Relationships among the lactulose breath test, intestinal gas volume, and gastrointestinal symptoms in patients with irritable bowel syndrome

Validation of a Hand-Held Point-of-Care Device to Measure Breath Hydrogen and Its Utility in Detecting Response to Antibiotic Treatment

BACKGROUND

Breath testing for small intestinal bacterial overgrowth (SIBO) is typically performed using clinic-based equipment or single-use test kits.

AIMS

This study aimed to evaluate the utility of a portable, point-of-care breath analysis device (AIRE®, FoodMarble) in patients suspected to have SIBO. A technical assessment including a comparison to existing mail-in kits was first performed. Then, postprandial breath hydrogen levels of patients before and after antibiotic treatment were gathered and compared to levels seen in a healthy cohort.

METHODS

For the comparison, 50 patients suspected of having SIBO were provided with an AIRE device and performed concurrent LHBTs at-home with a mail-in breath test kit. For the postprandial analysis, twenty-four patients with chronic GI symptoms measured their postprandial hydrogen for 7 days prior to antibiotic treatment and for 7 days after treatment. 10 healthy controls also measured their postprandial hydrogen for 7 days.

RESULTS

Substantial agreement was demonstrated between AIRE and the mail-in kits for the performance of lactulose hydrogen breath tests (κ = 0.8). Prior to treatment, patients had significantly greater daily postprandial hydrogen than healthy controls (p < 0.001). The mean postprandial hydrogen of patients reduced significantly after treatment (p < 0.001).

CONCLUSIONS

Measuring postprandial hydrogen shows potential as a means of differentiating patients with chronic GI symptoms from healthy controls and may be useful in monitoring patients before, during, and after treatment. Future studies could help determine if pre-treatment breath gas levels are predictive of response to antibiotic treatment.

Evaluation of abdominal gas by plain abdominal radiographs

BACKGROUND

Our aim was to determine the reliability of plain abdominal radiographs for the evaluation of abdominal gas content in patients with functional digestive symptoms.

METHODS

Abdominal CT scan scout views, mimicking a conventional plain abdominal radiograph, were obtained from 30 patients both during episodes of abdominal distension and basal conditions. Physicians (n = 50) were instructed to rate the estimated volume of gas in the 60 images presented in random sequence using a scale graded from 0 to ≥600 ml.

KEY RESULTS

The gas volumes estimated in the scout views differed from those measured by CT by a median of 90 (95% CI 70-102) ml, and the misestimation was not related to the absolute volume in the image. The accuracy of the observers, measured by their mean misestimation, was not related to their specialty or the training status (misestimation by 96 (95% CI 85-104) ml in staff vs 78 (70-106) ml in residents; p = 0.297). The accuracy was independent of the order of presentation of the images. Gas volume measured by CT in the images obtained during episodes of abdominal distension differed by a median of 39 (95% CI 29-66) ml from those during basal conditions, and this difference was misestimated by a median of 107 (95% CI 94-119) ml. The accuracy of these estimations was not related to the absolute gas volumes (R = -0.352; p < 0.001) or the magnitude of the differences.

CONCLUSIONS & INFERENCES

Plain abdominal radiographs have limited value for the evaluation of abdominal gas volume in patients with functional gut disorders.

Microbiota stability in healthy individuals after single-dose lactulose challenge-A randomized controlled study

BACKGROUND AND AIMS

Lactulose is a common food ingredient and widely used as a treatment for constipation or hepatic encephalopathy and a substrate for hydrogen breath tests. Lactulose is fermented by the colon microbiota resulting in the production of hydrogen (H2). H2 is a substrate for enteropathogens including Salmonella Typhimurium (S. Typhimurium) and increased H2 production upon lactulose ingestion might favor the growth of H2-consuming enteropathogens. We aimed to analyze effects of single-dose lactulose ingestion on the growth of intrinsic Escherichia coli (E. coli), which can be efficiently quantified by plating and which share most metabolic requirements with S. Typhimurium.

METHODS

32 healthy volunteers (18 females, 14 males) were recruited. Participants were randomized for single-dose ingestion of 50 g lactulose or 50 g sucrose (controls). After ingestion, H2 in expiratory air and symptoms were recorded. Stool samples were acquired at days -1, 1 and 14. We analyzed 16S microbiota composition and abundance and characteristics of E. coli isolates.

RESULTS

Lactulose ingestion resulted in diarrhea in 14/17 individuals. In 14/17 individuals, H2-levels in expiratory air increased by ≥20 ppm within 3 hours after lactulose challenge. H2-levels correlated with the number of defecations within 6 hours. E. coli was detectable in feces of all subjects (2 x 10(2)-10(9) CFU/g). However, the number of E. coli colony forming units (CFU) on selective media did not differ between any time point before or after challenge with sucrose or lactulose. The microbiota composition also remained stable upon lactulose exposure.

