Small intestinal bacterial overgrowth--an incidental finding?

Impact of Small Intestinal Bacterial Overgrowth in Patients with Inflammatory Bowel Disease and Other Gastrointestinal Disorders-A Retrospective Analysis in a Tertiary Single Center and Review of the Literature

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) is often found in patients with gut dysbiosis such as irritable bowel syndrome. Recently, the association of SIBO and inflammatory bowel disease (IBD) has been described in some cases. While clinical symptoms might be similar in IBD and SIBO, treatment is quite different for both diseases. Therefore, the differentiation between SIBO or a flare in IBD patients is key to optimizing treatment for these patients.

METHODS

We retrospectively investigated our patients with IBD receiving a glucose breath test for SIBO and correlated the results with the clinical symptoms (clinical remission or active disease).

RESULTS

128 patients with the diagnosis "colitis" were analyzed in our cohort. Fifty-three (41.4%) patients had Crohn's disease and 22 (17.2%) patients were suffering from ulcerative colitis. Seventy-four (57.8%) were female and 54 (42.2%) were male patients. A total of 18 (14.1%) patients had a positive testing for SIBO. Eleven (61.1%) cases were associated with CD patients and two (11.1%) with UC. IBD patients in clinical remission had a positive SIBO in six (19.4%) cases, while IBD patients with active disease were positive in nine (15.3%) cases. The proportion of positive SIBO in active IBD patients was higher; however, it did not reach significance. Older age was a risk factor for SIBO in patients with CD (p < 0.003).

CONCLUSIONS

In our study, we could show that an increased amount of SIBO was found in IBD patients and was especially more frequent in patients with CD than in those with UC. In UC patients, SIBO rates were not different to patients with other gastrointestinal diseases investigated (e.g., infectious colitis, collagenous colitis, or irritable bowel syndrome). In active IBD, positive SIBO was detected more often numerically compared to quiescent disease; however, due to the low number of patients included, it was not significant. However, older age was a significant risk factor for SIBO in patients with CD. SIBO is of clinical relevance in the vulnerable patient cohort with IBD, and its real prevalence and impact needs to be investigated in further and larger clinical trials.

Small Intestinal Bacterial Overgrowth-Pathophysiology and Its Implications for Definition and Management

The concept of small intestinal bacterial overgrowth (SIBO) arose in the context of maldigestion and malabsorption among patients with obvious risk factors that permitted the small bowel to be colonized by potentially injurious colonic microbiota. Such colonization resulted in clinical signs, symptoms, and laboratory abnormalities that were explicable within a coherent pathophysiological framework. Coincident with advances in medical science, diagnostic testing evolved from small bowel culture to breath tests and on to next-generation, culture-independent microbial analytics. The advent and ready availability of breath tests generated a dramatic expansion in both the rate of diagnosis of SIBO and the range of associated gastrointestinal and nongastrointestinal clinical scenarios. However, issues with the specificity of these same breath tests have clouded their interpretation and aroused some skepticism regarding the role of SIBO in this expanded clinical repertoire. Furthermore, the pathophysiological plausibility that underpins SIBO as a cause of maldigestion/malabsorption is lacking in regard to its purported role in irritable bowel syndrome, for example. One hopes that the application of an ever-expanding armamentarium of modern molecular microbiology to the human small intestinal microbiome in both health and disease will ultimately resolve this impasse and provide an objective basis for the diagnosis of SIBO.

Nutritional Aspects in Inflammatory Bowel Diseases

Crohn’s disease (CD) and ulcerative colitis (UC) are chronic, relapsing, inflammatory disorders of the digestive tract that characteristically develop in adolescence and early adulthood. The reported prevalence of malnutrition in inflammatory bowel disease (IBD) patients ranges between 20% and 85%. Several factors, including reduced oral food intake, malabsorption, chronic blood and proteins loss, and intestinal bacterial overgrowth, contribute to malnutrition in IBD patients. Poor nutritional status, as well as selective malnutrition or sarcopenia, is associated with poor clinical outcomes, response to therapy and, therefore, quality of life. The nutritional assessment should include a dietetic evaluation with the assessment of daily caloric intake and energy expenditure, radiological assessment, and measurement of functional capacity.

Glucose breath test and Crohn's disease: Diagnosis of small intestinal bacterial overgrowth and evaluation of therapeutic response

OBJECTIVE

Small intestinal bacterial overgrowth (SIBO) is characterized by an abnormal proliferation of bacterial species in the small bowel. It has been shown that patients with Crohn's disease (CD) have a higher risk of SIBO development. The aim of the present study was to investigate SIBO prevalence in CD patients, possible clinical predictors of SIBO development and response to antibiotic therapy.

