, refractory symptoms, vomiting, elevated CRP (>140 mg/L), or a high baseline white blood cell count (> 15 × 10^9 cells per liter) 1. In such cases, antibiotics with broad-spectrum coverage, including gram-negative and anaerobic organisms, are recommended. Common regimens for outpatient treatment of mild uncomplicated diverticulitis include a combination of an oral fluoroquinolone and metronidazole or monotherapy with oral amoxicillin-clavulanate 1.

For patients requiring hospitalization due to more severe diverticulitis, intravenous antibiotics such as piperacillin-tazobactam, ampicillin-sulbactam, or ceftriaxone plus metronidazole are appropriate options. It's also important to note that patients with penicillin allergies can be treated with alternative regimens such as clindamycin plus a fluoroquinolone. The duration of antibiotic treatment typically ranges from 4 to 7 days but can be extended based on the patient's clinical response, immune status, and severity of presentation 1.

During treatment, patients should initially follow a clear liquid diet, gradually progressing to low-fiber foods as symptoms improve, and should be instructed to contact their healthcare provider if fever persists, pain worsens, or they are unable to tolerate oral intake. The selective use of antibiotics, based on the severity and complications of diverticulitis, aims to minimize unnecessary antibiotic exposure while ensuring effective treatment for those who require it, thus optimizing outcomes in terms of morbidity, mortality, and quality of life.

From the FDA Drug Label

Intra-abdominal Infections caused by E. coli, Klebsiella species (including K pneumoniae), Streptococcus species, Bacteroides fragilis, Prevotella melaninogenica, Bacteroides vulgatus and Clostridium species (other than Clostridium difficile [see WARNINGS])

1. 6 Complicated Intra-Abdominal Infections Two randomized, active controlled trials of cIAI were performed A double-blind trial was conducted primarily in North America to compare the efficacy of sequential intravenous/oral moxifloxacin 400 mg once a day for 5 to 14 days to intravenous /piperacillin/tazobactam followed by oral amoxicillin/clavulanic acid in the treatment of patients with cIAI, including peritonitis, abscesses, appendicitis with perforation, and bowel perforation

The best antibiotics to treat diverticulitis are not explicitly stated in the provided drug labels. However, based on the information provided, Cefotetan and Moxifloxacin may be considered as options for the treatment of intra-abdominal infections, which include diverticulitis.

• Cefotetan is indicated for the treatment of intra-abdominal infections caused by susceptible strains of designated organisms, including E. coli, Klebsiella species, and Bacteroides fragilis.
• Moxifloxacin has been shown to be effective in the treatment of complicated intra-abdominal infections, including those caused by E. coli, Klebsiella pneumoniae, and Bacteroides fragilis. It is essential to note that the choice of antibiotic should be based on the specific causative organisms and their susceptibility patterns, as well as the severity of the infection and the patient's condition 2 3.

From the Research

Antibiotics for Diverticulitis

The following antibiotics have been studied for the treatment of diverticulitis:

• Amoxicillin-clavulanate: This antibiotic has been shown to be effective in treating diverticulitis, with no differences in 1-year admission risk, 1-year urgent surgery risk, 3-year elective surgery risk, or 1-year Clostridioides difficile infection risk compared to metronidazole-with-fluoroquinolone 4.
• Metronidazole-with-fluoroquinolone: This combination of antibiotics has been commonly used to treat diverticulitis, but the U.S. Food and Drug Administration has advised that fluoroquinolones be reserved for conditions with no alternative treatment options 4.
• Ciprofloxacin: This antibiotic has been used in combination with metronidazole to treat diverticulitis, but its use has been questioned due to the risk of Clostridioides difficile infection 4.
• Ceftriaxone and metronidazole: This combination of antibiotics has been shown to be non-inferior to piperacillin/tazobactam for the treatment of complicated diverticulitis, with no significant differences in 30-day readmission or all-cause mortality, 30-day antibiotic failure, or 90-day Clostridioides difficile infection rate 5.
• Piperacillin/tazobactam: This antibiotic has been used to treat complicated diverticulitis, but its effectiveness compared to other antibiotics is still being studied 5.

Treatment Duration and Outcomes

The duration of antibiotic treatment for diverticulitis can vary, but most studies have used a treatment duration of 7-10 days:

• A study of outpatient treatment of uncomplicated acute diverticulitis found that oral antibiotics for 7 days were effective in treating the condition, with only 3% of patients requiring admission to the hospital 6.
• Another study found that the rate of emergency surgery within 30 days may be lower with no antibiotics compared to antibiotics, but the evidence is still limited and uncertain 7.

Choosing the Best Antibiotic

The choice of antibiotic for diverticulitis depends on various factors, including the severity of the condition, the presence of comorbidities, and the risk of antibiotic resistance:

• Amoxicillin-clavulanate may be a good option for outpatient treatment of uncomplicated diverticulitis, as it has been shown to be effective and has a lower risk of Clostridioides difficile infection compared to metronidazole-with-fluoroquinolone 4.
• Ceftriaxone and metronidazole may be a good option for the treatment of complicated diverticulitis, as it has been shown to be non-inferior to piperacillin/tazobactam 5.