Prevalence of small intestinal bacterial overgrowth syndrome among patients with inflammatory bowel disease and its impact on nutritional status and clinical manifestations
Authors: Stepanov Yu.M. , Titova M.V. , Nedzvetska N.V. 
Published: October 2021

Background. In recent years, there has been high interest in the prevalence of small intestinal bacterial overgrowth (SIBO) syndrome in various populations. Chronic inflammatory bowel disease (IBD) is known to be a heterogeneous group of disorders, with a high degree of geographical variability in terms of symptoms, nature of progression, clinical manifestations, or combination with other types of pathologies. Since the involvement of the intestinal microbiome plays an important role in the etiopathogenesis of inflammatory bowel disease, the combination of SIBO and IBD is increasingly being considered and studied recently. Since the symptoms of both pathological conditions are significantly echoed, and therefore exacerbated by the combination, the manifestations of malnutrition become more pronounced, which negatively affects the nutritional status of patients with IBD. The purpose of the study is to determine the frequency of SIBO in patients with IBD depending on the nosological forms and to investigate its effect on clinical and laboratory indicators of nutritional status and clinical manifestations. Materials and methods. We examined 100 patients with IBD, aged 19 to 79 years, on average (42.54 ± 1.50) years, including 70 patients with ulcerative colitis (UC), and 30 — with Crohn’s disease (CD). All patients underwent general clinical examination, anthropometric measurements, general and biochemical blood tests (with the determination of total protein, albumin, prealbumin). To characterize the state of the small intestine microbiota (presence of SIBO), all patients underwent a hydrogen breath test with glucose loading using a Gastro+ Gastrolyzer gas analyzer from Bedfont Scientific Ltd (UK). Results. The analysis of SIBO frequency showed the changes in the state of the small intestinal microflora in 45 % of patients with IBD. The prevalence of SIBO was higher in the group of patients with CD — 53.3 % (16) than in the group with UC — 41.4 % (29). The presence of SIBO in the group of patients with UC had statistical significance and a direct correlation with the duration of the disease — (9.3 ± 6.2) versus (2.9 ± 3.1) years (p = 0.001, r = 0.55). There was a decrease in weight and body mass index (BMI) in patients with SIBO, especially in patients with Crohn’s disease, and accounted for (19.8 ± 3.5) kg/m2. There was a significant difference between the levels of total protein in patients with SIBO and without it, both in the basic group and in the group of UC: (65.8 ± 8.4) vs. (70.2 ± 8.2) g/l (p=0.009, r = –0.232) and (66.5 ± 8.3) vs. (70.7 ± 7.4) g/l (p = 0.029), respectively, and albumin levels were reduced in both nosological groups. No relationship was found between the severity of abdominal pain and the presence of SIBO. When SIBO was detected, the manifestations of flatulence significantly prevailed in patients with UC — 75.8 % (n=22), and diarrheal syndrome in patients with CD — 75 % (n = 12). Conclusions. The obtained results indicate a high prevalence of SIBO in patients with IBD. Patients with CD suffered from SIBO more often (53.3 %) than patients with UC (41.4%) (with a predominance of patients with severe disease). A direct correlation of SIBO with the disease duration in patients with UC (r = 0.55, р < 0.05) was revealed, which is explained by the violation of physiological barriers that prevent the emergence of SIBO, due to more episodes of exacerbation, long-term use of drugs and concomitant pathology with time. The negative impact of SIBO on nutritional status manifested in weight loss, reduced BMI and other anthropometric (mid-upper arm circumference, mid-arm muscle circumference, triceps skinfold) and laboratory (total protein, albumin, prealbumin) parameters in these patients. The most common symptoms in patients with IBD with SIBO were abdominal pain, diarrhea, and flatulence that reflected the typical clinical picture of SIBO.