In this study, we examined the clinical value of MBP and CBP for preventing SSI in patients undergoing elective laparoscopic colorectal surgery. Our results indicated that CBP exerted an independent, significant effect on overall SSI prevention, especially for cases of incisional SSI. In contrast, MBP exerted no preventive effects on either incisional or organ-space SSI. To the best of our knowledge, this is the first study to demonstrate the independent preventive effect of CBP and the non-effectiveness of MBP for SSI among patients undergoing laparoscopic colorectal surgery.
Recent randomized controlled studies have revealed that the combination of MBP and CBP is more effective in preventing SSI following colorectal surgery than MBP alone [8]. CBP has been identified as a cause of C. difficile enterocolitis and methicillin-resistant Staphylococcus aureus infections [20]. However, previous studies have demonstrated that short-term preoperative use of CBP is safe given the low risk of such infections [9]. A few studies have also demonstrated that the combination of MBP and CBP is more effective in preventing SSI than MBP alone in patients undergoing laparoscopic colorectal surgery for cancer [14]. Other studies have suggested that CBP alone is sufficiently effective for reducing SSI because MBP exerts no effect on SSI rates following colorectal surgery [15]. However, no studies have examined the preventive effect of MBP and CBP on SSI specifically among patients undergoing laparoscopic surgery. At our center, CBP was added to the MBP protocol for colorectal surgery in 2021. Furthermore, MBP is now omitted in some cases of right-sided colectomy, tumor obstruction, and general frailty. Despite potential selection bias in the present study, our results indicated that MBP did not exert significant preventive effects on SSI, in contrast to CBP. However, eliminating MBP during laparoscopic surgery may affect the surgical field and cause contamination in patients with intracorporeal anastomosis. Thus, further studies are required to determine whether MBP can be omitted in laparoscopic surgery.
In the multivariate analyses for SSI risk factors, male sex was associated with both incisional SSI and organ-space SSI [21, 22], rectal resection and perioperative transfusion were associated with organ-space SSI, and stoma formation was associated with incisional SSI [23–25], similar to findings reported in previous studies [8–12]. Furthermore, CBP reduced the SSI rate after conversion surgery, which is consistent with a previous study that focused on CBP for open colorectal surgery [26]. Our results also suggest that CBP can reduce SSI risk in patients with tumor obstruction and those treated without MBP, who are often excluded from such analyses. However, CBP was not associated with a decreased risk of SSI in patients with stoma formation, those with benign disease, or those who had undergone preoperative therapy. In such cases, the preventive effect of CBP may be limited because stoma formation and preoperative therapy have been highlighted as strong risk factors for SSI themselves [23, 24, 27].
In the culture analysis, Bacteroides species were isolated more frequently in the non-CBP group than in the CBP group. Considering its spectrum, metronidazole appeared to suppress the growth of Bacteroides species and may have contributed the decrease in the SSI rate, which is consistent with the results of a previous randomized controlled trial [9]. In contrast, Nichols et al. reported that MBP alone did not affect microorganism concentrations in the colon [28]. In the current study, the preventive effect of CBP against SSI was poor in patients with benign disease. A previous study of gut microbiota reported greater enrichment of Bacteroides fragilis in patients with colorectal cancer than in healthy volunteers [29]. This may explain the significant effect of CBP in the malignant disease group and limited effect of CBP in the benign disease group.
Our findings also indicated that the occurrence of SSI significantly prolonged the duration of hospitalization after surgery, consistent with previous findings [30]. Furthermore, the postoperative hospital stay was significantly longer among patients with organ-space SSI than among those with incisional SSI only. This highlights the importance of preventing SSI to avoid elevated healthcare costs [31].
This study had some limitations, including its small sample size and single-center, retrospective design, which may limit the statistical power of the results. Although selection bias occurred with respect to bowel preparations, its influence was likely small for CBP, which was introduced at a later period. However, selection bias may have been larger when determining whether patients had received MBP. To address these issues, we performed multivariate logistic regression analyses of risk factors for SSI and subgroup analyses of the preventive effects of CBP. Lastly, diagnoses of SSI were made by surgeons in our department, and some cases of SSI may have been missed.