Operative site bacteriology as an indicator of postoperative infectious complications in elective colorectal surgery.

Toward the completion of elective colorectal operations, 75 patients had qualitative aerobic and anaerobic cultures of specimens obtained from peritoneal irrigation fluid, anastomoses sites, and abdominal wound irrigation fluid to determine if a correlation exists between intraoperative flora and postoperative infectious complications. Patients enrolled in this prospective study received a mechanical bowel prep and a 12-18 hour course of perioperative intravenous antibiotics. Comparisons were made between the 60 (80%) patients who had no postoperative infections and the 15 (20%) who developed postoperative infectious complications (9 wound infections, 6 intraabdominal infections). There were significantly more low anterior resections in patients who developed postoperative infection compared to those who had no postoperative infection (26% vs 2%), while there were more colocolostomies in the group with no infections (38% vs 7%). Streptococcus spp., Bacteroides fragilis group, and Escherichia coli were the most commonly isolated organisms from each of the three sites sampled. Isolation of > or = 3 organisms from incisional wound cultures (P = 0.017) and < or = 4 organisms from peritoneal irrigation (P = 0.009) or anastomotic culture (P = 0.004) correlated with development of postoperative infectious complications. Thus, patients with infectious complications had significantly more isolates than those without infectious complications, and were more likely to have had a low anterior resection. These data suggest that future clinical studies should reexamine the duration of perioperative antimicrobials based on early laboratory reports of qualitative and quantitative operative site bacteriology.