Evaluation of the intestinal microbiota and short-chain fatty acids content in patients with chronic inflammatory bowel diseases

Background. The pathogenesis of chronic inflammatory bowel disease (IBD) is still not fully clarified. It is known that disorders of the intestinal microbiota lead to an increased intestinal permeability, activation of mucous and adaptive immunity, impaired production and intestinal absorption of short-chain fatty acids (SCFA). The ratio of acetic, propionic, butyric acids is an important indicator of the integrity of the intestinal microbial community. Thus, the study of the composition of the intestinal microbiota and the concentrations of fecal SCFA is a very promi­sing approach to broadening the understanding of IBD pathoge­nesis. The purpose of our study was to determine the features of the production of fecal SCFA and the composition of colon microbiota in patients with IBD. Materials and methods. The study, which was carried out at the Department of Intestinal Diseases of the Institute of Gastroenterology of the National Academy of Medical Sciences of Ukraine, involved 74 patients with IBD with an average age of (43.2 ± 1.8) years, who according to nosology were divided into 2 groups: group I — those with ulcerative colitis (UC) (n = 66), group II — individuals with Crohn’s disease (CD) (n = 8). The diagnoses of CD and UC were established accor­ding to generally accepted diagnostic standards in gastroenterology. Determination of fecal SCFA was carried out by chromatographic method with the use of hardware-software complex for medical researches on the basis of the gas chromatographer Chromateс Crystal 5000. The intestinal microflora was evaluated using a microbiological study of the colon content. Results. Patients with IBD had significant changes in the spectrum of SCFA, which were similar in both UC and CD: a decrease in acetic acid in the UC group by 5.7 times, in the CD group by 10.5 times (p < 0.05), butyric acid in the UC group by 1.6 times, in the CD group by 1.5 times (p < 0.05), and an increase in propionic acid in the UC group by 4 times and in the CD group by 3.3 times (p < 0.05) compared with the control group. There was also a significant increase in the anaerobic index in patients with IBD. Microbiological study of feces showed a significant decrease in Lactobacillus, which was observed in all patients with IBD, as well as a decrease in Bifidobacterium in 19.7 % of those with UC and in 37.5 % with CD. There was a decrease of other representatives of the normal microflora: Enterococci (in 15.2 % in the UC group and 25 % in the CD group) and Escherichia coli (in 15.2 % in the UC group and 12.5 % in the CD group). Excessive growth of opportunistic flora was also detected: hemolytic Escherichia coli was increased in 19.7 % of patients with UC and in 12.5 % of those with CD; Proteus was detected in 12.1 % of people with UC and in 37.5 % with CD. The excessive growth of Candida was found in 43.9 % of patients in the UC group and in 87.5 % of indivi­duals with CD. Conclusions. Quantitative and qualitative deviations of the intestinal microbiota, such as a decrease in the number of major symbionts and an increase in the number of opportunistic pathogens, were observed in all examined patients with IBD. The obtained results showed that changes in SCFA concentrations in both nosologies of IBD differed significantly from those in the control group, which in combination with primary genetic defects of the barrier function of the epithelium and its regenerative abi­lity can lead to deterioration in the course and prognosis of IBD. Evalua­tion of the ratio of SCFA fractions with the calculation of the anaerobic index may be useful for the diagnosis of intestinal dysbiosis in patients with IBD.