MATERIAL AND METHODS

Sixty-eight patients (42 male, 26 female; mean age 49.3 ± 12.8 years) with CD reporting abdominal complaints were prospectively evaluated for SIBO with H2/CH4 glucose breath test (GBT).

RESULTS

Of the 68 patients enrolled, 18 (26.5%) tested positive for SIBO. Patients with SIBO exhibited increased stool frequency and significant reduction of stool solidity (p = 0.014), were older than patients tested negative to GBT (54.3 ± 13.0 years vs. 47.5 ± 12.3 years, p = 0.049), reported a longer history of CD (21.2 ± 10.3 years vs. 15.7 ± 10.2 years, p = 0.031) and showed a significant higher frequency of prior surgery (p = 0.001), revealing an association of number of surgical procedures (OR = 2.8315, 95% CI = 1.1525-6.9569, p = 0.023) with SIBO. Breath test normalization occurred in 13/15 patients evaluated after antibiotic and probiotic therapy. Although vitamin B12 levels were lower in patients with SIBO (p = 0.045) and a significant improvement was found after treatment (p = 0.011), this could be due to the heterogeneity, regarding vitamin B12 treatment, in our cohort.

CONCLUSION

SIBO is a frequent but underestimated condition in CD, which often mimics acute flare, effectively identified with GBT and could be treated with a combined antibiotic and probiotic therapy.

Prevalence of Small Intestinal Bacterial Overgrowth among Chronic Pancreatitis Patients: A Case-Control Study

Background. Patients with chronic pancreatitis (CP) exhibit numerous risk factors for the development of small intestinal bacterial overgrowth (SIBO). Objective. To determine the prevalence of SIBO in patients with CP. Methods. Prospective, single-centre case-control study conducted between January and September 2013. Inclusion criteria were age 18 to 75 years and clinical and radiological diagnosis of CP. Exclusion criteria included history of gastric, pancreatic, or intestinal surgery or significant clinical gastroparesis. SIBO was detected using a standard lactulose breath test (LBT). A healthy control group also underwent LBT. Results. Thirty-one patients and 40 controls were included. The patient group was significantly older (53.8 versus 38.7 years; P < 0.01). The proportion of positive LBTs was significantly higher in CP patients (38.7 versus 2.5%: P < 0.01). A trend toward a higher proportion of positive LBTs in women compared with men was observed (66.6 versus 27.3%; P = 0.056). The subgroups with positive and negative LBTs were comparable in demographic and clinical characteristics, use of opiates, pancreatic enzymes replacement therapy (PERT), and severity of symptoms. Conclusion. The prevalence of SIBO detected using LBT was high among patients with CP. There was no association between clinical features and the risk for SIBO.

Clinical predictors of small intestinal bacterial overgrowth by duodenal aspirate culture

BACKGROUND

There has been increasing interest in small intestinal bacterial overgrowth (SIBO) after reports of a link with irritable bowel syndrome (IBS), yet our understanding of this entity is limited.

AIM

Our aim was to estimate the yield of patients undergoing duodenal aspirate culture, and to identify symptoms and features that predict SIBO.

METHODS

A medical chart review of patients who had undergone duodenal aspirate culture at an academic medical centre in 2003 was performed to record clinical characteristics and culture results. The associations between aspirate results and symptoms, medical diagnoses and medication use were assessed using logistic regression.

RESULTS

A total of 675 patients had available aspirate results. Mean age of the sample was 53 (s.d. 17) and 443 (66%) were female patients. Overall, 8% of aspirates were positive for SIBO; 2% of IBS patients had SIBO. Older age, steatorrhoea and narcotic use were associated with SIBO (P < 0.05). PPI use was not associated with SIBO, but was associated with bacterial growth not meeting criteria for SIBO (P < 0.05). Inflammatory bowel disease (IBD), small bowel diverticula and pancreatitis were positively associated with an abnormal duodenal aspirate (P < 0.05), but other conditions including IBS were not associated with SIBO.

CONCLUSION

Older age, steatorrhoea, narcotic use, IBD, small bowel diverticula and pancreatitis were associated with small intestinal bacterial overgrowth based on abnormal duodenal aspirate culture results. However, no clear associations of true small intestinal bacterial overgrowth with IBS or PPI use were detected, in contrast to recent speculation.

Diagnosis of small intestinal bacterial overgrowth: the challenges persist!

