Are hydrogen breath tests valid in the elderly?

Small Intestinal Bacterial Overgrowth (SIBO), a clinically overdiagnosed entity?

Small intestinal bacterial overgrowth (SIBO) is a clinical entity recognized since ancient times; it represents the consequences of bacterial overgrowth in the small intestine associated with malabsorption. Recently, SIBO as a term has been popularized due to its high prevalence reported in various pathologies since the moment it is indirectly diagnosed with exhaled air tests. In the present article, the results of duodenal/jejunal aspirate culture testing as a reference diagnostic method, as well as the characteristics of the small intestinal microbiota described by culture-dependent and culture-independent techniques in SIBO, and their comparison with exhaled air testing are presented to argue about its overdiagnosis.

Breath Tests for the Non-invasive Diagnosis of Small Intestinal Bacterial Overgrowth: A Systematic Review With Meta-analysis

BACKGROUND/AIMS

Small intestinal bacterial overgrowth (SIBO) diagnosis is usually based on non-invasive breath tests (BTs), namely lactulose BT (LBT) and glucose BT (GBT). However, divergent opinions and problems of parameter standardization are still controversial aspects. We aim to perform a meta-analysis to analyze diagnostic performance of LBT/GBT for SIBO diagnosis.

METHODS

We searched in main literature databases articles in which SIBO diagnosis was achieved by LBT/GBT in comparison to jejunal aspirate culture (reference gold standard). We calculated pooled sensitivity, specificity, positive, and negative likelihood ratios and diagnostic odd ratios. Summary receiver operating characteristic curves were drawn and pooled areas under the curve were calculated.

RESULTS

We selected 14 studies. Pooled sensitivity of LBT and GBT was 42.0% and 54.5%, respectively. Pooled specificity of LBT and GBT was 70.6% and 83.2%, respectively. When delta over baseline cut-off > 20 H₂ parts per million (ppm) was used, GBT sensitivity and specificity were 47.3% and 80.9%; when the cutoff was other than and lower than > 20 ppm, sensitivity and specificity were 61.7% and 86.0%. In patients with abdominal surgery history, pooled GBT sensitivity and specificity gave the impression of having a better performance (81.7% and 78.8%) compared to subjects without any SIBO predisposing condition (sensitivity = 40.6% and specificity = 84.0%).

CONCLUSIONS

GBT seems to work better than LBT. A cut-off of delta H2 expired other than and lower than > 20 ppm shows a slightly better result than > 20 ppm. BTs demonstrate the best effectiveness in patients with surgical reconstructions of gastrointestinal tract.

Scintigraphy Demonstrates High Rate of False-positive Results From Glucose Breath Tests for Small Bowel Bacterial Overgrowth

BACKGROUND & AIMS

Breath tests for hydrogen and/or methane are used to detect small bowel bacterial overgrowth (SBBO), but false-positive results can arise from clinical conditions that accelerate small bowel transit and deliver unabsorbed glucose to the colon. We investigated the prevalence of false-positive results from glucose breath tests by also evaluating patients with scintigraphy.

METHODS

In a retrospective study, we reviewed data from glucose breath tests performed with concurrent scintigraphy on 139 patients with suspected SBBO at the Medical College of Wisconsin from January 2003 through July 2013. Results from breath tests were considered abnormal (positive) if there was an increasing curve of hydrogen or methane by >15 parts per million above baseline within 90 minutes. Scintigraphy was used to determine whether this increase occurred before or after the glucose bolus arrived at the cecum. Data from a subset of 45 patients with prior upper gastrointestinal surgery were analyzed separately.

RESULTS

Forty-six of the patients (33%) had abnormal results from breath tests. On the basis of scintigraphy findings, 22 of these patients (48%) had false-positive results, which were caused by colon fermentation of unabsorbed glucose. Colon fermentation caused false-positive results in 65% of patients who had undergone upper gastrointestinal surgery and 13% of patients without prior surgery. Patients with false-positive results caused by colonic fermentation had shorter mean oro-cecal transit times (18 minutes) compared with patients with positive breath-test results because of SBBO (79 minutes) or negative results (86 minutes).

CONCLUSIONS

Almost half of positive results from glucose breath tests are false because of colonic fermentation. All patients with abnormal results from breath tests should be considered for confirmatory repeat breath testing with concurrent scintigraphy to distinguish SBBO from colonic fermentation. Most patients who have undergone upper gastrointestinal surgery have abnormal results from breath tests and should be assessed by using concurrent scintigraphy with the initial breath test.

