Methane production and small intestinal bacterial overgrowth in children living in a slum

AIM:To analyze small intestinal bacterial overgrowth in school-aged children and the relationship between hydrogen and methane production in breath tests.METHODS:This transversal study included 85 children residing in a slum and 43 children from a private school,all aged between 6 and 10 years,in Osasco,Brazil.For characterization of the groups,data regarding the socioeconomic status and basic housing sanitary conditions were collected.Anthropometric data was obtained in children from both groups.All children completed the hydrogen(H 2) and methane(CH 4) breath test in order to assess small intestinal bacterial overgrowth(SIBO).SIBO was diagnosed when there was an increase in H 2 ≥ 20 ppm or CH 4 ≥ 10 ppm with regard to the fasting value until 60 min after lactulose ingestion.RESULTS:Children from the slum group had worse living conditions and lower nutritional indices than children from the private school.SIBO was found in 30.9%(26/84) of the children from the slum group and in 2.4%(1/41) from the private school group(P = 0.0007).Greater hydrogen production in the small intestine was observed in children from the slum group when compared to children from the private school(P = 0.007).A higher concentration of hydrogen in the small intestine(P 0.001) and in the colon(P 0.001) was observed among the children from the slum group with SIBO when compared to children from the slum group without SIBO.Methane production was observed in 63.1%(53/84) of the children from the slum group and in 19.5%(8/41) of the children from the private school group(P 0.0001).Methane production was observed in 38/58(65.5%) of the children without SIBO and in 15/26(57.7%) of the children with SIBO from the slum.Colonic production of hydrogen was lower in methaneproducing children(P = 0.017).CONCLUSION:Children who live in inadequate environmental conditions are at risk of bacterial overgrowth and methane production.Hydrogen is a substrate for methane production in the colon.     

Breath testing to evaluate lactose intolerance in irritable bowel syndrome correlates with lactulose testing and may not reflect true lactose malabsorption

OBJECTIVES: An increased prevalence of lactose intolerance is seen in irritable bowel syndrome (IBS). Recently, we demonstrated a high prevalence of abnormal lactulose breath test results in IBS suggesting bacterial overgrowth. Because symptoms of lactose intolerance result from bacterial fermentation, the purpose of this study was to determine whether an abnormal lactose breath test is reflective of malabsorption or early presentation to bacteria. METHODS: Subjects with diarrhea-predominant IBS were enrolled. On day 1, subjects underwent a lactulose breath test after an overnight fast. Within 1 wk, subjects returned after fasting for a lactose breath test with simultaneous blood glucose measurements every 15 min to complete a lactose tolerance test (LTT). Symptoms were evaluated 3 h after lactose administration. RESULTS: Twenty subjects completed the study. One subject inadvertently received dextrose through the intravenous and was excluded. Of the remaining 19 subjects, three (16%) had an abnormal LTT suggesting malabsorption. In all, 10 subjects (53%) had an abnormal lactose breath test, 14 (74%) had an abnormal lactulose breath test, and 11 (58%) had symptoms after lactose administration. The agreement with symptoms was moderate (kappa = 0.47) and fair (kappa = 0.24) when compared to the lactose breath test and LTT, respectively. There was a fair correlation between lactose breath test and LTT (kappa = 0.29). However, lactose breath test hydrogen levels >166 ppm were universally predictive of abnormal LTT. Finally, a significant correlation was seen between the hydrogen production on lactose and lactulose breath test (r = 0.56, p = 0.01). CONCLUSIONS: Lactose breath testing in IBS subjects does not seem to reflect malabsorption; it may be an indicator of abnormal lactulose breath test, suggesting bacterial overgrowth.     

Breath hydrogen analysis in patients with ileoanal pouch anastomosis.

The possible influence on functional outcomes of hydrogen production in the ileoanal pouch after restorative proctocolectomy was investigated by means of lactulose H2 breath tests. Eight of 15 patients had significant increases in breath hydrogen after 10 g lactulose. One patient declined to participate in further investigations, the remaining seven responders had no evidence of small bowel bacterial overgrowth after glucose H2 breath tests. The ability to produce hydrogen by anaerobic fermentation of lactulose in the pouch was unrelated to the age of the patients or of the pouch. Seven of eight responders had successive breath tests after ingestion of lactulose 20 g and wheat starch 100 g. Five of seven had significant increases after lactulose but none after wheat starch. The overall function of the pouch continence, spontaneity of defecation, and 24 hour stool frequency was significantly better in responders than in non-responders. The absence of H2 production of 100 g wheat starch may indicate either increased absorption or defective fermentation.     

