Protection from gastrointestinal diseases with the use of probiotics

Evaluation of immunomodulation by Lactobacillus casei Shirota: immune function, autoimmunity and gene expression

Lactic acid bacteria are claimed to have immunomodulating effects. Stimulation as well as suppression of T helper (Th)1 mediated immune responses, have been described for various strains. Experiments involving Lactobacillus casei Shirota (LcS) detected mainly enhancement of innate immune responses and promotion of Th1 mediated immune reactivity. To confirm and further investigate modulation of Th1 responses and development of autoimmune disease by LcS, the consequences of oral administration of LcS were assessed in several experiments. The effect of LcS varied between the different models. No modulation was found in the mitogen-induced cell proliferation and cytokine release assays in mesenteric lymph nodes of Wistar rats. LcS inhibited the Th1 mediated immune response in an adapted murine Local Lymph Node Assay (LLNA) in BALB/c mice, whereas experimental autoimmune encephalomyelitis (EAE) in Lewis rats was aggravated. These varying effects on Th1 responses indicate that beneficial as well as harmful effects on immune related disorders could occur after LcS consumption. Since microarray analysis is suggested to be more sensitive and predictive than functional tests, gene expression profiling was included as an alternative endpoint in the testing of immunomodulation. The detected gene expression profiles did not reflect the effects of LcS on the immune system. Microarray analysis may therefore have no more predictive value than immune function assays when investigating immunomodulation by probiotics. To gain further insight into effects of probiotics on immune function, experiments including cytokine assays and gene expression analysis combined with disease models could be useful.

Probiotics and their potential health claims

Many studies have attempted to identify specific positive health effects of probiotics. One of the challenges in generalizing health effects of probiotics is that different strains exert disparate effects on human health. As a result, the efficacy of one strain or species cannot necessarily be inferred from another. The objective of this review is to examine the current scientific literature that could be used as the basis for potential health claims. More specifically, this paper will review existing evidence of different probiotic strains to prevent and treat diarrhea, treat irritable bowel syndrome (IBS), treat inflammatory bowel disease, and prevent colon cancer. The strongest evidence is related to the use of Lactobacillus rhamnosus GG in the prevention and treatment of rotavirus-associated diarrhea. Further examination of the literature also shows promise in the treatment of some forms of IBS with probiotics. Future studies that use consistent supplementation regimes will allow more definitive conclusions to be drawn on the effects of probiotics on IBS, inflammatory bowel disease, and colon cancer.

Probiotic bacteria Bifidobacterium animalis MB5 and Lactobacillus rhamnosus GG protect intestinal Caco-2 cells from the inflammation-associated response induced by enterotoxigenic Escherichia coli K88

Probiotic bacteria may provide protection against intestinal damage induced by pathogens, but the underlying mechanisms are still largely unknown. We investigated whether Bifidobacterium animalis MB5 and Lactobacillus rhamnosus GG (LGG) protected intestinal Caco-2 cells from the inflammation-associated response induced by enterotoxigenic Escherichia coli (ETEC) K88, by inhibiting pathogen attachment to the cells, which is the first step of ETEC pathogenicity, and regulating neutrophil recruitment, a crucial component of inflammation. A partial reduction of ETEC adhesion was exerted by probiotics and their culture supernatant fractions either undigested or digested with proteases. ETEC viability was unaffected by the presence of B. animalis, LGG or their supernatant fractions in the culture medium, indicating an absence of probiotic bactericidal activity. Probiotics and their supernatant fractions, either undigested or digested with proteases, strongly inhibited the neutrophil transmigration caused by ETEC. Both B. animalis and LGG counteracted the pathogen-induced up regulation of IL-8, growth-related oncogene-alpha and epithelial neutrophil-activating peptide-78 gene expression, which are chemokines essential for neutrophil migration. Moreover, the probiotics prevented the ETEC-induced increased expression of IL-1beta and TNF-alpha and decrease of transforming growth factor-alpha, which are regulators of chemokine expression. These results indicate that B. animalis MB5 and LGG protect intestinal cells from the inflammation-associated response caused by ETEC K88 by partly reducing pathogen adhesion and by counteracting neutrophil migration, probably through the regulation of chemokine and cytokine expression.

Effects of probiotics on the severity of experimental acute pancreatitis

OBJECTIVE

This study was designed to evaluate the effects of probiotics on the severity of experimental acute pancreatitis.

DESIGN

Experimental study.

SETTING

Experiments were done in a laboratory at Haydarpasa Numune Teaching and Research Hospital.

SUBJECTS

A total of 50 Wistar rats were randomly divided into five groups.

INTERVENTIONS

Group 1 was control group. Group 2 received an intraperitoneal injection of a 20% solution in 0.15 mol/l NaCL. Group 3 was injected NaCL and fed with probiotics. Acute pancreatitis was induced in rats by intrperitoneal injection of L-Arginine in groups 4 and 5. The rats in group 5 were treated with probiotics. The pancreas was removed for histologic examination. Evaluation of the pathologic changes was done by a new combined histopathologic grading scale.

RESULTS

The mean scores of fibrosis, acinar cell loss, oedema, parenchymal necrosis, mononuclear cells infiltration, polymorphonuclear leucocytes infiltration, ductal damage and atypical reactive regeneration in group 5 were significantly lower than group 4.

CONCLUSIONS

We demonstrated that enteral feedings with added probiotics can reduce the severity of acute pancreatitis.

SPONSORSHIP

None.

