Global and deep molecular analysis of microbiota signatures in fecal samples from patients with irritable bowel syndrome.

BACKGROUND & AIMS: Irritable bowel syndrome (IBS) has been associated with disruptions to the intestinal microbiota, but studies have had limited power, coverage, and depth of analysis. We aimed to define microbial populations that can be used discriminate the fecal microbiota of patients with IBS from that of healthy subjects and correlate these with IBS intestinal symptom scores. METHODS: The microbiota composition was assessed by global and deep molecular analysis of fecal samples from 62 patients with IBS patients and 46 healthy individuals (controls). We used a comprehensive and highly reproducible phylogenetic microarray in combination with quantitative polymerase chain reaction. RESULTS: The intestinal microbiota of IBS patients differed significantly (P = .0005) from that of controls. The microbiota of patients, compared with controls, had a 2-fold increased ratio of the Firmicutes to Bacteroidetes (P = .0002). This resulted from an approximately 1.5-fold increase in numbers of Dorea, Ruminococcus, and Clostridium spp (P < .005); a 2-fold decrease in the number of Bacteroidetes (P < .0001); a 1.5-fold decrease in numbers of Bifidobacterium and Faecalibacterium spp (P < .05); and, when present, a 4-fold lower average number of methanogens (3.50 × 10(7) vs 8.74 × 10(6) cells/g feces; P = .003). Correlation analysis of the microbial groups and IBS symptom scores indicated the involvement of several groups of Firmicutes and Proteobacteria in the pathogenesis of IBS. CONCLUSIONS: Global and deep molecular analysis of fecal samples indicates that patients with IBS have a different composition of microbiota. This information might be used to develop better diagnostics and ultimately treatments for IBS.

Effect of a multispecies probiotic supplement on quantity of irritable bowel syndrome-related intestinal microbial phylotypes.

BACKGROUND: Probiotics can alleviate the symptoms of irritable bowel syndrome (IBS), possibly by stabilizing the intestinal microbiota. Our aim was to determine whether IBS-associated bacterial alterations were reduced during multispecies probiotic intervention consisting of Lactobacillus rhamnosus GG, L. rhamnosus Lc705, Propionibacterium freudenreichii ssp. shermanii JS and Bifidobacterium breve Bb99. The intervention has previously been shown to successfully alleviate gastrointestinal symptoms of IBS. METHODS: The faecal microbiotas of 42 IBS subjects participating in a placebo-controlled double-blind multispecies probiotic intervention were analysed using quantitative real-time polymerase chain reaction (qPCR). Eight bacterial targets within the gastrointestinal microbiota with a putative IBS association were measured. RESULTS: A phylotype with 94% similarity to Ruminococcus torques remained abundant in the placebo group, but was decreased in the probiotic group during the intervention (P = 0.02 at 6 months). In addition, the clostridial phylotype, Clostridium thermosuccinogenes 85%, was stably elevated during the intervention (P = 0.00 and P = 0.02 at 3 and 6 months, respectively). The bacterial alterations detected were in accordance with previously discovered alleviation of symptoms. CONCLUSIONS: The probiotic supplement was thus shown to exert specific alterations in the IBS-associated microbiota towards the bacterial 16S rDNA phylotype quantities described previously for subjects free of IBS. These changes may have value as non-invasive biomarkers in probiotic intervention studies.

Diarrhoea-predominant irritable bowel syndrome distinguishable by 16S rRNA gene phylotype quantification.