Breath hydrogen testing in bacterial overgrowth of the small intestine

The indirect, noninvasive technique of breath hydrogen (H2) analysis was evaluated in 45 patients suspected of having bacterial overgrowth of the small intestine. Bacterial overgrowth, defined as a jejunal culture yielding at least 10(5) organisms/ml, was present in 27 patients. After dietary preparation and a 12-h fast, subjects received in random order and on separate days 50 g of glucose or 50 g of rice flour in the form of two pancakes. Normal values were established in 20 healthy controls. Twelve of 27 patients with proven bacterial overgrowth had an elevated (greater than 15 ppm) fasting breath H2 level on at least 1 test day. Fifteen of 18 patients with negative cultures had low fasting breath H2 levels. Based on values in controls, a positive breath test was defined as an increase in breath H2 of greater than or equal to 12 ppm after glucose or greater than or equal to 14 ppm after rice flour. A 2-h glucose breath H2 test had a sensitivity of 93% and a specificity of 78% in the diagnosis of overgrowth. The predictive value of a positive test was 86% and that of a negative test was 88%. The combination of both a high fasting breath H2 level and a diagnostic rise of breath H2 after glucose was present in 41% of patients with overgrowth and in none of the patients without overgrowth. Extending the test to 4 h did not increase sensitivity, but decreased specificity. Rice flour was a less satisfactory substrate in predicting the presence of bacterial overgrowth. In conclusion, a high fasting breath H2 level after dietary preparation suggests bacterial overgrowth but lacks sensitivity. The finding of a rise in breath H2 of at least 12 ppm within 2 h of a 50-g glucose challenge is a simple screen for bacterial overgrowth. The combined criteria of a high fasting breath H2 level and a significant rise after glucose are specific for bacterial overgrowth.     

Detection of bacterial overgrowth in IBS using the lactulose H2 breath test: comparison with 14C-D-xylose and healthy controls

OBJECTIVES Recent reports suggest bacterial overgrowth is commonly associated with irritable bowel syndrome (IBS) when diagnosed using the lactulose hydrogen breath test (LHBT). We employed this test to examine whether similar findings exist in a geographically distinct population of Rome II positive IBS patients and compared it to the 14C-D-xylose breath test, a test with acknowledged greater specificity for bacterial overgrowth. METHODS: In the first series, Rome II IBS patients underwent a 10 g lactulose breath test and a standardized 1 g 14C-D-xylose breath test and answered IBS symptom questionnaires. A positive test required an elevated breath hydrogen concentration within 90 min, two distinct peaks, and an increase >20 ppm. In a second series, control patients lacking gastrointestinal symptoms underwent a lactulose breath test. A positive test required an elevation of breath hydrogen >20 ppm within 90 or 180 min. These criteria were also applied to lactulose breath tests from IBS cases in series one. RESULTS: The IBS patients were predominantly female (64%) and most reported severe symptoms (80%). The majority had diarrhea predominant symptoms (63%) and only 3% were constipation predominant. In the first series, only 10% of patients had a positive lactulose breath test and 13% had a positive 14C-D-xylose test. In the second series, the number of abnormal LHBTs was much higher but no differences were found between IBS patients and controls. CONCLUSION: The lactulose breath test did not reliably detect a common association between bacterial overgrowth and IBS in our patient population.     

Breath hydrogen test to evaluate lactose absorption and small bowel bacterial overgrowth in children

