Identification of SIBO Subtypes along with Nutritional Status and Diet as Key Elements of SIBO Therapy.

Small intestinal bacterial overgrowth (SIBO) is a pathology of the small intestine and may predispose individuals to various nutritional deficiencies. Little is known about whether specific subtypes of SIBO, such as the hydrogen-dominant (H+), methane-dominant (M+), or hydrogen/methane-dominant (H+/M+), impact nutritional status and dietary intake in SIBO patients. The aim of this study was to investigate possible correlations between biochemical parameters, dietary nutrient intake, and distinct SIBO subtypes. This observational study included 67 patients who were newly diagnosed with SIBO. Biochemical parameters and diet were studied utilizing laboratory tests and food records, respectively. The H+/M+ group was associated with low serum vitamin D (p < 0.001), low serum ferritin (p = 0.001) and low fiber intake (p = 0.001). The M+ group was correlated with high serum folic acid (p = 0.002) and low intakes of fiber (p = 0.001) and lactose (p = 0.002). The H+ group was associated with low lactose intake (p = 0.027). These results suggest that the subtype of SIBO may have varying effects on dietary intake, leading to a range of biochemical deficiencies. Conversely, specific dietary patterns may predispose one to the development of a SIBO subtype. The assessment of nutritional status and diet, along with the diagnosis of SIBO subtypes, are believed to be key components of SIBO therapy.

The relationship between small intestinal bacterial overgrowth and constipation in children - a comprehensive review.

Small intestinal bacterial overgrowth (SIBO) is characterized by an increase in the bacterial population of the small intestine due to an imbalance between the amount of bacteria and the intestinal barrier. Pediatric SIBO presents with a wide spectrum of symptoms, ranging from mild gastrointestinal complaints to malabsorption or malnutrition. Breath tests are commonly used as noninvasive diagnostic tools for SIBO, but a standardized methodology is currently unavailable. Intestinal flora produces methane which slows intestinal transit and increases the contractile activity of small intestine. Emerging literature suggests a correlation between overgrowth of methanogenic bacteria in the intestines and constipation. Treatment of SIBO involves administration of antibacterial therapy in addition to management of underlying conditions and optimal dietary adjustments. However, research on antibiotic treatment for pediatric patients with constipation and SIBO is limited and has yielded conflicting results. In the current review, we summarize the state-of-the-art of the field and discuss previous treatment attempts and currently used regimens for SIBO patients with constipation, with a focus on pediatric populations.

Critical appraisal of the SIBO hypothesis and breath testing: A clinical practice update endorsed by the European society of neurogastroenterology and motility (ESNM) and the American neurogastroenterology and motility society (ANMS).

BACKGROUND: There is compelling evidence that microbe-host interactions in the intestinal tract underlie many human disorders, including disorders of gut-brain interactions (previously termed functional bowel disorders), such as irritable bowel syndrome (IBS). Small intestinal bacterial overgrowth (SIBO) has been recognized for over a century in patients with predisposing conditions causing intestinal stasis, such as surgical alteration of the small bowel or chronic diseases, including scleroderma and is associated with diarrhea and signs of malabsorption. Over 20 years ago, it was hypothesized that increased numbers of small intestine bacteria might also account for symptoms in the absence of malabsorption in IBS and related disorders. This SIBO-IBS hypothesis stimulated significant research and helped focus the profession's attention on the importance of microbe-host interactions as a potential pathophysiological mechanism in IBS. PURPOSE: However, after two decades, this hypothesis remains unproven. Moreover, it has led to serious unintended consequences, namely the widespread use of unreliable and unvalidated breath tests as a diagnostic test for SIBO and a resultant injudicious use of antibiotics. In this review, we examine why the SIBO hypothesis remains unproven and, given the unintended consequences, discuss why it is time to reject this hypothesis and its reliance on breath testing. We also examine recent IBS studies of bacterial communities in the GI tract, their composition and functions, and their interactions with the host. While these studies provide important insights to guide future research, they highlight the need for further mechanistic studies of microbe-host interactions in IBS patients before we can understand their possible role in diagnosis and treatment of patient with IBS and related disorders.

