Review article: bifidobacteria as probiotic agents -- physiological effects and clinical benefits

Effective enzymatic synthesis of lactosucrose and its analogues by beta-D-galactosidase from Bacillus circulans

In the present study, beta-d-galactosidase from Bacillus circulans was proved to be a suitable biocatalyst for the production of lactosucrose (beta-d-Galp-(1-->4)-alpha-d-Glcp-(1-->2)-beta-d-Fruf, I) and its analogues from lactose and sucrose. During the hydrolysis of lactose, the formation of four transfer products was followed by high performance liquid chromatography with refraction index detector. In addition, the transfer products were isolated from the reaction mixture and identified to be I, beta-d-Galp-(1-->3)-alpha-d-Glcp-(1-->2)-beta-d-Fruf (II), beta-d-Galp-(1-->4)-beta-d-Galp-(1-->4)-alpha,beta-d-Glcp (III), and beta-d-Galp-(1-->4)-beta-d-Galp-(1-->4)-alpha-d-Glcp-(1-->2)-beta-d-Fruf (IV) by mass spectrometry with an electrospray ionization source and nuclear magnetic resonance spectroscopy. The order for the production of the transfer products was III > I > IV > II in the initial stage of the reaction, and the same relationship was also observed for the hydrolytic rates of transfer products. Furthermore, the effects of synthetic conditions including reaction temperature, reaction time, concentration of substrate, molar ratio of donor/acceptor, and enzyme concentration on the formation of transfer products were examined. We found that the optimal synthetic conditions were different for the production of I and II. Under the optimal conditions, the amount of total transfer products kept increasing during the early 4 h incubation, and a maximum yield of 146 g/L for total transfer products was obtained at 4 h of reaction.

Effects of Lactobacillus rhamnosus GG on proliferation and polyamine metabolism in HGC-27 human gastric and DLD-1 colonic cancer cell lines

Previous in vitro and in vivo studies have suggested that lactobacilli can exert antiproliferative effects on the gastrointestinal epithelium. However, their role in affecting the cellular proliferative mechanisms is not completely clear. The aim of this study was to investigate the effects of increasing concentrations of Lactobacillus rhamnosus strain GG (L. GG) homogenate on cell growth and proliferation (by MTT, [3H]-thymidine incorporation and polyamine biosynthesis) in neoplasms originating from different gastrointestinal tracts. Thus, HGC-27 human gastric cancer cells and DLD-1 human colonic adenocarcinoma cells were evaluated. Besides, in order to verify which bacterial fraction was involved in the antiproliferative effects, the cytoplasm and cell wall extracts were tested separately. Gastric HGC-27 and colonic DLD-1 cells showed significant differences in their proliferative behavior, in particular in their polyamine profile and biosynthesis. Notwithstanding, one and the other proved to be sensitive to the growth inhibition by the highest concentrations of bacterial homogenate. Both HGC-27 and DLD-1 cells were resistant to the bacterial cell wall fractions, whereas increasing cytoplasm fraction concentrations induced an evident antiproliferative effect. These data suggest that cytoplasm extracts could be the responsible for L. GG action on proliferation in these two cell lines from gastric and colonic neoplasms.

Prospects for the development of probiotics and prebiotics for oral applications

There has been a paradigm shift towards an ecological and microbial community-based approach to understanding oral diseases. This has significant implications for approaches to therapy and has raised the possibility of developing novel strategies through manipulation of the resident oral microbiota and modulation of host immune responses. The increased popularity of using probiotic bacteria and/or prebiotic supplements to improve gastrointestinal health has prompted interest in the utility of this approach for oral applications. Evidence now suggests that probiotics may function not only by direct inhibition of, or enhanced competition with, pathogenic micro-organisms, but also by more subtle mechanisms including modulation of the mucosal immune system. Similarly, prebiotics could promote the growth of beneficial micro-organisms that comprise part of the resident microbiota. The evidence for the use of pro or prebiotics for the prevention of caries or periodontal diseases is reviewed, and issues that could arise from their use, as well as questions that still need to be answered, are raised. A complete understanding of the broad ecological changes induced in the mouth by probiotics or prebiotics will be essential to assess their long-term consequences for oral health and disease.