Small intestinal bacterial overgrowth: duodenal aspiration vs glucose breath test

BACKGROUND

The diagnosis of small intestinal bacterial overgrowth (SIBO) remains challenging. Our aim was to examine the diagnostic yield of duodenal aspiration/culture and glucose breath test (GBT), and effects of gender, race and demographics on prevalence of SIBO.

METHODS

Patients with unexplained gas, bloating and diarrhea and negative endoscopy, imaging and blood tests were prospectively enrolled in two centers in USA. Randomly, within 1 week each patient underwent both duodenal aspiration/culture and GBT. The diagnostic yield of each test and relationship of symptoms, and effects of ethnicity, age, and gender on prevalence of SIBO were assessed and compared.

KEY RESULTS

Duodenal culture was positive in 62/139 (44.6%) subjects and GBT was positive in 38/139 (27.3%) subjects with an overall diagnostic agreement of 65.5%. The sensitivity, specificity, positive and negative predictive value of GBT was 42%, 84%, 68%, and 64%, respectively. Ethnicity or gender did not influence SIBO, but SIBO positive patients were older (p = 0.0018). Symptom patterns were similar except bloating was more prevalent in GBT positive and gas in culture positive subjects.

CONCLUSIONS & INFERENCES

Duodenal aspiration/culture identifies 45% of patients with suspected SIBO. GBT has lower sensitivity but good specificity for detection of SIBO. There were no ethnic or gender differences in the prevalence of SIBO, but patients with SIBO were older. Because GBT is non-invasive, it should be considered first in patients with suspected SIBO.

Breath testing for small intestinal bacterial overgrowth: maximizing test accuracy

The diagnosis of small intestinal bacterial overgrowth (SIBO) has increased considerably owing to a growing recognition of its association with common bowel symptoms including chronic diarrhea, bloating, abdominal distention, and the irritable bowel syndrome. Ideally, an accurate and objective diagnosis of SIBO should be established before initiating antibiotic treatment. Unfortunately, no perfect test exists for the diagnosis of SIBO. The current gold standard, small-bowel aspiration and quantitative culture, is limited by its high cost, invasive nature, lack of standardization, sampling error, and need for dedicated infrastructure. Although not without shortcomings, hydrogen breath testing provides the simplest noninvasive and widely available diagnostic modality for suspected SIBO. Carbohydrates such as lactulose and glucose are the most widely used substrates in hydrogen breath testing, with glucose arguably providing greater testing accuracy. Lactose, fructose, and sorbitol should not be used as substrates in the assessment of suspected SIBO. The measurement of methane in addition to hydrogen can increase the sensitivity of breath testing for SIBO. Diagnostic accuracy of hydrogen breath testing in SIBO can be maximized by careful patient selection for testing, proper test preparation, and standardization of test performance as well as test interpretation.

Gastro 2013 APDW/WCOG Shanghai working party report: chronic diarrhea: definition, classification, diagnosis

Diarrhea is best defined as passage of loose stools often with more frequent bowel movements. For clinical purposes, the Bristol Stool Form Scale works well to distinguish stool form and to identify loose stools. Laboratory testing of stool consistency has lagged behind. Acute diarrhea is likely to be due to infection and to be self-limited. As diarrhea becomes chronic, it is less likely to be due to infection; duration of 1 month seems to work well as a cut-off for chronic diarrhea, but detailed scientific knowledge is missing about the utility of this definition. In addition to duration of diarrhea, classifications by presenting scenario, by pathophysiology, and by stool characteristics (e.g. watery, fatty, or inflammatory) may help the canny clinician refine the differential diagnosis of chronic diarrhea. In this regard, a careful history remains the essential part of the evaluation of a patient with diarrhea. Imaging the intestine with endoscopy and radiographic techniques is useful, and biopsy of the small intestine and colon for histological assessment provides key diagnostic information. Endomicroscopy and molecular pathology are only now being explored for the diagnosis of chronic diarrhea. Interest in the microbiome of the gut is increasing; aside from a handful of well-described infections because of pathogens, little is known about alterations in the microbiome in chronic diarrhea. Serological tests have well-defined roles in the diagnosis of celiac disease but have less clearly defined application in autoimmune enteropathies and inflammatory bowel disease. Measurement of peptide hormones is of value in the diagnosis and management of endocrine tumors causing diarrhea, but these are so rare that these tests are of little value in screening because there will be many more false-positives than true-positive results. Chemical analysis of stools is of use in classifying chronic diarrhea and may limit the differential diagnosis that must be considered, but interpretation of the results is still evolving. Breath tests for assessment of carbohydrate malabsorption, small bowel bacterial overgrowth, and intestinal transit are fraught with technical limitations that decrease sensitivity and specificity. Likewise, tests of bile acid malabsorption have had limited utility beyond empirical trials of bile acid sequestrants.