Small intestinal bacterial overgrowth in diabetic gastroenteropathy.

BACKGROUND: Although diabetic gastroenteropathy (DGE) is associated with small intestinal bacterial overgrowth (SIBO), most studies have evaluated SIBO with a hydrogen breath test, which may be affected by altered transit in DGE. The risk factors for the consequences of SIBO in DGE are poorly understood. We aimed to evaluate the prevalence of, risk factors for, and gastrointestinal symptoms associated with SIBO in patients with DGE. METHODS: In 75 patients with DGE and dyspepsia, we tested for SIBO (≥105 colony forming units /mL of aerobic and/or anaerobic bacteria in a duodenal aspirate) and assessed gastric emptying (GE) of solids, symptoms during a GE study and during an enteral lipid challenge (300 kcal/2 h), and daily symptoms with a Gastroparesis Cardinal Symptom Index diary for 2 weeks. Symptoms and GE were compared in patients with versus without SIBO. KEY RESULTS: Of 75 patients, 34 (45%) had SIBO, which was not associated with the use of proton pump inhibitors, daily symptoms, GE, or symptoms during a GE study. During enteral lipid challenge, severe nausea (p = 0.006), fullness (p = 0.02) and bloating (p = 0.009) were each associated with SIBO. Twenty patients (59%) with versus 13 (32%) without SIBO had at least one severe symptom during the lipid challenge (p = 0.006). CONCLUSIONS & INFERENCES: Among patients with DGE 45% had SIBO, which was associated with symptoms during enteral lipid challenge but not with delayed GE, symptoms during a GE study, or daily symptoms. Perhaps bacterial products and even fatty acids are recognized by and activate mast cells that drive the increased lipid sensitivity in SIBO.

Glucose breath test for the detection of small intestine bacterial overgrowth: Impact of diet prior to the test.

BACKGROUND: Glucose breath test (GBT) is used for the diagnosis of small intestine bacterial overgrowth. A restrictive diet without fibers and/or fermentable food is recommended on the day before the test. The aim of our retrospective study was to evaluate the impact of two different restrictive diets on the results of GBT. METHODS: A change of the pretest restrictive diet was applied in our lab on September 1, 2020. The recommended diet was a fiber-free diet before this date, and a fiber-free diet plus restriction of all fermentable food afterward. We thus compared the results of GBT performed before (group A) and after (group B) this pretest diet modification. Demographics, reasons to perform GBT, digestive symptoms, and hydrogen and methane baseline values and variations after glucose ingestion were compared between the two groups. KEY RESULTS: 269 patients underwent GBT in group A, and 316 patients in group B. The two groups were comparable in terms of demographics. Methane and hydrogen baseline values were significantly higher in group A (respectively 14 [18] vs. 8 [14] ppm, p < 0.01 and 11 [14] vs. 6 [8] ppm, p < 0.01). The percentage of positive tests was higher in group A for methane (43% vs. 28%, p < 0.05), and for hydrogen (18% vs. 12%, p = 0.03). CONCLUSION & INFERENCES: This retrospective study suggests the importance of the restrictive diet prior to GBT. A strict limitation of fibers and fermentable food decreased hydrogen and methane baseline values, and the prevalence of positive GBT. Thus a strict restrictive diet should be recommended on the day before the test, in order to limit the impact of food on hydrogen and methane breath levels, and possibly improve the diagnosis quality of GBT.

Small Intestinal Bacterial Overgrowths and Intestinal Methanogen Overgrowths Breath Testing in a Real-Life French Cohort.

