S815
SESSION II: CLINICAL USES OF PROPHYLAXIS Antimicrobial Prophylaxis for Appendectomy and Colorectal Surgery Sherwood L. Gorbach
From the Department of Community Health and Medicine, Tufts University School of Medicine, Boston, Massachusetts
Because of the high density of bacteria in the large intestine, appendectomy and colorectal surgery incur a high risk of postoperative infection. The abdominal wall incision is at greatest risk, although deep wound infections with abscesses, fistulas, and anastomotic leaks can also develop. The aerobic and anaerobic components of the intestinal microflora are the common pathogens, particularly Escherichiacoli among the aerobes and Bacteroides fragilis among the anaerobes. In an effort to reduce postoperative infectious complications, antimicrobial prophylaxis is widely used-with good reasonin these operations.
Appendicitis It is generally accepted that patients with perforated or gangrenous appendicitis should receive antibiotics preoperatively since this situation constitutes active infection and is not, in a strict sense, antimicrobial prophylaxis [1, 2]. An argument has arisen, however, over the use of preoperative antibiotics in nonperforated appendicitis; indeed, several retrospective studies have failed to show any benefit of prophylactic antibiotics in this setting [3-6], yet more recent studies have forced a reconsideration of this position [2, 7-11]. A major problem in resolving this polemic is the difficulty of establishing the pathophysiologic state of the appendix preoperatively. In light of the pathologist's final diagnosis, the
Reprints and correspondence: Dr. Sherwood L. Gorbach, Tufts University School of Medicine, 136 Harrison Avenue, Boston, Massachusetts 02111. Reviews of Infectious Diseases 1991;13(Suppl lO):S81S-20 © 1991 by The University of Chicago. AU rights reserved. 0162-0886/91/1305-0006$02.00
preoperative clinical diagnosis is notoriously inaccurate [2, 3, 12, 13]. An overtly gangrenous or perforated appendix is encountered in 1'\J20 % of patients undergoing an operation for acute appendicitis; 10%-20% of patients have a normal appendix, and the remaining 60%-70% have nonperforated appendicitis. As shown in a recent study by Browder et al. [2], intraoperative diagnosis based on direct inspection by the surgeon has a poor correlation with the final pathologic diagnosis. In that study the surgeon underestimated the severity of disease in 38 % of cases, frequently missing gangrene, necrosis, or microperforation. In addition, gram stain and culture results for specimens obtained during the procedure are not predictive of the subsequent development of infection or of the type of pathogen in the infected wound [2, 7, 10, 14, 15]. These studies illustrate the difficulty of predicting preoperatively which patients have the more severe forms of appendicitis that definitely require antimicrobial therapy. Several prospective studies have indicated that all patients undergoing appendectomy, whether they have a nonperforated or even a normal appendix, benefit from antimicrobial prophylaxis in terms of a reduced rate of postoperative wound infection. Donovan et al. [16] found a postoperative infection rate of 20 % among patients with a normal appendix who underwent appendectomy and received no antibiotic prophylaxis; the rate was 4 % among those receiving clindamycin and 6 % among those receiving cefazolin. Bauer et al. [11] reported rates of postoperative wound infection of 5 % among placebo-treated controls with a normal appendix and 1% among cefoxitintreated patients (n = 558; P < .007). It appears from these studies that removal of the appendix- whatever its pathologic state - exposes the patient to inadvertent contamination by bowel flora, thereby raising the risk of wound infection.
Downloaded from http://cid.oxfordjournals.org/ at Boston University on August 3, 2015
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 (>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.
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Gorbach
infection in high-risk patients with gangrene or perforation. On the other hand, cephalosporins with good activity against both aerobes and anaerobes, such as cefoxitin [11,32-34] and ceftizoxime [2, 19], have produced favorable results and represent good choices for prophylaxis for appendicitis. It appears that a short antibiotic course - either a single dose [11] or three doses [2, 18]- is sufficient. In patients found to have gangrenous appendicitis and/or abscess formation, it may be necessary to continue antibiotic administration for an additional 3-5 days since these settings represent treatment of active infection rather than prophylaxis.