Synbiotic Therapy Improves Quality of Life and Reduces Symptoms in Pediatric Ulcerative Colitis

The management of ulcerative colitis in children often requires aggressive pharmacological therapy or colonic resection. The authors hypothesized that synbiotic therapy would improve symptoms and quality of life in children diagnosed with ulcerative colitis. Pediatric study participants (8-18 years; n = 9) with ulcerative colitis in remission were provided synbiotic therapy (Bifidobacterium longum R0175 20 billion cfu/d, 15 g/d of inulin; n = 4) or placebo (maltodextrin + ascorbic acid capsule; 15 g/d of non-resistant maltodextrin; n = 5) for 10 months in a pilot study (phase I). At 10 months, the study was unblinded and synbiotic therapy was administered to 8 pediatric study participants (phase II). Quality of life was measured using the Short Inflammatory Bowel Disease Questionnaire (SIBDQ). The SIBDQ was administered at baseline and every 2 months. Study participants kept a daily record of symptoms. Phase I quality-of-life scores were significantly better for those receiving the synbiotic therapy versus the placebo (P = .014). Severe symptoms occurred in 60% of the control study participants, whereas no study participants receiving synbiotic therapy experienced severe symptoms (P = .032). Phase II quality-of-life scores were significantly better posttreatment with synbiotic therapy (P = .034). No adverse effects were reported. Synbiotic therapy (B longum R0175 + inulin), when provided in addition to conventional treatment, appears to be a safe and effective strategy for managing pediatric ulcerative colitis in remission.

Probiotics and functional gastrointestinal disorders in children

Chronic constipation is one of the most frequent complaints in childhood. Although there is evidence that gastrointestinal flora is important in gut motility, there is little evidence that gut flora is abnormal in constipation. Lactobacilli and bifidobacteria increase stool frequency and decrease consistency in normal individuals. But, according to several reviews, the evidence of probiotics for efficacy in constipation is limited. Fiber supplements, lactose-free diets, and lactobacillus supplementation are effective in the management of children with recurrent abdominal pain and irritable bowel syndrome. Several studies with Lactobacillus GG in children showed negative results in children with chronic constipation. Because Bifidobacterium animalis DN-173 010 has been shown to be effective in adults with constipation-predominant irritable bowel syndrome this study should also be performed in a well-designed large placebo-controlled trial in children with constipation.

Effect of the consumption of a fermented dairy product containing Bifidobacterium lactis DN-173 010 on constipation in childhood: a multicentre randomised controlled trial (NTRTC: 1571)

BACKGROUND

Constipation is a frustrating symptom affecting 3% of children worldwide. Randomised controlled trials show that both polyethylene glycol and lactulose are effective in increasing defecation frequency in children with constipation. However, in 30-50%, these children reported abdominal pain, bloating, flatulence, diarrhoea, nausea and bad taste of the medication. Two recent studies have shown that the fermented dairy product containing Bifidobacterium lactis strain DN-173 010 is effective in increasing stool frequency in constipation-predominant irritable bowel syndrome patients with a defecation frequency < 3/week and in constipated women with a defecation frequency < 3/week. Goal of this study is to determine whether this fermented dairy product is effective in the treatment of constipated children with a defecation frequency < 3/week.

METHODS/DESIGN

It is a two nation (The Netherlands and Poland) double-blind, placebo-controlled randomised multicentre trial in which 160 constipated children (age 3-16 years) with a defecation frequency <3/week will be randomly allocated to consume a fermented dairy product containing Bifidobacterium lactis DN-173 010 or a control product, twice a day, for 3 weeks. During the study all children are instructed to try to defecate on the toilet for 5-10 minutes after each meal (3 times a day) and daily complete a standardized bowel diary. Primary endpoint is stool frequency. Secondary endpoints are stool consistency, faecal incontinence frequency, pain during defecation, digestive symptoms (abdominal pain, flatulence), adverse effects (nausea, diarrhoea, bad taste) and intake of rescue medication (Bisacodyl). Rate of success and rate of responders are also evaluated, with success defined as > or = 3 bowel movements per week and < or =1 faecal incontinence episode over the last 2 weeks of product consumption and responder defined as a subject reporting a stool frequency > or = 3 on the last week of product consumption. To demonstrate that the success percentage in the intervention group will be 35% and the success percentage in the control group (acidified milk without ferments, toilet training, bowel diary) will be 15%, with alpha 0.05 and power 80%, a total sample size of 160 patients was calculated.

CONCLUSION

This study is aimed to show that the fermented dairy product containing Bifidobacterium lactis strain DN-173 010 is effective in increasing stool frequency after 3 weeks of product consumption in children with functional constipation and a defecation frequency < 3/week.