The aim of this study was to determine the lactose absorption capacity and possible existence of bacterial overgrowth in the small bowel in asymptomatic school children of low social economic level in Marilia, a city located in the interior of S?o Paulo state. Eighty three children aging 7 to 15 years old without any gastrointestinal manifestations at least 30 days prior to the tests were studied. All the patients had fasted for at least 8 hours before the tests were performed. Lactose absorption was evaluated by breath hidrogen test after an overload of lactose 18 g in 10% aquous solution. Lactose intolerance was determined by the occurrence of clinical symptoms, such as diarrhea, abdominal pain, flatulence, etc in the following 24 hours after the test was performed. Bacterial overgrowth was evaluated by the breath hidrogen test after a 10 g lactulose load in aqueous solution. Lactose malabsorption was detected in 19 (22.9%) children and lactose intolerance was observed in 10 (12%) children. Lactose intolerance was more frequently observed in children who showed lactose malabsorption (6/19; 31.6%) than in those who presented a normal test (4/64; 6.3%) (P = 0.008). Bacterial overgrowth was detected in six (7.2%) children and showed no statistical relationship with lactose malabsorption. Ontogenetic lactose malabsorption verified in this group of school children is similar to the reported for Caucasian populations. Presence of bacterial overgrowth confirms the existence of asymptomatic environmental enteropathy in children of low social economic level.     

Lactulose breath test results in patients with persistent abdominal symptoms following Giardia lamblia infection

OBJECTIVE: Bacterial overgrowth has been implicated in the pathogenesis of irritable bowel syndrome (IBS). The objective of this study was to investigate whether post-infectious IBS following Giardia lamblia infection is related to intestinal bacterial overgrowth, as diagnosed by the lactulose breath test (LBT). MATERIAL AND METHODS: Seventy-seven patients with persistent gastrointestinal complaints related to a recent outbreak of G. lamblia infection were included in the study. Despite one or several courses of treatment with metronidazole during the previous months, 23 of the patients were still stool positive for G. lamblia, whereas the remaining 54 patients had cleared the infection. All patients and 42 healthy volunteers underwent a LBT with 10 g lactulose, and their customary and post-LBT abdominal symptoms were scored. RESULTS: Ninety-five percent of the patients had IBS. Lactulose-induced hydrogen breath excretion was not significantly different in patients and controls. Customary and post-LBT symptoms were abnormally high in the patients, irrespective of both G. lamblia infection status and LBT results. Furthermore, lactulose challenge replicated the patients' customary complaints in 70% of the patients. CONCLUSIONS: Gastrointestinal complaints in patients with persistent or cleared giardiasis were unrelated to hydrogen breath excretion after lactulose challenge. Post-giardiasis IBS cannot be ascribed to intestinal bacterial overgrowth, as diagnosed by LBT.     

The lactulose hydrogen breath test as a diagnostic test for small-bowel bacterial overgrowth.

The lactulose hydrogen breath test has been evaluated as a diagnostic test for small-bowel bacterial overgrowth using the 14C-glycocholate breath test for comparison. Twenty-seven patients with suspected bacterial overgrowth and 37 control patients were studied. The lactulose test was positive in 8 out of 9 patients with Subsequently proven bacterial overgrowth, all of whom had positive 14C-glycocholate tests. However, 6 patients with ileal disease or resection had positive 14C-glycocholate tests but negative lactulose tests. subsequent bacteriological study of duodenal juice from these patients was negative. Negative results were obtained by both tests in the remaining 12 patients, none of whom were subsequently shown to have bacterial overgrowth. All 37 control subjects had negative lactulose tests. The lactulose breath test is a simple and promising diagnostic test for the detection of small-bowel bacterial overgrowth and, unlike the 14C-glycocholate test, has the advantage of being able to distinguish bacterial overgrowth from ileal disease.     

Association between hypothyroidism and small intestinal bacterial overgrowth

OBJECTIVES: Small intestinal bacterial overgrowth is defined as an abnormally high bacterial population level in the small intestine. Intestinal motor dysfunction associated with hypothyroidism could predispose to bacterial overgrowth. Luminal bacteria could modulate gastrointestinal symptoms and interfere with levothyroxine absorption. The aims of the present study were to assess the prevalence and clinical pattern of bacterial overgrowth in patients with a history of overt hypothyroidism and the effects of bacterial overgrowth decontamination on thyroid hormone levels. METHODS: A total of 50 consecutive patients with a history of overt hypothyroidism due to autoimmune thyroiditis was enrolled. Diagnosis of bacterial overgrowth was based on positivity to a hydrogen glucose breath test. Bacterial overgrowth positive patients were treated with 1,200 mg rifaximin each day for a week. A glucose breath test, gastrointestinal symptoms, and thyroid hormone plasma levels were reassessed 1 month after treatment. RESULTS: A total of 27 patients with a history of hypothyroidism demonstrated a positive result to the breath test (27 of 50, 54%), compared with two in the control group (two of 40, 5%). The difference was statistically significant (P < 0.001). Abdominal discomfort, flatulence, and bloating were significantly more prevalent in the bacterial overgrowth positive group. These symptoms significantly improved after antibiotic decontamination. Thyroid hormone plasma levels were not significantly affected by successful bacterial overgrowth decontamination. CONCLUSIONS: The history of overt hypothyroidism is associated with bacterial overgrowth development. Excess bacteria could influence clinical gastrointestinal manifestations. Bacterial overgrowth decontamination is associated with improved gastrointestinal symptoms. However, fermenting carbohydrate luminal bacteria do not interfere with thyroid hormone levels.     

