Effects of Synbiotics to Prevent Postoperative Infectious Complications in Highly Invasive Abdominal Surgery.

Postoperative infectious complication (POIC) is one of the most common complications following highly invasive abdominal surgeries, such as hepatectomy, esophagectomy, and pancreatoduodenectomy. The surgical stress temporarily deteriorates the intestinal microenvironment, and the fecal concentrations of beneficial bacteria such as Bifidobacterium and Lactobacillus decrease following highly invasive abdominal surgery. In parallel with these changes, the concentrations of fecal short-chain fatty acids (SCFAs) such as acetic acid, propionic acid, and butyric acid also decrease after surgery. In contrast, the fecal concentration of lactic acid increases under this condition because of the deterioration of the metabolism from lactic acid to SCFAs by normal intestinal microflora. Decreased fecal concentration of SCFAs may lead to an impaired intestinal barrier function under stressful condition. Translocation of bacteria from the gut to lymphatic and bloodstream leads to bacteremia and subsequent POICs. The incidence of POICs in patients with unhealthy intestinal microflora before surgery may be more because their intestine is more susceptible to bacterial translocation induced by surgical stress. Therefore, improving the intestinal microenvironment and intestinal barrier function before surgery is crucial to prevent POICs following highly invasive abdominal surgeries. In this regard, the use preoperative synbiotics therapy may be one of the effective ways because it has been shown to improve intestinal microflora, increase fecal SCFAs, prevent bacterial translocation, and reduce the incidence of POICs in several randomized controlled trial in patients undergoing highly invasive abdominal surgeries.