Effect of antimicrobial prophylaxis on the incidence of infections in clean surgical wounds in hospitals undergoing renovation.

Objective: To measure the effect of cephazolin prophylaxis on the rate of surgical site infection among patients with clean surgical wounds, categorized by risk group, in a hospital undergoing renovation.

Design: Randomized, double-blind clinical trial.

Setting: Saint Paul General Hospital, Coquimbo, Chile, during a period when it was undergoing significant interior remodeling.

Patients: General surgery patients who received antibiotic prophylaxis before clean wound surgery between March 2003 and May 2004 and a matched control group of patients who did not receive such prophylaxis.

Results: A total of 303 patients participated in the study. The rate of infection among patients with an American Society of Anesthesiologists (ASA) classification of 1 in the prophylaxis group was 7.3%, whereas among ASA 1 patients in a no-prophylaxis control group it was 10.3% (P=.40). In the prophylaxis group, the ASA 2 and ASA 3 patients combined had an infection rate of 10.5%, whereas in the no-prophylaxis group these patients had a rate of 30.0% (relative risk, 0.33 [95% confidence interval, 0.58-0.96]; P=.03). Both the ASA 2 and ASA 3 patients were protected from infection by prophylaxis; these patients had 1.7 and 2.2 times, respectively, more risk of developing a surgical site infection than did ASA 1 patients after a clean surgical procedure, but the ASA 2 and ASA 3 patients who did not receive prophylaxis had 4.3 and 4.8 times, respectively, greater risk of infection (relative risk, 0.91 [95% confidence interval, 0.83-0.99]; P=.02). Prophylaxis significantly reduced the rate of infection in the ASA 2 and ASA 3 groups.

Conclusions: We recommend the use of antimicrobial prophylaxis with cephalosporins in ASA 2 and ASA 3 patients undergoing clean wound surgery during a period when significant renovations are being performed in the hospital.