Antibiotic Management for Appendicitis
For uncomplicated appendicitis, administer a single preoperative dose of broad-spectrum antibiotics (cefoxitin, cefotetan, or piperacillin-tazobactam) within 60 minutes before surgery and discontinue within 24 hours postoperatively; for complicated appendicitis with adequate source control, limit postoperative antibiotics to 3-5 days maximum. 1, 2
Uncomplicated Appendicitis
Preoperative Prophylaxis
Administer a single dose of broad-spectrum antibiotics 0-60 minutes before surgical incision to reduce wound infections and intra-abdominal abscess formation 2
Recommended single-agent regimens include: 2
- Ticarcillin-clavulanate
- Cefoxitin
- Cefotetan
- Ertapenem
- Moxifloxacin
- Tigecycline
Acceptable combination regimens: metronidazole plus cefazolin, cefuroxime, ceftriaxone, levofloxacin, or ciprofloxacin 2
Postoperative Management
- No postoperative antibiotics are indicated for uncomplicated appendicitis 1, 2
- Discontinue antibiotics within 24 hours after surgery 1
Complicated Appendicitis (Perforated, Abscess, Peritonitis)
Initial Antibiotic Selection
Initiate broad-spectrum IV antibiotics immediately upon diagnosis that cover enteric gram-negative organisms (E. coli) and anaerobes (Bacteroides spp.) 1
Preferred broad-spectrum single agents: 1, 3
- Piperacillin-tazobactam (3.375g IV q6h or 4.5g IV q6h for severe cases)
- Ampicillin-sulbactam
- Ticarcillin-clavulanate
- Imipenem-cilastatin
- Ertapenem
Alternative combination regimens: 1
- Ampicillin + clindamycin (or metronidazole) + gentamicin
- Ceftriaxone + metronidazole
- Ticarcillin-clavulanate + gentamicin
Duration of Therapy
Limit postoperative antibiotics to 3-5 days maximum when adequate source control is achieved 1, 2
- Discontinuation after 24 hours is safe in adults with adequate source control and is associated with shorter hospital stays and lower costs 1
- Do not extend antibiotics beyond 5 days postoperatively even if minor physiological abnormalities persist, as outcomes are equivalent to longer courses 1
- Base discontinuation on clinical resolution: afebrile status, normalizing white blood cell count, and tolerating oral diet 1
Critical Pitfall
Avoid prolonging antibiotics beyond 3-5 days in complicated appendicitis with adequate source control (strong recommendation, high-quality evidence) 1, 2. The STOP-IT trial demonstrated that fixed-duration therapy (approximately 4 days) had similar outcomes to 8-day courses 1.
Pediatric Considerations
Uncomplicated Appendicitis in Children
- Single preoperative dose of second- or third-generation cephalosporin (cefoxitin or cefotetan) 1, 2
- No postoperative antibiotics required 1, 2
Complicated Appendicitis in Children
- Use same broad-spectrum coverage as adults: piperacillin-tazobactam, ampicillin-sulbactam, or triple therapy (ampicillin + clindamycin/metronidazole + gentamicin) 1
- Switch to oral antibiotics after 48 hours if clinically improving 2
- Total antibiotic duration should be less than 7 days postoperatively 2
- Extended-spectrum antibiotics (piperacillin-tazobactam, ceftazidime, cefepime, carbapenems) offer no advantage over narrower-spectrum agents in children 1
Antibiotics to Avoid
Do not use the following agents for empiric therapy: 2
- Ampicillin-sulbactam (inadequate coverage)
- Cefotetan (inadequate coverage)
- Clindamycin alone
- Aminoglycosides as monotherapy
Additional critical pitfalls: 2
- Do not routinely cover Enterococcus in community-acquired appendicitis
- Do not provide empiric antifungal coverage for Candida
- Avoid quinolones unless local E. coli susceptibility is ≥90%
Special Considerations
When Metronidazole is NOT Needed
Metronidazole is not indicated when using broad-spectrum beta-lactam/beta-lactamase inhibitor combinations or carbapenems 1, as these agents already provide adequate anaerobic coverage.
Aminoglycoside Considerations
When aminoglycosides are used in combination therapy, administer separately from piperacillin-tazobactam due to in vitro inactivation 3. Monitor aminoglycoside levels in patients with renal impairment 3.
Inadequate Source Control
Continue antibiotics beyond 3-5 days only if adequate source control has not been achieved (e.g., undrained abscess, ongoing peritonitis) 1. In such cases, base duration on clinical and laboratory resolution rather than arbitrary time limits 1.