INTRODUCTION: Breath testing has become a widely used tool to diagnose small intestinal bacterial overgrowths (SIBOs) and intestinal methanogen overgrowths (IMOs) in clinical settings. Owing to the heterogeneity in clinical manifestations and lack of standardization among centers performing breath testing, SIBO and IMO can be easily overlooked by the clinician. We studied the prevalence and symptoms of SIBO/IMO in French patients referred for breath testing after seeking medical advice. METHODS: Breath test data and symptoms of 331 patients were assessed for SIBO/IMO using the H 2 /CH 4 lactulose breath test (LBT). Wilcoxon test or χ 2 test were used to compare patients with SIBO/IMO with patients without SIBO/IMO. LBT positive patients (H 2 +, CH 4 +, and CH 4 +/H 2 +) were compared using Kruskal-Wallis test for continuous data or χ 2 test for categorical data. RESULTS: Among the 186 (68.1%) patients tested positive for an overgrowth with 40.3%, 47.3%, and 12.4% for H 2 +, CH 4 + and CH 4 +/H 2 +, respectively, the presence of diarrhea was significantly increased in hydrogen type overgrowths ( P < 0.001). No significant difference according to age, gender, and symptoms was associated with a positive test except for joint pain that was less prevalent among LBT positive patients ( P = 0.038). In 86.5% of IMOs, positivity with CH 4 values ≥10 ppm could be identified at baseline. DISCUSSION: There are little discriminating symptoms that can help the clinician to identify patients likely to have a SIBO/IMO. However, SIBO/IMOs remain a common disorder widely underdiagnosed that need further studies to better apprehend functional bowel disorders.

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.

A systematic review and meta-analysis on the prevalence of non-malignant, organic gastrointestinal disorders misdiagnosed as irritable bowel syndrome.

Treatable gastrointestinal disorders in patients with symptoms typical for irritable bowel syndrome (IBS) may be overlooked. The prevalence of five gastrointestinal conditions-bile acid diarrhoea (BAD), carbohydrate malabsorption (CM), microscopic colitis (MC), pancreatic exocrine insufficiency (PEI) and small intestinal bacterial overgrowth (SIBO) was systematically assessed from studies including consecutive patients meeting diagnostic criteria for IBS. 4 databases were searched from 1978 to 2020. Studies were included if they evaluated the prevalence of these conditions in secondary healthcare setting. Estimated pooled rates were calculated and statistical heterogeneity between studies was evaluated using Q and I2 statistics. Seven studies (n = 597) estimated the pooled prevalence for BAD as 41% (95% CI 29-54). 17 studies (n = 5068) estimated that of MC as 3% (95% CI 2-4%). Two studies (n = 478) suggested a rate of 4.6% (range: 1.8-6.1%) for PEI. Using breath testing, 26 studies (n = 6700) and 13 studies (n = 3415) estimated the prevalence of lactose and fructose malabsorption as 54% (95% CI 44-64%) and 43% (95% CI 23-62%); 36 studies (n = 4630) and 22 studies (n = 2149) estimated that of SIBO as 49% (95% CI 40-57%) with lactulose and 19% (95% CI 13-27%) with glucose. Rates of all conditions were significantly higher than in healthy controls. A significant proportion of patients presenting to secondary care with IBS have an organic condition which may account for their symptoms. Failure to exclude such conditions will deny patients effective treatment.

Effects of Proton Pump Inhibitors on the Small Bowel and Stool Microbiomes.

BACKGROUND: Proton pump inhibitor (PPI) use is extremely common. PPIs have been suggested to affect the gut microbiome, and increase risks of Clostridium difficile infection and small intestinal bacterial overgrowth (SIBO). However, existing data are based on stool analyses and PPIs act on the foregut. AIMS: To compare the duodenal and stool microbiomes in PPI and non-PPI users. METHODS: Consecutive subjects presenting for upper endoscopy without colonoscopy were recruited. Current antibiotic users were excluded. Subjects taking PPI were age- and gender-matched 1:2 to non-PPI controls. Subjects completed medical history questionnaires, and duodenal aspirates were collected using a validated protected catheter. A subset also provided stool samples. Duodenal and stool microbiomes were analyzed by 16S rRNA sequencing. RESULTS: The duodenal microbiome exhibited no phylum-level differences between PPI (N = 59) and non-PPI subjects (N = 118), but demonstrated significantly higher relative abundances of families Campylobacteraceae (3.13-fold, FDR P value < 0.01) and Bifidobacteriaceae (2.9-fold, FDR P value < 0.01), and lower relative abundance of Clostridiaceae (88.24-fold, FDR P value < 0.0001), in PPI subjects. SIBO rates were not significantly different between groups, whether defined by culture (> 103 CFU/ml) or 16S sequencing, nor between subjects taking different PPIs. The stool microbiome exhibited significantly higher abundance of family Streptococcaceae (2.14-fold, P = 0.003), and lower Clostridiaceae (2.60-fold, FDR P value = 8.61E-13), in PPI (N = 22) versus non-PPI (N = 47) subjects. CONCLUSIONS: These findings suggest that PPI use is not associated with higher rates of SIBO. Relative abundance of Clostridiaceae was reduced in both the duodenal and stool microbiomes, and Streptococcaceae was increased in stool. The clinical implications of these findings are unknown.

