Survival of lactic acid bacteria in a dynamic model of the stomach and small intestine: validation and the effects of bile

This study was conducted to validate a dynamic model of the stomach and small intestine to quantify the survival of lactic acid bacteria and to assess the influence of gastrointestinal secretions. The survival of a single strain of each of the following species, Bifidobacterium bifidum, Lactobacillus acidophilus, Lactobacillus bulgaricus, and Streptococcus thermophilus, was measured under physiological conditions (e.g., peristalsis, changes in pH, and changes in concentrations of enzymes and bile) and were compared with data obtained from humans. No significant differences were found between the in vitro and in vivo data, indicating that the model has a predictive value for the survival of these bacteria in humans. The survival of these strains of lactic acid bacteria in the gastrointestinal model was investigated under two different conditions in the small intestine: simulation of physiological secretion of bile and low bile secretion. Reductions in viability were significantly different between the bacterial species. The dose-response effect of bile on the survival of the tested bacteria was significant, demonstrating the bactericidal effect of bile salts. This study demonstrates the differences among bacterial species in their sensitivity to gastric and intestinal secretions.

Ineffectiveness of Lactobacillus johnsonii LA1 for prophylaxis of postoperative recurrence in Crohn's disease: a randomised, double blind, placebo controlled GETAID trial

BACKGROUND AND AIMS

Early endoscopic recurrence is frequent after intestinal resection for Crohn's disease. Bacteria are involved, and probiotics may modulate immune responses to the intestinal flora. Here we tested the probiotic strain Lactobacillus johnsonii LA1 in this setting.

PATIENTS AND METHODS

This was a randomised, double blind, placebo controlled study. Patients were eligible if they had undergone surgical resection of <1 m, removing all macroscopic lesions within the past 21 days. Patients were randomised to receive two packets per day of lyophilised LA1 (2 x 10(9) cfu) or placebo for six months; no other treatment was allowed. The primary endpoint was endoscopic recurrence at six months, with grade >1 in Rutgeerts' classification or an adapted classification for colonic lesions. Endoscopic score was the maximal grade of ileal and colonic lesions. Analyses were performed primarily on an intent to treat basis.

RESULTS

Ninety eight patients were enrolled (48 in the LA1 group). At six months, endoscopic recurrence was observed in 30/47 patients (64%) in the placebo group and in 21/43 (49%) in the LA1 group (p = 0.15). Per protocol analysis confirmed this result. Endoscopic score distribution did not differ significantly between the LA1 and placebo groups. There were four clinical recurrences in the LA1 group and three in the placebo group.

CONCLUSION

L johnsonii LA1 (4 x 10(9) cfu/day) did not have a sufficient effect, if any, to prevent endoscopic recurrence of Crohn's disease.

Comparative study of bacterial groups within the human cecal and fecal microbiota

The composition of the human cecal microbiota is poorly known because of sampling difficulties. Samples of cecal fluid from eight subjects were collected via an intestinal tube. Feces were also collected. Total anaerobes, facultative anaerobes, bifidobacteria, and Bacteroides were enumerated by culture methods, and the predominant phylogenetic groups were quantified by molecular hybridization using a set of six rRNA-targeted probes. The numbers of strict anaerobes, bifidobacteria, Bacteroides, and members of the Clostridium coccoides group and Clostridium leptum subgroup were lower in the cecum. Facultative anaerobes represented 25% of total bacteria in the cecum versus 1% in the feces.

Combined oral and enema treatment with Pentasa (mesalazine) is superior to oral therapy alone in patients with extensive mild/moderate active ulcerative colitis: a randomised, double blind, placebo controlled study

BACKGROUND AND AIMS

Oral aminosalicylates are well established in the treatment of active mild/moderate ulcerative colitis (UC) when the disease is extensive (that is, beyond the splenic flexure). The majority of clinical symptoms relate to disease activity in the distal part of the colon and therefore this study was designed to investigate if adding a mesalazine enema to oral mesalazine has additional benefit for patients with extensive mild/moderate active UC.

METHODS

A randomised double blind study was performed in 127 ambulatory patients. All received 4 g/day (twice daily dosing) oral mesalazine for eight weeks. During the initial four weeks, they additionally received an enema at bedtime containing 1 g of mesalazine or placebo. Disease activity was assessed using the ulcerative colitis disease activity index, with clinical and endoscopic signs at four and eight weeks.