AIM: To study whether selected bacterial 16S ribosomal RNA (rRNA) gene phylotypes are capable of distinguishing irritable bowel syndrome (IBS). METHODS: The faecal microbiota of twenty volunteers with IBS, subdivided into eight diarrhoea-predominant (IBS-D), eight constipation-predominant (IBS-C) and four mixed symptom-subtype (IBS-M) IBS patients, and fifteen control subjects, were analysed at three time-points with a set of fourteen quantitative real-time polymerase chain reaction assays. All assays targeted 16S rRNA gene phylotypes putatively associated with IBS, based on 16S rRNA gene library sequence analysis. The target phylotypes were affiliated with Actinobacteria, Bacteroidetes and Firmicutes. Eight of the target phylotypes had less than 95% similarity to cultured bacterial species according to their 16S rRNA gene sequence. The data analyses were made with repeated-measures ANCOVA-type modelling of the data and principle component analysis (PCA) with linear mixed-effects models applied to the principal component scores. RESULTS: Bacterial phylotypes Clostridium cocleatum 88%, Clostridium thermosuccinogenes 85%, Coprobacillus catenaformis 91%, Ruminococcus bromii-like, Ruminococcus torques 91%, and R. torques 93% were detected from all samples analysed. A multivariate analysis of the relative quantities of all 14 bacterial 16S rRNA gene phylotypes suggested that the intestinal microbiota of the IBS-D patients differed from other sample groups. The PCA on the first principal component (PC1), explaining 30.36% of the observed variation in the IBS-D patient group, was significantly altered from all other sample groups (IBS-D vs control, P = 0.01; IBS-D vs IBS-M, P = 0.00; IBS-D vs IBS-C, P = 0.05). Significant differences were also observed in the levels of distinct phylotypes using relative values in proportion to the total amount of bacteria. A phylotype with 85% similarity to C. thermosuccinogenes was quantified in significantly different quantities among the IBS-D and control subjects (-4.08 +/- 0.90 vs -3.33 +/- 1.16, P = 0.04) and IBS-D and IBS-M subjects (-4.08 +/- 0.90 vs -3.08 +/- 1.38, P = 0.05). Furthermore, a phylotype with 94% similarity to R. torques was more prevalent in IBS-D patients' intestinal microbiota than in that of control subjects (-2.43 +/- 1.49 vs -4.02 +/- 1.63, P = 0.01). A phylotype with 93% similarity to R. torques was associated with control samples when compared with IBS-M (-2.41 +/- 0.53 vs -2.92 +/- 0.56, P = 0.00). Additionally, a R. bromii-like phylotype was associated with IBS-C patients in comparison to control subjects (-1.61 +/- 1.83 vs -3.69 +/- 2.42, P = 0.01). All of the above mentioned phylotype specific alterations were independent of the effect of time. CONCLUSION: Significant phylotype level alterations in the intestinal microbiotas of IBS patients were observed, further emphasizing the possible contribution of the gastrointestinal microbiota in IBS.

Microbial community analysis reveals high level phylogenetic alterations in the overall gastrointestinal microbiota of diarrhoea-predominant irritable bowel syndrome sufferers.

BACKGROUND: A growing amount of scientific evidence suggests that microbes are involved in the aetiology of irritable bowel syndrome (IBS), and the gastrointestinal (GI) microbiota of individuals suffering from diarrhoea-predominant IBS (IBS-D) is distinguishable from other IBS-subtypes. In our study, the GI microbiota of IBS-D patients was evaluated and compared with healthy controls (HC) by using a high-resolution sequencing method. The method allowed microbial community analysis on all levels of microbial genomic guanine plus cytosine (G+C) content, including high G+C bacteria. METHODS: The collective faecal microbiota composition of ten IBS-D patients was analysed by examining sequences obtained using percent G+C (%G+C) -based profiling and fractioning combined with 16S rRNA gene clone library sequencing of 3267 clones. The IBS-D library was compared with an analogous healthy-control library of 23 subjects. Real-time PCR analysis was used to identify phylotypes belonging to the class Gammaproteobacteria and the order Coriobacteriales. RESULTS: Significant differences were found between clone libraries of IBS-D patients and controls. The microbial communities of IBS-D patients were enriched in Proteobacteria and Firmicutes, but reduced in the number of Actinobacteria and Bacteroidetes compared to control. In particular, 16S rDNA sequences belonging to the family Lachnospiraceae within the phylum Firmicutes were in greater abundance in the IBS-D clone library. CONCLUSIONS: In the microbiota of IBS-D sufferers, notable differences were detected among the prominent bacterial phyla (Firmicutes, Actinobacteria, Bacteroidetes, and Proteobacteria) localized within the GI tract.

Elevated pro-inflammatory and lipotoxic mucosal lipids characterise irritable bowel syndrome.

