The influence of antibiotic and mechanical bowel preparation on the microbiome in colorectal cancer surgery: A pilot study

• Published in: Surgery in practice and science Vol. 22; p. 100302
• Main Authors: Lange, Undine Gabriele, Lehr, Konrad, Thieme, René, Hoffmeister, Albrecht, Feisthammel, Jürgen, Gockel, Ines, Link, Alexander, Jansen-Winkeln, Boris
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.09.2025; Elsevier
• Subjects: Bowel preparation; Colorectal surgery; Gut microbiome; Preoperative oral antibiotics; Preoperative oral antibiotics; Bowel preparation; Gut microbiome; Colorectal surgery
• ISSN: 2666-2620; 2666-2620
• DOI: 10.1016/j.sipas.2025.100302

•Oral antibiotics reduces bacterial microdiversity in mucosal bowel samples.•Unlike others, Enterococcus and Escherichia/Shigella were more prevalent afterwards.•Effect size was large for reduction of Bacteroides and Ruminococcacaeae. The extent to which bowel preparation mechanical (MBP) or oral antibiotic (OA) or in combination (MBP/OA)) should be performed prior to elective colorectal surgery is the subject of ongoing debate. The aim of our study was to investigate the effect of MPB/OA [with single-shot intravenous antibiotic administration before incision (MPB/OA+ivAB)] on the microbiome of patients with colorectal carcinoma (CRC) operated minimally-invasive. We were studying 16 consecutive patients who underwent elective resection surgery for CRC at our centre in a prospective panel study. MBP was performed and 1 g parmomomycin/500 mg metronidazole was administered orally one day preoperatively; 1 g ertapenem was administered intravenously 30 min prior incision. Three mucosal samples were taken preoperatively during colonoscopy and intraoperatively and analysed by 16S rRNA V1-V2 gene sequencing. Before MPB/OA+ivOA, the genera Phocaeicola (10 %), Bacteroides (7 %) and unclassified Ruminococcaceae (6 %) were predominant. After preparation, all bacteria were reduced except Enterococcus (7 %) and Escherichia/Shigella (6 %), which had increased. Significant reductions were seen for Bacteroides (p = 0.01), Haemophilus (p = 0.047), Holdemanella (p = 0.004), Neisseria (p = 0.004), Odoribacter (p = 0.027), unclassified Clostridiales (p = 0.008) and unclassified Ruminococcacaeae (p = 0.009). Large effect sizes (Cohens’d) were seen for Bacteroidetes (d = 0.864) and unclassified Ruminococcacaeae (d = 0.909). In our pilot study, we observed a significant reduction in seven bacterial genera after MBP/OA+ivAB in patients with CRC. Some of these bacterial genera have been associated with anastomotic insufficiency. Further, large in-depth analyses are needed to evaluate perioperative microbial drift with postoperative complications.