Use of the lactose-[13C]ureide breath test for diagnosis of small bowel bacterial overgrowth: comparison to the glucose hydrogen breath test

PURPOSE

The glucose hydrogen breath test (GHBT) is commonly used as a noninvasive test to diagnose small bowel bacterial overgrowth (SBBO) but its validity has been questioned. Our aim was to evaluate the lactose-[(13)C]ureide breath test (LUBT) to diagnose SBBO and to compare it with the GHBT, using cultures of intestinal aspirates as a gold standard.

METHODS

In 22 patients with suspected SBBO (14 male, age range 18-73 years) aspirates were taken from the region of the ligament of Treitz under sterile conditions and cultured for bacterial growth. More than 10(6) colony-forming units/mL fluid or the presence of colonic flora was defined as culture positive (c+). After oral intake of 50 g glucose and 2 g of lactose-[(13)C]ureide, end-expiratory breath samples were obtained up to 120 min. The (13)C/(12)C ratio in breath CO(2) was determined by isotope ratio-mass spectrometry and hydrogen concentration in breath was analyzed electrochemically.

RESULTS

After analyzing receiver operating characteristic curves of the LUBT results, total label recovery of >0.88% at 120 min was considered positive. The test had a sensitivity of 66.7% and a specificity of 100% to predict c+. In the GHBT, an increase of the signal of > or =12 ppm from baseline was considered positive. The sensitivity and specificity of the test were 41.7 and 44.4%, respectively.

CONCLUSIONS

The new stable isotope-labeled LUBT has excellent specificity but suboptimal sensitivity. In contrast, the standard GHBT lacks both high sensitivity and specificity. The LUBT is superior to the GHBT for detecting SBBO.

Diabetic diarrhea

Diabetic patients with diarrhea may present clinical challenges in diagnosis and treatment. Particular diagnoses are more prevalent in diabetic patients than in the general population. Medications are often a culprit for chronic diarrhea, and the medication list should always be carefully scrutinized for those with diarrhea as a side effect. In diabetic patients, metformin is a common cause of diarrhea. Diabetic patients are more likely to have associated diseases (eg, celiac sprue and microscopic colitis) that present with diarrhea as the sole complaint. Ingested sugar-free foods that may contain sorbitol or other agents can cause diarrhea in diabetic patients. Finally, diabetic enteropathy can itself cause diarrhea. The various etiologies can be diagnosed with a thorough history and appropriate diagnostic tests. This article focuses on the etiologies of diarrhea that are seen with higher incidence in diabetic patients.

Rifaximin in the management of colonic diverticular disease

Rifaximin is a rifamycin derivative that acts by inhibiting bacterial RNA synthesis. Since it is virtually unabsorbed after oral administration, its bioavailability within the GI tract is high, with intraluminal and fecal drug concentrations largely exceeding the minimum inhibitory concentration values observed in vitro against a broad spectrum of bacteria, including Gram-positive and Gram-negative bacteria, both aerobes and anaerobes. The GI tract, therefore, represents the primary therapeutic target and the disorders in which intestinal bacteria have a pathogenic role represent the main indication. This is the case with colonic diverticular disease. As a consequence, the broad antibacterial activity of rifaximin appears to be of value in the treatment of this clinical condition. Clinical trials have provided evidence of the substantial benefit of rifaximin in diverticular disease. Indeed, available data show the efficacy of the drug in achieving symptomatic relief in patients with uncomplicated disease. A therapeutic gain of approximately 30%, compared with fiber supplementation only, can be expected after cyclic administration of rifaximin for 12 months. However, its value in the prevention of inflammatory complications of the disease needs to be further explored. Recent studies have shown some evidence of synergy between rifaximin and mesalazine and suggest that a combined treatment could be worthwhile in selected subsets of patients with diverticular disease.

