Where does the Surgical Site Infection (SSI) Originate From? -Influence of Surgical Field Contamination to the SSI (wound)-

Katsunori Nishikawa, Yuujirou Tanaka, Akira Matsumoto, Takenori Hayashi, Susumu Kawano, Hideyuki Suzuki, Nobuyoshi Hanyuu and Shuuichi Iwabuchi

Division of Surgery, Machida Municipal Hospital

Background: The prevalence of surgical site infection (SSI) makes it important role to prevent postoperative infection, but intraoperative bacterial contamination (IBC), a major cause of SSI, has not been well studied. We studied the relationship between IBC and SSI. Methods: Subjects were 104 patients undergoing elective digestive tract surgery-20 with upper digestive surgery and 84 with colorectal surgery-between September 2004 and January 2006. Seven samples-1) irrigation fluid after laparotomy, 2) irrigation fluid before abdominal closure (CLOS), 3) swab being of gloved fingers before peritoneal lavage, 4) cutting sutures ligated for peritoneal closure (SUT), 5) swab being of gloved fingers after peritoneal suture, 6) subcutaneous swab being of the surgical wound (SUBCUT), and 7) swab being of surgical drapes around the surgical wound- were obtained intraoperatively and examined for bacterial identification. SSI, in this study, was defined as an occurrence of infection within 30 days after surgery at the site during the operation without postoperative anastomotic leakage. Results: Overall SSI was 0% (0/20) in upper digestive surgery and 27% (23/84) in colorectal surgery. The risk of SSI was 7.78 in stoma construction and 5.02 in intraoperative bacterial detection (IBD) (p<0.05). IBD was 56% in colorectal surgery and mechanical preparation and oral antibiotic administration did not reduce IBD. In the SSI group, bacteria were detected in 61% of CLOS and 52% of SUBCUT sites, compared to 25% of CLOS and 21% of SUBCUT in the non-SSI group. Of the 7 IBD samples, bacterial detection from CLOS was the only individual risk factor for SSI (4.88). Microorganisms from SUT and SUBCUT were identical to those from SSI wounds. Conclusion: Intraoperative contamination is considered as an important factor in SSI. Bacterial contamination of remaining irrigation fluid and the subcutaneous surgical wound seems to be highly correlated, and SSI does not develop without bacteria. Thorough IBC control must thus be considered top priority in SSI prevention.

Key words
surgical site infection (SSI), intraoperative bacterial contamination (IBC), colorectal surgery

Reprint requests
Katsunori Nishikawa Division of Surgery, Machida Municipal Hospital
2-15-41 Asahimachi, Machida, 194-0023 JAPAN

Accepted
June 27, 2007

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