Colorectal Surgery Several studies of colorectal operations have shown that preoperative antibiotic prophylaxis reduces the rate of postoperative infections [35-38]. In a review of randomized, controlled trials conducted between 1965 and 1980, Baum et al. [37] reported that patients undergoing colorectal operations without prophylaxis or with inappropriate prophylaxis developed wound infections at rates of30%-60%, while patients receiving appropriate antibiotic prophylaxis had significantly lower rates of wound infection (often
SESSION II: CLINICAL USES OF PROPHYLAXIS Antimicrobial Prophylaxis for Appendectomy and Colorectal Surgery Sherwood L. Gorbach
From the Department of Community Health and Medicine, Tufts University School of Medicine, Boston, Massachusetts
Because of the high density of bacteria in the large intestine, appendectomy and colorectal surgery incur a high risk of postoperative infection. The abdominal wall incision is at greatest risk, although deep wound infections with abscesses, fistulas, and anastomotic leaks can also develop. The aerobic and anaerobic components of the intestinal microflora are the common pathogens, particularly Escherichiacoli among the aerobes and Bacteroides fragilis among the anaerobes. In an effort to reduce postoperative infectious complications, antimicrobial prophylaxis is widely used-with good reasonin these operations.
Appendicitis It is generally accepted that patients with perforated or gangrenous appendicitis should receive antibiotics preoperatively since this situation constitutes active infection and is not, in a strict sense, antimicrobial prophylaxis [1, 2]. An argument has arisen, however, over the use of preoperative antibiotics in nonperforated appendicitis; indeed, several retrospective studies have failed to show any benefit of prophylactic antibiotics in this setting [3-6], yet more recent studies have forced a reconsideration of this position [2, 7-11]. A major problem in resolving this polemic is the difficulty of establishing the pathophysiologic state of the appendix preoperatively. In light of the pathologist's final diagnosis, the
Reprints and correspondence: Dr. Sherwood L. Gorbach, Tufts University School of Medicine, 136 Harrison Avenue, Boston, Massachusetts 02111. Reviews of Infectious Diseases 1991;13(Suppl lO):S81S-20 © 1991 by The University of Chicago. AU rights reserved. 0162-0886/91/1305-0006$02.00
preoperative clinical diagnosis is notoriously inaccurate [2, 3, 12, 13]. An overtly gangrenous or perforated appendix is encountered in 1'\J20 % of patients undergoing an operation for acute appendicitis; 10%-20% of patients have a normal appendix, and the remaining 60%-70% have nonperforated appendicitis. As shown in a recent study by Browder et al. [2], intraoperative diagnosis based on direct inspection by the surgeon has a poor correlation with the final pathologic diagnosis. In that study the surgeon underestimated the severity of disease in 38 % of cases, frequently missing gangrene, necrosis, or microperforation. In addition, gram stain and culture results for specimens obtained during the procedure are not predictive of the subsequent development of infection or of the type of pathogen in the infected wound [2, 7, 10, 14, 15]. These studies illustrate the difficulty of predicting preoperatively which patients have the more severe forms of appendicitis that definitely require antimicrobial therapy. Several prospective studies have indicated that all patients undergoing appendectomy, whether they have a nonperforated or even a normal appendix, benefit from antimicrobial prophylaxis in terms of a reduced rate of postoperative wound infection. Donovan et al. [16] found a postoperative infection rate of 20 % among patients with a normal appendix who underwent appendectomy and received no antibiotic prophylaxis; the rate was 4 % among those receiving clindamycin and 6 % among those receiving cefazolin. Bauer et al. [11] reported rates of postoperative wound infection of 5 % among placebo-treated controls with a normal appendix and 1% among cefoxitintreated patients (n = 558; P < .007). It appears from these studies that removal of the appendix- whatever its pathologic state - exposes the patient to inadvertent contamination by bowel flora, thereby raising the risk of wound infection.
Downloaded from http://cid.oxfordjournals.org/ at Boston University on August 3, 2015
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 (>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.
5816
Gorbach
infection in high-risk patients with gangrene or perforation. On the other hand, cephalosporins with good activity against both aerobes and anaerobes, such as cefoxitin [11,32-34] and ceftizoxime [2, 19], have produced favorable results and represent good choices for prophylaxis for appendicitis. It appears that a short antibiotic course - either a single dose [11] or three doses [2, 18]- is sufficient. In patients found to have gangrenous appendicitis and/or abscess formation, it may be necessary to continue antibiotic administration for an additional 3-5 days since these settings represent treatment of active infection rather than prophylaxis.
Colorectal Surgery Several studies of colorectal operations have shown that preoperative antibiotic prophylaxis reduces the rate of postoperative infections [35-38]. In a review of randomized, controlled trials conducted between 1965 and 1980, Baum et al. [37] reported that patients undergoing colorectal operations without prophylaxis or with inappropriate prophylaxis developed wound infections at rates of30%-60%, while patients receiving appropriate antibiotic prophylaxis had significantly lower rates of wound infection (often