Small intestinal bacterial overgrowth was originally defined in the context of an overt malabsorption syndrome and diagnostic tests were developed and validated accordingly. More recently, the concept of intestinal contamination with excessive numbers of bacteria, especially those of colonic type, has been extended beyond the bounds of frank maldigestion and malabsorption to explain symptomatology in disorders as diverse as irritable bowel syndrome, celiac sprue and nonalcoholic fatty liver disease. Owing to a lack of consensus with regard to the optimal diagnostic criteria (the 'gold standard') for the diagnosis of bacterial overgrowth, the status of these new concepts is unclear. This review sets out to critically appraise the various diagnostic approaches that have been taken and are currently employed to diagnose small intestinal bacterial overgrowth.

Critical evaluation of diagnosing bacterial overgrowth in the proximal small intestine

BACKGROUND

Clinical small bowel bacterial overgrowth (SBBO) syndrome can be objectified by bacterial overgrowth tests. As direct culture of jejunal aspirates has disadvantages, noninvasive tests such as breath tests (BTs) are used. Major drawback of lactulose BT might be rapid lactulose transit to the colon. We evaluated diagnosing bacterial overgrowth using experimental and standard BT, and culture and molecular-based methods.

STUDY

Bacterial overgrowth was analyzed in 11 controls and 15 SBBO predisposed subjects. During experimental breath testing, an occlusive balloon limited lactulose to the small intestine. Jejunal fluid was analyzed using culture and molecular-based methods. Bacterial overgrowth was diagnosed on the basis of 20 ppm hydrogen or methane increase above baseline within 90 minutes or more than 10 CFU/mL excluding lactobacilli and streptococci and furthermore using all published definitions.

RESULTS

Experimental and standard BT showed no changes in timing of hydrogen excretion between controls and SBBO subjects. Using standard BT, 3/11 controls and 8/15 SBBO subjects were bacterial overgrowth positive. Total counts showed no significant differences between controls and SBBO subjects using culture and molecular-based methods. Bacterial overgrowth was diagnosed in 0/9 controls and 4/12 SBBO subjects using culture-based methods. Other definitions used in literature revealed no significant differences between controls and SBBO subjects.

CONCLUSIONS

In a small group of subjects, the experimental BT did not improve the ability of lactulose BT to diagnose bacterial overgrowth. Culturing showed less bacterial overgrowth in controls compared with BT. Remarkably, current diagnostic criteria do not seem to be accurate in discriminating between SBBO subjects and controls.

Prevalence of small bowel bacterial overgrowth and its association with nutrition intake in nonhospitalized older adults

OBJECTIVES

To determine the prevalence of small bowel bacterial overgrowth (SBBO) in older adults and to assess whether SBBO is associated with abdominal complaints and nutrient intake.

DESIGN

Cross-sectional survey.

SETTING

Eight senior residence sites in Stuttgart, Germany.

PARTICIPANTS

Older adults living independently in senior residence houses.

MEASUREMENTS

The prevalence of SBBO was measured in 328 subjects, of whom 294 were aged 61 and older, by measuring hydrogen concentration (parts per million; ppm) in exhaled air after ingestion of 50 g glucose. Anthropometric data were obtained and nutritional status was recorded with a computer-aided diet history.

RESULTS

The prevalence of a positive hydrogen breath test (>10 ppm increase) was 15.6% in older adults, compared with 5.9% in subjects aged 24 to 59. The intake of inhibitors of gastric acid production contributed significantly to the high prevalence of a positive breath test in older adults, which was associated with lower body weight, lower body mass index, lower plasma albumin concentration, and higher prevalence of diarrhea. Subjects with a positive hydrogen breath test consumed significantly less fiber, folic acid, and vitamins B2 and B6 than those without. No difference was observed in the intake of energy, protein, fat, or carbohydrates.

CONCLUSION

Prevalence of SBBO is associated with reduced body weight, which is paralleled by reduced intake of several micronutrients. Malabsorption resulting from diarrhea might be an aggravating factor contributing to weight loss in these subjects.

Aging and intestinal motility: a review of factors that affect intestinal motility in the aged

Normal aging is associated with significant changes in the function of most organs and tissues. In this regard, the gastrointestinal tract is no exception. The purpose of this review is to detail the important age-related changes in motor function of the various parts of the gastrointestinal tract and to highlight some of the important motility changes that may occur, either in relation to common age-related disorders, or as a result of certain drugs commonly prescribed in the aged. A major confounding factor in the interpretation of motor phenomena throughout the gastrointestinal tract in this age group is the frequent coexistence of neurological, endocrinological and other disease states, which may be independently associated with dysmotility. Overall, current data are insufficient to implicate normal aging as a cause of dysmotility in the elderly. Normal aging is associated with various changes in gastrointestinal motility, but the clinical significance of such changes remains unclear. More important is the impact of various age-related diseases on gastrointestinal motility in the elderly: for example, long-standing diabetes mellitus may reduce gastric emptying in up to 50% of patients; depression significantly prolongs whole-gut transit time; hypothyroidism may prolong oro-caecal transit time; and chronic renal failure is associated with impaired gastric emptying. In addition, various, frequently used drugs in the elderly cause disordered gastrointestinal motility. These drugs include anticholinergics, especially antidepressants with an anticholinergic effect, opioid analgesics and calcium antagonists.

