Evaluation of the rice breath hydrogen test for small intestinal bacterial overgrowth

Aetiology, diagnosis and management of small intestinal bacterial overgrowth

Small intestinal bacterial overgrowth is a small bowel disorder characterised by excessive amounts of bacteria populating the small intestine leading to symptoms of abdominal pain, bloating and change in bowel habit. This creates some degree of diagnostic uncertainty due to the overlap of these symptoms with numerous other gastrointestinal conditions. Quantitative culture of jejunal aspirates is the gold standard diagnostic test but has largely been replaced by glucose and lactulose breath tests due to their relative ease and accessibility. The approach to treatment centres around reducing bacterial numbers through antibiotic therapy and managing any predisposing factors. Further research is required in order to define the optimum antibiotic choice and duration of therapy as well as the potential diagnostic utility of home breath testing and capsule-based technology.

Pd Nanoparticle Film on a Polymer Substrate for Transparent and Flexible Hydrogen Sensors

Alongside the rise in fully automated equipment and wearable devices, there is currently a high demand for optically transparent and flexible gas sensors operating at room temperature. Nanoparticle films are ideal H₂-sensing materials that can be coupled with flexible substrates because of their discrete nanogranular structure and unique interparticle electrical responsiveness. In this work, we present an optically transparent and flexible H₂ sensor based on a Pd nanoparticle film, prepared on a polyethylene terephthalate sheet using a straightforward nanocluster deposition technique. Hundreds of bending cycles demonstrated that the sensor has good electrical stability and mechanical robustness without significant degradation in H₂-sensing performance. The H₂-sensing behaviors under bent state were systematically evaluated. The loading of tensile and compressive strains under bent state produced a positive and negative influence, respectively, on the sensing performances. The possible influence mechanism of the tensile and compressive strains on the H₂-sensing performance was attributed to the changes in the percolation network topology and the interparticle space induced by the strains. The ability to detect a H₂ concentration as low as 15 ppm, dynamic response range as wide as 0-10%, and sub-10 s response time was achieved. In addition, the sensor can be operated in the relative humidity range of 0-90% at room temperature. These results demonstrate that the sensor exhibits significant potential for next-generation transparent and flexible H₂ detectors.

American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery medical guidelines for clinical practice for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient

American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery Medical Guidelines for Clinical Practice are systematically developed statements to assist health-care professionals in medical decision making for specific clinical conditions. Most of the content herein is based on literature reviews. In areas of uncertainty, professional judgment was applied. These guidelines are a working document that reflects the state of the field at the time of publication. Because rapid changes in this area are expected, periodic revisions are inevitable. We encourage medical professionals to use this information in conjunction with their best clinical judgment. The presented recommendations may not be appropriate in all situations. Any decision by practitioners to apply these guidelines must be made in light of local resources and individual patient circumstances. The American Society for Parenteral & Enteral Nutrition fully endorses sections of these guidelines that address the metabolic and nutritional management of the bariatric surgical patient.

Diagnosis of small intestinal bacterial overgrowth: the challenges persist!

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

Critical evaluation of diagnosing bacterial overgrowth in the proximal small intestine

BACKGROUND

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

STUDY

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

RESULTS

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

CONCLUSIONS

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

American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery Medical Guidelines for Clinical Practice for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient

American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery Medical Guidelines for Clinical Practice are systematically developed statements to assist healthcare professionals in medical decision making for specific clinical conditions. Most of the content herein is based on literature reviews. In areas of uncertainty, professional judgment was applied. These guidelines are a working document that reflects the state of the field at the time of publication. Because rapid changes in this area are expected, periodic revisions are inevitable. We encourage medical professionals to use this information in conjunction with their best clinical judgment. The presented recommendations may not be appropriate in all situations. Any decision by practitioners to apply these guidelines must be made in light of local resources and individual patient circumstances. The American Society for Parenteral & Enteral Nutrition fully endorses sections of these guidelines that address the metabolic and nutritional management of the bariatric surgical patient.

A systematic review of diagnostic tests for small intestinal bacterial overgrowth

BACKGROUND

A growing number of studies seem to suggest that small intestinal bacterial overgrowth (SIBO) is a common clinical problem. Although various techniques are available to make this diagnosis, tradition has accepted small bowel aspirate (>10(5) cfu/ml) as a gold standard. In this systematic review, the validity of culture and other diagnostic testing for SIBO is evaluated.

METHODS

We performed a systematic review of the literature from 1966 to present using electronic databases (PubMed and OVID). Full paper review of those abstracts that fulfilled preset criteria was carried out to evaluate the validity of various tests in diagnosing SIBO. Finally, all papers were evaluated against published standards for studies on diagnostic testing.

RESULTS

Seventy-one papers met the criteria for detailed review. Studies were very heterogeneous with regards to patient populations, test definitions, sample size, and methods in general. Small bowel colony counts appeared elevated in most gastrointestinal diseases compared to controls. The traditional definition of >10(5) cfu/ml was usually indicative of stagnant loop conditions. Although, numerous diagnostic tests were studied, not even culture papers met the quality standards described by Reid et al. Breath testing and other diagnostic testing suffered therefore from the lack of a gold standard against which to validate in addition to the poor quality.

CONCLUSIONS

There is no validated diagnostic test or gold standard for SIBO. In this context, the most practical method to evaluate SIBO in studies at this time would be a test, treat, and outcome technique.

