What are the recommended preoperative antibiotics for acute appendicitis?

From the Guidelines

Preoperative antibiotics are strongly recommended for patients with appendicitis, with a single dose of broad-spectrum antibiotics given from 0 to 60 min before the surgical skin incision. The standard regimen includes a single dose of a broad-spectrum antibiotic, such as cefazolin 2g IV (plus metronidazole 500mg IV if concerned for anaerobic coverage), or ampicillin-sulbactam 3g IV, as recommended by the 2020 update of the WSES Jerusalem guidelines 1. For patients with beta-lactam allergies, alternatives include clindamycin 600-900mg IV plus gentamicin 5mg/kg IV or ciprofloxacin 400mg IV. These antibiotics help prevent surgical site infections by reducing the bacterial load at the surgical site before incision. The choice of antibiotic should cover common gastrointestinal flora including gram-negative organisms and anaerobes.

• Key points to consider when administering preoperative antibiotics for appendicitis include:
  • Timing: administering antibiotics from 0 to 60 min before the surgical skin incision is crucial for effectiveness 1
  • Coverage: broad-spectrum antibiotics should cover common gastrointestinal flora, including gram-negative organisms and anaerobes
  • Dosage: a single dose is typically sufficient for uncomplicated appendicitis, while complicated cases may require continued postoperative antibiotics
• The evidence supporting preoperative antibiotics for appendicitis is strong, with a Cochrane meta-analysis and multiple RCTs demonstrating a significant reduction in surgical site infections and intra-abdominal abscesses 1.

From the FDA Drug Label

1. 2 Complicated Intra-abdominal Infections (Adult and Pediatric Patients) Meropenem for injection is indicated for the treatment of complicated appendicitis and peritonitis caused by viridans group streptococci, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacteroides fragilis, B. thetaiotaomicron,and Peptostreptococcusspecies.

• Scip preop antibiotics for appendicitis: The FDA drug label for meropenem 2 indicates that it is used to treat complicated appendicitis, but it does not provide information on its use as a preoperative antibiotic.
• The FDA drug label for ertapenem 3 provides information on its use in the treatment of complicated intra-abdominal infections, including appendicitis, but also does not provide information on its use as a preoperative antibiotic. The information provided in the drug labels does not directly answer the question about the use of these antibiotics as preoperative prophylaxis for appendicitis.

From the Research

Preoperative Antibiotics for Appendicitis

• The use of preoperative antibiotics in appendicitis is a common practice, with studies suggesting that broad-spectrum antibiotics can successfully treat uncomplicated acute appendicitis in approximately 70% of patients 4.
• A systematic review of the literature recommends that patients with acute appendicitis should receive preoperative, broad-spectrum antibiotics, while postoperative antibiotics are only recommended in cases of perforation 5.
• The choice of antibiotic regimen is important, with studies comparing different regimens such as ceftriaxone plus metronidazole versus ertapenem and/or cefoxitin for pediatric appendicitis, showing that a simplified once-daily regimen of ceftriaxone and metronidazole is cost-effective and effective in perforated patients 6.
• Antibiotics as first-line therapy for acute appendicitis have been shown to be effective, with a population-based study confirming previous results of randomized studies, and suggesting that antibiotic treatment can be offered as the first-line therapy to a majority of unselected patients with acute appendicitis 7.

Specific Antibiotic Regimens

• Piperacillin-tazobactam monotherapy or combination therapy with either cephalosporins or fluroquinolones with metronidazole have been shown to be effective in treating uncomplicated acute appendicitis 4.
• Cefotetan, a second-generation, broad-spectrum cephalosporin, has been shown to be an effective adjunctive regimen in patients with complicated appendicitis 8.
• Ceftriaxone plus metronidazole has been shown to be a cost-effective and effective regimen in the treatment of nonperforated, perforated, and abscessed appendicitis 6.

Patient Selection

• Patients with high-risk CT findings, such as appendicolith, mass effect, or a dilated appendix, are more likely to fail antibiotic treatment and may require surgical management 4.
• Patients without high-risk CT findings may be considered for antibiotic treatment as first-line therapy, while those with high-risk CT findings may require surgical management 4.
• Unfit patients without high-risk CT findings may be considered for an antibiotics-first approach, while those with high-risk CT findings may require perioperative risk assessment and patient preferences to be considered 4.