CONCLUSION

Ingestion of a single dose of 50 g lactulose does not significantly alter E. coli density in stool samples of healthy volunteers. 50 g lactulose therefore seems unlikely to sufficiently alter growth conditions in the intestine for a significant predisposition to infection with H2-consuming enteropathogens such as S. Typhimurium (www.clinicaltrials.gov NCT02397512).

Breath Hydrogen Testing in East and Southeast Asia

Breath hydrogen tests are popular, noninvasive tests for the assessment of carbohydrate fermentation in patients with irritable bowel syndrome (IBS) and functional dyspepsia (FD). There is limited information regarding the utility of breath hydrogen and methane tests in IBS and FD patients in East and Southeast Asia. This review aims to summarize current literature about common indications of breath testing in this region, the genesis of functional gastrointestinal symptoms by provocative breath testing and provide suggestions for correct use. The most common testing indication is the assessment of lactose intolerance, followed by small intestinal bacterial overgrowth (SIBO) and differentiation of intestinal gas profiles in research setting. Studies in this region not only documented a high prevalence of lactose malabsorption but a population, both healthy and IBS, that is highly symptomatic to typical lactose intakes. Breath hydrogen assessment of other fermentable carbohydrates (FODMAPs) are fairly uncommon, whereas methane breath testing is almost nonexistent. Cumulative hydrogen production following lactulose was also not excessive in IBS patients compared with controls. The evidence however, for the detection of SIBO suggests limited reliability in the use of lactulose or glucose breath testing alone and inconclusive data on its correlation with symptoms. Conversely, little has been carried out in FD. In conclusion, breath testing should be limited in the predicting patients with SIBO for directing clinical management but can be considered in the objective assessment of lactose malabsorption within a low FODMAP diet. Recommendations to improve the interpretation of breath testing in research were also provided.

The effects and mechanism of action of methane on ileal motor function

BACKGROUND

Methane has been associated with constipation-predominant irritable bowel syndrome, slowing intestinal transit time by augmenting contractile activity. However, the precise mechanism underlying this effect remains unclear. Therefore, we investigated the mechanisms underlying the effect of methane on contractile activity, and whether such effects are mediated by nerve impulses or muscular contraction.

METHODS

We connected guinea pig ileal muscle strips to a force/tension transducer and measured amplitudes of contraction in response to electrical field stimulation (EFS; 1, 2, 8, 16 Hz) following methane infusion in the presence of tetradotoxin (TTX), atropine, guanethidine, or GR 113808. We then performed calcium imaging using Oregon Green 488 BAPTA-1 AM in order to visualize changes in calcium fluorescence in response to EFS following methane infusion in the presence of TTX, atropine, or a high K⁺ solution.

KEY RESULTS

Methane significantly increased amplitudes of contraction (P<.05), while treatment with TTX abolished such contraction. Methane-induced increases in amplitude were inhibited when lower-frequency (1, 2 Hz) EFS was applied following atropine infusion (P<.05). Neither guanethidine nor GR 113808 significantly altered contraction amplitudes. Methane significantly increased calcium fluorescence, while this increase was attenuated following atropine infusion (P<.05). Although calcium fluorescence was increased by the high K⁺ solution under pretreatment with TTX, the intensity of fluorescence remained unchanged after methane infusion.

CONCLUSIONS AND INFERENCES

The actions of methane on the intestine are influenced by the cholinergic pathway of the enteric nervous system. Our findings support the classification of methane as a gasotransmitter.

Effects of daikenchuto, a Japanese herb, on intestinal motility after total gastrectomy: a prospective randomized trial

PURPOSE

This study aimed to assess the efficacy of daikenchuto (DKT), a commonly prescribed, traditional Japanese herbal medicine, on postoperative intestinal dysfunction after gastric cancer surgery.

METHODS

Patients with gastric cancer scheduled for a total gastrectomy were randomly assigned before surgery to receive either no treatment (n = 40; control group) or DKT (7.5 g/day, t.i.d.) for 3 months (n = 41) postoperatively. We examined gastrointestinal motility, stool attributes, the quantity of bowel gas, the quality of life, and the incidence of postoperative ileus.

RESULTS

During the hospital stay, significant differences were observed between the DKT group and controls in the number of stools per day (1.1 ± 0.6 vs 0.8 ± 0.4, respectively; P = 0.037) and stool consistencies (Bristol scale ratings were 3.7 ± 0.8 vs 3.1 ± 0.8, respectively; P = 0.041). The DKT group showed significant reductions in gas volume scores, calculated from abdominal radiographs, at 7 days, 1 month, and 3 months after surgery. The groups did not show significant differences in quality of life scores (based on the Gastrointestinal Symptom Rating Scale) or in the incidence of postoperative ileus.