RESULTS

Remission was obtained in 44% (95% confidence interval (CI) 31%, 58%) of the mesalazine enema group (Me) and in 34% (95% CI 21%, 49%) of the placebo enema group (Pl) at four weeks (p = 0.31) and in 64% (95% CI 50%, 76%) of the Me group versus 43% (95% CI 28%, 58%) of the Pl group at eight weeks (p = 0.03). Improvement was obtained in 89% (95% CI 78%, 96%) of the Me group versus 62% (95% CI 46%, 75%) of the Pl group at four weeks (p = 0.0008) and in 86% (95% CI 75%, 94%) of the Me group versus 68% (95% CI 53%, 81%) of the Pl group at eight weeks (p = 0.026).

CONCLUSION

In patients with extensive mild/moderate active UC, the combination therapy is superior to oral therapy. It is safe, well accepted, and may be regarded as firstline treatment.

Bifidobacterium animalis strain DN-173 010 shortens the colonic transit time in healthy women: a double-blind, randomized, controlled study

BACKGROUND

A previous study has suggested that Bifidobacterium animalis DN-173 010 shortens the colonic transit time in women.

AIM

To confirm this effect and to determine whether modifications of the faecal bacterial mass and/or faecal secondary bile salts may be the explanation.

METHODS

A double-blind, cross-over study was performed. Thirty-six healthy women were studied in four consecutive 10-day periods. During periods 2 and 4, they ingested three 125 g cups per day of a fermented milk which was either a product containing B. animalis DN-173 010 or a control without bifidobacteria. Periods 1 and 3 were run-in and washout periods, respectively. The total and segmental colonic transit times were assessed using a pellet method. In 12 subjects, all stools were collected and analysed for pH, faecal weight, bacterial mass and bile acids.

RESULTS

The total and sigmoid transit times were significantly shorter during dosing with B. animalis compared to the control period. The other transit times, faecal weight, pH, bacterial mass and bile acids were not significantly affected.

CONCLUSIONS

B. animalis DN-173 010 shortens the colonic transit time in healthy women. This effect is not explained by modifications of the faecal bacterial mass or secondary bile acids.

Effect of chronic ingestion of a fermented dairy product containing Lactobacillus acidophilus and Bifidobacterium bifidum on metabolic activities of the colonic flora in humans

Nine healthy volunteers were studied before, during, and after ingesting a fermented dairy product containing Lactobacillus acidophilus, Bifidobacterium bifidum, and mesophilic cultures (Streptococcus lactis and S cremoris) for 3 wk. Hydrogen and methane productions and fecal beta-galactosidase and beta-glucosidase activities were measured as indicators of fermentation capacity of the colonic flora. Fecal concentrations of nitroreductase, azoreductase, and beta-glucuronidase, which may be implicated in colonic carcinogenesis, were also assessed. Hydrogen and methane productions, fecal beta-galactosidase, beta-glucuronidase, and azoreductase activities did not change over three 3-wk periods whereas fecal beta-glucosidase activity increased (42 +/- 6, 91 +/- 12, and 40 +/- 6 IU/g N, P less than 0.01) and nitroreductase decreased (0.87 +/- 0.13, 0.54 +/- 0.11, and 0.57 +/- 0.08 IU/g N, P less than 0.05).

Effect of the microbial lactase (EC 3.2.1.23) activity in yoghurt on the intestinal absorption of lactose: an in vivo study in lactase-deficient humans

Breath hydrogen excretion was measured in eight lactase (EC 3.2.1.108)-deficient volunteers ingesting 18 g lactose in the form of milk, yoghurt and heated yoghurt. Total excess hydrogen excretion (area under curve) was significantly lower after yoghurt and heated yoghurt, than after milk: 103 (SE 29), 191 (SE 32), and 439 (SE 69) respectively (P less than 0.001). The oro-caecal transit time of fermentable components from yoghurt and heated yoghurt (mainly lactose) was longer than that from milk: 165 (SE 17), 206 (SE 19), v. 103 (SE 19) min (P less than 0.01). An intestinal perfusion technique was used in the same subjects after ingestion on two consecutive days of 18 g lactose in yoghurt and heated yoghurt. Significantly less lactose was recovered from the terminal ileum after yoghurt than after heated yoghurt meals: 1740 (SE 260) v. 2825 (SE 461) mg (P less than 0.05), and approximately one-fifth of the lactase activity contained in yoghurt reached the terminal ileum. These findings indicate that more than 90% of the lactose in yoghurt is digested in the small intestine of lactase-deficient subjects and suggest that both the lactase activity contained in the viable starter culture and a slow oro-caecal transit time are responsible for this excellent absorption.

