Proton pump inhibitor therapy does not affect hydrogen production on lactulose breath test in subjects with IBS

Assessment of small intestinal bacterial overgrowth and methane production in patients on chronic proton-pump inhibitor treatment: prevalence and role of rifaximin in its management in primary care

BACKGROUND

Although proton pump inhibitor (PPI) drugs have considered able to induce small intestinal bacterial overgrowth (SIBO), no data are so far available from primary care (PC). We assessed the prevalence of SIBO and methane (CH4) production consequent to chronic PPI therapy using Lactulose Breath Test (LBT). Secondary aim was to explore the possible role of rifaximin in treating PPI-induced SIBO patients.

METHODS

One hundred twenty-five gastroesophageal reflux disease patients, constantly treated with PPI for at least 6 months and undergoing to LBT, were retrospectively assessed. An age-matched control population (control) of 100 patients, which had not used PPI in the last 6 months, was also enrolled. In the PPI group, SIBO positive patients and CH4 producers were treated with rifaximin 1200 mg/daily for 14 days and re-checked with LBT one month after the end of treatment. The area under the curve (AUC) before and after treatment was also calculated for both SIBO positive patients and CH4 producers.

RESULTS

In the PPI group, SIBO prevalence was significantly higher vs. controls (38/125 [30.4%] vs. 27/100 [27%], P<0.05). 77/125 (61.6%) PPI patients were found to be CH4 producers vs. 21/100 (21%) controls (P<0.05). Among SIBO patients in the PPI group, 34 (89.4%) were also CH4 producers vs. 17/27 (63%) controls (P<0.05). After treatment, LBT resulted negative in 15/22 SIBO patients (68.1%) (P<0.05) and in 18/34 CH4 producers (52.9%) (P<0.05). At the AUC analysis, an overall reduction of 54.2% for H2 in SIBO patients and of 47.7% for CH4 was assessed after rifaximin treatment (P<0.05).

CONCLUSIONS

Our data showed that chronic use of PPI could be able to increase the prevalence of SIBO and to shift the intestinal microbial composition towards a CH4-producing flora. rifaximin could represent a useful therapeutical option for PPI-induced SIBO and for modulating CH4-producing flora.

Proton Pump Inhibitor Therapy Does Not Affect Prognosis of Cirrhosis Patients With Acute Decompensation and Acute-on-Chronic Liver Failure: A Single-Center Prospective Study

Background: The aim of this study was to investigate the impact of proton pump inhibitor (PPI) therapy on complications and prognosis in cirrhosis patients with and without acute-on-chronic liver failure (ACLF).

Materials and Methods: Cirrhosis patients with acute decompensation (AD) (n = 489) admitted in our center were enrolled in this prospective observational cohort study. According to treatment received, patients were identified as users or nonusers of PPI. Clinical and laboratory data, complications during hospitalization, and overall survival were recorded in all the patients.

Results: Of the 489 patients, 299 (61.1%) patients received PPI therapy. The logistic regression analysis showed that age, albumin, history of previous hepatic encephalopathy (HE), and the chronic liver failure-sequential organ failure assessment (CLIF-SOFA) score were independent risk factors for HE in patients with decompensated cirrhosis [odds ratio (OR) = 1.07, 95% CI: 1.03–1.12, p = 0.001; OR = 1.13, 95% CI: 1.04–1.24, p = 0.006; OR = 242.52, 95% CI: 40.17–1464.11, p < 0.001; and OR = 2.89, 95% CI: 2.11–3.96, p < 0.001, respectively]. Previous severe liver injury and previous bacterial infections were independent risk factors for spontaneous bacterial peritonitis (SBP) in patients with decompensated cirrhosis (OR = 3.43, 95% CI: 1.16–10.17, p = 0.026 and OR = 6.47, 95% CI: 2.29–18.29, p < 0.001, respectively). The multivariate Cox proportional hazards regression model showed that the type and dose of the PPI used were not related to 28-day and 90-day mortality in cirrhosis patients with AD or ACLF.

Conclusion: PPI use does not appear to increase mortality or the risk of HE and SBP in the hospitalized cirrhosis patients with and without ACLF.

A meta-analysis on small intestinal bacterial overgrowth in patients with different subtypes of irritable bowel syndrome

BACKGROUND

Enteric microbiota is increasingly being recognized as an important factor in the pathogenesis of irritable bowel syndrome (IBS). The reported prevalence of small intestinal bacterial overgrowth (SIBO) in subjects with IBS is highly variable, and there is no consensus on the role of SIBO in different subtypes of IBS, and indications and methods of testing.