Coculture fermentations of Bifidobacterium species and Bacteroides thetaiotaomicron reveal a mechanistic insight into the prebiotic effect of inulin-type fructans

Four bifidobacteria, each representing a cluster of strains with specific inulin-type-fructan degradation capacities, were grown in coculture fermentations with Bacteroides thetaiotaomicron LMG 11262, a strain able to metabolize both oligofructose and inulin. In a medium for colon bacteria with inulin as the sole added energy source, the ability of the bifidobacteria to compete for this substrate reflected phenotypical variation. Bifidobacterium breve Yakult, a strain that was not able to degrade oligofructose or inulin, was outcompeted by B. thetaiotaomicron LMG 11262. Bifidobacterium adolescentis LMG 10734, a strain that could degrade oligofructose (displaying a preferential breakdown mechanism) but that did not grow on inulin, managed to become competitive when oligofructose and short fractions of inulin started to accumulate in the fermentation medium. Bifidobacterium angulatum LMG 11039(T), a strain that was previously shown to degrade all oligofructose fractions simultaneously and to be able to partially break down inulin, was competitive from the beginning of the fermentation, consuming short fractions of inulin from the moment they appeared. Bifidobacterium longum LMG 11047, representing a cluster of bifidobacteria that shared both high fructose consumption and oligofructose degradation rates and were able to perform partial breakdown of inulin, was the dominating strain in a coculture with B. thetaiotaomicron LMG 11262. These observations indicate that distinct subgroups within the large-intestinal Bifidobacterium population will be stimulated by different groups of prebiotic inulin-type fructans, a variation that could be reflected in differences concerning their health-promoting effects.

Occurrence of bifidobacteria in faeces of calves fed milk or a combined diet

The development of faecal bacteria composition in calves fed milk or a combined diet was investigated from 4 to 21 days of age. On day 7, bifidobacteria in faeces of milk-fed calves already increased from about 7.6 to 9.2 log CFU/g and did not change until the end of the study, whereas in calves fed the combined diet bifidobacteria only moderately increased to 7.9 log CFU/g and decreased slowly until day 21. The counts of bifidobacteria in calves on a combined diet were significantly (p < 0.01) lower compared to those in milk-fed calves. Bifidobacterial counts determined by cultivation or by fluorescence in situ hybridisation (FISH) did not differ significantly. Our results showed that the occurrence of bifidobacteria in calf faeces is highly dependent on the diet composition. Faecal bacteria flora of calves fed exclusively by milk is rich in bifidobacteria, but in calves on a combined diet coliforms dominated.

Inhibitory effect of conjugated alpha-linolenic acid from bifidobacteria of intestinal origin on SW480 cancer cells

In this study, we assessed the ability of six strains of bifidobacteria (previously shown by us to possess the ability to convert linoleic acid to c9, t11-conjugated linoleic acid (CLA) to grow in the presence of alpha-linolenic acid and to generate conjugated isomers of the fatty acid substrate during fermentation for 42 h. The six strains of bifidobacteria were grown in modified MRS (mMRS) containing alpha-linolenic acid for 42 h at 37 degrees C, after which the fatty acid composition of the growth medium was assessed by gas liquid chromatography (GLC). Indeed, following fermentation of one of the strains, namely Bifidobacterium breve NCIMB 702258, in the presence of 0.41 mg/ml alpha-linolenic acid, 79.1% was converted to the conjugated isomer, C18:3 c9, t11, c15 conjugated alpha-linolenic acid (CALA). To examine the inhibitory effect of the fermented oils produced, SW480 colon cancer cells were cultured in the presence of the extracted fermented oil (10-50 microg/ml) for 5 days. The data indicate an inhibitory effect on cell growth (p <or= 0.001) of CALA, with cell numbers reduced by 85% at a concentration of 180 microM, compared with a reduction of only 50% with alpha-linolenic acid (p <or= 0.01).

The dual role of bacteriocins as anti- and probiotics

Bacteria employed in probiotic applications help to maintain or restore a host's natural microbial floral. The ability of probiotic bacteria to successfully outcompete undesired species is often due to, or enhanced by, the production of potent antimicrobial toxins. The most commonly encountered of these are bacteriocins, a large and functionally diverse family of antimicrobials found in all major lineages of Bacteria. Recent studies reveal that these proteinaceous toxins play a critical role in mediating competitive dynamics between bacterial strains and closely related species. The potential use of bacteriocin-producing strains as probiotic and bioprotective agents has recently received increased attention. This review will report on recent efforts involving the use of such strains, with a particular focus on emerging probiotic therapies for humans, livestock, and aquaculture.