Basic aspects and pharmacology of probiotics: an overview of pharmacokinetics, mechanisms of action and side-effects

Probiotics have been defined as non-pathogenic micro-organisms that, when ingested, exert a positive influence on host health or physiology. Their pharmacology is more complex than that of inert drugs but is now being studied in detail. Some strains have a high survival capacity until they reach the faeces, whereas others are rapidly killed by acid and bile (a characteristic that can be used for the delivery of active intracellular components). Potential translocation and permanent colonization are rare but possible events; and should come under closer scrutiny. Mechanisms of action can be direct or indirect through modifications of the endogenous flora or through immunomodulation. The active components are poorly known but include bacterial formylated peptides, peptidoglycan cell wall constituents and nucleotides. Although the safety of commercial probiotics is excellent, this aspect should be studied in more detail, especially in immunocompromised hosts.

Probiotics and intestinal health effects: a clinical perspective

Probiotics are viable non-pathogenic micro-organisms which, when ingested, exert a positive influence on host health or physiology. We have critically analysed the evidence for the efficacy of specific probiotic strains in human gastrointestinal diseases. The best evidence can be obtained with randomised controlled trials which avoid bias. Good evidence has been obtained with several strains in the prevention or treatment of antibiotic-associated disorders, in the treatment (and to a lesser extent prevention) of gastroenteritis and acute diarrhoea and in the alleviation of lactose intolerance. We also analysed the recent randomised controlled trials performed in patients with Clostridium difficile or Helicobacter pylori, inflammatory bowel disease, irritable bowel syndrome, non-ulcer dyspepsia and colon cancer.

Foetal outcome in women with inflammatory bowel disease treated during pregnancy with oral mesalazine microgranules

BACKGROUND

Little information is available about the safety of high doses of mesalazine during pregnancy.

AIM

To study the fate of pregnancy and foetal outcome in women taking 1-4 g/day of mesalazine microgranules for inflammatory bowel disease.

PATIENTS AND METHODS

Case reports were collected from the Pharmacovigilance Department of Ferring SA, France, from a survey conducted in three gastroenterology units, and from a teratology information service. The evolution of pregnancy and foetal outcome were assessed by questionnaire.

RESULTS

The study covered a total of 123 pregnancies (126 foetuses). Ninety-six women took mesalazine during the first trimester, 85 during the second and 83 during the third. The mean daily dose was 2.1+/-0.8 g; 86 women received <3 g/day (low-dose group), 37 women received > or =3 g/day (high-dose group). The following abnormalities were observed in the low-dose and high-dose groups, respectively: ectopic pregnancy (1/0), spontaneous abortions (1/1), foetal death (0/1), premature deliveries (3/5, P < 0.05), congenital malformations (3/1) and one case of lethal oxalosis. Abnormalities were not considered to be related to mesalazine.

CONCLUSIONS

The use of oral mesalazine microgranules during pregnancy is safe at doses < or =2 g/day, and probably also at a dose of 3 g/day.

Review article: gut flora and inflammatory bowel disease

The pathogenesis of inflammatory bowel disease involves interactions between the host susceptibility, mucosal immunity and intestinal microflora. There is therefore great interest in the changes in the endogenous flora in inflammatory bowel disease patients and in the establishment of potential genetic variations in host responses to endogenous bacteria. In this review, we summarize the modifications in the various regional ecosystems in the gastrointestinal tract during inflammatory bowel disease (luminal bacteria in faeces or inside the gastrointestinal tract, bacteria in mucus and bacteria directly attached to the mucosa). Results were obtained following a 'candidate microorganism strategy' and, as is occurring increasingly frequently, following a 'full description strategy', which has progressed largely due to the development of culture-independent techniques. The possibility of modifying the ecosystem using prebiotics or probiotics offers hope for new treatment developments, particularly in the prevention of relapse.

