Fecal bacteria can predict the efficacy of rifaximin in patients with diarrhea-predominant irritable bowel syndrome.

Rifaximin for treating diarrhea-predominant irritable bowel syndrome (IBS-D) by regulating intestinal microbiota has been studied and recommended. In this study, we tried to investigate the effect of rifaximin on different components of intestinal microbiota and explore which component of gut microbiota can predict the efficacy of rifaximin in IBS-D. Healthy controls (HC) and IBS-D patients meeting the Rome III criteria were recruited, and IBS-D patients were orally administered 400 mg rifaximin three times daily for 2 weeks. Subjects were tested for small intestinal bacterial overgrowth (SIBO), their symptoms were recorded, and fecal and rectal mucosal samples were collected before and after treatment. Fecal and rectal mucosal bacterial data were obtained via 16S rRNA sequencing, and fecal fungal data were obtained via ITS2 sequencing. IBS-D patients were divided into two subgroups based on fecal bacterial composition, IBS1 (patients whose fecal bacterial composition were different from HC) and IBS0 (patients whose fecal bacterial profiles were similar to HC). Rifaximin increased fecal Bifidobacterium and decreased E. coli and Enterobacter in IBS1 patients. Although rectal mucosal bacteria and fecal fungi were not significantly altered in all patients after rifaximin intervention, rifaximin enhanced the connections among fecal bacteria, mucosal bacteria and fecal fungi in IBS1 patients. Compared with IBS0, we surprisingly found rifaximin ameliorated abdominal symptoms of IBS1 much better. Receiver operating curve analysis revealed patients whose fecal microbial dysbiosis indices (MDI) were higher than -3.006 could be diagnosed as IBS1. Fecal bacterial dysbiosis could be a biomarker for rifaximin treatment for IBS-D.

Li Y ，Hong G ，Yang M ，Li G ，Jin Y ，Xiong H ，Qian W ，Hou X ... -  《-》

Gut fungal dysbiosis and altered bacterial-fungal interaction in patients with diarrhea-predominant irritable bowel syndrome: An explorative study.

Little is known about intestinal fungi in IBS patients whose gut bacteria have been investigated a lot. In order to explore causal relationship between IBS and gut mycobiome, and use gut fungi to diagnose or even treat IBS, further characterization of it in IBS is required. Fifty-five diarrhea-predominant IBS (D-IBS) patients fulfilling Rome III criteria, and 16 healthy controls (HC) were recruited. Fresh fecal samples were collected and used for 16s rRNA and ITS2 high-throughput sequencing. Diversity and composition of gut bacteria and fungi, as well as bacterial-fungal interactions in D-IBS patients, were characterized. Specific fungal taxa differentiating D-IBS from HC were recognized by LEfSe and RandomForest methods, and their association with clinical symptoms was assessed by Spearman's correlation. Diarrhea-predominant irritable bowel syndrome patients showed abnormal (IBS-dysbiosis) or normal (HC-like IBS) fecal bacterial structure and diversity compared with healthy controls. However, fecal fungal signatures differed absolutely between D-IBS and HC, which indicated a more susceptible alteration of gut fungi than bacteria in D-IBS. Fecal fungi showed significant correlations with IBS symptoms, especially Mycosphaerella, Aspergillus, Sporidiobolus, and Pandora which were identified to potentially differentiate D-IBS from HC. Moreover, compared with HC there were markedly declined bacterial-fungal interactions in D-IBS, in which Candida changed from negative to positive correlations with bacteria, and Eurotium changed from positive correlations to irrelevance, while Debaryomyces gained negative correlations with bacteria. Gut fungal dysbiosis and altered bacterial-fungal interactions were present in patients with D-IBS, and gut fungi could be used to diagnose D-IBS.

Hong G ，Li Y ，Yang M ，Li G ，Qian W ，Xiong H ，Bai T ，Song J ，Zhang L ，Hou X ... -  《-》

Duodenal and rectal mucosal microbiota related to small intestinal bacterial overgrowth in diarrhea-predominant irritable bowel syndrome.

Small intestinal bacterial overgrowth (SIBO) has been proposed as an etiologic factor in irritable bowel syndrome, particularly the diarrhea-predominant subtype (IBS-D). We aimed to identify potential intestinal microbial pattern in IBS-D patients with SIBO. Diarrhea-predominant irritable bowel syndrome patients fulfilling Rome III criteria were recruited and randomly divided into an exploratory cohort (57 cases) and a validation cohort (20 cases). SIBO was identified according to standard glucose hydrogen breath test. For 16S rRNA gene sequencing, samples of duodenal mucosa, duodenal fluid, rectal mucosa, and fresh feces were collected and performed. The α and β diversity, as well as differences in microbial composition and function, in SIBO+ and SIBO- IBS-D subjects were evaluated. The microbial diversity and composition obviously differed between SIBO+ and SIBO- IBS-D in duodenal and rectal mucosa but not in duodenal fluid and fresh feces. For rectal mucosal microbiota, it displayed markedly reduced aerobe and Gram-negative bacteria and increased facultative anaerobe and Gram-positive bacteria, moreover, altered functions of microbial metabolism in SIBO+ IBS-D. Significantly higher rectal mucosa-related microbial dysbiosis index was observed in SIBO+ IBS-D, and a cut-off value at -0.37 had a sensitivity of 56.55% and specificity of 90.91% to identify the SIBO in IBS-D subjects. Mucosal microbiota, rather than luminal bacteria, has a more apparent dysbiosis in SIBO+ IBS-D patients relative to those without SIBO. Rectal mucosa-associated microbiota may act as a potential predictor of SIBO in IBS-D patients.

Yang M ，Zhang L ，Hong G ，Li Y ，Li G ，Qian W ，Xiong H ，Bai T ，Song J ，Hou X ... -  《-》

Double-Blind Placebo-Controlled Study of Rifaximin and Lactulose Hydrogen Breath Test in Gulf War Veterans with Irritable Bowel Syndrome.

Tuteja AK ，Talley NJ ，Stoddard GJ ，Verne GN ... -  《-》

[Clinical features of irritable bowel syndrome with small intestinal bacterial overgrowth and a preliminary study of effectiveness of Rifaximin].

Liu ZJ ，Wei H ，Duan LP ，Zhu SW ，Zhang L ，Wang K ... -  《-》