In vitro kinetic analysis of fermentation of prebiotic inulin-type fructans by Bifidobacterium species reveals four different phenotypes

Kinetic analyses of bacterial growth, carbohydrate consumption, and metabolite production of 18 Bifidobacterium strains grown on fructose, oligofructose, or inulin were performed. A principal component analysis of the data sets, expanded with the results of a genetic screen concerning the presence of a beta-fructofuranosidase gene previously encountered in Bifidobacterium animalis subsp. lactis DSM 10140(T), revealed the existence of four clusters among the bifidobacteria tested. Strains belonging to a first cluster could not degrade oligofructose or inulin. Strains in a second cluster could degrade oligofructose, displaying a preferential breakdown mechanism, but did not grow on inulin. Fructose consumption was faster than oligofructose degradation. A third cluster was composed of strains that degraded all oligofructose fractions simultaneously and could partially break down inulin. Oligofructose degradation was substantially faster than fructose consumption. A fourth, smaller cluster consisted of strains that shared high fructose consumption and oligofructose degradation rates and were able to perform partial breakdown of inulin. For all strains, a metabolic shift toward more acetate, formate, and ethanol production, at the expense of lactate production, was observed during growth on less readily fermentable energy sources. No correlation between breakdown patterns and the presence of the beta-fructofuranosidase gene could be detected. These variations indicate niche-specific adaptation of bifidobacteria and could have in vivo implications on the strain specificity of the stimulatory effect of inulin-type fructans on bifidobacteria.

What is the evidence for the use of probiotics in functional disorders?

A rationale for the use of probiotics for a number of functional gastrointestinal symptoms and syndromes can be developed, and an experimental basis for their use continues to emerge, but data from well-conducted clinical trials of probiotics in this area remain scarce. Irritable bowel syndrome (IBS) has attracted the most attention; recent revelations regarding the potential pathogenic roles of the enteric flora and immune activation have led to reawakened interest in bacterio-therapy for this common and challenging disorder. Some recent randomized, controlled studies attest to the efficacy of some probiotics in alleviating individual IBS symptoms, and selected strains have a more global impact. Evidence for long-term efficacy is also beginning to emerge, though more studies are needed in this regard. In other functional syndromes, data are far from adequate to make recommendations, but there is evidence for efficacy of probiotics in treating individual symptoms such as diarrhea, constipation, and bloating. The interpretation of much of the literature in this area is complicated by lack of quality control, use of many different species and strains, and, above all, significant deficiencies in trial methodology.

Structural and thermodynamic analyses of solute-binding Protein from Bifidobacterium longum specific for core 1 disaccharide and lacto-N-biose I

Recently, a gene cluster involving a phosphorylase specific for lacto-N-biose I (LNB; Galbeta1-3GlcNAc) and galacto-N-biose (GNB; Galbeta1-3GalNAc) has been found in Bifidobacterium longum. We showed that the solute-binding protein of a putative ATP-binding cassette-type transporter encoded in the cluster crystallizes only in the presence of LNB or GNB, and therefore we named it GNB/LNB-binding protein (GL-BP). Isothermal titration calorimetry measurements revealed that GL-BP specifically binds LNB and GNB with K(d) values of 0.087 and 0.010 microm, respectively, and the binding process is enthalpy-driven. The crystal structures of GL-BP complexed with LNB, GNB, and lacto-N-tetraose (Galbeta1-3GlcNAcbeta1-3Galbeta1-4Glc) were determined. The interactions between GL-BP and the disaccharide ligands mainly occurred through water-mediated hydrogen bonds. In comparison with the LNB complex, one additional hydrogen bond was found in the GNB complex. These structural characteristics of ligand binding are in agreement with the thermodynamic properties. The overall structure of GL-BP was similar to that of maltose-binding protein; however, the mode of ligand binding and the thermodynamic properties of these proteins were significantly different.