METHODS

A comprehensive literature search was performed for studies applying tests for SIBO in subjects with IBS. After applying prospectively decided exclusion criteria, the eligible papers were examined using a meta-analysis approach for the prevalence of SIBO in subjects with IBS using different tests. The odds ratios of SIBO among subjects with IBS as compared with healthy controls using different tests were calculated.

RESULTS

Of the available studies (22, 17, 5, and 3 using lactulose and glucose hydrogen breath tests [LHBT and GHBT], jejunal aspirate culture, and more than one tests, respectively) meeting the inclusion criteria, 36.7% (95% confidence interval [CI] 24.2-44.6) had a positive test for SIBO. Patients with IBS were 2.6 (95% CI 1.3-6.9) and 8.3 (95% CI 3.0-5.9) times more likely to have a positive test for SIBO as compared with healthy controls using GHBT and jejunal aspirate culture, respectively. Patients with diarrhea-predominant IBS were more likely to have positive GHBT as compared with the other subtypes.

CONCLUSIONS

Patients with IBS were more likely to have SIBO as compared with healthy subjects using GHBT and jejunal aspirate culture but not using LHBT. Patients with diarrhea-predominant IBS more often have SIBO.

Prevalence and predictors of small intestinal bacterial overgrowth in irritable bowel syndrome: a systematic review and meta-analysis

BACKGROUND

The reported prevalence of small intestinal bacterial overgrowth (SIBO) among individuals with irritable bowel syndrome (IBS) is highly variable. The aim of the study is to estimate the prevalence and identify predictors of SIBO in IBS.

METHODS

PubMed, Cochrane Library, and EMBASE through July 2017 were searched to identify studies evaluating the prevalence of SIBO in IBS. The pooled prevalence of SIBO among individuals with IBS and the pooled odds ratio (OR) of SIBO among those with IBS compared with healthy controls were calculated. Predictors of SIBO among IBS patients were also evaluated.

RESULTS

Fifty studies (8398 IBS, 1432 controls) met the inclusion criteria. Overall pooled prevalence of SIBO in IBS was 38% (95% CI 32-44) and was higher among individuals with IBS (OR 4.7, 95% CI 3.1-7.2) compared with controls. The pooled prevalence of SIBO in IBS was higher in studies diagnosed by breath tests (40%, 95% CI 33-46) compared with cultures (19%, 95% CI 8-30). Among those with IBS, female gender (OR 1.5, 95% CI 1.0-2.1), older age (standard mean difference 3.1 years, 95% CI 0.9-5.4), and IBS-diarrhea (OR 1.7, 95% CI 1.3-2.3) compared with other IBS subtypes increased the odds of SIBO; proton pump inhibitor (PPI) use (OR 1.1, 95% CI 0.7-1.7) was not associated with SIBO.

CONCLUSIONS

More than one-third of IBS patients tested positive for SIBO, and the odds of SIBO in IBS were increased by nearly fivefold. The prevalence of SIBO varied according to the diagnostic modality performed. Female gender, older age, and IBS-diarrhea, but not PPI use, were associated with SIBO among individuals with IBS.

Meta-analysis: proton pump inhibitors moderately increase the risk of small intestinal bacterial overgrowth

The use of proton pump inhibitors (PPIs) may potentially predispose to the development of small intestinal bacterial overgrowth (SIBO), but this association is controversial due to conflicting results from studies conducted to date. The aim of this meta-analysis was to evaluate the association between the use of PPIs and the risk of SIBO. We systematically searched the online PubMed, Embase, and Cochrane Library databases and Web of Science for relevant articles published up to November 2016. Two researchers identified and extracted data independent of each other. The pooled analysis was performed using the generic inverse-variance random-effects model. Subgroup and sensitivity analysis were conducted to assess the stability and heterogeneity of the pooled results. The risk of publication bias was evaluated by assessing for funnel plot asymmetry and by Egger's test and Begg's test. A total of 19 articles met the eligibility criteria for the meta-analysis, reporting on 7055 subjects. The pooled odds ratio (OR) showed a statistically significant association between increased risk of SIBO and PPI use (OR 1.71, 95% confidence interval 1.20-2.43). Subgroup analyses demonstrated an association between SIBO and PPI use in studies that employed small bowel aspirates culture and glucose hydrogen breath tests (GHBT) as diagnostic tests for SIBO. Our meta-analysis suggests that the use of PPI moderately increases the risk of SIBO, thereby highlighting the need for appropriate prescribing of PPIs.

Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus

OBJECTIVES

Breath tests (BTs) are important for the diagnosis of carbohydrate maldigestion syndromes and small intestinal bacterial overgrowth (SIBO). However, standardization is lacking regarding indications for testing, test methodology and interpretation of results. A consensus meeting of experts was convened to develop guidelines for clinicians and research.

METHODS

Pre-meeting survey questions encompassing five domains; indications, preparation, performance, interpretation of results, and knowledge gaps, were sent to 17 clinician-scientists, and 10 attended a live meeting. Using an evidence-based approach, 28 statements were finalized and voted on anonymously by a working group of specialists.

RESULTS

Consensus was reached on 26 statements encompassing all five domains. Consensus doses for lactulose, glucose, fructose and lactose BT were 10, 75, 25 and 25 g, respectively. Glucose and lactulose BTs remain the least invasive alternatives to diagnose SIBO. BT is useful in the diagnosis of carbohydrate maldigestion, methane-associated constipation, and evaluation of bloating/gas but not in the assessment of oro-cecal transit. A rise in hydrogen of ≥20 p.p.m. by 90 min during glucose or lactulose BT for SIBO was considered positive. Methane levels ≥10 p.p.m. was considered methane-positive. SIBO should be excluded prior to BT for carbohydrate malabsorption to avoid false positives. A rise in hydrogen of ≥20 p.p.m. from baseline during BT was considered positive for maldigestion.

CONCLUSIONS

BT is a useful, inexpensive, simple and safe diagnostic test in the evaluation of common gastroenterology problems. These consensus statements should help to standardize the indications, preparation, performance and interpretation of BT in clinical practice and research.

Short article: Risk of small intestinal bacterial overgrowth with chronic use of proton pump inhibitors in children

BACKGROUND

Some theorize that prolonged use of proton pump inhibitors (PPIs) may increase the risk of small intestinal bacterial overgrowth (SIBO). Chronic acid suppression and resultant hypochlorhydria may lead to an altered intraluminal environment, which, in turn, may promote the growth of bacteria in the small intestine. A handful of studies measured the risk of SIBO in adults taking PPIs and obtained mixed results; however, this risk has not been exclusively measured in children.

AIM

This study aimed to measure the risk of SIBO in children taking PPI versus those not taking PPI.

PATIENTS AND METHODS

This was a prospective cohort study. Evaluation of SIBO was performed using the glucose hydrogen breath test. Patients younger than 18 years of age taking a PPI longer than 6 months were compared with healthy control participants. After ingestion of glucose substrate, breath samples were obtained every 15 min for 2 h. An increase in breath hydrogen or methane above 12 ppm was considered diagnostic of SIBO.

RESULTS

Overall, 83 participants were tested, of whom 56 were taking PPIs. SIBO was detected in five (8.9%) of the 56 participants taking PPI versus one (3.7%) of the 27 participants in the control group (P=0.359), with a relative risk of 2.4 (95% confidence interval: 0.29-19.6).

CONCLUSION

To our knowledge, this is the first study in the English literature measuring the risk of SIBO in children taking PPIs. Our results indicate a potential risk of SIBO in chronic PPI users; however, this is not statistically significant. This is an important finding as PPIs are readily prescribed for children and are often taken longer than 6 months' duration.

Diagnosis and treatment of small intestinal bacterial overgrowth

A huge number of bacteria are hosted in the gastrointestinal tract, following a gradient increasing towards the colon. Gastric acid secretion and intestinal clearance provide the qualitative and quantitative partitioning of intestinal bacteria; small intestinal bacteria overgrowth (SIBO) occurs when these barrier mechanisms fail. Diagnosis of SIBO is challenging due to the low specificity of symptoms, the frequent association with other diseases of the gastrointestinal tract and the absence of optimal objective diagnostic tests. The therapeutic approach to SIBO is oriented towards resolving predisposing conditions, and is supported by antibiotic treatment to restore the normal small intestinal microflora and by modifications of dietary habits for symptomatic relief. In the near future, metagenomics and metabolomics will help to overcome the uncertainties of SIBO diagnosis and the pitfalls of therapeutic management, allowing the design of a personalized strategy based on the direct insight into the small intestinal microbial community.

Proton pump inhibitor therapy and its association with spontaneous bacterial peritonitis incidence and mortality: A meta-analysis

BACKGROUND

Previous meta-analyses reported proton pump inhibitor (PPI) therapy is associated with increased incidence of spontaneous bacterial peritonitis (SBP) in cirrhotic patients. However, this conclusion was based on case-control studies. Moreover, the association between PPI use and mortality of SBP has not yet been confirmed.