Orocecal transit time and bacterial overgrowth in patients with Crohn's disease

Bacterial overgrowth is frequent in patients with Crohn's disease (CD) and can contribute to symptoms. Motility abnormalities can predispose to bacterial overgrowth. The hydrogen (H2) and methane (CH4) breath test is a sensitive and simple tool for the diagnosis of bacterial overgrowth and for the evaluation of orocecal transit time (OCTT). In this study, we investigated the prevalence of OCTT modifications and bacterial overgrowth in a series of consecutive adult patients with CD. In 43 healthy subjects and 67 patients with CD. we performed the lactulose breath test using a gas analyzer that offers the opportunity of measuring both H2 and CH4. Of the patients, 24 had undergone an ileocolic resection before the test with ablation of the ileocecal valve. At the time of the test 15 patients had active disease, whereas in 52 subjects the disease was quiescent. Fifty-seven patients and forty controls were evaluable for OCTT and bacterial overgrowth. In 10 patients and in 3 controls, no H2 or CH4 peak was recorded during the 8-hour test. Out of 57 patients, 13 (23%) were affected by bacterial overgrowth. The prevalence of bacterial overgrowth was higher in patients with previous surgery (30%) than in nonoperated patients (18%). In all patients with bacterial overgrowth, an antibiotic treatment induced a normalization of the test and an improvement of the symptoms. We observed a longer OCTT in the patients compared to controls, although this difference was not statistically significant (154 +/- 45 vs. 136 +/- 45 minutes). OCTT was significantly longer compared to controls in the 14 CD patients with previous ileocolic resection ( 180 +/- 53 vs. 136 + 45 minutes; p < 0.004). In conclusion, we found that a significant proportion of unselected patients with CD has bacterial overgrowth and prolongation of OCTT. We suggest that the modifications in OCTT in patients with CD can predispose to bacterial overgrowth. The lactulose breath test is a simple method that can be more widely used in patients with CD.     

Small bowel bacterial overgrowth in patients with alcoholic cirrhosis

A total of 89 patients with alcoholic cirrhosis and 40 healthy subjects were included in a study to assess the prevalence of intestinal bacterial overgrowth and to analyze its relationship with the severity of liver dysfunction, presence of ascites, and development of spontaneous bacterial peritonitis (SBP). Bacterial overgrowth was measured by means of a breath test after ingestion of glucose. Intestinal bacterial overgrowth was documented in 27 (30.3%) of the 89 patients with alcoholic cirrhosis and in none of the healthy subjects. The prevalence of intestinal bacterial overgrowth was significantly higher in cirrhotics with ascites (37.1%) than in those with no evidence of ascites (5.3%) and among patients with Pugh-Child class C (48.3%) than in patients with class A (13.1%) or B (27%). Twelve (17.1%) of the 70 patients with ascites developed an episode of SBP. The prevalence of spontaneous bacterial peritonitis was significantly higher in patients who had intestinal bacterial overgrowth (30.7%) than in patients who did not (9.09%). We conclude that intestinal bacterial overgrowth occurs in approximately one third of patients with cirrhosis secondary to alcohol, particularly in patients with ascites and advanced liver dysfunction. Moreover, bacterial overgrowth may be a condition favoring infection of the ascitic fluid.This study was supported in part by a grant (No. 91/0675) from Fondo de Investigaciones Sanitarias (FIS), Madrid, Spain.This article originally appeared inDigestive Diseases and Sciences, Volume 40, Number 6, June 1995, pp. 1252–1256.     

