Luminal and mucosal-associated intestinal microbiota in patients with diarrhea-predominant irritable bowel syndrome

Abstract

BackgroundRecent studies have suggested a role for an altered intestinal microbiota in the pathophysiology of irritable bowel syndrome (IBS). However, no consensus has been reached regarding the association between specific enteric bacterial groups and IBS. The aim of this study was to investigate the fecal and mucosal-associated microbiota using two independent techniques in intestinal samples from diarrhea-predominant IBS (D-IBS) and healthy controls.MethodsFecal and colonic mucosal biopsy samples were obtained from 10 D-IBS patients and 10 healthy controls. Colonic tissue was collected during a un-sedated un-prepped flexible sigmoidoscopy. Fecal and tissue samples were processed immediately upon collection for culture under aerobic and anaerobic conditions or frozen for further molecular analysis. DNA was extracted from all frozen samples and used to enumerate specific bacterial groups using quantitative real-time PCR (qPCR).ResultsCulture analysis of intestinal samples demonstrated a significant reduction in the concentration of aerobic bacteria in fecal samples from D-IBS patients when compared to healthy controls (1.4 × 107 vs. 8.4 × 108 CFUs/g feces, P = 0.002). qPCR analysis demonstrated a significant 3.6 fold increase (P = 0.02) in concentrations of fecal Lactobacillus species between D-IBS patients and healthy controls.ConclusionsOur culture and molecular data indicate that quantitative differences exist in specific bacterial groups in the microbiota between D-IBS and healthy subjects.

Change of Fecal Flora and Effectiveness of the Short-term VSL#3 Probiotic Treatment in Patients With Functional Constipation

“…(Table 1). 16 Quantitative RT-PCR assays were conducted in 96-well plates using a ABI PRISM7000 system (Applied Biosystems). Quantitative RT-PCR standards were generated by PCR amplifying and cloning the target 16S rRNA from an appropriate positive control strain.…”

Dysbiosis of the Intestinal Microbiota in IBS

“…A total of 7 765 IBS subjects were included in the final data analysis revealing a significantly lower abundance of Bifidobaterium spp. In the latest study based on culturing, aerobes were elevated in the faecal samples of IBS-D patients compared with control subjects, whereas anaerobes, Clostridium spp., Bacteroides spp., Lactobacillus spp., Bifidobacterium spp., and Escherichia coli were not altered in IBS-D (Carroll et al, 2010). Taken together, evidence for increased numbers of aerobes and comparably low counts of bifidobacteria exist from culture based analyses with the latter giving good grounds for prebiotic and probiotic therapy research.…”

Commensal Bugs from the Gut-Shaping Human Health and Disease

“…These are the good bacteria in healthy controls as they bind to the epithelial cells making a competitive environment for the pathogens and enhance gut barrier functioning [81]. A significant increase in the quantity of aerobic bacteria and Lactobacillus was noted in IBS-D fecal samples but not in mucosal ones [82]. Elevation in the level of Ruminococcus, Clostridium, Dorea species and a decrease in the quantity of Bifidobacterium and Faecalibacterium species have been demonstrated in IBS [80,[83][84][85][86][87][88][89].…”