Hannover Medical School, Institute of Medical Microbiology and Hospital Epidemiology, Hannover, Germany.
Hannover Medical School, Department of Gastroenterology, Hepatology and Endocrinology, Hannover, Germany.
PLoS One. 2018 May 8;13(5):e0196977. doi: 10.1371/journal.pone.0196977. eCollection 2018.
Clostridium difficile infection (CDI) is a major cause of hospital-acquired diarrhea. Secondary bile acids were shown to confer resistance to colonization by C. difficile. 7α-dehydroxylation is a key step in transformation of primary to secondary bile acids and required genes have been located in a single bile acid-inducible (bai) operon in C. scindens as well as in C. hiranonis, two Clostridium sp. recently reported to protect against C. difficile colonization.
To analyze baiCD gene abundance in C. difficile positive and negative fecal samples.
MATERIAL & METHODS: A species-specific qPCR for detecting baiCD genes was established. Fecal samples of patients with CDI, asymptomatic toxigenic C. difficile colonization (TCD), non-toxigenic C. difficile colonization (NTCD), of C. difficile negative (NC) patients, and of two patients before and after fecal microbiota transplantation (FMT) for recurrent CDI (rCDI) were tested for the presence of the baiCD genes.
The prevalence of the baiCD gene cluster was significantly higher in C. difficile negative fecal samples than in samples of patients diagnosed with CDI (72.5% (100/138) vs. 35.9% (23/64; p<0.0001). No differences in baiCD gene cluster prevalence were seen between NC and NTCD or NC and TCD samples. Both rCDI patients were baiCD-negative at baseline, but one of the two patients turned positive after successful FMT from a baiCD-positive donor.
Fecal samples of CDI patients are less frequently baiCD-positive than samples from asymptomatic carriers or C. difficile-negative individuals. Furthermore, we present a case of baiCD positivity observed after successful FMT for rCDI.
艰难梭菌感染（CDI）是医院获得性腹泻的主要原因。次级胆汁酸被证明可以抵抗艰难梭菌的定植。7α-脱羟化是将初级胆汁酸转化为次级胆汁酸的关键步骤，所需基因已在 C. scindens 中的单个胆汁酸诱导（bai）操纵子以及最近报道可预防艰难梭菌定植的 C. hiranonis 中定位。
分析 CDI 阳性和阴性粪便样本中 baiCD 基因的丰度。
建立了用于检测 baiCD 基因的种特异性 qPCR。检测了 CDI 患者、无症状产毒艰难梭菌定植（TCD）、非产毒艰难梭菌定植（NTCD）、艰难梭菌阴性（NC）患者以及 2 例复发性 CDI（rCDI）粪便微生物群移植（FMT）前后的粪便样本中 baiCD 基因的存在。
baiCD 基因簇在 CDI 阴性粪便样本中的流行率明显高于诊断为 CDI 的患者样本（72.5%（100/138）比 35.9%（23/64；p<0.0001）。NC 和 NTCD 或 NC 和 TCD 样本之间 baiCD 基因簇流行率无差异。2 例 rCDI 患者基线时均为 baiCD 阴性，但其中 1 例在成功接受来自 baiCD 阳性供体的 FMT 后转为阳性。
CDI 患者的粪便样本 baiCD 阳性率低于无症状携带者或艰难梭菌阴性个体的样本。此外，我们报告了 1 例 rCDI 成功 FMT 后 baiCD 阳性的病例。
