Large intestine microbiocoenosis disorders and the incidence of small intestinal bacterial overgrowth syndrome in patients suffering from inflammatory bowel diseases

Abstract

Background. Inflammatory bowel diseases (IBD) typically presented by Crohn’s disease (CD) and ulcerative colitis (UC) are still regarded as one of the most difficult and unsolved challenges in contemporary gastroenterology due to its wide spread, high incidence, severe disease progression and complications in diagnosis. Unfortunately, the etiology of IBD is still unknown, but the hypothesis of an immune “hyper-response” caused by environmental factors in relation to the altered gut microbiota or pathogenic microorganisms in a genetically susceptible host is considered the most plausible. The changes of microbiota in IBD are widely recognized and their studies are of great significance for deeper understanding of etiology and pathogenesis of these diseases, as well as for the search of new alternative methods of their treatment. Therefore, the studies of the intestinal dysbiosis in IBD attract more and more attention of the scientists worldwide. Purpose: the current paper aims at studying the features of intestinal dysbiosis and the incidence of small intestine bacterial overgrowth (SIBO) in patients with IBD depending on the disease area and gender. Materials and methods. Forty-six patients with IBD aged 20 to 79 years have been examined, their average age was (47.4 ± 2.4) years. The patients have been distributed into two groups according to the di­sease area. The first group consisted of 15 individuals with CD, the second group included 31 patients with UC. There were 19 females and 27 males in these groups. All patients underwent hydrogen breath test for SIBO detection and the bacteriologic fecal culture. Results. The microbiological study has revealed the presence of deep qualitative and quantitative changes in the colonic microflora in 97.8 % of patients with IBD, with predominance of dysbiosis II in 48.4 % of people with UC and dysbiosis II and III in 33.3 % of individuals with CD. These changes were caused by a decrease in the quantity of bifidobacteria and lactobacillus flora, an increase in the concentration of opportunistic microorganisms and yeast-like fungi. The results obtained after performing hydrogen breath tests evidence the high incidence of SIBO in patients with IBD (50 %). The analysis of the received data allows revealing the fact that SIBO prevailed in patients with UC (51.6 %). The certain difference has been noted between males and females: in both groups of patients with detected SIBO, the males prevailed. Conclusions. The results obtained indicate that virtually all patients with IBD are characterized by changes in the gut microbiota, mainly due to a sharp decrease in the number of major symbionts of colonic microbiocenosis and an increase in the concentration of opportunistic microflora. Fecal microbiological examination and hydrogen breath test are the most available non-invasive methods that allow rapid detection of intestinal microflora disturbances.

Keywords

• inflammatory bowel diseases
• intestinal microflora
• small intestinal bacterial overgrowth syndrome
• hydrogen breath test