A link between irritable bowel syndrome and fibromyalgia may be related to findings on lactulose breath testing

BACKGROUND: An association between irritable bowel syndrome (IBS) and small intestinal bacterial overgrowth (SIBO) has been found. OBJECTIVE: To compare the prevalence and test results for bacterial overgrowth between IBS and fibromyalgia. METHODS: Subjects with independent fibromyalgia and IBS were compared with controls in a double blind study. Participants completed a questionnaire, and a lactulose hydrogen breath test was used to determine the presence of SIBO. The prevalence of an abnormal breath test was compared between study participants. Hydrogen production on the breath test was compared between subjects with IBS and fibromyalgia. The somatic pain visual analogue score of subjects with fibromyalgia was compared with their degree of hydrogen production. RESULTS: 3/15 (20%) controls had an abnormal breath test compared with 93/111 (84%) subjects with IBS (p<0.01) and 42/42 (100%) with fibromyalgia (p<0.0001 v controls, p<0.05 v IBS). Subjects with fibromyalgia had higher hydrogen profiles (p<0.01), peak hydrogen (p<0.0001), and area under the curve (p<0.01) than subjects with IBS. This was not dependent on the higher prevalence of an abnormal breath test. The degree of somatic pain in fibromyalgia correlated significantly with the hydrogen level seen on the breath test (r = 0.42, p<0.01). CONCLUSIONS: An abnormal lactulose breath test is more common in fibromyalgia than IBS. In contrast with IBS, the degree of abnormality on breath test is greater in subjects with fibromyalgia and correlates with somatic pain.     

Small bowel bacterial overgrowth in patients with alcoholic cirrhosis

A total of 89 patients with alcoholic cirrhosis and 40 healthy subjects were included in a study to assess the prevalence of intestinal bacterial overgrowth and to analyze its relationship with the severity of liver dysfunction, presence of ascites, and development of spontaneous bacterial peritonitis (SBP). Bacterial overgrowth was measured by means of a breath test after ingestion of glucose. Intestinal bacterial overgrowth was documented in 27 (30.3%) of the 89 patients with alcoholic cirrhosis and in none of the healthy subjects. The prevalence of intestinal bacterial overgrowth was significantly higher in cirrhotics with ascites (37.1%) than in those with no evidence of ascites (5.3%) and among patients with Pugh-Child class C (48.3%) than in patients with class A (13.1%) or B (27%). Twelve (17.1%) of the 70 patients with ascites developed an episode of SBP. The prevalence of spontaneous bacterial peritonitis was significantly higher in patients who had intestinal bacterial overgrowth (30.7%) than in patients who did not (9.09%). We conclude that intestinal bacterial overgrowth occurs in approximately one third of patients with cirrhosis secondary to alcohol, particularly in patients with ascites and advanced liver dysfunction. Moreover, bacterial overgrowth may be a condition favoring infection of the ascitic fluid.     

Colonic hydrogen absorption: quantification of its effect on hydrogen accumulation caused by bacterial fermentation of carbohydrates.

The aim of the study was to assess (quantitatively) colonic hydrogen absorption. Hydrogen volumes in flatus and breath were measured over periods of six hours in normal subjects during fasting and after ingestion of the non-absorbable carbohydrate lactulose to simulate the effect of fermentable dietary fibres. If less than 76 ml/6 h of hydrogen accumulated in the colon then all of it was absorbed, as suggested by the intercept of the regression line of the correlation between hydrogen volumes in flatus and breath after ingestion of lactulose. As total flatus volume increased, efficiency of colonic hydrogen absorption decreased from 90% to 20%. The positive correlation between hydrogen volumes of flatus and breath showed that the eightfold interindividual differences in flatus volume after ingestion of 12.5 g of lactulose were caused by differences in bacterial net gas production, not gas absorption. Differences in colonic gas emptying rate are the consequence rather than the cause of interindividual differences in flatus volume. In conclusion: (1) colonic hydrogen absorption is highly effective at low colonic hydrogen accumulation rates, but not at higher accumulation rates; (2) ineffective colonic gas absorption is the consequence and not the cause of high colonic gas accumulation rate after ingestion of non-absorbable carbohydrates; and (3) future therapeutic approaches to the large interindividual variability in colonic gas accumulation after ingestion of poorly absorbable fermentable carbohydrates, such as some kinds of dietary fibres, should be directed towards altering colonic bacterial metabolism.     

