Longitudinal Analyses of Gut-Associated Bacterial Microbiota in Ulcerative Colitis Patients.

BACKGROUND

The normal colonic microbiota is associated with the etiology of ulcerative colitis (UC). Several bacterial species are associated with the initiation and amplification of disease process. However, the etiology and mechanism of UC are poorly understood. The present study aimed to investigate, characterize, and compare the main composition of the mucosa-associated intestinal microflora in colonoscopic biopsy specimens of UC and non-UC patients.

METHODS

Aerobic and facultative-anaerobic mucosa-associated bacteria were isolated and diagnosed from colonoscopic biopsy specimens of 40 UC patients and 40 patients without UC. Patients were selected as control from the same centers and colonoscopy was carried out for other reasons (mainly colorectal screening). Isolation and characterization for aerobic and facultative-anaerobic intestinal bacteria were carried out by conventional culture techniques. DNA extraction from biopsies and polymerase chain reaction (PCR) amplification of bacterial 16S rRNA with gene-targeted and species-specific primers was performed for detection of anaerobic bacterial species.

RESULTS

Several species of mucosa-associated aerobic and facultative anaerobic bacteria were found in biopsy specimens and there were no significant differences between UC patients and non-UC patients. Our investigation for detection of the anaerobic intestinal flora showed Faecalibacterium prausnitzii, Prevotella, and Peptostreptococcus productus were the predominant microflora in controls and have significant differences (P = 0.002, 0.025 and 0.039, respectively).

CONCLUSION

This is the first investigation of the intestinal mucosa-associated microflora in patients with UC in Iran. These results, although limited by sample size, allow a better understanding of changes in mucosa-associated bacterial flora in these patients, showing that decrease of Faecalibacterium prausnitzii, Provetella, and Peptostreptococcus productus in the intestinal tract may translate into a reduction in the important role of this beneficial bacterial species, which can lead to reduced protection of the gut mucosa and UC development.