Diagnosis Of Small Intestinal Bacterial Overgrowth Research Articles

How to Interpret Hydrogen Breath Tests

Hydrogen breath tests using various substrates like glucose, lactulose, lactose and fructose are being used more and more to diagnose small intestinal bacterial overgrowth (SIBO) and lactose or fructose malabsorption. Though quantitative culture of jejunal aspirate is considered as gold standard for the diagnosis of SIBO, hydrogen breath tests, in spite of their low sensitivity, are popular for their non-invasiveness. Glucose hydrogen breath test is more acceptable for the diagnosis of SIBO as conventionally accepted double-peak criterion on lactulose hydrogen breath test is very insensitive and recently described early-peak criterion is often false positive. Hydrogen breath test is useful to diagnose various types of sugar malabsorption. Technique and interpretation of different hydrogen breath tests are outlined in this review.

Combined oro-caecal scintigraphy and lactulose hydrogen breath testing demonstrate that breath testing detects oro-caecal transit, not small intestinal bacterial overgrowth in patients with IBS

ObjectivesRecent studies using the lactulose hydrogen breath test (LHBT) suggest most patients with irritable bowel syndrome (IBS) have small intestinal bacterial overgrowth (SIBO). However, the validity of the LHBT has...

The Role of Small Intestinal Bacterial Overgrowth in the Pathophysiology of Irritable Bowel Syndrome

Small intestinal bacterial overgrowth (SIBO) is a clinical condition caused by excessive number of bacteria in the small bowel. SIBO is characterized by symptoms of diarrhea, abdominal pain, or bloating which may be associated with excessive gas of small intestine due to increased production by bacterial fermentation in the gut. In the last decade, SIBO has been occupied as a hot topic of interests by a group of researchers because of its potential role in the development of irritable bowel syndrome (IBS).1 In the diagnosis of SIBO, a bacterial count greater than 105 colony-forming units/mL by small bowel culture is believed to be the gold standard.2 But small bowel culture through jejunal aspirate is time-consuming, invasive, and potential for contamination. Due to several flaws of small bowel culture, a number of non-invasive and indirect tests for diagnosing SIBO have been developed. Breath test, the most common indirect method for evaluating SIBO, utilizes the metabolism of carbohydrates by bacterial enzymes, in turn indirectly measures bacterial activity of small bowel. Different carbohydrates have different properties. As lactulose is a non-absorbable carbohydrate, it easily reaches the site of potential overgrowth in the small bowel, although non-absorbed carbohydrate has limitations by the intestinal transit time. In patients with rapid transit, lactulose may produce an early hydrogen peak which makes it difficult to discriminate the true SIBO from a phenomenon by rapid intestinal transit, therefore specificity of lactulose hydrogen breath test (LHBT) is relatively low.3 Pimentel and colleagues4 suggested a concept that SIBO is a major pathogenic mechanism underlying IBS in 2000. They have found 78% of 202 IBS subjects to be positive for LHBT which is suggestive of SIBO. They also demonstrated a significant improvement in symptoms including abdominal pain, bloating, and diarrhea by treating SIBO with antibiotics and converted many IBS patients from Rome criteria positive to negative. Since then, SIBO has been proposed as an etiologic factor in IBS, but also the potential role of SIBO in IBS has been strongly debated about the methods used in diagnosing SIBO. A prevalence of SIBO in subjects meeting diagnostic criteria for IBS varies from 4% to 64%, depending on the kind of test and criteria used to define a positive result.5 In addition, a recent well-designed study from the US6 using LHBT to diagnose SIBO could not discriminate patients with IBS from healthy subjects, which was a consistent finding the authors demonstrated previously.7 Therefore, the proposed etiologic role of SIBO diagnosed by LHBT in IBS patients is controversial and the correlation between the normalization of the LHBT following antibiotic treatment and symptom improvement has become less clear. Glucose, on the other hand, is rapidly absorbed in the proximal small bowel. Thereby detecting hydrogen in this test means SIBO in a proximal location. Glucose hydrogen breath test (GHBT) is the most commonly used test in the diagnosis of SIBO, although GHBT may be less sensitive for the diagnosis of SIBO since it is absorbed in the proximal small bowel. GHBT has been reported to have a overall sensitivity between 25% to 93% and a specificity from 34% to 96% in detecting SIBO.3,5 In this issue of the Journal of Neurogastroenterology and Motility, Ghoshal et al. reported the frequency of SIBO in patients with IBS and chronic non-specific diarrhea (CNSD) with comparison to healthy controls by using GHBT. The authors found that SIBO was more common in patients with CNSD (21.9%) than those with IBS (8.5%) and healthy controls (2%). Since CNSD including diarrhea predominant IBS (D-IBS) had higher frequency of SIBO, the authors suggested clinicians to consider testing for SIBO among them. However, since false positive GHBT could result from rapid intestinal transit in patients with diarrhea, the frequency of SIBO in patients with CNSD and D-IBS demonstrated in the author's study might have been overestimated in part.