Small intestinal bacterial overgrowth

Small intestinal bacterial overgrowth (SIBO) syndrome is characterized in its florid form by diarrhoea and weight loss. The most common underlying factors are dysmotility, small intestinal obstruction, blind or afferent loops. Small intestinal bacterial overgrowth can be diagnosed by: 1) culture of jejunum aspirate for bacterial counts, 2) ¹⁴C-D-xylose breath testing, 3) non-invasive hydrogen breath testing using glucose or lactulose or 4) ¹⁴C-glycocholic acid breath testing. The treatment usually consists of the eradication of bacterial overgrowth with repeated course of antimicrobials, correction of associated nutritional deficiencies and, when possible, correction of the underlying predisposing conditions.     

Small intestinal bacterial overgrowth

Small intestinal bacterial overgrowth (SIBO) syndrome is characterized in its florid form by diarrhoea and weight loss. The most common underlying factors are dysmotility, small intestinal obstruction, blind or afferent loops. Small intestinal bacterial overgrowth can be diagnosed by: 1) culture of jejunum aspirate for bacterial counts, 2) 14C-D-xylose breath testing, 3) non-invasive hydrogen breath testing using glucose or lactulose or 4) 14C-glycocholic acid breath testing. The treatment usually consists of the eradication of bacterial overgrowth with repeated course of antimicrobials, correction of associated nutritional deficiencies and, when possible, correction of the underlying predisposing conditions.     

Lactulose hydrogen and [14C]xylose breath tests in patients with ileoanal anastomosis

To study the intestinal bacterial flora and mouth to pouch transit time after ileoanal anastomosis, lactulose hydrogen and [¹⁴C]xylose breath tests were performed on 19 patients with ileoanal anastomosis and J-pouch and 8 patients with conventional ileostomy. Evaluated by the [¹⁴C]xylose breath test, patients with ileoanal anastomosis and ileal pouch showed no difference in the bacterial flora of the proximal small bowel when compared with ileostomy patients. The lactulose hydrogen breath test showed a significant rise in breath hydrogen, indicating bacterial overgrowth, in 68% of patients with ileoanal anastomosis but in none with conventional ileostomy (p<0.01). It was concluded that this peak in breath hydrogen was produced by the bacteria in the pouch. Thus the lactulose hydrogen breath test can be used to measure mouth to pouch transit time in 2/3 of patients with ileoanal anastomosis. Mouth to pouch transit time was 63±9 min and it correlated inversely with stool frequency (p<0.05).

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Résumé Pour étudier la flore intestinale bactérienne et le temps de transit bucco-anal après anastomose iléo-anale des tests respiratoires au lactulose hydrogène C14 xylose ont été réalisés chez 19 patients avec anastomose iléoanale et poche en J et chez 8 malades avec une iléostomie conventionnelle. Lors du test C14 xylose il n'y avait aucune différence en ce qui concerne la flore bactérienne de l'intestin grèle proximal chez les malades qui avaient une anastomose iléo-anale avec poche et chez ceux qui avaient une iléostomie. Le test au lactulose hydrogène montrait une augmentation significative de l'hydrogène respiratoire indiquant une pullulation bactérienne chez 68% des malades avec anastomose iléo-anale mais chez aucun de ceux qui avaient une iléostomie conventionnelle (p<0.01). On conclue que le pic d'hydrogène respiratoire était produit par les bactéries dans la poche. Ainsi le test au lactulose hydrogène respiratoire peut être usé pour mesurer le temps de transit bouche-poche chez 2/3 des patients avec une anastomose iléo-anale. Le temps de transit bouche-poche était de 63±9 mn et était corrélé inversement avec la fréquence des selles (p<0.05).

     

Evaluation of the hydrogen breath test in man: definition and elimination of the early hydrogen peak.

