Antimicrobial prophylaxis for appendectomy and colorectal surgery.

Current opinion favors the use of antimicrobial prophylaxis in all operations for acute appendicitis. In clinical trials with placebo controls, the reduction in the rate of postoperative infectious complications is most apparent in perforated and/or gangrenous appendicitis, but benefits are also seen in nonperforated appendicitis and even in those with a normal appendix. In elective colorectal operations, it has been established that all patients should receive prophylactic antibiotics. The choices are an oral bowel preparation consisting of neomycin or kanamycin combined with erythromycin or metronidazole; a parenteral antimicrobial drug such as cefoxitin or cefotetan; or a combined oral/parenteral regimen. Risk factors for postoperative wound infection include a prolonged duration of surgery (greater than 3.5 hours) and rectal resection. The most popular prophylactic regimen employed by American surgeons, particularly in the presence of adverse risk factors, is oral neomycin/erythromycin along with a short course (one to three doses) of a systemic cephalosporin active against anaerobes.