Bacterial Flora in Inflammatory Bowel Disease

Abstract

The pathogenesis of inflammatory bowel disease (IBD) involves an interaction between host susceptibility (which is partly genetically determined), mucosal immunity and the intestinal milieu. Micro-organisms have physiological effects on mucosal structure, epithelial turnover, the intestinal immune cells and, thus, on many intestinal functions. Toll-like receptors and nucleotide oligomerisation-binding domain proteins in host cells recognise specific bacterial molecules and modify the immune response. Human studies have repeatedly shown that the microbiota of patients with IBD differs from that of controls and is unstable, both in the intestinal lumen and at the surface of the mucosa. A single pathogen has not been identified, but potentially pro-inflammatory micro-organisms have been found in samples from IBD patients more often than from healthy controls. These include Mycobacterium paratuberculosis, and enteroadherent and invasive Escherichia coli in Crohn’s disease (CD). Ecological descriptions of the microbiota present in patients with IBD (either in the faeces or adherent to the mucosa) have repeatedly reported a decrease in usually dominant bacteria, especially those from the dominant phylum Firmicutes. A decrease in the biodiversity of Firmicutes has been observed in CD, while a recent study has shown that a decrease in Firmicutes, especially Faecalibacterium prausnitzii, was associated with CD and the post-operative recurrence of CD lesions in the ileum. Taken together, these results suggest that dysbiosis, or an imbalance within the (dominant) intestinal microbiota, may favour IBD.

Gut microbiome diversity in acute infective and chronic inflammatory gastrointestinal diseases in North India

“…Similar results have been reported in earlier studies [63][64][65]. The Clostridium leptum subgroup was reduced non-significantly in CD patients but increased sharply in UC patients, as observed in earlier studies [65][66][67]. The difference was more pronounced between UC and CD patients.…”

Real-Time Analysis of Mucosal Flora in Patients with Inflammatory Bowel Disease in India

“…The losses of normal intestinal bacterial taxa, such as Bacteroides, Lactobacillus, Ruminococcus, and Bifidobacterium, observed by us supported earlier observations (3,11,16,27) proving the hypothesis that loss of commensal organisms profoundly modifies gut mucosal homoeostasis through loss of essential micronutrients (short chain fatty acids) and redox potential (2). The Clostridium leptum subgroup was reduced nonsignificantly in CD patients but increased sharply in UC patients (P ϭ 0.0155), as observed earlier (9,18,27). The difference was more pronounced between UC and CD patients (P ϭ 0.0118).…”

The Gut Microbiota as Target for Innovative Drug Development: Perspectives and a Case Study of Inflammatory Bowel Diseases

“…Using a wide range of different techniques, changes in the population diversity of both the luminal and mucosa-associated microbiota have been demonstrated. Luminal changes were mainly associated with a decrease in the diversity of the Firmicutes, in particular Lactobacilli and Clostridia, and Bacteroidetes (Manichanh et al, 2006;Marteau, 2009;Scanlan et al, 2006;Sokol et al, 2009), while an increase in the Enterobacteriaceae population was reported for CD (Seksik et al, 2003). All reports described a reduced diversity of the mucosa-associated microbial communities in IBD.…”