Small Intestinal Bacterial Overgrowth

Small intestinal bacterial overgrowth (SIBO) is defined as the presence of an abnormally high bacterial population level in the small intestine. It is associated with various conditions of predisposing small bowel motility disorders and with neuromuscular diseases and bowel stasis resulting from surgery. The most common symptoms associated with SIBO include diarrhea, flatulence, abdominal pain and bloating. Quantitative culture of small intestinal contents and a variety of indirect tests have been used over the years in an effort to facilitate the diagnosis of SIBO. However, in the case of microbiological quantifi cation, there is a lack of clarity on the cut-offs that defi ne a positive culture and technical difficulties associated with transporting and culturing the aspirate. The indirect tests including breath tests based on bacterial metabolism of a variety of substrates have advantages over the direct culture method, in that they are simple to use, cheap and non-invasive, but there is also no breath test specifi cally validated for the diagnosis of SIBO. In conclusion, the accuracy of all current tests remains limited due to the lack of reliability of culture methods and the lack of a standard definition of the normal quantity gut flora in the small bowel. Currently, the ideal approach to treat SIBO is to treat, if possible, the underlying disease include structural problem or small bowel motility disorders, then to modify the gastrointestinal microbiota, usually with antibiotics, in a way that will result in improved symptoms. Furthermore, it can be useful to address nutritional defi ciencies that may be associated with the development of SIBO.

Persistent elevated tissue‐transglutaminase in cystic fibrosis

Persistent elevated tissue‐transglutaminase in cystic fibrosis

Small Intestinal Bacterial Overgrowth Recurrence After Antibiotic Therapy

Current treatment for small intestinal bacterial overgrowth (SIBO) is based on courses of broad-spectrum antibiotics. No data concerning SIBO recurrence are available. The aims of the present study were to investigate SIBO recurrence as assessed by glucose breath test (GBT) after antibiotic treatment and conditions associated to SIBO recurrence. Eighty consecutive patients affected by SIBO and decontaminated by rifaximin (1,200 mg per day for 1 wk) were enrolled. Diagnosis of SIBO was based on GBT. GBT was reassessed at 3, 6, and 9 months after evidence of GBT normalization. GBT positivity recurrence, predisposing conditions, and gastrointestinal symptoms were evaluated. Ten (10/80, 12.6%), 22 (22/80, 27.5%), and 35 (35/80, 43.7%) patients showed positivity to GBT at 3, 6, and 9 months after successful antibiotic treatment, respectively. At multivariate analysis, older age (OR 1.09, 95% CI 1.02-1.16), history of appendectomy (OR 5.9, 95% CI 1.45-24.19), and chronic use of proton pump inhibitors (PPIs) (OR 3.52, 95% CI 1.07-11.64) were significantly associated to GBT positivity recurrence. All gastrointestinal symptoms significantly increased at 3, 6, and 9 months in patients with evidence of GBT positivity recurrence. GBT positivity recurrence rate was high after antibiotic treatment. Older age, history of appendectomy, and chronic use of PPIs were associated with GBT positivity recurrence. Patients with evidence of GBT positivity recurrence showed gastrointestinal symptoms relapse thus suggesting SIBO recurrence.

S1269 Small Intestinal Bacterial Overgrowth in a Children Population Affected By Irritable Bowel Syndrome: A Case-Control Study

Introduction: Small intestinal bacterial overgrowth (SIBO) is a condition characterized by abnormally high bacterial population level in the small intestine, exceeding 106 organisms/ ml. Recent data suggest that SIBO could play a role in irritable bowel syndrome (IBS) in adults. Few studies are actually available assessing the prevalence of SIBO in children and no data exist about SIBO prevalence in children affected by IBS. Aim: Aim of our study was to assess SIBO prevalence in IBS children with respect to healthy controls. Methods: Fortythree consecutive IBS children according to Rome II criteria were enrolled (17 males/26 females, mean age 9,5 years). Eleven patients (25%) were classified as post-infectious IBS (PI-IBS) on the basis of clinical history. The control population accounted of 56 sex and age matched healthy children (22 males/34 females, mean age 10 years). SIBO diagnosis was based on lactulose breath test (LBT) positivity according standard criteria (two distinct peaks, consisting of two consecutive H2 values >10 p.p.m. above the basal value after 10 g lactulose ingestion). Results: LBT positivity was found in 56% of IBS children (24/43) with respect to 15% of healthy controls (10/56). The difference between the two groups resulted to be statistically significant (p< 0.01). SIBO prevalence was similar between PIIBS and non PI-IBS patients (p= n.s.). Conclusions: This is the first case-control study testing SIBO prevalence in IBS children. Our results seem to suggest a significant association between SIBO and IBS. Further researches are needed to confirm this findings and evaluate the role of SIBO decontamination on IBS symptoms.