[The role of intraepithelial lymphocytes in pathogenesis of small intestinal bacterial overgrowth syndrome]. / Rola limfocytów sródnablonkowych w patogenezie zespolu przerostu bakteryjnego jelita cienkiego.

Small intestinal bacterial overgrowth (SIBO) is a frequent cause of chronic abdominal complaints. So far, a lot information has been gathered on its pathogenesis but are still doubts that raise question why its causes chronic diarrhea in some and constipation in other patients. AIM: The aim of the study was to assess the number of endothelial lymphocytes (IELs) in the duodenal and ileum mucosa in patients with SIBO with dominant diarrhea (SIBO-D) and dominant constipation (SIBO-C). MATERIALS AND METHODS: The study was performed in 30 healthy patients (group I) and 40 patients with SIBO and diarrhoea (group II), and in 4o patients with constipation (group III). To diagnose SIBO the lactulose hydrogen breath test (LHBT) was performed. To determine the number of intraepithelial lymphocytes in duodenal and jejunal mucosa the histological assessment was performed using haematoxylin-eosin staining. Moreover, immunochistochemical method was used to assess the number of enterochromatoffin cells (EC, chromogranin A - LK-2H10) in these some parts of the gut. RESULTS: The results of LHBT were similar in group II and III - 75,6±18,1 ppm and 66,9±16,2 ppm(p>0,05). The number of IELs in duodenal mucosa in controls was 14,6±4,1/100 EN, in group II - 28,3±6,8/100 EN (p<0.01), and in group III - 23,0±9,9/100 EN (p<0,05), and similar differences were in jejunal mucosa. The number of EC in both parts of the gut was higher in SIBO compared to controls. Furthermore, in patients with SIBO-D the number of IELs in duodenum, as well as in jejunum, was positively correlated with the number of EC cells ( p<0,05, p=0,056, respectively). CONCLUSIONS: In patients with SIBO, particularly with SIBO-D, increased number of IELs I EC cells may be a cause of diverse abdominal symptoms.

Association of Small Intestinal Bacterial Overgrowth With Heart Failure and Its Prediction for Short-Term Outcomes.

Background Small intestinal bacterial overgrowth (SIBO) is a common pathological condition of intestinal microbiota. The prevalence of SIBO and its prognostic value in patients with heart failure (HF) are unknown. Methods and Results A total of 287 patients tested for SIBO using lactulose hydrogen-methane breath test were evaluated. At least 1 of the following criteria fulfilled was SIBO positive: patients with fasting hydrogen level ≥20 parts per million (ppm) or a ≥20 ppm rise in hydrogen by 90 minutes were diagnosed with SIBO (H2) positive; and patients with methane levels ≥10 ppm at any test point were diagnosed with SIBO (CH4) positive. The association between SIBO and the composite of cardiovascular death and HF rehospitalization was investigated. In 287 consecutive patients with HF, 128 (45%) were positive for SIBO. Our result showed SIBO increased the risk of HF rehospitalization in patients with HF with reduced ejection fraction (P<0.001), and the risk of cardiovascular death in patients with HF with preserved EF (P=0.011). SIBO was an independent risk factor of primary end point in patients with HF (hazard ratio [HR], 2.13; 95% CI; 1.26-3.58; P=0.005). In addition, SIBO (CH4) showed a prognostic value on adverse outcomes (HR, 2.35; 95% CI, 1.38-4.02; P<0.001), whereas the association between SIBO (H2) and outcomes was not statistically significant. Conclusions There was high prevalence of SIBO in patients with HF, and SIBO was independently associated with poor outcomes. Proactive treatment for SIBO may provide extra benefit for patients with HF.