Interdigestive and postprandial motility in small-intestinal bacterial overgrowth

BACKGROUND

Motility disorders are believed to be of major pathogenetic importance in small-intestinal bacterial overgrowth (SIBO). The aim of this study was to investigate interdigestive and postprandial motility in a group of patients with SIBO and to compare the results with those of healthy volunteers.

METHODS

Twenty healthy subjects and 14 patients with SIBO were included. Exclusion criteria were obvious predisposing conditions. Antroduodenojejunal pressure recording was performed after an overnight fast. After a 5-h interdigestive recording a standard meal was given, and postprandial recording performed for 30 min.

RESULTS

Significantly fewer patients than healthy subjects had phase-III activity in the antrum (3 of 14 versus 15 of 20; P < 0.01), and more patients lacked phase III completely (5 of 14 versus 0 of 20; P < 0.05). Propagated single contractions in the proximal duodenum during late phase II and postprandially were also significantly reduced (1 (0-5) versus 8 (5-12) per 30 min (median; interquartile range (IQR)) (P < 0.01) and 0.5 (IQR, 0-6.5) versus 8 (IQR, 6-13) per 30 min (P < 0.01), respectively). In the distal part of the duodenum the patients had significantly prolonged duration of phase III (7.8; IQR, 5.6-9.2 versus 5.9; IQR, 4.2-6.6 min) (P < 0.05) and increased motility index of phase III (6685; IQR, 4870-9999 versus 3605; IQR, 2579-5544 mm Hg x min/30 min) (P < 0.05), late phase II (10,285; IQR, 6105-11,384 versus 6650; IQR, 4639-9102) (P < 0.05), and postprandially (12,960; IQR, 8454-18,644 versus 7917; IQR, 6132-10,551) (P < 0.05). Retrograde contractions predominated in the late part of phase III in the proximal duodenum in both groups. The cycle length of the MMC and the number of clustered contractions showed no difference between the two groups.

CONCLUSIONS

A significant proportion of patients with SIBO, compared with healthy subjects, lack interdigestive phase-III activity, not only in the small intestine but also in the gastric antrum. They also have fewer propagated contractions in the proximal duodenum during interdigestive phase II. On the other hand, the motility index in the distal part of the duodenum was higher in patients with SIBO during phase III, late phase II, and postprandially. The results are compatible with a reduced clearing function in the stomach and proximal duodenum and/or a compensatory increase of motility in the region of the duodenojejunal flexure.

Small-bowel bacterial overgrowth in children with chronic diarrhea, abdominal pain, or both

OBJECTIVE

To evaluate the frequency of small-bowel bacterial overgrowth (SBBO) as a cause of chronic digestive symptoms in a large cohort of children, using the glucose breath hydrogen test (BHT).

DESIGN

Patients were 53 children (aged 2 months to 12 years) with chronic diarrhea, abdominal pain, or both. Diagnosis of SBBO was defined with a BHT by a change in H2 concentration of 10 ppm H2 or more in expired air after an oral glucose load. Patients with a positive BHT result were included in group 1 and treated with a combination of colistin and metronidazole for 10 days; a second BHT was performed 1 month later. Group 2 comprised patients with a negative BHT result. Group 3 (n = 15) was a control group of healthy subjects, and group 4 (n = 6) a comparison group of subjects with bacteriologically documented SBBO.

RESULTS

Eighteen patients (34%) had a positive BHT result and 35 a negative result. The BHT results were comparable in groups 1 and 4 and in groups 2 and 3, respectively. Fasting H2 levels were higher in group 1 than in groups 2 (p < 0.001) and 3 (p < 0.01). In group 1, children were younger than in group 2 (1 +/- 1 year vs 3.9 +/- 3 years; p < 0.001) and diarrhea was frequent (83%), but 17% of patients had abdominal pain alone. Fetid stools (p < 0.01), mucus in stools (p < 0.01), and flatulence (p < 0.05) were more frequent in group 1 than in group 2. Antibiotic treatment of children in group 1 led to a rapid disappearance of symptoms and normalization of BHT results.

CONCLUSION

SBBO appears to be a frequent cause of chronic digestive symptoms in children, especially before the age of 2 years. The BHT provides a simple and noninvasive method of detecting it. The recognition of SBBO in children leads to effective treatment.