AIM: To investigate the pathophysiology of irritable bowel syndrome (IBS) by comparing the global mucosal metabolic profiles of IBS patients with those of healthy controls. METHODS: Fifteen IBS patients fulfilling the Rome II criteria, and nine healthy volunteers were included in the study. A combined lipidomics (UPLC/MS) and metabolomics (GC x GC-TOF) approach was used to achieve global metabolic profiles of mucosal biopsies from the ascending colon. RESULTS: Overall, lipid levels were elevated in patients with IBS. The most significant upregulation was seen for pro-inflammatory lysophosphatidylcholines. Other lipid groups that were significantly upregulated in IBS patients were lipotoxic ceramides, glycosphingolipids, and di- and triacylglycerols. Among the metabolites, the cyclic ester 2(3H)-furanone was almost 14-fold upregulated in IBS patients compared to healthy subjects (P = 0.03). CONCLUSION: IBS mucosa is characterised by a distinct pro-inflammatory and lipotoxic metabolic profile. Especially, there was an increase in several lipid species such as lysophospholipids and ceramides.

Development and application of the human intestinal tract chip, a phylogenetic microarray: analysis of universally conserved phylotypes in the abundant microbiota of young and elderly adults.

In this paper we present the in silico assessment of the diversity of variable regions of the small subunit ribosomal RNA (SSU rRNA) gene based on an ecosystem-specific curated database, describe a probe design procedure based on two hypervariable regions with minimal redundancy and test the potential of such probe design strategy for the design of a flexible microarray platform. This resulted in the development and application of a phylogenetic microarray for studying the human gastrointestinal microbiota--referred as the human intestinal tract chip (HITChip). Over 4800 dedicated tiling oligonucleotide probes were designed based on two hypervariable regions of the SSU rRNA gene of 1140 unique microbial phylotypes (< 98% identity) following analysis of over 16,000 human intestinal SSU rRNA sequences. These HITChip probes were hybridized to a diverse set of human intestinal samples and SSU rRNA clones to validate its fingerprinting and quantification potential. Excellent reproducibility (median Pearson's correlation of 0.99) was obtained following hybridization with T7 polymerase transcripts generated in vitro from SSU rRNA gene amplicons. A linear dose-response was observed with artificial mixtures of 40 different representative amplicons with relative abundances as low as 0.1% of total microbiota. Analysis of three consecutively collected faecal samples from ten individuals (five young and five elderly adults) revealed temporal dynamics and confirmed that the adult intestinal microbiota is an individual-specific and relatively stable ecosystem. Further analysis of the stable part allowed for the identification of a universal microbiota core at the approximate genus level (90% sequence similarity). This core consists of members of Actinobacteria, Bacteroidetes and Firmicutes. Used as a phylogenetic fingerprinting tool with the possibility for relative quantification, the HITChip has the potential to bridge the gaps in our knowledge in the quantitative and qualitative description of the human gastrointestinal microbiota composition.

In school-aged children a combination of galacto-oligosaccharides and Lactobacillus GG increases bifidobacteria more than Lactobacillus GG on its own.

The aim of this study was to compare a combination of Lactobacillus GG (LGG) and galacto-oligosaccharides (GOS) with LGG on its own, and their effects on the intestinal microbiota in school-aged children. The randomized, double-blinded, crossover study comprised 30 healthy children. There were two 3-week study periods with a 4-week wash-out period in between. The children ingested daily 65 ml of milk-based fruit juice containing either LGG alone (6.5 x 10(9) CFU) or LGG plus 2 g of GOS. Symptom diaries were filled during the study periods. Fecal samples were collected at the beginning and end of both study periods. At the end of both study periods, the amount of bifidobacteria was significantly greater after the ingestion of LGG + GOS compared with LGG alone (geometric mean 9.33 x 10(9) vs. 4.28 x 10(9) CFU/g, p < 0.001). No significant differences were seen in the amount of lactobacilli or LGG, nor did gastrointestinal symptoms, defecation frequency, consistency of stools or ease of defecation differ between the two study periods. Ingestion of LGG combined with 2 g of GOS increased the bifidobacteria more than LGG on its own and thus GOS clearly has a prebiotic effect in children. The children tolerated well a daily intake of 2 g of GOS.

Clinical studies on alleviating the symptoms of irritable bowel syndrome.