Diagnosing Small Intestinal Bacterial Overgrowth: A Comparison of Lactulose Breath Tests to Small Bowel Aspirates.

BACKGROUND: Duodenal aspiration (DA) and lactulose breath tests (LBT) are commonly performed to diagnose small intestinal bacterial overgrowth (SIBO). There are no data directly comparing these tests. AIMS: To investigate the agreement between DA and LBT for the diagnosis of SIBO. METHODS: A retrospective cohort study of adult patients who underwent a LBT and a DA at a tertiary care center over 9 years was assembled. LBT was considered positive if the hydrogen baseline or peak change measurement was ≥ 20 ppm, and/or if the methane baseline or peak change was ≥ 10 ppm. DA was considered positive if > 100,000 cfu/mL of gram-negative flora was identified on culture, and contaminated if > 100,000 cfu/mL of gram-positive flora was identified. RESULTS: A total of 106 patients were evaluated; 81 (76.4%) were female; the mean age was 53.4 ± 15.9 years. 21 patients (19.8%) had evidence of contamination on DA. 14 (16.5%) patients had a positive DA result. Patients with diabetes mellitus and those with PPI use were more likely to have a positive DA (94.4% vs. 71.4%, p = 0.007; 62% vs. 28.6%, p = 0.021, respectively). 33 (31.1%) patients had a positive LBT. Patients with a history of small bowel resection were more likely to have a positive LBT (12.1% vs. 1.4%, p = 0.016). DA and LBT results agreed in 54 patients (63.5%; kappa = - 0.02), indicating poor agreement. CONCLUSIONS: The agreement between LBT and DA in evaluation for SIBO was poor. LBT may be favorable to DA, as LBT is safer, cheaper, and less likely to yield a contaminant result.

High Prevalence of Small Intestinal Bacterial Overgrowth among Functional Dyspepsia Patients.

BACKGROUND: Small intestinal bacterial overgrowth (SIBO), characterized by either increased numbers or presence of colonic type bacteria in the small bowel has been previously described in functional dyspepsia (FD), based on breath testing. In this study, we aim to examine the prevalence of SIBO among FD patients using small bowel aspirate culture. METHODS: We prospectively enrolled outpatients fulfilling Rome IV criteria for FD. Severity of symptoms was graded using the patient assessment of upper gastrointestinal symptom severity index (PAGI-SYM) questionnaire. Patients underwent upper gastrointestinal endoscopy and duodenal fluid was aspirated in sterile traps. SIBO was defined as ≥103 colony forming units/mL of duodenal aspirate and/or presence of colonic type bacteria. Patients undergoing gastroscopy due to gastroesophageal reflux symptoms - control group (CG) - and patients with irritable bowel syndrome (IBS) fulfilling Rome IV criteria were also recruited. RESULTS: We enrolled 227 FD subjects, 30 CG, and 90 IBS patients. Among FD patients, 144 (63.4%), 64 (28.2%), and 19 (8.4%) had postprandial distress syndrome (PDS), epigastric pain syndrome (EPS), and overlapping PDS-EPS syndrome, respectively. SIBO prevalence was 20.8%, 12.5%, and 31.6% among PDS, EPS, and overlapping PDS-EPS FD subtypes, respectively. Overall, SIBO prevalence was significantly higher in FD (44/227 [19.4%]) compared to CG (1/30 [3.3%]) (p = 0.037) and similar to IBS (44/227 [19.4%] vs. 15/90 [16.7%], p = 0.63) subjects. SIBO presence was associated neither with total nor with any subscale score of the PAGI-SYM questionnaire. CONCLUSION: In a cohort of Greek FD patients, SIBO prevalence was similar to that of IBS subjects and higher compared to that of controls.

