Bacterial Profiling of Colorectal Cancer Biopsies: A Culture-Based Study in Indian Patients

The role of microorganisms that initiate and facilitate the process of colorectal cancer has become clear now, as cited in various research reports. More information is needed about mechanisms through which the microbial community or single bacterium promotes carcinogenesis. The present work deals with the isolation and identification of bacteria from 9 colorectal cancer biopsy samples and 9 adjacent biopsy samples. Different media, such as Brain heart infusion (BHI), Anaerobic Basal Agar (ABA), and Trypticase soy agar (TSA), and culture conditions have been manipulated to maximize the tapping of bacteria residing in biopsy samples. A total of 75 bacteria were isolated from the tumorus and adjacent site. Enterococcus, Escherichia, Klebsiella, Shigella, Citrobactror, Morganella and Veillonella have been found to be enriched in most of the cancerous biopsies, while biopsies collected from adjacent tissues had Escherichia,Shigella, Enterococcus, and Streptococcus bacteria. A culture-based approach to determining bacterial diversity has its own advantage, which allows the study of a single bacterium to understand the events leading to the development of intestinal carcinogenesis. This culture-based approach may provide novel insight into the pathology and potentially lead to new therapeutic modalities targeting the specific bacteria implicated in the inflammation and carcinogenesis of colorectal cancer.多项已发表研究均证实，可启动并促进结直肠癌发生发展的微生物的作用已得到明确。但目前仍需更多关于微生物群落或单一细菌促癌机制的相关研究。本研究针对9份结直肠癌活检样本及9份癌旁活检样本中的细菌开展分离与鉴定工作。通过优化脑心浸液培养基（Brain heart infusion, BHI）、厌氧基础琼脂（Anaerobic Basal Agar, ABA）与胰蛋白酶大豆琼脂（Trypticase soy agar, TSA）等多种培养基及培养条件，本研究最大限度地获取了活检样本中的寄居细菌。最终从肿瘤组织及癌旁组织中共分离得到75株细菌。研究发现，多数癌组织活检样本中富集肠球菌属（Enterococcus）、埃希菌属（Escherichia）、克雷伯菌属（Klebsiella）、志贺菌属（Shigella）、柠檬酸杆菌属（Citrobactror）、摩根菌属（Morganella）与韦荣球菌属（Veillonella）；而癌旁组织活检样本中则存在埃希菌属、志贺菌属、肠球菌属与链球菌属（Streptococcus）细菌。基于培养的细菌多样性分析方法具有独特优势，可通过分离单一细菌以探究肠道癌变发生发展过程中的相关事件。该基于培养的研究方法可为结直肠癌的病理学研究提供全新视角，并有潜力开发出针对结直肠癌炎症及癌变相关特定细菌的新型治疗策略。