Review article: Small intestinal bacterial overgrowth, bile acid malabsorption and gluten intolerance as possible causes of chronic watery diarrhoea

BACKGROUND

Chronic watery diarrhoea is one of the most common symptoms prompting GI evaluation. Recently, new diagnostic considerations have emerged as possible factors in chronic diarrhoea.

AIM

To review available data regarding diagnosis and treatment of chronic diarrhoea with an emphasis on bacterial overgrowth and bile acid malabsorption.

METHODS

A systematic search of the English language literature of chronic diarrhoea was performed focused on three possible aetiologies of diarrhoea: small intestinal bacterial overgrowth (SIBO), idiopathic bile salt malabsorption (IBAM), gluten responsive enteropathy.

RESULTS

Recent studies suggest that SIBO and bile acid malabsorption may have been underestimated as possible causes of chronic watery diarrhoea. Gluten intolerance with negative coeliac serology is a contentious possible cause of watery diarrhoea, but requires further research before acceptance as an entity.

CONCLUSION

In patients with otherwise unexplained chronic watery diarrhoea, small intestinal bacterial overgrowth and bile salt malabsorption should be considered and investigated.

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.

Small Bowel Bacterial Overgrowth in Symptomatic Older People: Can It Be Diagnosed Earlier?

BACKGROUND/OBJECTIVES

In older people, small bowel bacterial overgrowth syndrome may be a common, but under-diagnosed, cause of diarrhoea and nutrient malabsorption. We aim to determine which clinical features and baseline laboratory investigations indicate a high likelihood of small bowel bacterial overgrowth as defined by a positive glucose breath test.

METHODS

A retrospective analysis of records for all patients referred for glucose breath test over a 6-year period to a teaching hospital.

RESULTS

Out of 197 referrals, 168 patient records were located and analysed (62 male, 106 female; median age 65). Patient characteristics predictive of a positive glucose breath test were: increasing age (p < 0.01), low serum vitamin B12 (p = 0.02), low serum albumin (p = 0.03), previous partial gastrectomy (p < 0.01), previous right hemi-colectomy (p < 0.01), presence of small bowel diverticulae (p = 0.01) and concurrent use of a proton pump inhibitor (p < 0.01). 52.5% (n = 21/40) of patients studied who were over 75 years old versus 21.8% (n = 28/128) of those under 75 years old had a positive glucose breath test (p < 0.01). The median time to diagnosis, from first hospital visit to positive glucose breath test, was 39 weeks.

CONCLUSIONS

There is often a significant delay in diagnosis of small bowel bacterial overgrowth. We suggest that this diagnosis should be considered earlier in the investigative algorithm in older patients with indicative symptoms and a predisposing factor (including previous partial gastrectomy, previous right hemi-colectomy, small bowel diverticulae or use of a proton pump inhibitor) or concurring laboratory indices (low vitamin B12 or albumin).

Small Bowel Bacterial Overgrowth: Presentation, Diagnosis, and Treatment

Small bowel bacterial overgrowth (SBBO) syndrome is associated with excessive numbers of bacteria in the proximal small intestine. The pathology of this condition involves competition between the bacteria and the human host for ingested nutrients. This competition leads to intraluminal bacterial catabolism of nutrients, often with production of toxic metabolites and injury to the enterocyte. A complex array of clinical symptoms ensues, resulting in chronic diarrhea, steatorrhea, macrocytic anemia, weight loss, and less commonly, protein-losing enteropathy. Therapy is targeted at correction of underlying small bowel abnormalities that predispose to SBBO and appropriate antibiotic therapy. The symptoms and signs of SBBO can be reversed with this approach.

Small bowel bacterial overgrowth: presentation, diagnosis, and treatment

Small bowel bacterial overgrowth (SBBO) syndrome is associated with excessive numbers of bacteria in the proximal small intestine. The pathology of this condition involves competition between the bacteria and the human host for ingested nutrients. This competition leads to intraluminal bacterial catabolism of nutrients, often with production of toxic metabolites and injury to the enterocyte. A complex array of clinical symptoms ensues, resulting in chronic diarrhea, steatorrhea, macrocytic anemia, weight loss, and less commonly, protein-losing enteropathy. Therapy is targeted at correction of underlying small bowel abnormalities that predispose to SBBO and appropriate antibiotic therapy. The symptoms and signs of SBBO can be reversed with this approach.

