Synbiotics, Surgical Infection and Colonization Resistance

Abstract

In our recent randomized controlled study to assess the effect of perioperative oral administration of synbiotics on surgical outcome in patients undergoing laparoscopic colorectal resection, the efficacy of synbiotics as a treatment to reduce the incidence of infectious complications was not validated. However, this study incorporated molecularbased methods and a large sample size, and microbiological examinations showed that dysbiosis induced by surgery was greatly improved by perioperative synbiotic treatment, resulting in the decrease of potentially pathogenic bacteria, such as Clostridium difficile. This study also provided novel evidence that could explain, in part, the mechanisms whereby probiotics enhance colonization resistance in the gastrointestinal tract.Keywords: Postoperative complication; Probiotics; Bifidobacterium; Clostridium difficile; Bacterial translocation; Short chain fatty acids DescriptionThe gut microbiota performs a wide range of beneficial functions for human health and homeostasis, maintaining nutrition, strengthening the immune system and improving colonization resistance. There is also increasing evidence that gut microbial imbalances (dysbiosis) are associated with various intestinal-related diseases such as inflammatory bowel diseases and irritable bowel syndrome, as well as infectious complications after surgery [1][2][3][4].Probiotics are defined as live microorganisms that have positive effects on human health when ingested in sufficient amounts. The therapeutic effects of probiotic administration on disorders presumably associated with dysbiosis have been extensively examined [1][2][3][5][6][7]. Several randomized controlled trials, including pancreatoduodenectomy, hepatobiliary resection and liver transplantation, demonstrate that the use of probiotics in patients undergoing abdominal surgery is a promising approach to the prevention of post-operative infectious complications [8][9][10][11]. Nevertheless, the effectiveness of probiotics treatment for prevention of infectious complications after colorectal surgery remains inconclusive [1,3,[12][13][14][15][16][17][18][19][20][21], possibly due to differences in patient groups, varying preparations of probiotics, and heterogeneity in the quality of methods. Whether or not beneficial bacteria actually survive in the intestine also remains unclear.We recently published the results of a randomized controlled study to assess the effect of perioperative oral administration of synbiotics, a combination of probiotics (Lactobacillus casei strain Shirota and Bifidobacterium breve strain Yakult) and prebiotics (dietary supplement of probiotics), on surgical outcome in patients undergoing laparoscopic colorectal resection [22]. In this study, surgical site infection (SSI) occurred in 17.3% of synbiotics group patients and in 22.7% of control group patients (OR 0.761, 95%CI 050-1.16; p=0.20). Overall, the rate of postoperative complications, including anastomotic leakage, did not differ significantly between groups. The efficacy o...