Analysis of the incidence and risk factors for wound infections in open bariatric surgery

Background: Our clinical impression derived from >95% follow-up of patients was that our wound infection rate was higher than the 1-10% reported in the literature. The purpose of this study was to determine the incidence and risk factors for wound infection in open bariatric surgery. Methods: We queried our prospectively acquired bariatric surgery outcomes database, and retrospectively audited the charts of patients operated from April 1 to March 31, 2003. Risk categories were obtained using the National Nosocomial Infection Surveillance (NNIS) definitions and stratification. Expected site-specific rates were adjusted for duration of operation, degree of wound contamination, and underlying disease condition. Results: 269 patients undergoing a standardized open Roux-en-Y gastric bypass were studied. The mean age (SD) was 39.5 (10.5) years and the mean BMI was 54.3 (9.9). Operating time averaged 63 (17) minutes, and length of stay was 4.1 (1.3) days. Based on NNIS categories 10.9 wound infections were expected, but 54 were observed, for a rate of 20%. Bacterial isolates included S. aureus (39%), alpha-hemolytic strep (26%), Enterococcus (16%), P. mirabilis (9%), and multiple other bacteria at 10%. Epidural analgesia and delayed antibiotic prophylaxis administration (after the incision was made) increased the odds of developing a wound infection, whereas gender, age, BMI, duration of surgery, and incidence of diabetes had no effect. There was a high correlation between wound infection and subsequent incisional hernia formation. Conclusion: The incidence of wound infections following open bariatric surgery is high, and the current recommendations for antibiotic prophylaxis are ineffective. As these infections carry significant morbidity, effective methods to prevent them are needed.