AIMS

To evaluate the association between PPI use and SBP incidence and mortality using case-control and cohort studies.

METHODS

We searched Medline, Embase and Web of Knowledge for relevant articles published up to January 2015. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a random-effects model.

RESULTS

A total of 10 case-control and six cohort studies involving 8145 patients were analyzed. The overall analysis indicated that PPI use was associated with SBP (OR=2.11, 95% CI: 1.46-3.06). The association was limited in case-control studies (OR=2.97, 95% CI: 2.06-4.26) but not in cohort studies (OR=1.18, 95% CI: 0.99-1.14). PPI therapy was not associated with mortality during hospitalization or within 30 days after SBP (OR=1.54, 95% CI: 0.92-2.59).

CONCLUSIONS

We could not establish causality that PPI use increases the incidence or mortality of SBP.

Systematic review and meta-analysis of the possible association between pharmacological gastric acid suppression and spontaneous bacterial peritonitis

BACKGROUND

Observational studies have presented conflicting results with regard to an association between gastric acid suppression and spontaneous bacterial peritonitis (SBP). Our aim was to carry out a meta-analysis investigating the possible association between the use of proton pump inhibitors or H2-receptor antagonists and SBP.

METHODS

We searched several databases from inception through 15 December 2014 to identify observational studies that provided data on the association of gastric acid suppression with SBP as their primary outcome, and carried out random effects meta-analyses.

RESULTS

Fourteen observational studies (six case-control and eight cohort) evaluating the association between proton pump inhibitors and SBP revealed a pooled odds ratio (OR) of 2.32 [95% confidence interval (CI) 1.57-3.42, I(2)=82%]. The subgroup analysis based on study design revealed a pooled OR of 2.52 (95% CI 1.71-3.71, I(2)=16%) for case-control studies, and a pooled OR of 2.18 (95% CI 1.24-3.82, I(2)=89%) for cohort studies. Sensitivity analysis including only the peer-reviewed publications in the cohort subgroup revealed a pooled OR of 1.49 (95% CI 1.15-1.95, I(2)=27%). The subgroup analysis for high-quality studies revealed a pooled OR of 1.49 (95% CI 1.19-1.88, I(2)=21%). The pooled OR for H2-receptor antagonists and SBP was 1.93 (95% CI 1.15-3.24, I(2)=0%).

CONCLUSIONS

There appear to be statistically significant, but quantitatively small, associations between gastric acid suppression and SBP. However, the magnitude of the possible association diminished when analysis focused on higher quality data that were more robust. Furthermore, the quality evidence in support of the association, as per the GRADE framework, was very low.

Proton pump inhibitor therapy does not increase the incidence of spontaneous bacterial peritonitis in cirrhosis: a multicenter prospective study

BACKGROUND & AIM

Retrospective studies show an association between proton pump inhibitor (PPI) therapy and spontaneous bacterial peritonitis (SBP). We investigate the relationship between PPI and SBP in decompensated cirrhotic patients in a large nationwide prospective study.

METHODS

Seven hundred seventy patients with a diagnosis of decompensated cirrhosis were admitted consecutively in 23 hospitals in Argentina from March 2011 to April 2012; the patients were carefully investigated for PPI consumption in the previous 3 months. In total, 251 patients were excluded because of active gastrointestinal hemorrhage, antibiotic use during the preceding weeks, HIV-positive status and immunosuppressive therapy.

RESULTS

Two hundred twenty-six out of 519 patients (43.5%) had received PPI therapy within the last 3 months. In 135 patients, PPIs were administered for longer than 2 weeks. A bacterial infection was shown in 255 patients (49.1%). SBP was diagnosed in 95 patients out of 394 patients with ascites (24.7%). There was no significant difference in the rate of PPI consumption between the infected and the non-infected patients (44.3% vs. 42.8%) or between the SBP patients and the patients with ascites without SBP (46% vs. 42%). In the SBP patients, the duration of PPI administration did not influence the rate of SBP occurrence. The type of bacteria and the origin of SBP infection were similar in the patients with and without PPI.

CONCLUSION

In the current large, multicenter, prospective study, PPI therapy, specifically evaluated at admission of consecutive cirrhotic patients, was not associated with a higher risk of SBP.

