What antibiotics are used to treat acute appendicitis?

From the Guidelines

Antibiotics are a recommended treatment option for uncomplicated appendicitis, with a common regimen including intravenous piperacillin-tazobactam or ertapenem for 1-3 days, followed by oral antibiotics like amoxicillin-clavulanate for a total 7-10 day course. For adults with uncomplicated appendicitis, the use of antibiotics is supported by the most recent guidelines, including the 2020 update of the WSES Jerusalem guidelines 1. The recommended antibiotic regimens target both aerobic and anaerobic bacteria commonly found in appendicitis.

Key Considerations

• The choice of antibiotic regimen should be based on local microbiologic data, cost, allergies, and formulary availability 1.
• Patients with uncomplicated appendicitis can be safely treated with antibiotics, but those with appendicolith, perforation, abscess, or severe symptoms are generally not candidates for antibiotic-only management and should undergo appendectomy 1.
• The use of broad-spectrum antibiotics given preoperatively is effective in decreasing wound infection and postoperative intra-abdominal abscess, with no apparent difference in the nature of the removed appendix 1.

Antibiotic Regimens

• Intravenous piperacillin-tazobactam (3.375g every 6 hours) or ertapenem (1g daily) for 1-3 days, followed by oral antibiotics like amoxicillin-clavulanate (875/125mg twice daily) for a total 7-10 day course.
• Alternatively, a fully oral regimen may include ciprofloxacin (500mg twice daily) plus metronidazole (500mg three times daily) for 7-10 days.

Monitoring and Follow-up

• Patients should be monitored for improvement within 24-48 hours; persistent or worsening symptoms indicate the need for surgical intervention.
• Antibiotic therapy works by controlling the bacterial infection and reducing inflammation in the appendix. However, antibiotics carry approximately a 30% risk of recurrence within one year 1.

From the FDA Drug Label

In patients treated for IAI (primarily patients with perforated or complicated appendicitis), the clinical success rates were 83.7% (36/43) for ertapenem and 63. 6% (7/11) for ticarcillin/clavulanate in the EPP analysis. The antibiotic ertapenem can be used to treat appendicitis, with a clinical success rate of 83.7% in patients with perforated or complicated appendicitis 2.

• The clinical success rate for ertapenem is higher than that of ticarcillin/clavulanate (63.6%) in the treatment of intra-abdominal infections (IAI), which includes appendicitis.
• Ertapenem is a suitable option for the treatment of appendicitis, particularly in cases of perforated or complicated appendicitis.

From the Research

Antibiotics for Appendicitis

• The use of antibiotics for appendicitis has been studied in various research papers, with some suggesting that broad-spectrum antibiotics can successfully treat uncomplicated acute appendicitis in approximately 70% of patients 3.
• A review of the literature found that antibiotic therapy was associated with fewer immediate complications than surgery, but more subsequent failures 4.
• The choice of antibiotic regimen can vary, with some studies comparing the effectiveness of different regimens, such as ceftriaxone plus metronidazole versus anti-pseudomonal antibiotics for perforated appendicitis in children 5, 6.
• A population-based study found that antibiotic treatment can be offered as the first-line therapy to a majority of unselected patients with acute appendicitis, with fewer complications compared to primary surgery 7.
• The diagnosis of acute appendicitis is typically based on history, physical examination, laboratory evaluation, and imaging, with specific imaging findings on computed tomography (CT) helping to identify patients who may be more likely to fail antibiotic treatment 3.
• The treatment of appendicitis with antibiotics may be associated with a higher risk of recurrence, with one study finding that 38 patients (11%) experienced recurrent appendicitis at 1-year follow-up 7.

Types of Antibiotics Used

• Broad-spectrum antibiotics, such as piperacillin-tazobactam monotherapy or combination therapy with either cephalosporins or fluoroquinolones with metronidazole, have been used to treat uncomplicated acute appendicitis 3.
• Ceftriaxone plus metronidazole has been compared to anti-pseudomonal antibiotics for perforated appendicitis in children, with similar post-operative complication rates found between the two groups 6.
• Amoxicillin + clavulanic acid, cefotaxime, or a fluoroquinolone, often with metronidazole or tinidazole, have been used in some studies 4.

Patient Selection

• Patients with uncomplicated acute appendicitis may be more likely to benefit from antibiotic treatment, while those with complicated appendicitis or high-risk CT findings may require surgical management 3.
• The decision to use antibiotics or surgery should be based on individual patient factors, including the presence of high-risk CT findings, patient preferences, and perioperative risk assessment 3.