Tolerance to low-digestible carbohydrates: symptomatology and methods

Low-digestible carbohydrates (LDCs) are incompletely or not absorbed in the small bowel and fermented in the colon. They are usually well tolerated but may also have some dose-related undesirable effects due to their natural osmotic potential and/or excessive fermentation: borborygmi, excessive flatus, bloating, abdominal cramps and eventually diarrhoea. There is an important intersubject variability in the tolerance to LDCs because of differences in absorption capacity, motility pattern, colonic response and intestinal sensitivity. There is also a great intrasubject variability, depending on the type of LDC, dosage and type of consumption. Absorption of LDC in the small intestine can be assessed using hydrogen breath test or intubation techniques or analysis of ileostomy effluents. Double-blind, placebo-controlled studies are required to assess the subjective symptoms of intolerance, and the experimental conditions may influence the results.

Use of mesalazine slow release suppositories 1 g three times per week to maintain remission of ulcerative proctitis: a randomised double blind placebo controlled multicentre study

BACKGROUND

Daily administration of rectal formulations of mesalazine is effective in preventing relapse of ulcerative proctitis. Maintenance of remission with lower doses would be an advantage.

AIM

The efficacy of mesalazine suppositories (Pentasa) 1 g three times a week v placebo to maintain remission in patients with cryptogenetic proctitis was studied.

METHODS

Ninety five patients with cryptogenetic proctitis were randomised within two weeks of remission to receive for one year or until relapse three suppositories per week of either Pentasa (n = 48) or placebo (n = 47). In the case of a relapse, the patients received one suppository/day.

RESULTS

It was found that 25 of 48 subjects v 18 of 47 remained in remission in the mesalazine and placebo groups respectively. The relapse rate was lower in the mesalazine group for the following time intervals: 0-90 days (19% v 38%, p = 0.035), 0-180 days (29% v 54%, p = 0.017), 0-270 days (38% v 60%, p = 0.031), and 0-365 days (48% v 62%, p = 0.18). Treatment of relapse with one suppository/day induced remission in 11 of 18 and 2 of 26 patients in the mesalazine and placebo groups respectively (p = 0.001). Overall, 61% v 28% patients remained in the protocol and were in remission at one year (p = 0.001). Tolerance was good.

CONCLUSION

Mesalazine suppositories 1 g three times a week are effective for preventing relapses of cryptogenetic proctitis. Increasing the dose to 1 g/day is effective in a high proportion of subjects who relapsed.

Effect of chronic administration of ursodeoxycholic acid on the ileal absorption of endogenous bile acids in man

The effect of long-term administration of ursodeoxycholic acid on the ileal absorption of endogenous bile acids was determined using the tauro 23 (75Se) selena-25 homotaurocholic acid test in a controlled double-blind study involving healthy subjects (n = 15). Subjects received placebo or 13 to 15 mg/kg/day ursodeoxycholic acid for 5 wk. In the placebo group (n = 7) there was no change in the composition of serum bile acids or in the mean percentage of retention of tauro 23(75Se) selena-25 homotaurocholic acid (36.1% +/- 6.0% vs. 38.7% +/- 6.7%). In contrast, in the ursodeoxycholic acid group, serum ursodeoxycholic acid conjugates increased and the percentage of retention of tauro 23 (75Se) selena-25 homotaurocholic acid fell from 45.8% +/- 6.8% to 20.5% +/- 5.7% (p less than 0.01). We conclude that ursodeoxycholic acid administration reduces ileal absorption of endogenous bile acids. These findings provide a rational explanation for the changes in the composition of the bile acid pool during ursodeoxycholic acid therapy and could have important therapeutic implications.

Digestibility and bulking effect of ispaghula husks in healthy humans

The digestibility of ispaghula, a mucilage from Plantago ovata composed mainly of arabinoxylans, and its faecal bulking effect were studied in seven healthy volunteers who ingested a low fibre controlled diet plus either placebo or 18 g/day of ispaghula for two 15 day periods. Whole gut transit time and gas excretion in breath and flatus were not different during the periods of ispaghula and placebo ingestion. Faecal wet and dry weights rose significantly, however, during ispaghula ingestion. Faecal short chain fatty acid concentrations and the molar proportions of propionic and acetic acids also increased. Most of the ispaghula had reached the caecum four hours after ingestion in an intact highly polymerised form. During ispaghula ingestion, the increase in the faecal output of neutral sugars was accounted for by the faecal excretion of arabinose and xylose in an intact highly polymerised form; the apparent digestibilities of these sugars were 24 (11) and 53% (6) respectively (mean (SEM)). In conclusion, ispaghula is more resistant to fermentation than previously reported in humans, and its bulking effect largely results from intact material.