Nitazoxanide for the Treatment of SIBO Related Gastrointestinal Symptoms in Pediatric Population

Purpose: Many pediatric patients present with symptoms of Small Intestinal Bacterial Overgrowth (SIBO). Intestinal anaerobic bacteria are known to contribute to the symptoms exhibited by these patients. However, without a definitive test to confirm SIBO, many pediatric practitioners empirically treat these patients with a course of antibiotics with or without probiotics. Nitazoxanide (NTZ) is a first in class thiazolide antibiotic with a targeted anaerobic antibacterial activity, placebo-like safety profile, high gastrointestinal (GI) concentration, and has limited to no activity against probiotic species. To date no studies have evaluated the empiric use of NTZ for the treatment of GI related symptoms in pediatric SIBO patients. Methods: A chart review was performed on patients treated with NTZ from February 2006 to May 2007. The diagnosis of SIBO was made by the attending physician based on the patient's history, signs and symptoms. Efficacy was measured as resolution of the patient's GI related symptoms, 3–8 weeks after the end of therapy. Primary markers for resolution included: abdominal pain, diarrhea, constipation, bloating, and/or flatulence. Overall 22 patients met the inclusion criteria for review. Results: Of the 22 patients treated with NTZ, 13 (median age – 6.8 years) patients returned to the office for adequate follow up. Nine patients were prescribed NTZ for SIBO and have not returned to the office for any GI complaints. The range of NTZ doses used was 100 mg – 500 mg BID for 5–10 days depending on age of the pediatric patient. The mean dose and duration was 422 mg/d for 7.7 days. The most common dose was 200 mg BID for 10 Days (N = 5). All patients treated with NTZ and a probiotic (13/13 [100%]) had complete resolution of symptoms that were present at initial visit. No clinically significant adverse reactions attributable to NTZ were identified during the study. Conclusion: Nitazoxanide appears to be a safe and effective therapy for the empiric treatment of SIBO related GI symptoms in pediatric patients. Larger controlled clinical trials are warranted to support these findings.Table. Results

Nitazoxanide for the Treatment of SIBO-Related Gastrointestinal Symptoms

Purpose: Small intestinal bacterial overgrowth (SIBO) is a clinical condition defined as an abnormally high bacterial population in the small intestine. SIBO symptoms are variable, with abdominal pain or discomfort, bloating, diarrhea, and flatulence being the most common. Nitazoxanide (NTZ) is a first in class thiazolide antibiotic with a targeted anaerobic antibacterial activity, placebo-like safety profile, and high gastrointestinal (GI) concentration. To date no studies have evaluated the empiric use of NTZ for the treatment of GI related symptoms in SIBO patients. The purpose of this paper is to report on practice experience utilizing NTZ for the treatment of SIBO-related GI symptoms in a community setting. Methods: A chart review was performed on eleven consecutive patients treated with NTZ for the diagnosis of SIBO. The diagnosis of SIBO was made by the attending physician based on the patient's symptoms and positive lactulose breath test. Patients meeting this criteria were prescribed NTZ 500 mg twice daily for five days. Efficacy was measured as resolution of the patient's GI related symptoms 2–4 weeks after the end of therapy; repeat lactulose breath tests were not performed. The primary markers for resolution included: abdominal pain, diarrhea, bloating, and/or flatulence. Results: Of the eleven patients treated with NTZ, seven were available for follow-up evaluation. The four remaining patients have not returned to the clinic with any GI related complaints. A complete resolution of symptoms was reported in five out of the seven patients treated with NTZ. Of the two patients that did not respond to therapy, one patient was not able to tolerate the medication due to an unknown reason. The other nonresponder had failed multiple previous regimens including antibiotics, probiotics, and pancreatic enzymes. Table one summarizes patient responses to NTZ therapy.Table 1Conclusion: The empiric use of nitazoxanide 500 mg twice daily appears to be a safe and effective therapy for the treatment of SIBO-related GI symptoms. To further support these findings, larger controlled clinical trials are warranted.

