Department of Microbiology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran.
BMC Cancer. 2019 Sep 5;19(1):879. doi: 10.1186/s12885-019-6115-1.
Enterotoxigenic Bacteroides fragilis (ETBF) is an enterotoxin-producing bacterium that possibily has a role in the occurrence and progression of colorectal cancer (CRC) by modulating the mucosal immune response and inducing epithelial cell changes. The aim of this study was to investigate the frequency of ETBF in stool samples of CRC patients and healthy volunteers.
A total of 60 stool samples from confirmed CRC patients and 60 stool samples from healthy volunteers with no personal or familial history or diagnosis of colorectal disease were collected. Stool samples were screened for direct detection of B. fragilis using PCR targeting the marker genes of neu and bft. Enterotoxin isotypes bft-1, bft-2 and bft-3 were also detected in B. fragilis positive samples.
The frequency of B. fragilis among CRC and control cases was 58.3 and 26.6%, respectively (P < 0.05). The rate of bft gene in CRC cases was significantly higher than in controls (P < 0.05). Also, the presence of bft gene in CRC patients stage III was significantly higher than stages I and II (P < 0.05). Enterotoxin isotype bft-2 was detected with higher frequency among CRC patients than healthy control (P < 0.05).
Our results show the association between fecal ETBF and CRC, and we suggest that detection of ETBF may be a potential marker for colorectal cancer diagnosis. However, additional investigations on tumor and paired normal tissue samples are required to substantiate this possible correlation.
产肠毒素脆弱拟杆菌（ETBF）是一种产生肠毒素的细菌，通过调节黏膜免疫反应和诱导上皮细胞变化，可能在结直肠癌（CRC）的发生和发展中起作用。本研究旨在调查 CRC 患者和健康志愿者粪便样本中 ETBF 的频率。
共收集 60 例确诊 CRC 患者和 60 例无结直肠疾病个人或家族史或诊断的健康志愿者的粪便样本。使用针对 neu 和 bft 标记基因的 PCR 筛选粪便样本以直接检测 B. fragilis。还检测了 B. fragilis 阳性样本中的肠毒素同种型 bft-1、bft-2 和 bft-3。
CRC 和对照组中 B. fragilis 的频率分别为 58.3%和 26.6%（P<0.05）。CRC 病例中 bft 基因的检出率明显高于对照组（P<0.05）。此外，CRC 患者 III 期 bft 基因的存在明显高于 I 期和 II 期（P<0.05）。CRC 患者中肠毒素同种型 bft-2 的检出频率明显高于健康对照组（P<0.05）。
我们的结果表明粪便 ETBF 与 CRC 之间存在关联，我们建议检测 ETBF 可能是结直肠癌诊断的潜在标志物。然而，需要对肿瘤和配对正常组织样本进行进一步研究，以证实这种可能的相关性。