Do patients with short-bowel syndrome need a lactose-free diet?

We compared the tolerance of a diet providing 20 g/d lactose and a lactose-free diet in 14 patients with short-bowel syndrome with either the colon in continuity (group A, n = 8) or a terminal jejunostomy (group B, n = 6). Lactose tolerance was studied after a single 20-g lactose load in the fasting state, and during two 3-d periods during which the subjects consumed their usual diet plus either 20 g/d lactose, with no more than 4 g/d as milk, or no lactose. Records and measurements included symptoms, fecal weight, and during the 8 h after the lactose load, breath-hydrogen excretion (group A) or lactose and hexoses flow rates in stomal effluents (group B). Results are expressed as medians with ranges in parentheses. Lactose absorption was 61% (0-90) in group A and 53% (18-84) in group B, and no symptoms of intolerance were noticed. During the lactose-rich diet as compared to the lactose-free diet, no symptoms were noticed nor was there any worsening of diarrhea: 1534 g/d (240-4760) versus 1466 (1590-7030) in group A, and 4122 g/d (1730-6830) versus 3496 (1590-7030) in group B. We conclude that a diet providing 20 g/d lactose with no more than 4 g/d as milk is well tolerated in the majority of patients with short-bowel syndrome, and that a lactose-free diet has usually no benefit in these subjects.

Nutritional advantages of probiotics and prebiotics

The potential ‘nutritional advantages’ of probiotics and prebiotics consist of preventive, and sometimes curative, effects against certain diseases. The evidence supporting such advantages, which requires randomised controlled trials and consistency of results from study to study, is rapidly increasing. This article summarizes the effects against diseases of intestinal origin. There is a high level of evidence for positive effects of some prebiotics to alleviate constipation and treat hepatic encephalopathy. Interesting aspects, but with a lower level of evidence at the present time, include prevention of colon cancer, intestinal infection, and recurrence of inflammatory bowel disease. There is a high level of evidence for positive effects of some probiotics in the alleviation of lactose intolerance, antibiotic-associated intestinal disorders and gastroenteritis. Evidence is rapidly growing regarding the prevention of recurrence of inflammatory bowel diseases. Positive trials have suggested preventive effects against intestinal colonization with specific gut pathogens includingClostridium difficileandHelicobacter pylori.

Effects of chicory inulin in constipated elderly people: a double-blind controlled trial

The impact of the daily consumption of 15 g chicory native inulin on fecal levels of bifidobacteria, stool parameters and quality of life of elderly constipated volunteers was investigated in a randomized, double-blind, controlled versus placebo clinical trial. The impact of supplementation on constipation was assessed with questionnaires on bowel motor function parameters, visual analogue scales on bowel symptoms and quality of life. Fecal bacteria counts were determined at the beginning and at the end of the supplementation. Inulin supplementation led to a significant increase in total fecal bacteria (P < 0.01) and bifidobacteria (P < 0.001) concentrations after 28 days of consumption. Volunteers (n = 25) in the inulin group reported increased satisfaction about digestion (P < 0.01) and reduced defecation difficulties (P < 0.001) during the supplementation. Slight gastrointestinal symptoms (flatulence) were reported but did not lead to discontinuation. Daily supplementation with 15 g inulin improves constipation and quality of life in an elderly population with constipation.

Adverse events in patients treated with 5-aminosalicyclic acid: 1993-1994 pharmacovigilance report for Pentasa in France

BACKGROUND

The incidence of the side-effects of 5-aminosalicylic acid (5-ASA) in clinical practice is not known.

AIM

To present the safety reports on the use of Pentasa in France.

METHODS

Pentasa-related adverse events were recorded from 1 January 1993 to 31 December 1994. Spontaneous reports to Ferring S.A. came from physicians or pharmacovigilance regional centres.

RESULTS

In 1993 and 1994, 51 and 79 adverse events were reported; the estimated gross incidence was 6.6 and 9.0 per million days of therapy. Detailed information was obtained 64% of cases in 1993 and 53% in 1994. Adverse events with a high likelihood of causalty included five cases of diarrhoea, 14 cases of pancreatitis, seven cases of liver abnormalities, seven of blood dyscrasias, two cases of renal insufficiency (one of which was in a fetus), and eight of cardiac disorders including three myocarditis.

