Authors: Balsari A, Ceccarelli A, Dubini F, Fesce E, Poli G.

Summary: The focal microbial flora composition has been studied in patients affected by irritable bowel syndrome. The statistical analysis of the results showed a decrease of coliforms, lactobacilli and, to a lesser extent, bifidobacteria, as compared to control healthy individuals. Hypotheses on the cause of these modifications and their role in the maintenance and severity of the disease are discussed.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7121297&dopt=Abstract

Authors: Erja Malinen, Ph.D., Teemu Rinttilä, M.Sc., Kajsa Kajander, M.Sc., Jaana Mättö, Ph.D., Anna Kassinen, M.Sc., Lotta Krogius, M.Sc., Maria Saarela, Ph.D., Riitta Korpela, Ph.D., and Airi Palva, Ph.D.

Objective: The gut microbiota may contribute to the onset and maintenance of irritable bowel syndrome (IBS). In this study, the microbiotas of patients suffering from IBS were compared with a control group devoid of gastrointestinal (GI) symptoms.

Methods: Fecal microbiota of patients (n = 27) fulfilling the Rome II criteria for IBS was compared with age- and gender-matched control subjects (n = 22). Fecal samples were obtained at 3 months intervals. Total bacterial DNA was analyzed by 20 quantitative real-time PCR assays covering approximately 300 bacterial species.

Conclusions: With these real-time PCR assays, quantitative alterations in the GI microbiota of IBS patients were found. Increasing microbial DNA sequence information will further allow designing of new real-time PCR assays for a more extensive analysis of intestinal microbes in IBS.

Study link: http://www.blackwell-synergy.com/doi/abs/10.1111/j.1572-0241.2005.40312.x

Authors: Madden JA, Hunter JO.

Institution: Gastroenterology Research Unit, Unit E7, Box 201 A, Addenbrookes NHS Trust, Hill's Road, CB2 2QQ, Cambridge, UK.

Summary: Irritable bowel syndrome (IBS) is a multi-factorial gastrointestinal condition affecting 8-22 % of the population with a higher prevalence in women and accounting for 20-50 % of referrals to gastroenterology clinics. It is characterised by abdominal pain, excessive flatus, variable bowel habit and abdominal bloating for which there is no evidence of detectable organic disease. Suggested aetiologies include gut motility and psychological disorders, psychophysiological phenomena and colonic malfermentation.

The faecal microflora in IBS has been shown to be abnormal with higher numbers of facultative organisms and low numbers of lactobacilli and bifidobacteria. Although there is no evidence of food allergy in IBS, food intolerance has been identified and exclusion diets are beneficial to many IBS patients. Food intolerance may be due to abnormal fermentation of food residues in the colon, as a result of disruption of the normal flora.

The role of probiotics in IBS has not been clearly defined. Some studies have shown improvements in pain and flatulence in response to probiotic administration, whilst others have shown no symptomatic improvement. It is possible that the future role of probiotics in IBS will lie in prevention, rather than cure.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12215182&query_hl=69

Authors: Nobaek S, Johansson ML, Molin G, Ahrne S, Jeppsson B.

Institution: Department of Surgery, Lund University, Lund University Hospital, Sweden.

Objectives: The influence of the gastrointestinal (GI) microflora in patients with irritable bowel syndrome (IBS) has not been clearly elucidated. This study was undertaken to see if patients with IBS have an imbalance in their normal colonic flora, as some bacterial taxa are more prone to gas production than others. We also wanted to study whether the flora could be altered by exogenous supplementation.

Results: All patients tolerated the products well. The patients receiving Lb. plantarum had these bacteria on rectal biopsies. There were no major changes of Enterobacteriaceae in either group, before or after the study, but the Enterococci increased in the placebo group and remained unchanged in the test group. Flatulence was rapidly and significantly reduced in the test group compared with the placebo group (number of days with abundant gas production, test group 6.5 before, 3.1 after vs 7.4 before and 5.6 after for the placebo group). Abdominal pain was reduced in both groups. At the 12-month follow-up, patients in the test group maintained a better overall GI function than control patients.

Conclusions: The results of the study indicate that the administration of Lb. plantarum with known probiotic properties decreased pain and flatulence in patients with IBS. The fiber content of the test solution was minimal and it is unlikely that the fiber content could have had any effect. This type of probiotic therapy warrants further studies in IBS patients.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10811333&query_hl=74

Authors: Dear KL, Elia M, Hunter JO.

Institution: Department of Gastroenterology, Addenbrooke's Hospital NHS Trust, Cambridge, UK.

Summary: Abnormal fermentation may be an important factor in irritable bowel syndrome (IBS). Gastroenteritis or antibiotic therapy may damage the colonic microflora, leading to increased fermentation and the accumulation of gas. Gas excretion may be measured by whole-body calorimetry but there has only been one such study on IBS to date.

We aimed to assess the relationship between IBS symptoms and fermentation rates in IBS. A purpose-built, 1.4-m3, whole-body calorimeter was used to assess excretion of H2 and CH4 in IBS subjects while consuming a standard diet and, again, after open randomization on either the standard diet together with the antibiotic metronidazole or a fiber-free diet to reduce fermentation. Metronidazole significantly reduced the 24-hr excretion of hydrogen (median value compared to the control group, 397 vs 230 ml/24 hr) and total gas (H2 + CH4; 671 vs 422 ml/min) and the maximum rate of gas excretion (1.6 vs 0.8 ml/min), as did a no-fiber polymeric diet (hydrogen, 418 vs 176 ml/min; total gas, 564 vs 205 ml/min; maximum rate of gas excretion, 1.35 vs 0.45 ml/min), with a significant improvement in abdominal symptoms.

IBS may be associated with rapid excretion of gaseous products of fermentation, whose reduction may improve symptoms.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15844715&dopt=Citation

Authors: King TS, Elia M, Hunter JO.

Institution: Department of Gastroenterology, Addenbrooke's Hospital, Cambridge, UK.

Background: The cause of irritable bowel syndrome (IBS) is unknown. It may follow gastroenteritis and be associated with an abnormal gut flora and with food intolerance. Our study was designed to assess whether these factors were associated with colonic malfermentation.

Methods: We carried out a crossover controlled trial of a standard diet and an exclusion diet matched for macronutrients in six female IBS patients and six female controls. During the final 72 h on each diet, faecal excretion of fat, nitrogen, starch, and non-starch polysaccharide NSP was measured, and total excretion of hydrogen and methane collected over 24 h in a purpose-built 1.4 m3 whole-body calorimeter. Breath hydrogen and methane excretion were then measured for 3 h after 20 g oral lactulose.

Interpretation: Colonic-gas production, particularly of hydrogen, is greater in patients with IBS than in controls, and both symptoms and gas production are reduced by an exclusion diet. This reduction may be associated with alterations in the activity of hydrogen-consuming bacteria. Fermentation may be an important factor in the pathogenesis of IBS.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9777836&dopt=Abstract