Current views on the etiopathogenesis, clinical manifestation, diagnostics, treatment and correlation with other nosological entities of SIBO

Small intestinal bacterial overgrowth (SIBO) is a disease of great clinical and socioeconomic importance caused by an excessive amount of bacteria in the upper alimentary tract. Physiological microbiota are replaced by pathogenic bacteria mainly from large intestine, which is called dysbacteriosis. SIBO disturbs digestion and absorption in the alimentary tract, which seems to cause inflammation. SIBO affects the morphology and function of the digestive system and causes systemic complications (e.g. osteoporosis, macrocytic anemia). Inflammation interferes with gene expression responsible for producing and secreting mucus, therefore, a correlation between SIBO and cystic fibrosis, irritable bowel syndrome and chronic abdominal pain are postulated. All conditions leading to bacterial growth such as congenital and anatomical abnormalities in the digestive tract, motility disorder or immunological deficits are risk factors of SIBO. A typical clinical manifestation of SIBO comprises meteorism, enterectasia, abdominal discomfort and diarrhea. Diagnostic procedures such as glucose, lactulose, methane, 13C mixed triglyceride breath tests are being used in diagnosing SIBO.

Breath tests and irritable bowel syndrome

Breath tests are non-invasive tests and can detect H₂ and CH₄ gases which are produced by bacterial fermentation of unabsorbed intestinal carbohydrate and are excreted in the breath. These tests are used in the diagnosis of carbohydrate malabsorption, small intestinal bacterial overgrowth, and for measuring the orocecal transit time. Malabsorption of carbohydrates is a key trigger of irritable bowel syndrome (IBS)-type symptoms such as diarrhea and/or constipation, bloating, excess flatulence, headaches and lack of energy. Abdominal bloating is a common nonspecific symptom which can negatively impact quality of life. It may reflect dietary imbalance, such as excess fiber intake, or may be a manifestation of IBS. However, bloating may also represent small intestinal bacterial overgrowth. Patients with persistent symptoms of abdominal bloating and distension despite dietary interventions should be referred for H₂ breath testing to determine the presence or absence of bacterial overgrowth. If bacterial overgrowth is identified, patients are typically treated with antibiotics. Evaluation of IBS generally includes testing of other disorders that cause similar symptoms. Carbohydrate malabsorption (lactose, fructose, sorbitol) can cause abdominal fullness, bloating, nausea, abdominal pain, flatulence, and diarrhea, which are similar to the symptoms of IBS. However, it is unclear if these digestive disorders contribute to or cause the symptoms of IBS. Research studies show that a proper diagnosis and effective dietary intervention significantly reduces the severity and frequency of gastrointestinal symptoms in IBS. Thus, diagnosis of malabsorption of these carbohydrates in IBS using a breath test is very important to guide the clinician in the proper treatment of IBS patients.

Microbiota, gastrointestinal infections, low-grade inflammation, and antibiotic therapy in irritable bowel syndrome: an evidence-based review

BACKGROUND

Post-infectious irritable bowel syndrome (PI-IBS) prevalence, small intestinal bacterial overgrowth (SIBO), altered microbiota, low-grade inflammation, and antibiotic therapy in IBS are all controversial issues.

AIMS

To conduct an evidence-based review of these factors.

METHODS

A review of the literature was carried out up to July 2012, with the inclusion of additional articles as far as August 2013, all of which were analyzed through the Oxford Centre for Evidence-Based Medicine (OCEBM) system.

RESULTS

1.There is greater SIBO probability in IBS when breath tests are performed, but prevalence varies widely (2-84%). 2.The gut microbiota in individuals with IBS is different from that in healthy subjects, but a common characteristic present in all the patients has not been established. 3.The incidence and prevalence of PI-IBS varies from 9-10% and 3-17%, respectively, and the latter decreases over time. Bacterial etiology is the most frequent but post-viral and parasitic cases have been reported. 4.A sub-group of patients has increased enterochromaffin cells, intraepithelial lymphocytes, and mast cells in the intestinal mucosa, but no differences between PI-IBS and non-PI-IBS have been determined. 5.Methanogenic microbiota has been associated with IBS with constipation. 6.Rifaximin at doses of 400mg TID/10days or 550mg TID/14days is effective treatment for the majority of overall symptoms and abdominal bloating in IBS. Retreatment effectiveness appears to be similar to that of the first cycle.

CONCLUSIONS

Further studies are required to determine the nature of the gut microbiota in IBS and the differences in low-grade inflammation between PI-IBS and non-PI-IBS. Rifaximin has shown itself to be effective treatment for IBS, regardless of prior factors.