Gnotobiotic mouse immune response induced by Bifidobacterium sp. strains isolated from infants

Bifidobacterium, which is a dominant genus in infants' fecal flora and can be used as a probiotic, has shown beneficial effects in various pathologies, including allergic diseases, but its role in immunity has so far been little known. Numerous studies have shown the crucial role of the initial intestinal colonization in the development of the intestinal immune system, and bifidobacteria could play a major role in this process. For a better understanding of the effect of Bifidobacterium on the immune system, we aimed at determining the impact of Bifidobacterium on the T-helper 1 (T(H)1)/T(H)2 balance by using gnotobiotic mice. Germfree mice were inoculated with Bifidobacterium longum NCC2705, whose genome is sequenced, and with nine Bifidobacterium strains isolated from infants' fecal flora. Five days after inoculation, mice were killed. Transforming growth factor beta1 (TGF-beta1), interleukin-4 (IL-4), IL-10, and gamma interferon (IFN-gamma) gene expressions in the ileum and IFN-gamma, tumor necrosis factor alpha (TNF-alpha), IL-10, IL-4, and IL-5 secretions by splenocytes cultivated for 48 h with concanavalin A were quantified. Two Bifidobacterium species had no effect (B. adolescentis) or little effect (B. breve) on the immune system. Bifidobacterium bifidum, Bifidobacterium dentium, and one B. longum strain induced T(H)1 and T(H)2 cytokines at the systemic and intestinal levels. One B. longum strain induced a T(H)2 orientation with high levels of IL-4 and IL-10, both secreted by splenocytes, and of TGF-beta gene expression in the ileum. The other two strains induced T(H)1 orientations with high levels of IFN-gamma and TNF-alpha splenocyte secretions. Bifidobacterium's capacity to stimulate immunity is species specific, but its influence on the orientation of the immune system is strain specific.

Four-week short chain fructo-oligosaccharides ingestion leads to increasing fecal bifidobacteria and cholesterol excretion in healthy elderly volunteers

Background

Short-chain fructo-oligosaccharides (scFOS) are increasingly used in human diet for their prebiotic properties. We aimed at investigating the effects of scFOS ingestion on the colonic microflora and oro-fecal transit time in elderly healthy humans.

Methods

Stools composition, oro-fecal transit time, and clinical tolerance were evaluated in 12 healthy volunteers, aged 69 ± 2 yrs, in three consecutive periods: basal period (2 weeks), scFOS (Actilight^®) ingestion period (8 g/d for 4 weeks) and follow-up period (4 weeks). Two-way ANOVA, with time and treatment as factors, was used to compare the main outcome measures between the three periods.

Results

Fecal bifidobacteria counts were significantly increased during the scFOS period (9.17 ± 0.17 log cfu/g vs 8.52 ± 0.26 log cfu/g during the basal period) and returned to their initial values at the end of follow-up (8.37 ± 0.21 log cfu/g; P < 0.05). Fecal cholesterol concentration increased during the scFOS period (8.18 ± 2.37 mg/g dry matter vs 2.81 ± 0.94 mg/g dry matter during the basal period) and returned to the baseline value at the end of follow-up (2.87 ± 0.44 mg/g dry matter; P < 0.05). Fecal pH tended to decrease during scFOS ingestion and follow-up periods compared to the basal period (P = 0.06). Fecal bile acids, stool weight, water percentage, and oro-fecal transit time did not change throughout the study. Excess flatus and bloating were significantly more frequent during scFOS ingestion when compared to the basal period (P < 0.05), but the intensity of these symptoms was very mild.

Conclusion

Four-week 8 g/d scFOS ingestion is well tolerated and leads to a significant increase in fecal bifidobacteria in healthy elderly subjects. Whether the change in cholesterol metabolism found in our study could exert a beneficial action warrants further studies.

Efficacy and safety of faropenem in eradication therapy of Helicobacter pylori

AIMS

While triple therapy with a proton pump inhibitor, amoxicillin, and clarithromycin is the standard therapy for Helicobacter pylori eradication, it is ineffective against clarithromycin-resistant strains. To seek a better regimen for eradication therapy, we assessed the sensitivity of clinical strains seen in Japan to faropenem and then evaluated the efficacy and safety of eradication therapy containing this antibiotic.

METHODS

Minimum inhibitory concentrations (MICs) of faropenem were determined in 78 Japanese clinical H. pylori isolates using the agar dilution method. H. pylori-positive patients were consecutively assigned to a 7-day eradication therapy protocol with LAF (lansoprazole 60 mg/day, amoxicillin 2000 mg/day, and faropenem 600 mg/day), and then to a 14-day protocol. The outcomes of the therapies were assessed by (13)C-urea breath tests.

RESULTS

All 78 strains showed MICs of faropenem that were equal to or less than 0.2 microg/mL. The eradication rates according to intention-to-treat analyses were 46.5% with the 7-day therapy (n = 43) and 62.5% with the 14-day therapy (n = 32). No special measures were required to treat the adverse events observed in approximately one-third of the patients.