Small Intestinal Bacterial Overgrowth Syndrome: A Guide for the Appropriate Use of Breath Testing.

The increased availability of noninvasive breath tests, each with limitations, has led to widespread testing for small intestinal bacterial overgrowth (SIBO) in patients with non-specific gastrointestinal complaints. The lactulose breath test (LBT) is based upon an incorrect premise and therefore incorrect interpretations which has resulted in the over-diagnosis of SIBO and the excessive use of antibiotics in clinical practice. Despite limitations, the glucose breath test (GBT) should be exclusively employed when considering SIBO in appropriately chosen patients. This review suggests guidelines for the optimal use and appropriate interpretation of the GBT for suspected SIBO. The LBT should be discarded from future use, and the literature based upon the LBT should be discounted accordingly.

The overlap between irritable bowel syndrome and organic gastrointestinal diseases.

Irritable bowel syndrome (IBS) is a common functional bowel disorder characterised by symptoms of recurrent abdominal pain associated with a change in bowel habit. This condition is one of the most frequent reasons to seek a gastroenterology consultation in primary and secondary care. The diagnosis of IBS is made by identifying characteristic symptoms, as defined by the Rome criteria, and excluding organic gastrointestinal diseases that might otherwise explain these symptoms. Organic conditions that can be mistaken for IBS include coeliac disease, inflammatory bowel disease (IBD), colorectal cancer, and, in those with diarrhoea-predominant symptoms, chronic gastrointestinal infections, microscopic colitis, and primary bile acid diarrhoea. The concept of small intestinal bacterial overgrowth being associated with IBS is shrouded with controversy and uncertainty, mainly because of invalid tests due to poor sensitivity and specificity, potentially leading to incorrect assumptions. There is insufficient evidence to link IBS-type symptoms with exocrine pancreatic insufficiency or with symptomatic uncomplicated diverticular disease, since both are hampered by conflicting data. Finally, there is growing appreciation that IBS can present in patients with known but stable organic gastrointestinal diseases, such as quiescent IBD or coeliac disease. Recognising functional gut symptoms in these individuals is paramount so that potentially harmful escalations in immunosuppressive therapy can be avoided and attention can be focused on addressing disorders of gut-brain interaction. This Review endeavours to aid clinicians who practise adult gastroenterology in recognising the potential overlap between IBS and organic gastrointestinal diseases and highlights areas in need of further research and clarity.

Acute gastric injury after ingestion of substrate with hyperosmolar glucose and benzoate inversely related with small intestinal bacterial overgrowth.

BACKGROUND/AIMS: The occurrence of gastrointestinal symptoms and the presence of small intestinal bacterial overgrowth (SIBO) could be determined after ingestion of substrate with highly concentrated glucose for glucose breath test (GBT), after which endoscopic images for acute gastric injury have not been clarified. The aims of this study were to investigate the prevalence and relationship of acute gastric injury with SIBO after GBT. MATERIALS AND METHODS: A cohort of 235 patients with functional gastrointestinal symptoms undergoing breath test with 50 g glucose solution, immediately followed by upper endoscopy were surveyed. The acute gastric injury in endoscopic images and the GBT for hydrogen (H2) or methane (CH4) were assessed. RESULTS: The prevalence of acute gastric injury was 28.1% (66/235) after GBT. There were significant differences in GBT positivity (+) with and without gastric injury (25.8% vs 40.8%, p=0.03). In subtypes, GBT (H2) + was significantly lower in group with gastric injury than in the group without. No differences were seen in GBT (CH4) + between two groups. On multivariate analysis, the subtype of GBT (H2) + (Odds ratio (OR)=0.42; 95% Confidence interval (CI)=0.20-0.90; p=0.03) inversely and female (OR=2.11; 95% CI=1.11-4.00; p=0.02) were significantly related with gastric injury. Whereas gastric injury was the only independent related factor for GBT + inversely (OR=0.51; 95% CI=0.27-0.97; p=0.04). CONCLUSION: Highly concentrated glucose might provoke acute gastric injury, which could predict the absence of SIBO.

AGA Clinical Practice Update on Small Intestinal Bacterial Overgrowth: Expert Review.