The impact of alcohol consumption and cholecystectomy on small intestinal bacterial overgrowth

BACKGROUND

The etiology of small intestinal bacterial overgrowth (SIBO) is diverse and frequently multi-factorial. SIBO is thought to result from structural changes of the gastrointestinal tract, disordered peristalsis of the stomach and/or small intestine, or a disruption of the normal mucosal defenses of the small intestine. Alcoholics are reported to have higher rates of SIBO, as diagnosed by jejunal aspirate; however, no data are available on the association between moderate alcohol consumption and SIBO.

AIM

To evaluate the association between moderate alcohol consumption and SIBO and identify risk factors for SIBO using the lactulose breath test (LBT).

METHODS

A retrospective chart review was completed for 210 consecutive patients who underwent the LBT between 2008 and 2010. We reviewed demographic data, including age, race, body mass index, alcohol and tobacco history, medication use, comorbid medical conditions, and history of abdominal surgery.

RESULTS

The study included 196 patients (68 % female; mean age 55 years), 93 of whom had a positive LBT (47.4 %). Of those patients who consumed a moderate amount of alcohol, 58 % had a positive LBT, compared to 38.9 % of abstainers (P = 0.008). Those with a history of cholecystectomy had significantly lower rates of a positive LBT than those who had not (33.3 vs. 51.7 % respectively; P = 0.031). Neither proton pump inhibitor (PPI) use nor tobacco use was associated with a positive LBT.

CONCLUSION

In this retrospective review, moderate alcohol consumption was a strong risk factor for SIBO. Cholecystectomy appeared to be protective against SIBO. Neither PPI use nor tobacco use was associated with an increased risk of SIBO.

Association between symptoms of irritable bowel syndrome and methane and hydrogen on lactulose breath test

Whether hydrogen and methane gas produced during lactulose breath test (LBT) are associated with symptoms of irritable bowel syndrome (IBS) is not determined. We aimed to investigate whether hydrogen and methane on LBT are associated with IBS symptoms. Sixty-eight IBS patients meeting the Rome III criteria for IBS, and 55 healthy controls, underwent LBT. The IBS subjects recorded their customary gastrointestinal symptoms on a questionnaire using visual analogue scales. LBT positivity was defined to be above 20 ppm rise of hydrogen or 10 ppm rise of methane within 90 min. Gas amounts produced during LBT were determined by calculating area under the curve of hydrogen and methane excretion. Symptom severity scores were not different between the LBT (+) IBS and LBT (-) IBS subjects and also between methane producers and non-methane producers. Gas amounts produced during LBT were not associated with IBS symptoms, except a weak correlation between total gas amounts and a few IBS symptoms such as bloating (r = 0.324, P = 0.039), flatulence (r = 0.314, P = 0.046) and abdominal pain (r = 0.364, P = 0.018) only in LBT (+) IBS. In conclusion, hydrogen and methane gas on LBT are not useful for predicting the customary symptoms and subtypes of IBS.

Proton pump inhibitor use and the risk of small intestinal bacterial overgrowth: a meta-analysis

BACKGROUND & AIMS

Use of proton pump inhibitors (PPIs) could predispose individuals to small intestinal bacterial overgrowth (SIBO) by altering the intraluminal environment and bacterial flora. There is controversy regarding the risk of SIBO among PPI users because of conflicting results from prior studies. A systematic review and meta-analysis were performed to evaluate the association between PPI use and SIBO, using objective clinical outcome measures.

METHODS

Clinical studies comparing SIBO risk among adult users of PPIs vs nonusers were identified in MEDLINE/PubMed, EMBASE, the Cochrane Central Register of Controlled Trials, and the National Institutes of Health Clinical Trials databases through July 2012. Two reviewers independently extracted data on study characteristics and outcomes. The primary metameter was the odds ratio (OR) of SIBO among PPI users vs nonusers. Subgroup analyses were performed to examine the influence of study characteristics, such as SIBO diagnostic modality, on study outcome.

RESULTS

Eleven studies (n = 3134) met inclusion criteria. The pooled OR of SIBO in PPI users vs nonusers was 2.282 (95% confidence interval [CI], 1.238-4.205). No significant single large study or temporal effect was seen. Subgroup analysis revealed an association between SIBO and PPI use in studies that used duodenal or jejunal aspirate cultures to diagnose SIBO (OR, 7.587; 95% CI, 1.805-31.894), but no relationship was found between SIBO and PPI use in studies that used the glucose hydrogen breath test (OR, 1.93; 95% CI, 0.69-5.42). Funnel plot analysis identified 4 outlying studies, indicating the possible presence of publication bias.

