Molecular characterization of the microbiota in patients with ulcerative colitis in the Kingdom of Saudi Arabia

Abstract

Background Ulcerative colitis (UC) is a chronic inflammatory disorder of the gastrointestinal tract. Herein, we report a comparative analysis of intestinal microbiota in Saudi patients with UC and healthy individuals using a culture-independent approach. Materials and methods Intestinal biopsies of the five Saudi patients with UC and five healthy citizens were collected, homogenized, and DNA extracted. Genomic libraries of 16S rDNA were constructed using these biopsies. Results and discussion Among the 96 clones analyzed, 39 distinct bacterial strains were found to belong to two main genera: Bacteroides (46%) and clostridium (26%). Levels of uncultured bacteria and uncultured Bacteroidetes were higher in patients with UC than in healthy individuals, and there was a marked decrease in bacterial diversity and evenness in patients with UC relative to healthy individuals. A group of bacteria in healthy individuals was absent in the microbiome of patients with UC, including Bacteroides fragilis, Bacteroides vulgatus, Prevotella spp., Bacteroides coprocola, Escherichia coli, and Streptococcus thermophiles, whereas another group of bacteria found in Saudi patients with UC was not detected in healthy individuals, including Staphylococcus warneri, Bacteruim LF48, Weissella confusa, and enterococci. The results confirm that UC is a multifactorial disease in origin, and some specific bacteria act as etiological agents of UC. Conclusion UC is a multifactorial illness, expressed not only by the dysbiosis of the intestinal microbial flora but also is referred to other causes like the type of diet of each patient, his/her immunity, and genetics.