CONCLUSIONS

Pentasa seldom has adverse effects. The majority of the adverse events do not seem to be dose-related. Clinicians should be aware of exceptional but severe adverse events including pancreatitis, cardiac disorders, blood dyscrasias and renal insufficiency.

Tolerance of probiotics and prebiotics

The clinical efficacy of probiotics and prebiotics has been proved in several clinical settings. The authors review their proved or potential side effects. Probiotics as living microorganisms may theoretically be responsible for 4 types of side effects in susceptible individuals: infections, deleterious metabolic activities, excessive immune stimulation, and gene transfer. Very few cases of infection have been observed. These occurred mainly in very sick patients who received probiotic drugs because of severe medical conditions. Prebiotics exert an osmotic effect in the intestinal lumen and are fermented in the colon. They may induce gaseousness and bloating. Abdominal pain and diarrhea only occur with large doses. An increase in gastroesophageal reflux has recently been associated with large daily doses. Tolerance depends on the dose and individual sensitivity factors (probably the presence of irritable bowel syndrome or gastroesophageal reflux), and may be an adaptation to chronic consumption.

Effect of vasodilators on hepatic microcirculation in cirrhosis: a study in the isolated perfused rat liver

We studied the effects of a series of vasodilators on intrahepatic vascular resistance of isolated perfused cirrhotic rat livers in basal conditions and during norepinephrine-induced vasoconstriction. Cirrhosis was induced by repeated intraperitoneal injections of carbon tetrachloride. The vasodilators were a nonselective beta-adrenergic antagonist (propranolol), an alpha 1-adrenergic antagonist (prazosin), a nonselective beta-adrenergic agonist (isoproterenol), an alpha 2-agonist (clonidine), nitrovasodilators (nitroglycerin and nitroprusside), calcium channel blockers (verapamil, diltiazem, nifedipine), papaverine, diazoxide and pentoxifylline. In basal conditions, isoproterenol, nitroglycerin, papaverine, pentoxifylline and nitroprusside demonstrated significant vasodilatory activity. However, the response was weak and isoproterenol was the only drug active in the therapeutic range of concentrations. Propranolol, prazosin, verapamil, diltiazem, nifedipine and diazoxide were ineffective. Prazosin, papaverine and pentoxifylline reduced norepinephrine-induced vasoconstriction, whereas isoproterenol, clonidine and propranolol were ineffective. We conclude that several vasodilators can reduce resistance in the cirrhotic rat liver, but their potency is low and few are effective at therapeutic concentrations. Furthermore, their activity may be blunted when resistance is increased by norepinephrine.

Bacterial flora in inflammatory bowel disease

The pathogenesis of inflammatory bowel disease (IBD) involves an interaction between host susceptibility (which is partly genetically determined), mucosal immunity and the intestinal milieu. Micro-organisms have physiological effects on mucosal structure, epithelial turnover, the intestinal immune cells and, thus, on many intestinal functions. Toll-like receptors and nucleotide oligomerisation-binding domain proteins in host cells recognise specific bacterial molecules and modify the immune response. Human studies have repeatedly shown that the microbiota of patients with IBD differs from that of controls and is unstable, both in the intestinal lumen and at the surface of the mucosa. A single pathogen has not been identified, but potentially pro-inflammatory micro-organisms have been found in samples from IBD patients more often than from healthy controls. These include Mycobacterium paratuberculosis, and enteroadherent and invasive Escherichia coli in Crohn's disease (CD). Ecological descriptions of the microbiota present in patients with IBD (either in the faeces or adherent to the mucosa) have repeatedly reported a decrease in usually dominant bacteria, especially those from the dominant phylum Firmicutes. A decrease in the biodiversity of Firmicutes has been observed in CD, while a recent study has shown that a decrease in Firmicutes, especially Faecalibacterium prausnitzii, was associated with CD and the post-operative recurrence of CD lesions in the ileum. Taken together, these results suggest that dysbiosis, or an imbalance within the (dominant) intestinal microbiota, may favour IBD.

Manipulation of the bacterial flora in inflammatory bowel disease

In this chapter we summarize the clinical and experimental data which indicate that bacteria, especially from the endogenous microflora, play a role in the pathogenesis of Crohn's disease, ulcerative colitis and pouchitis. We review the clinical trials, focusing on randomized controlled trials which used antibiotics or probiotics to treat situations of IBD or prevent recurrence, and we discuss the future of this approach.