CONCLUSIONS

PPI use statistically was associated with SIBO risk, but only when the diagnosis was made by a highly accurate test (duodenal or jejunal aspirate culture). Differences in study results could arise from the use of different tests to diagnose SIBO.

Proton pump inhibitor therapy use does not predispose to small intestinal bacterial overgrowth

OBJECTIVES

Small intestinal bacterial overgrowth (SIBO) occurs due to alteration of the microbiota within the upper gastrointestinal tract. Proton pump inhibitor (PPI) therapy has been suggested as a risk factor for SIBO; however, the published reports have yielded conflicting results on the association between PPI therapy and risk of developing SIBO. The aim of this study was to compare the prevalence of SIBO as measured by glucose hydrogen breath testing (GHBT) in patients on PPI therapy compared with those not on PPI therapy.

METHODS

A retrospective chart review was completed for all patients who underwent GHBT testing from 2004 to 2010. Breath samples for hydrogen (H₂) and methane (CH₄) were collected before and every 20 min for 120 min following ingestion of a 50-g oral glucose load. We used the following criteria to define a positive GHBT (a) increase in H₂ > 20 parts per million (p.p.m.) over baseline, (b) sustained rise H₂ > 10 p.p.m. over baseline, (c) CH₄ > 15 p.p.m. over baseline, and (d) either rise H₂ > 20 p.p.m. over baseline or CH₄ > 15 p.p.m.

RESULTS

A total of 1,191 patients (70% female) were included, of whom 566 (48%) were on PPI therapy. GHBT positivity did not differ significantly between PPI users and nonusers by any of the diagnostic criteria used and PPI use was not significantly associated with GHBT positivity using any of these criteria. GHBT positivity was associated with older age (odds ratio (OR) 1.03, 95% confidence interval (CI) 1.01-1.04) and antidiarrheal use (OR 1.99, 95% CI 1.15-3.44) using H₂ > 20, older age (OR 1.01, 95% CI 1.00-1.02) and diarrhea (OR 1.53, 95% CI 1.13-2.09) using H₂ > 10, and older age (OR 1.01, 95% CI 1.00-1.02) using either H₂ > 20 or CH₄ > 15. PPI use was not significantly associated with GHBT positivity using any of these criteria.

CONCLUSIONS

In this large, adequately powered equivalence study, PPI use was not found to be significantly associated with the presence of SIBO as determined by the GHBT.

Volatile compounds in health and disease

PURPOSE OF REVIEW

To summarize the recent progress made in noninvasive monitoring of volatile compounds in exhaled breath and above biological liquids, as they are becoming increasingly important in assessing the nutritional and clinical status and beginning to provide support to conventional clinical diagnostics and therapy. To indicate the potential of these developments in medicine and the specific areas which are currently under investigation.

RECENT FINDINGS

The significance of the following breath gases and their concentrations are reported: acetone and the influence of diet; ammonia confirmed as an indicator of dialysis efficacy; hydrogen and the (13)CO(2)/(12)CO(2) ratio (following the ingestion of (13)C-labeled compounds) as related to gastric emptying and bowel transit times; hydrogen cyanide released by Pseudomonas and its detection in breath of children with cystic fibrosis; and multiple trace compounds in breath of patients with specific pathophysiological conditions and 'metabolic profiling'.

SUMMARY

Advanced analytical methods, especially exploiting mass spectrometry, are moving breath analysis towards the clinical setting; some trace gas metabolites are already being exploited in diagnosis and therapy. Much effort is being given to the search for biomarkers of tumours in the body. HCN as an indicator of the presence of Pseudomonas in the airways has real potential in therapeutically alleviating the symptoms of cystic fibrosis.

Questioning the bacterial overgrowth hypothesis of irritable bowel syndrome: an epidemiologic and evolutionary perspective