Prevalence of small bowel bacterial overgrowth and its association with nutrition intake in nonhospitalized older adults

OBJECTIVES

To determine the prevalence of small bowel bacterial overgrowth (SBBO) in older adults and to assess whether SBBO is associated with abdominal complaints and nutrient intake.

DESIGN

Cross-sectional survey.

SETTING

Eight senior residence sites in Stuttgart, Germany.

PARTICIPANTS

Older adults living independently in senior residence houses.

MEASUREMENTS

The prevalence of SBBO was measured in 328 subjects, of whom 294 were aged 61 and older, by measuring hydrogen concentration (parts per million; ppm) in exhaled air after ingestion of 50 g glucose. Anthropometric data were obtained and nutritional status was recorded with a computer-aided diet history.

RESULTS

The prevalence of a positive hydrogen breath test (>10 ppm increase) was 15.6% in older adults, compared with 5.9% in subjects aged 24 to 59. The intake of inhibitors of gastric acid production contributed significantly to the high prevalence of a positive breath test in older adults, which was associated with lower body weight, lower body mass index, lower plasma albumin concentration, and higher prevalence of diarrhea. Subjects with a positive hydrogen breath test consumed significantly less fiber, folic acid, and vitamins B2 and B6 than those without. No difference was observed in the intake of energy, protein, fat, or carbohydrates.

CONCLUSION

Prevalence of SBBO is associated with reduced body weight, which is paralleled by reduced intake of several micronutrients. Malabsorption resulting from diarrhea might be an aggravating factor contributing to weight loss in these subjects.

Aging and intestinal motility: a review of factors that affect intestinal motility in the aged

Normal aging is associated with significant changes in the function of most organs and tissues. In this regard, the gastrointestinal tract is no exception. The purpose of this review is to detail the important age-related changes in motor function of the various parts of the gastrointestinal tract and to highlight some of the important motility changes that may occur, either in relation to common age-related disorders, or as a result of certain drugs commonly prescribed in the aged. A major confounding factor in the interpretation of motor phenomena throughout the gastrointestinal tract in this age group is the frequent coexistence of neurological, endocrinological and other disease states, which may be independently associated with dysmotility. Overall, current data are insufficient to implicate normal aging as a cause of dysmotility in the elderly. Normal aging is associated with various changes in gastrointestinal motility, but the clinical significance of such changes remains unclear. More important is the impact of various age-related diseases on gastrointestinal motility in the elderly: for example, long-standing diabetes mellitus may reduce gastric emptying in up to 50% of patients; depression significantly prolongs whole-gut transit time; hypothyroidism may prolong oro-caecal transit time; and chronic renal failure is associated with impaired gastric emptying. In addition, various, frequently used drugs in the elderly cause disordered gastrointestinal motility. These drugs include anticholinergics, especially antidepressants with an anticholinergic effect, opioid analgesics and calcium antagonists.

Diagnosis of small intestinal bacterial overgrowth in patients with cirrhosis of the liver: poor performance of the glucose breath hydrogen test

BACKGROUND/AIMS

Small intestinal bacterial overgrowth is known to occur in association with cirrhosis of the liver and studies are needed to assess its pathophysiological role. The glucose breath hydrogen test as an indirect test for small intestinal bacterial overgrowth has been applied to patients with cirrhosis but has not yet been validated against quantitative culture of jejunal secretion in this particular patient population.

METHODS

Forty patients with cirrhosis underwent glucose breath hydrogen test and jejunoscopy. Jejunal secretions were cultivated quantitatively for aerobe and anaerobe microorganisms.

RESULTS

Small intestinal bacterial overgrowth was detected by culture of jejunal aspirates in 73% of patients, being associated with age and the administration of acid-suppressive therapy. The glucose breath hydrogen test correlated poorly with culture results, sensitivity and specificity ranging from 27%-52% and 36%-80%, respectively.

CONCLUSIONS

In patients with cirrhosis, the glucose breath hydrogen test correlates poorly with the diagnostic gold standard for small intestinal bacterial overgrowth. Until other non-invasive tests have been validated, studies addressing the role of small intestinal bacterial overgrowth in patients with cirrhosis should resort to microbiological culture of jejunal secretions.