CONCLUSIONS

Faropenem was found to have good antimicrobial action against H. pylori in vitro. The 14-day LAF therapy successfully eradicated H. pylori in about two-thirds of the patients although the incidence of adverse events was high.

Improving gastric transit, gastrointestinal persistence and therapeutic efficacy of the probiotic strain Bifidobacterium breve UCC2003

Given the increasing commercial and clinical relevance of probiotic cultures, improving their stress tolerance profile and ability to overcome the physiological defences of the host is an important biological goal. In order to reach the gastrointestinal tract in sufficient numbers to exert a therapeutic effect, probiotic bacteria must resist the deleterious actions of low pH, elevated osmolarity and bile salts. Cloning the listerial betaine uptake system, BetL, into the probiotic strain Bifidobacterium breve UCC2003 significantly improved probiotic tolerance to gastric juice and conditions of elevated osmolarity mimicking the gut environment. Furthermore, whilst stable colonization of the murine intestine was achieved by oral administration of B. breve UCC2003, strains harbouring BetL were recovered at significantly higher levels in the faeces, intestines and caecum of inoculated animals. Finally, in addition to improved gastric transit and intestinal persistence, this approach improved the clinical efficacy of the probiotic culture: mice fed B. breve UCC2003-BetL(+) exhibited significantly lower levels of systemic infection compared to the control strain following oral inoculation with Listeria monocytogenes.

Novel therapeutic approaches in IBS

Irritable bowel syndrome (IBS) remains an incompletely understood, common syndrome with significant unmet medical needs. Significant progress has been made in the development of novel therapies aimed at normalizing bowel habit alterations and abdominal discomfort, even though some of the most effective treatments are currently only available for patients under a restricted access program from the FDA. Preclinical evidence supports the potential usefulness of several compounds in development for the treatment of chronic abdominal pain. Recent new evidence for a possible role of altered microflora and altered host microbial interactions may provide new treatment targets in the future.

Molecular dissection of a bifidobacterial replicon

The 2.1-kb cryptic plasmid pCIBAO89 from Bifidobacterium asteroides harbors a 1.4-kb segment which is sufficient for its autonomous replication. The segment is divided into two parts, the presumed replication origin, ori89, and the rep gene encoding the putative 41-kDa Rep89 replication initiation protein. This minimal replication region of pCIBAO89 was functionally dissected by transcriptional analyses as well as by DNA-binding studies, and the information obtained was exploited to create a number of Escherichia coli-Bifidobacterium shuttle vectors capable of transforming various bifidobacteria with an efficiency of up to 10(6) transformants/mug DNA.

Effects of yogurt and bifidobacteria supplementation on the colonic microbiota in lactose-intolerant subjects

AIMS

Colonic metabolism of lactose may play a role in lactose intolerance. We investigated whether a 2-week supplementation of Bifidobacterium longum (in capsules) and a yogurt enriched with Bifidobacterium animalis could modify the composition and metabolic activities of the colonic microbiota in 11 Chinese lactose-intolerant subjects.

METHODS AND RESULTS

The numbers of total cells, total bacteria and the Eubacterium rectale/Clostridium coccoides group in faeces as measured with fluorescent in situ hybridization and the faecal beta-galactosidase activity increased significantly during supplementation. The number of Bifidobacterium showed a tendency to increase during and after supplementation. With PCR-denaturing gradient gel electrophoresis, in subjects in which B. animalis and B. longum were not detected before supplementation, both strains were present in faeces during supplementation, but disappeared after supplementation. The degree of lactose digestion in the small intestine and the oro-caecal transit time were not different before and after supplementation, whereas symptom scores after lactose challenge decreased after supplementation.

CONCLUSIONS

The results suggest that supplementation modifies the amount and metabolic activities of the colonic microbiota and alleviates symptoms in lactose-intolerant subjects. The changes in the colonic microbiota might be among the factors modified by the supplementation which lead to the alleviation of lactose intolerance.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides evidence for the possibility of managing lactose intolerance with dietary lactose (yogurt) and probiotics via modulating the colonic microbiota.

Prevention and treatment of enteric viral infections: possible benefits of probiotic bacteria

The structure and function of the intestinal epithelium is briefly described, with the principal mechanisms involved in diarrhea. Human enteric viruses and probiotics are presented. We then review how probiotic bacteria could interfere with virus-induced pathology, we present our own view and describe specific interactions that would be valuable targets for future studies.