Although studies indicate that small intestinal bacterial overgrowth (SIBO) is prevalent in irritable bowel syndrome (IBS), it remains unclear whether SIBO causes IBS. This review presents an epidemiologic and evolutionary inquiry that questions the bacterial overgrowth hypothesis of IBS, as follows. (1) Although the hypothesis may be biologically plausible, there is also a strong rationale for competing hypotheses; it is unlikely that SIBO is the predominant cause of IBS in all comers, because competing explanations are sensible and defensible. Moreover, data indicate that the test used to promulgate the SIBO hypothesis - the lactulose hydrogen breath test - may not have measured SIBO in the first place. (2) We do not have evidence of SIBO being absent before IBS symptoms, and present after IBS emerges. (3) There is not a dose-response relationship between small intestinal microbiota and IBS symptoms. (4) The relationship between SIBO and IBS is highly inconsistent among studies. (5) Many effective IBS therapies do not address SIBO at all, yet have a more favorable "number needed to treat" than antibiotics. (6) IBS does not behave like a traditional infectious disease, suggesting that microbes may not principally cause the syndrome. (7) Other factors may confound the relationship between SIBO and IBS, including proton pump inhibitors. (8) Whereas the brain-gut hypothesis is evolutionary sensible, the bacterial hypothesis is harder to defend from an evolutionary perspective. The article concludes that bacteria may contribute to some IBS symptoms, but that bacteria cannot be the only explanation, and a causal link between SIBO and IBS is not secure.

Restless legs syndrome is associated with irritable bowel syndrome and small intestinal bacterial overgrowth

BACKGROUND

Restless legs syndrome (RLS) is linked to gastrointestinal disorders. The prevalence of irritable bowel syndrome (IBS) and small intestinal bacterial overgrowth (SIBO) in RLS patients was determined.

METHODS

RLS subjects were recruited from unbiased ads that did not mention gastrointestinal symptoms. RLS diagnosis was confirmed by a neurologist and utilized the International RLS Study Group criteria. General population controls (GPC) were spouses of gastrointestinal clinic patients and were excluded for RLS. Completely healthy controls (CHC) were excluded for RLS and gastrointestinal symptoms. IBS was diagnosed by Rome II criteria. SIBO was diagnosed by the lactulose breath test (LBT).

RESULTS

There were 32 RLS subjects (23F/9M; 57 yo), 25 GPC (13F/12M; 58 yo) and 30 CHC (19F/11M; 44 yo). Twenty-nine had RLS unassociated with other GI diseases, one had celiac disease, and two had gastric resections. IBS was diagnosed in 28% of RLS subjects compared to 4% GPC (p=0.0317). SIBO was diagnosed in 69% of RLS subjects compared to 28% of GPC (p=0.0033) and 10% of CHC. Using a false positive rate of 10%, 59% of positive LBT results are associated with RLS.

CONCLUSIONS

IBS and SIBO are common in RLS. Three hypotheses developed are (a) RLS patients are selectively immunocompromised or genetically predisposed and thus more subject to SIBO; (b) SIBO leads to autoimmune changes, and subsequent auto-antibodies attack brain and/or peripheral nerves and (c) SIBO inflammation leads to increased hepcidin and CNS iron deficiency which, in turn, leads to RLS. These hypotheses bear further investigation.

Abnormal breath testing in IBS: a meta-analysis

BACKGROUND

Recent evidence suggests a role for enteric bacteria in the development of symptoms in subjects with irritable bowel syndrome (IBS). The concept was initially based on the common finding of an abnormal lactulose breath test to suggest the presence of small intestinal bacterial overgrowth (SIBO). Despite successful antibiotic studies based on these findings, the premise of bacterial overgrowth was met with skepticism due to the perceived inaccuracies of breath testing in humans. In this study, we conduct a systematic review and meta-analysis of the studies using breath testing in IBS subjects with comparison to healthy controls.

METHODS

A literature search was conducted to identify studies in which breath testing was conducted in subjects with IBS. Once abstract titles were identified, studies that examined breath testing in a case-control fashion were identified for paper review. After exclusion criteria were applied, the remaining papers were examined using meta-analysis, among which the prevalence of an abnormal breath test in IBS subjects was compared. Further analysis was conducted among studies with appropriate age- and sex-matched controls.

RESULTS

Eleven studies met criteria for inclusion in the meta-analysis. Although heterogeneity was identified among studies on the basis of substrate used, lactulose was the most common substrate. In pooling the 11 studies, breath testing was more often abnormal among IBS subjects than health controls (OR=4.46, 95% CI=1.69-11.80). This was further evident in more appropriately designed age- and sex-matched studies (OR=9.64, 95% CI=4.26-21.82). The overall sensitivity and specificity for breath testing in separating IBS from healthy controls was 43.6 and 83.6%.

CONCLUSIONS

This study demonstrates that the breath test findings in IBS appear to be valid. While this meta-analysis does not suggest that the breath test findings imply SIBO, the abnormal fermentation timing and dynamics of the breath test findings support a role for abnormal intestinal bacterial distribution in IBS.