What antibiotics (abx) are used to treat appendicitis?

From the Guidelines

For appendicitis, the recommended antibiotic regimen is a single dose of broad-spectrum antibiotics given preoperatively, such as ceftriaxone 1-2g IV daily plus metronidazole 500mg IV every 8 hours, with treatment duration typically 24 hours for uncomplicated cases treated surgically, while complicated appendicitis requires 5-7 days of therapy 1.

Antibiotic Regimens for Appendicitis

The choice of antibiotic regimen depends on the severity of the infection. For uncomplicated appendicitis, a single agent like cefazolin 1-2g IV every 8 hours may be sufficient. However, for complicated appendicitis (perforated or with abscess), broader coverage is needed with a combination therapy such as piperacillin-tazobactam 3.375g IV every 6 hours or ceftriaxone 1-2g IV daily plus metronidazole 500mg IV every 8 hours 1.

Key Considerations

• Antibiotics should be started preoperatively when appendectomy is planned 1.
• For patients managed non-operatively with antibiotics alone, a 7-10 day course is recommended, often with IV antibiotics for 1-3 days followed by oral options like amoxicillin-clavulanate 875/125mg twice daily 1.
• Antibiotic selection may need adjustment based on local resistance patterns, patient allergies, and culture results when available 1.

Special Considerations

• In pediatric patients, extended-spectrum antibiotics seem to offer no advantage over narrower-spectrum agents for children with surgically managed acute uncomplicated or complicated appendicitis 1.
• For perforated appendicitis, the most common combination is ampicillin, clindamycin (or metronidazole), and gentamicin, or alternatives such as ceftriaxone-metronidazole or ticarcillin-clavulanate plus gentamicin 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.

Meropenem is an antibiotic that can be used to treat appendicitis. The recommended dose for intra-abdominal infections, including appendicitis, is 1 gram given every 8 hours for adult patients 2.

From the Research

Antibiotics for Appendicitis

• The use of broad-spectrum antibiotics, such as piperacillin-tazobactam monotherapy or combination therapy with either cephalosporins or fluoroquinolones with metronidazole, has been shown to successfully treat uncomplicated acute appendicitis in approximately 70% of patients 3.
• A systematic review with meta-analysis found that antibiotic therapy was associated with fewer immediate complications than surgery, but more subsequent failures 4.
• A retrospective review compared outcomes of nonperforated, perforated, and abscessed cases who received either a historic regimen of cefoxitin and/or ertapenem or a simplified once-daily regimen of ceftriaxone and metronidazole, and found that the latter group had a shorter time to afebrile and significant antibiotic cost savings 5.
• Recent studies have shown the feasibility of antibiotic therapy for uncomplicated appendicitis, with approximately 90% of patients treated with antibiotics able to avoid surgery during the initial admission 6.
• A trial comparing a single intraoperative dose of metronidazole and cefoxitin found that metronidazole was associated with a lower rate of wound infections and a shorter length of postoperative hospital stay 7.

Specific Antibiotic Regimens

• Piperacillin-tazobactam monotherapy or combination therapy with either cephalosporins or fluoroquinolones with metronidazole have been shown to be effective in treating uncomplicated acute appendicitis 3.
• Ceftriaxone plus metronidazole has been found to be a streamlined, cost-effective regimen in the treatment of nonperforated, perforated, and abscessed appendicitis 5.
• Metronidazole has been shown to be effective in reducing the severity of infection and the rate of wound infections in severe appendicitis 7.