DESCRIPTION: Thanks to ready access to hydrogen breath testing, small intestinal bacterial overgrowth (SIBO) is now commonly diagnosed among individuals presenting with a variety of gastrointestinal and even nongastrointestinal symptoms and is increasingly implicated in lay press and media in the causation of a diverse array of disorders. Its definition, however, remains controversial and true prevalence, accordingly, undefined. The purpose of this review, therefore, was to provide a historical background to the concept of SIBO, critically review current concepts of SIBO (including symptomatology, pathophysiology, clinical consequences, diagnosis and treatment), define unanswered questions and provide a road map toward their resolution. METHODS: Best Practice Advice statements were developed following discussion by the 3 authors. Two authors each developed text around certain Best Practice Advice based on a review of available literature. All 3 authors reviewed the complete draft and after discussion, redrafting, and further review and revision, all of the authors agreed on a final draft. BEST PRACTICE ADVICE 1: The definition of SIBO as a clinical entity lacks precision and consistency; it is a term generally applied to a clinical disorder where symptoms, clinical signs, and/or laboratory abnormalities are attributed to changes in the numbers of bacteria or in the composition of the bacterial population in the small intestine. BEST PRACTICE ADVICE 2: Symptoms traditionally linked to SIBO include bloating, diarrhea, and abdominal pain/discomfort. Steatorrhea may be seen in more severe cases. BEST PRACTICE ADVICE 3: There is insufficient evidence to support the use of inflammatory markers, such as fecal calprotectin to detect SIBO. BEST PRACTICE ADVICE 4: Laboratory findings can include elevated folate and, less commonly, vitamin B-12 deficiency, or other nutritional deficiencies. BEST PRACTICE ADVICE 5: A major impediment to our ability to accurately define SIBO is our limited understanding of normal small intestinal microbial populations-progress in sampling technology and techniques to enumerate bacterial populations and their metabolic products should provide much needed clarity. BEST PRACTICE ADVICE 6: Controversy remains concerning the role of SIBO in the pathogenesis of common functional symptoms, such as those regarded as components of irritable bowel syndrome. BEST PRACTICE ADVICE 7: Management should focus on the identification and correction (where possible) of underlying causes, correction of nutritional deficiencies, and the administration of antibiotics. This is especially important for patients with significant maldigestion and malabsorption. BEST PRACTICE ADVICE 8: Although irritable bowel syndrome has been shown to respond to therapy with a poorly absorbed antibiotic, the role of SIBO or its eradication in the genesis of this response warrants further confirmation in randomized controlled trials. BEST PRACTICE ADVICE 9: There is a limited database to guide the clinician in developing antibiotic strategies for SIBO, in any context. Therapy remains, for the most part, empiric but must be ever mindful of the potential risks of long-term broad-spectrum antibiotic therapy.

Maldigestion Versus Malabsorption in the Elderly.

PURPOSE OF REVIEW: To evaluate recently published information about the frequency of maldigestion and malabsorption in older individuals, likely diagnoses causing these problems, and the diagnostic scheme when these diagnoses are being considered. RECENT FINDINGS: Although the prevalence of malnourishment and frank malnutrition may be increasing among older adults admitted to the hospital, this appears to be due to reduced food intake rather than maldigestion or malabsorption. The mechanisms of food digestion and absorption seem to be resilient, even in old age, but concurrent illness may produce malabsorption in older individuals. Illnesses that may be more common among the elderly include small intestinal bacterial overgrowth, exocrine pancreatic insufficiency, enteropathies, vascular disease, diabetes, and certain infections, such as Whipple's disease. In addition, older adults may have had previous surgeries or exposure to medicines which may induce malabsorption. The presentation of maldigestion and malabsorption in the elderly may be different than in younger individuals, and this may contribute to delayed recognition, diagnosis, and treatment. Diagnostic testing for maldigestion and malabsorption generally is similar to that used in younger patients. Maldigestion and malabsorption occur in older individuals and require a high level of suspicion, especially when weight loss, sarcopenia, or nutrient deficiencies are present.