Irritable bowel syndrome (IBS) is one of the most common diagnoses in gastroenterology, but current therapies are inefficient. Recent clinical trials suggest beneficial effects of certain probiotics in IBS. Because of the heterogeneity of IBS a probiotic combination may be more efficient than a single strain. We screened for optimal strains, and developed a multispecies probiotic combination consisting of L. rhamnosus GG, L. rhamnosus Lc705, P. freudenreichii ssp. shermanii JS and Bifidobacterium breve Bb99. The clinical efficacy of the probiotic combination was evaluated in IBS patients in a randomised, double-blind, placebo-controlled six-month intervention. During six months the subjects received daily either probiotic supplementation or placebo. IBS symptoms were followed by symptom diaries. The probiotic supplementation demonstrated significant value in reducing IBS symptoms. At the end of the study period the total symptom score (abdominal pain + distension + flatulence + rumbling) had reduced with 42% in probiotic group versus 6% for instance anti-inflammatory effects, balancing of the microbiota or motility-related effects induced by the probiotic. The probiotic activity may be enhanced by synergistic effects of the combination that each strain alone would not hold. In conclusion, we found a probiotic combination of LGG and three other strains to be effective in alleviating IBS symptoms.

Composition and temporal stability of gastrointestinal microbiota in irritable bowel syndrome--a longitudinal study in IBS and control subjects.

Irritable bowel syndrome (IBS) is a common intestinal disorder that includes continuous or recurrent intestinal pain and discomfort and altered bowel habits. The pathophysiology of IBS is incompletely understood, but it may involve an altered intestinal microbiota. The aim of the present study was to compare the composition and temporal stability of faecal microbiota of IBS patients and healthy controls by applying culture-based techniques and PCR-DGGE analysis. No difference in the prevalence or mean culturable manners of bacteroides, bifidobacteria, spore-forming bacteria, lactobacilli, enterococci or yeasts were observed between the IBS and the control groups, whereas slightly higher numbers of coliforms as well as an increased aerobe:anaerobe ratio was observed in the IBS group. PCR-DGGE revealed more temporal instability in the predominant bacterial population of IBS subjects than in controls. In 9 out of 21 IBS subjects and 5 out of 17 controls the PCR-DGGE profiles obtained from the samples of the same individual on different occasions (sampling points 0, 3 and 6 months) were clearly different. However, the instability in some of the IBS subjects could partly be explained by the antibiotic consumption during the study. The present study suggests that instability of intestinal microbiota may be involved in IBS. However, further studies are needed to associate the instability with specific IBS symptoms or with specific bacterial groups and species.

Analysis of the fecal microbiota of irritable bowel syndrome patients and healthy controls with real-time PCR.

OBJECTIVE: The gut microbiota may contribute to the onset and maintenance of irritable bowel syndrome (IBS). In this study, the microbiotas of patients suffering from IBS were compared with a control group devoid of gastrointestinal (GI) symptoms. METHODS: Fecal microbiota of patients (n = 27) fulfilling the Rome II criteria for IBS was compared with age- and gender-matched control subjects (n = 22). Fecal samples were obtained at 3 months intervals. Total bacterial DNA was analyzed by 20 quantitative real-time PCR assays covering approximately 300 bacterial species. RESULTS: Extensive individual variation was observed in the GI microbiota among both the IBS- and control groups. Sorting of the IBS patients according to the symptom subtypes (diarrhea, constipation, and alternating predominant type) revealed that lower amounts of Lactobacillus spp. were present in the samples of diarrhea predominant IBS patients whereas constipation predominant IBS patients carried increased amounts of Veillonella spp. Average results from three fecal samples suggested differences in the Clostridium coccoides subgroup and Bifidobacterium catenulatum group between IBS patients (n = 21) and controls (n = 15). Of the intestinal pathogens earlier associated with IBS, no indications of Helicobacter spp. or Clostridium difficile were found whereas one case of Campylobacter jejuni was identified by sequencing. CONCLUSIONS: With these real-time PCR assays, quantitative alterations in the GI microbiota of IBS patients were found. Increasing microbial DNA sequence information will further allow designing of new real-time PCR assays for a more extensive analysis of intestinal microbes in IBS.