Breath hydrogen test in the diagnosis of environmental enteropathy in children living in an urban slum

The aim of this study was to evaluate the breath hydrogen test in the diagnosis of small intestine bacterial overgrowth associated with asymptomatic environmental enteropathy in children living in an urban slum. Fifty school-age children living in a slum and 50 children who attended a private health clinic in the same town were included in the study. Breath hydrogen test was carried out after the administration of lactulose or glucose on two different days. Bacterial overgrowth was diagnosed when the hydrogen concentration increased more than 20 ppm in a sample collected for up to 60 min. Production of hydrogen was greater after the ingestion of lactulose than after the ingestion of glucose. Bacterial overgrowth was noted in 37.5% of the children living in the slum and in 2.1% of the control group (P<0.001). The children living in the slum presented a higher proportion of bacterial overgrowth when lactulose was used in the breath hydrogen test.

Critical appraisal of the management of severe malnutrition: 3. Complications

The high case-fatality of severe malnutrition is due to infections, dehydration, electrolyte disturbances and heart failure. We focus on the evidence about managing these complications of severe malnutrition. Signs of circulatory collapse in severely malnourished children should be treated with intravenous or bone marrow infusion of Ringer's lactate with additional dextrose and potassium at a rate 20-40 mL/kg fast with close monitoring of vital signs. Recommendations for slow or restricted fluids in the face of shock are unsafe, and hypotonic or maintenance solutions must be avoided to prevent hyponatraemia. However, the evidence that severely malnourished children do not tolerate excessive fluid administration is good, so caution must be exercised with regards to fluids in the initial phase of treatment. There is also good evidence that wide spectrum antibiotics need to be given empirically for severe malnutrition to prevent the otherwise unavoidable early mortality. There is a need for improved protocols for tuberculosis diagnosis, HIV management and treatment of infants under 6 months with severe malnutrition. The contribution of environmental enteropathy to poor growth and nutrition during the weaning period means that there should be more priority on improving environmental health, particularly better hygiene and less overcrowding. A T-cell mediated enteropathy contributes to growth failure and malnutrition, and it is related to environmental contamination of enteric organisms in the weaning period rather than allergic responses.

Hydrogen breath test with low-dose rice flour for assessment of exocrine pancreatic insufficiency

OBJECTIVES

The hydrogen (H2) breath test is widely used in the assessment of carbohydrate malabsorption. Severe exocrine pancreatic insufficiency markedly diminishes pancreatic amylase production and results in malabsorption of complex carbohydrates. Thus, the H2 breath test with low-dose rice flour starch was tested to determine its value in detecting exocrine pancreatic insufficiency by comparison with a direct measurement of pancreatic function.

METHODS

Ten patients with clinically suspected pancreatic insufficiency confirmed with a duodenal perfusion technique and measurement of trypsin and lipase output after cerulein stimulation were included. An H2-rice flour breath test was performed by orally administering 30 g of rice flour. End-alveolar breath samples were obtained before rice load and at 30-minute intervals thereafter for the next 5 hours.

RESULTS

The results are expressed as median (percentile 25-75). Patients included 8 men and 2 women with moderate to severe exocrine pancreatic insufficiency due to chronic pancreatitis, pancreatectomy, or cystic fibrosis. Stimulated duodenal output of lipase and trypsin was abnormally low in all patients (median release, 1.7; range, 0.5-4.5 and 0.8, range, 0.1-11.3 KU/h, respectively). Basal H2 excretion was 9 ppm (range, 7-17) and delta increase over basal H2 excretion was 4 ppm (range, 1-6). Correlation between H2-rice breath test and basal or stimulated duodenal output of lipase and trypsin was not significant.

CONCLUSION

In exocrine pancreatic insufficiency, an oral load of 30 g rice flour slightly raises H2 excretion in breath. This increase is not useful for detecting pancreatic insufficiency due to poor sensitivity and because it is influenced by extrapancreatic factors such as small bowel bacterial overgrowth.

Using breath tests wisely in a gastroenterology practice: an evidence-based review of indications and pitfalls in interpretation

Breath tests are a simple and safe alternative to more invasive investigation strategies for many gastroenterological conditions. Both the hydrogen breath tests and the new 13C stable radioisotope breath tests are nonradioactive and safe in children and pregnancy. The range of diseases that can be identified include Helicobacter pylori infection, lactose and fructose intolerance, bacterial overgrowth, bile salt wastage, pancreatic insufficiency, liver dysfunction, and abnormal small bowel transit. In this review, the physiology supporting these tests and the principles of normal gas dynamics in the gut are briefly reviewed and then related to the test preparation and interpretation in two parts: 1) detection of H. pylori and 2) small bowel, pancreatic, and hepatobiliary disorders. A MEDLINE search reviewing all English language abstracts from 1966 to March, 2001 was performed, with an additional review of abstracts from major national meetings from 1997 to 2001. Using the information from this review, the performance characteristics of the various tests were detailed, and an attempt is made to provide some literature-based guidance regarding their indications and limitations. The interpretation of "flat" breath tests and the selective use of methane collection and colonic alkalinization are discussed. Breath tests are valuable tools that are, in general, underutilized in evaluating dyspepsia and functional bloating and diarrhea, as well as suspected malabsorption, including lactose intolerance.