Jerusalem artichoke and chicory inulin in bakery products affect faecal microbiota of healthy volunteers

A study was conducted to test the effects of Jerusalem artichoke inulin (JA) or chicory inulin (CH) in snack bars on composition of faecal microbiota, concentration of faecal SCFA, bowel habit and gastrointestinal symptoms. Forty-five volunteers participated in a double-blind, randomized, placebo-controlled, parallel-group study. At the end of a 7 d run-in period, subjects were randomly assigned to three groups of fifteen subjects each, consuming either snack bars with CH or JA, or snack bars without fructans (placebo); for 7 d (adaptation period), they ingested one snack bar per day (7.7 g fructan/d) and continued for 14 d with two snack bars per day. The composition of the microbiota was monitored weekly. The consumption of CH or JA increased counts of bifidobacteria (+1.2 log10 in 21 d) and reduced Bacteroides/Prevotella in number and the Clostridium histolyticum/C. lituseburense group in frequency at the end of intervention (P < 0.05). No changes in concentration of faecal SCFA were observed. Consumption of snack bars resulted in a slight increase in stool frequency. Stool consistency was slightly affected in subjects consuming two snack bars containing CH or JA per day (P < 0.05). Consumption of CH or JA resulted in mild and sometimes moderate flatulence in a few subjects compared to placebo (P < 0.05). No structural differences were detected between CH and JA before and after processing. In conclusion, adaptation on increased doses of CH or JA in bakery products stimulates the growth of bifidobacteria and may contribute to the suppression of potential pathogenic bacteria.

The role of a probiotics mixture in the treatment of childhood constipation: a pilot study

Background

Inconsistent data exist about the efficacy of probiotics in the treatment of constipation. Several studies in adults with constipation showed positive effects of probiotics on constipation. Inconsistent data exist regarding the effect of a single probiotic strain in constipated children. The aim of this pilot study was to determine the effect of a mixture of probiotics containing bifidobacteria and lactobacilli in the treatment of childhood constipation.

Methods

Children aged 4–16 years with constipation as defined by the Rome III criteria were eligible for the study. During a 4 week period, children received a daily mix of 4 × 10⁹ colony forming units of a probiotic mixture (Ecologic^®Relief) containing Bifidobacteria (B.) bifidum, B. infantis, B. longum, Lactobacilli (L.) casei, L. plantarum and L. rhamnosus. Primary outcome measures were frequency of bowel movements (BMs) per week and stool consistency. Secondary outcome measures were number of faecal incontinence episodes per week, abdominal pain and side effects.

Results

Twenty children, 50% male, median age 8 (range 4–16) were included.

The frequency of BMs per week increased from 2.0 (1.0–5.0) to 4.2 (0.0–16.0) in week 2 (p = 0.10) and 3.8 (2.1–7.0) in week 4 (p = 0.13). In 12 children presenting with <3 BMs/week, BMs per week increased significantly from 1.0 (0.0–2.0) to 3.0 (0.0–7.0) in week 2 (p = 0.01) and 3.0 (0.0–10.0) in week 4 (p = 0.01). The stool consistency was reported as hard in 7 children at baseline, in 4 children at week 2 (p = 0.23) and in 6 children after 4 weeks of treatment (p = 1.00). A significant decrease in number of faecal incontinence episodes per week was found in the entire group: 4.0 (0.0–35.0) to 1.5 (0.0–14.0) in week 2 (p = 0.01) and 0.3 (0.0–7.0) in week 4 (p = 0.001). The presence of abdominal pain decreased significantly from 45% to 25% in week 2 (p = 0.04) and 20% at week 4 (p = 0.006). No side effects were reported.

Conclusion

This pilot study shows that a mixture of probiotics, has positive effects on symptoms of constipation. To confirm these findings, a large randomised placebo controlled trial is required.

Tetracycline resistance mediated by tet(W), tet(M), and tet(O) genes of Bifidobacterium isolates from humans

MICs of tetracyclines were determined for 86 human Bifidobacterium isolates and three environmental strains. The tet(O) gene was found to be absent in these isolates. tet(W) and tet(M) were found in 26 and 7%, respectively, of the Bifidobacterium isolates, and one isolate contained both genes. Chromosomal DNA hybridization showed that there was one chromosomal copy of tet(W) and/or tet(M).

Diarrhoea in the critically ill

PURPOSE OF REVIEW

The purpose of this review is to update the knowledge on diarrhoea, a common problem in critically ill patients. Epidemiological data will be discussed, with special emphasis on diarrhoea in tube-fed patients and during antibiotic therapy. The possible preventive and therapeutic measures will be presented.