Comparison of Lactose Versus Lactulose Breath Tests in Subjects Suspected with Small Intestinal Bacterial Overgrowth

Purpose: Evidence for comparative utility of various carbohydrate substrates in hydrogen breath testing (HBT) for the diagnosis of small intestinal bacterial overgrowth (SIBO) is scant. The aim of this study was to compare the yields for lactulose vs. lactose HBT in suspected SIBO. We determined: 1) the frequency of SIBO; 2) the level of rise in hydrogen (H) & methane (CH3); & 3) the time to rise in H or CH3 with the highest sensitivity for SIBO with each carbohydrate substrate. Methods: All subjects who underwent HBT from 2003–06 at Rush University Medical Center were identified using the HBT database, cross referenced to a billing database. Subjects were excluded if they had HIV, immunosuppression, antibiotic use, widespread malignancy or terminal illness. For HBT, 25 gm of lactose or 20 gm of lactulose were used. Two baseline samples & samples every 15 mins were taken up to 165 mins and analyzed using the Quinton Microlyzer for H, CH3 & carbon dioxide (CO2). The clinical data & the HBT results were obtained via chart review and were analyzed with chi- square, Fisher exact tests for categorical data, & Kruskal-Wallis tests for continuous variables, using SPSS v. 11.5 & S+7.0. HBT were considered positive for SIBO if there was a double peak in H or CH3 in lactose or lactulose HBT; or the hydrogen level was > 20 ppm before 90 min in lactulose HBT. The tests were read by a single experienced gastroenterologist. Results: Patient related variables such as age, gender, pre- or post- test symptoms or diagnosis, past medical or surgical history, medications, endoscopic or histological findings from EGD &/or colonoscopy, hemoglobin & albumin did not differ significantly between the patients receiving lactose HBT (N = 110) vs. lactulose HBT (N = 85). There was no statistically significant difference in the frequency of SIBO in subjects who underwent lactose (36.7%) versus lactulose (40%) HBT (P= 0.221). There was no statistically significant difference between mean CH3 levels at any time interval with either substrate, although there was a trend towards higher CH3 levels at all time intervals in lactulose HBT. Mean CH3 levels in lactose vs lactulose peaked at 30 mins vs 60 mins, respectively in those with SIBO. Conclusion: Lactose and lactulose HBT yield similar results in SIBO diagnosis. Use of the lactose substrate could be considered in those patients suspected to have lactose intolerance and SIBO.

Are Hydrogen Breath Tests Valid in the Elderly?

Hydrogen breath testing (HBT) is frequently used as an alternative to small bowel aspiration in the diagnosis of small intestinal bacterial overgrowth (SIBO). The role of the glucose HBT was assessed in 30 elderly patients. A positive HBT was recorded in 15 of 20 SIBO cases and 7 of 10 culture negatives (sensitivity 75% and specificity 30%). The correlation coefficients between hydrogen gas (H2) rise and total bacterial count (r = 0.21) and H2 rise and anaerobic count (r = 0) were not significant. Fasting H2 levels were raised in only 4 of the 20 SIBO cases. This study indicates that the HBT is not reliable in the diagnosis of SIBO in the elderly. There was no evidence from the data that different H2 levels or bacterial counts would significantly alter the reliability of the HBT. This work suggests that factors other than small bowel bacteria are involved in the production and expiration of H2 in the elderly, and that these factors need to be considered in the interpretation of this breath test.

Small intestine bacterial overgrowth is frequent in cystic fibrosis: combined hydrogen and methane measurements are required for its detection.

Hydrogen breath test (BT) is commonly used as a diagnostic tool for the detection of small intestine bacterial overgrowth (SIBO). It was reported that colonic methane production is far more frequent in cystic fibrosis (CF) patients than in other subjects. Therefore, measuring exclusively hydrogen in the diagnostic breath test for diagnosing SIBO might be of limited value. We aimed to assess the usefulness of combined measurement of hydrogen and methane expiration for the diagnosis of SIBO in CF. The study comprised 62 CF patients aged 5 to 18 years. Three-hundred-ninety subjects assessed due to gastrointestinal symptoms for the presence of SIBO served as a comparative group. In all subjects hydrogen/methane BT using glucose was performed. A positive BT was defined as fasting hydrogen > or = 20 ppm or fasting methane > or = 10 ppm or a rise of > or = 12 ppm hydrogen or > or = 6 ppm methane over baseline during the test. In 23 (37.1%) CF patients and in 52 (13.3%) subjects from the comparative group abnormal BT results were found. In seven (11.3%) CF patients and 29 (7.4%) of the other subjects studied methane measurement allowed diagnosis of SIBO. Small intestine bacterial overgrowth is frequent in cystic fibrosis. For its detection in cystic fibrosis and other gastrointestinal patients, combined hydrogen and methane measurement instead of hydrogen breath test should be applied. Without the additional measurement of methane a significant percentage of SIBO will be missed.