After ingestion of a non-absorbable carbohydrate breath hydrogen excretion increases early at about 10 minutes, and again later when the ingested carbohydrate enters the caecum. The late rise has been used as a marker of mouth to caecum transit time, but the source of the early rise has not been satisfactorily explained. We studied in 60 healthy volunteers the source and frequency of the early rise in breath hydrogen after ingestion of a non-absorbable carbohydrate. After ingestion of either lactulose solution (10 g in 150 ml water), lentil soup (46 g carbohydrate) or solid meal containing baked beans (15 g carbohydrate), breath hydrogen was significantly raised above basal concentrations within 10 minutes (81 +/- 27, 395 +/- 138 and 110 +/- 52% above basal respectively). A significant rise in breath hydrogen (75 +/- 21%) occurred 10 minutes after sham lactulose feeding (lactulose applied to oral cavity but not swallowed), but no early peak occurred after sham saccharin feeding (non-fermentable carbohydrate), intragastric or intraduodenal administration of lactulose. Ten of the 12 subjects given lactulose sham feeding were restudied after oral hygiene with chlorhexidine mouthwash. In these the early hydrogen peak was abolished. Oral hygiene also reduced the occurrence and magnitude of the early hydrogen rise after lactulose ingestion. These findings indicate that the early rise in breath hydrogen observed after ingestion of lactulose is produced by interaction with oral bacteria.     

Usefulness of the double-balloon enteroscope in colonoscopies performed in patients with previously failed colonoscopy

Jejunal flora, bile acid deconjugation, and breath hydrogen (H₂) and methane (CH₄) excretion were studied in 22 Billroth II (BII)-operated patients with chronic postprandial symptoms, dumping (9), vomiting (7), pain (10), and diarrhoea (14). Sixteen were below 90% of desirable weight. Two control groups were included, one comprising 5 symptom-free, BII-operated volunteers and another comprising 12 healthy, unoperated volunteers. The numbers of bacteria recovered from jejunal secretions in the postgastrectomy patients did not differ significantly from those recovered in the symptom-free BII-operated controls but were significantly lower in the unoperated controls. Production of fermentation gas in anaerobic media supplemented with carbohydrates occurred in 17 of 22 postgastrectomy patients and in 4 of 5 BII-operated controls but in none of the unoperated controls. Bacterial bile acid decon-jugating activity did not differ significantly between the postgastrectomy patients and the BII-operated controls but was significantly lower in the unoperated controls. Breath H₂ excretion after glucose ingestion was significantly higher in the postgastrectomy patients than in both the BII-operated and the unoperated controls. The addition of pectin or guar gum to the glucose meal largely prevented postprandial symptoms and breath hydrogen excretion. Six out of 12 postgastrectomy patients treated with metronidazole recorded symptomatic effects, mainly on diarrhoea. Our findings indicate that jejunal bacterial overgrowth may be a major cause of the symptoms in some postgastrectomy patients. The tests available for demonstration of small-bowel bacterial overgrowth, perhaps with the exception of the glucose H₂ breath test, did not differentiate satisfactorily between symptom-producing and non-symptom-producing abnormal jejunal flora. Thus these tests may seem to have a limited practical diagnostic value in such patients.     

Acidic colonic microclimate--possible reason for false negative hydrogen breath tests.

About 5% of normal subjects fail to produce increased hydrogen breath concentration after ingestion of the non-digestible carbohydrate lactulose (low hydrogen producers). The existence of low hydrogen producers limits the diagnostic use of hydrogen (H2) breath tests. We studied the effects of lactulose and of magnesium sulphate (MgSO4) pretreatment on stool-pH and on hydrogen exhalation after oral loading with lactulose or lactose in 17 hydrogen producers and 12 low hydrogen producers. In seven hydrogen producers acidification of stool pH by lactulose pretreatment (20 g tid) decreased hydrogen exhalation and three of seven (43%) became low hydrogen producers. In contrast, after pretreatment of eight low hydrogen producers with magnesium sulphate (5 g twice daily) all eight produced hydrogen after a lactulose load. Similarly four lactose intolerant low hydrogen producers had abnormal lactose hydrogen breath tests after MgSO4 pretreatment. MgSO4 pretreatment neither resulted in false positive lactose hydrogen breath tests in five lactose tolerant hydrogen producers, nor increased the hydrogen exhalation in five additional hydrogen producing controls after ingestion of lactulose. The results of these studies confirm that hydrogen production from lactulose decreases when the colonic pH is lower (lactulose pretreatment), and increases when colonic pH is higher (MgSO4 pretreatment). In low hydrogen producers the lacking increase of H2 exhalation after ingestion of non-digestible carbohydrates can be overcome by MgSO4 pretreatment, thus increasing the sensitivity of the test by avoiding false negative hydrogen breath tests in low hydrogen producers with disaccharide malabsorption or maldigestion. The underlying mechanism of this remarkable effect of MgSO4 pretreatment warrants further investigation.