RECENT FINDINGS

The need for concise definitions of diarrhoea was recently re-emphasized. The use of pump-driven continuous instead of intermittent enteral feeding is less often associated with diarrhoea. The discontinuation of enteral feeding during diarrhoea is not justified. Clostridium difficile-associated diarrhoea is frequent during antibiotic therapy with quinolones and cephalosporins. Formulas enriched with water-soluble fibres are probably effective to prevent diarrhoea, and promising data on the modulation of gut microflora with probiotics and prebiotics were recently released.

SUMMARY

Diarrhoea is common in critically ill patients, especially when sepsis and hypoalbuminaemia are present, and during enteral feeding and antibiotic therapy. The management of diarrhoea includes generous hydration, compensation for the loss of electrolytes, antidiarrheal oral medications, the continuation of enteral feeding, and metronidazole or glycopeptides in the case of moderate to severe C. difficile colitis. The place of enteral formulas enriched with water-soluble fibres, probiotics and prebiotics is not yet fully defined.

Anti-inflammatory effects of bifidobacteria by inhibition of LPS-induced NF-κB activation

AIM: Different strains of bifidobacteria were analysed for their effects on HT-29 intestinal epithelial cells (IECs) in in vitro models both of the non-inflamed and inflamed intestinal epithelium.

METHODS: A reporter gene system in HT-29 cells was used to measure levels of NF-κB activation after challenge with bifidobacteria or after bacterial pre-treatment following LPS challenge. IL-8 protein and pro-inflammatory gene expression was investigated using normal HT-29 cells.

RESULTS: None of the bifidobacteria tested induced activation of nuclear factor κB (NF-κB) indicating that bifidobacteria themselves do not induce inflammatory events in IECs. However, six out of eight bifidobacteria tested inhibited lipopolysaccharide- (LPS-) induced NF-κB activation in a dose- and strain-dependent manner. In contrast, NF-κB activation in response to challenge with tumor necrosis factor-α (TNF-α) was affected by none of the tested bifidobacteria, indicating that the inhibitory effect of bifidobacteria is specific for LPS-induced inflammation in IECs. As shown with two of the six inhibition-positive bifidobacteria, LPS-induced inhibition of NF-κB activation was accompanied by a dose-dependent decrease of interleukin 8 (IL-8) secretion and by lower mRNA levels for IL-8, TNF-α, cyclooxygenase 2 (Cox-2), and intercellular adhesion molecule 1 (ICAM-1).

CONCLUSION: Some strains of bifidobacteria are effective in inhibiting LPS-induced inflammation and thus might be appropriate candidates for probiotic intervention in chronic intestinal inflammation.

Experimental study of the effects of probiotics on Cryptosporidium parvum infection in neonatal rats

To date, there is no efficient treatment for cryptosporidiosis and parasite eradication relies on innate and acquired immunity. In this study, we investigated the effect of administration of probiotic bacteria on the development and progression of the experimental infection in suckling rats. Rats were fed daily with 2.10(7) CFU of Lactobacillus casei-containing mixture, starting 2 days before the infection until the spontaneous clearance of the parasite. Effects on weight gain, parasite burden, mucosal histology and production of mucosal cytokines (IFNgamma, IL10 and TNFalpha) were studied. Although a trend to a more rapid clearance of parasites was noted in rats treated with probiotics, no significant effect of probiotics administration was observed in terms of weight gain, parasite burden, mucosal damage, or kinetics of mucosal cytokines during the course of infection. Overall, our results showed that the daily administration of L. casei-containing mixtures was unable to eradicate the parasite in our model.

Probiotics and Prebiotics in Human Health

Probiotic bacteria are found in the intestines of humans and other mammals where they provide health benefits to the host. They do so by (1) providing nutrients and cofactors, (2) successfully competing with pathogens, and (3) stimulating host immune responses by producing specific polysaccharides. These bacteria can also alleviate the symptoms of disease-related metabolic disorders. Prebiotics are substances, usually poorly metabolized polysaccharides and oligosaccharides, that cannot be ingested effectively by the animal. They stimulate the growth of intestinal probiotic bacteria, which can utilize these carbohydrates, thereby promoting health of the organism. Genetic engineering has proven useful for the design of probiotic bacteria that counteract the symptoms of genetic and age-related diseases. Can these bacteria be engineered, through human-promoted accelerative evolution, so that they stimulate their own growth and that of other probiotic bacteria so as to crowd pathogens out of the intestine?