CONCLUSION

DKT improved bowel movements, stool properties, and bowel gas. These results suggested that DKT promoted early postoperative bowel functions after total gastrectomy.

Differential effects of FODMAPs (fermentable oligo-, di-, mono-saccharides and polyols) on small and large intestinal contents in healthy subjects shown by MRI

OBJECTIVES

The objective of this study was to investigate whether ingestion of fructose and fructans (such as inulin) can exacerbate irritable bowel syndrome (IBS) symptoms. The aim was to better understand the origin of these symptoms by magnetic resonance imaging (MRI) of the gut.

METHODS

A total of 16 healthy volunteers participated in a four-way, randomized, single-blind, crossover study in which they consumed 500 ml of water containing 40 g of either glucose, fructose, inulin, or a 1:1 mixture of 40 g glucose and 40 g fructose. MRI scans were performed hourly for 5 h, assessing the volume of gastric contents, small bowel water content (SBWC), and colonic gas. Breath hydrogen (H2) was measured and symptoms recorded after each scan.

RESULTS

Data are reported as mean (s.d.) (95% CI) when normally distributed and median (range) when not. Fructose increased area under the curve (AUC) from 0-5 h of SBWC to 71 (23) l/min, significantly greater than for glucose at 36 (11-132) l/min (P<0.001), whereas AUC SBWC after inulin, 33 (17-106) l/min, was no different from that after glucose. Adding glucose to fructose decreased AUC SBWC to 55 (28) l/min (P=0.08) vs. fructose. Inulin substantially increased AUC colonic gas to 33 (20) l/min, significantly greater than glucose and glucose+fructose (both P<0.05). Breath H2 rose more with inulin than with fructose. Glucose when combined with fructose significantly reduced breath H2 by 7,700 (3,121-12,300) p.p.m./min relative to fructose alone (P<0.01, n=13).

CONCLUSIONS

Fructose but not inulin distends the small bowel with water. Adding glucose to fructose reduces the effect of fructose on SBWC and breath hydrogen. Inulin distends the colon with gas more than fructose, but causes few symptoms in healthy volunteers.

Antibiotics for irritable bowel syndrome: rationale and current evidence

Irritable bowel syndrome (IBS) is the most common gastrointestinal condition effecting adults in developed countries worldwide. Over the last decade, evidence has emerged suggesting that gut bacteria play a role in the pathophysiology of IBS. While difficult to identify using noninvasive means, one of the most common attributable bacterial concepts in IBS is the small intestinal bacterial overgrowth hypothesis (SIBO). In this article, we review the different mechanisms by which gut flora and, specifically, SIBO may contribute to IBS and the evidence supporting the use of various antibiotic therapies in treating IBS.

Analysis of exhaled volatile compounds following acute superior mesenteric artery occlusion in a pilot rat study

BACKGROUND

Prompt diagnosis and treatment of acute mesenteric ischemia (AMI) requires a high index of suspicion for timely management. Poor clinical outcomes and delays in surgical treatment are demonstrated even in modern clinical series. Recognition of exhaled volatile organic compounds (VOCs) specific to AMI may facilitate early detection and diagnosis and improve patient outcomes.

METHODS

Adult Wistar rats (n = 5) were intubated and anesthetized, and control tracheostomy breath samples were collected using Tedlar gas sample bags. Intestinal ischemia was induced by placing an occlusive clip across the superior mesenteric artery, and breath samples were collected after 1 hour of intestinal ischemia and after 15 minutes of intestinal reperfusion. Gas chromatography was used to identify and measure levels of VOCs obtained, and measured retention indices were compared with known values in the Kovats retention index database.

RESULTS

Multiple retention indices (n = 41) were noted on gas chromatography, representing a variety of VOCs detected. Z,Z-farnesol (C15H26O), an isoprenoid, was the only compound detected that was undetectable during the control phase (median = 0 cts/sec) but which significantly elevated during the ischemic (median = 34 cts/sec, range = 25-37) and reperfusion (median = 148 cts/sec, range = 42-246) phases. Three other isoprenoid compounds (E,E-alpha-farnesene, germacrene A, and Z,Z-4,6,8-megastigmatriene) were also detected in all five animals, but their levels did not differ significantly between control, ischemic, and reperfusion phases.

CONCLUSIONS

This pilot study demonstrates the feasibility of analyzing exhaled VOCs using a novel rat model for AMI. These findings may be useful for the development and identification of similar assays for the rapid diagnosis of AMI.