Probiotic bacteria reduced duration and severity but not the incidence of common cold episodes in a double blind, randomized, controlled trial

To investigate the effect of long-term consumption of probiotic bacteria on viral respiratory tract infections (common cold, influenza), a randomized, double blind, controlled intervention study was performed during two winter/spring periods (3 and 5 month). Four hundred and seventy-nine healthy adults were supplemented daily with vitamins plus minerals with or without probiotic lactobacilli and bifidobacteria. The intake of the probiotic had no effect on the incidence of common cold infections (verum=158, control=153 episodes, influenza was not observed), but significantly shortened duration of episodes by almost 2 days (7.0+/-0.5 versus 8.9+/-1.0 days, p=0.045), reduced the severity of symptoms and led to larger increases in cytotoxic T plus T suppressor cell counts and in T helper cell counts.

Saccharomyces boulardii prevents TNF-α-induced apoptosis in EHEC-infected T84 cells

Induction of apoptosis and necrosis by enterohemorrhagic Escherichia coli (EHEC) has been reported in vivo and in vitro, but features of cell death were not noted in those reports. Since tumor necrosis factor-alpha (TNF-alpha) has been implicated in the apoptosis of invasive bacteria, we investigated the role of this cytokine in EHEC-induced apoptosis. We hypothesize that the probiotic yeast strain Saccharomyces boulardii that interferes with EHEC-induced pro-inflammatory pathways delays EHEC-induced apoptosis. By 6 h of infection, flow cytometry analysis of T84 cells demonstrated that 40% of cells were FITC-annexin-V-positive and 40% of cells incorporated both annexin and propidium iodide (PI). Simultaneously, western blot analysis demonstrated that procaspases-8 and -3 were cleaved. Fragmentation of internucleosomal DNA revealed evidence of apoptotic leader formation after 8 and 9 h of infection. Procaspase-9 activation and 3',3-dihexyloxacarbocyanine iodide (DiOC(6)) incorporation were observed at 3 h of infection. In cells preincubated with S. boulardii and infected with EHEC in the presence of yeast, the quantities of procaspases-8, -9 and -3 did not vary, and no DNA fragmentation was observed. The TNF-alpha transcript level and the level of secreted TNF-alpha increased considerably (P<0.001vs control cells) at 6 h of infection in EHEC-alone-infected cells, but were significantly reduced in cells infected in the presence of S. boulardii (P<0.001vs EHEC-alone-infected cells). The presence of anti-TNF-alpha antibody during infection reduced by 30% the level of FITC-annexin V-positive cells. Altogether, these findings demonstrated that: (i) EHEC infection stimulated TNF-alpha synthesis that is implicated in apoptosis of T84 cells; and (ii) S. boulardii induced a decrease in TNF-alpha and related apoptosis in EHEC-infected T84 cells.

Lactobacillus rhamnosus GG decreases lipopolysaccharide-induced systemic inflammation in a gastrostomy-fed infant rat model

OBJECTIVES

A gastrostomy-fed rat infant "pup-in-a-cup" model was used to test the hypothesis that enterally administered Lactobacillus rhamnosus GG (LGG) decreases the proinflammatory response induced by Escherichia coli lipopolysaccharide (LPS) in the developing infant rat small intestine, plasma, lung and liver.

METHODS

Two groups of 6- to 7-day-old pups were fed a rat milk substitute with LPS added via the gastrostomy tube for 6 days. One of the rat milk substitute-fed groups received supplemental LGG; another group received LPS without LGG. Age-matched mother-fed rat pups were used as controls.

RESULTS

LPS treatment blunted body growth, but LGG supplementation had no effect on weight increments. LGG decreased LPS-induced inflammation in intestinal tissue; CINC-1 (rodent IL-8 equivalent) production in plasma, liver, lung and distal small intestine; and tumor necrosis factor alpha (TNF-alpha) production in plasma and lung. Cytokine multiplex assay showed lung interleukin (IL)-1beta, IL-6, IL-10, IL-18, growth-related oncogene (GRO)/KC (rat CINC-1) and TNF-alpha were significantly higher in gastrostomy-fed, LPS-treated pups than in mother-reared pups, and LGG significantly blunted the LPS-induced elevation of IL-1beta, IL-10, IL-18, GRO/KC and TNF-alpha; liver GRO/KC was significantly higher in gastrostomy-fed, LPS-treated pups than in mother-reared pups, and LGG significantly blunted the LPS-induced elevation of GRO/KC.

CONCLUSIONS

LGG provided by the enteral route is able to downregulate LPS-induced proinflammatory mediators. This effect is not only present in the splanchnic organs, that is, the intestine and the liver, but extends to the plasma and a distal organ, the lung.

Probiotics and prebiotics for gastrointestinal infections

There is growing interest in and knowledge about the potential health-promoting benefits of both probiotics and prebiotics. Multiple mechanisms of action for the beneficial effect of probiotics and prebiotics have been postulated, including prevention of pathogenic bacteria growth, production of antimicrobial agents, stimulation of mucosal barrier function, and altering immunoregulation. Clinical trials support the efficacy of probiotics in the treatment of acute infectious diarrhea, the prevention of antibiotic associated diarrhea, and the prevention of recurrent Clostridium difficile infection. Although some data support the potential benefit of probiotic therapy in traveler's diarrhea, diverticular disease, and Helicobacter pylori, the strength of this evidence is limited. This paper will review the recent literature relevant to the mechanism of action and utility of probiotics and prebiotics in the treatment of gastrointestinal infections.

Effect of lactulose and Saccharomyces boulardii administration on the colonic urea-nitrogen metabolism and the bifidobacteria concentration in healthy human subjects

BACKGROUND

Protein fermentation products, especially ammonia, are implicated in the pathogenesis of certain diseases.

AIM

To investigate the influence of lactulose and Saccharomyces boulardii cells on the composition of the intestinal microbiota and on the metabolic fate of ammonia by means of lactose-[(15)N, (15)N]-ureide.

METHODS

An at random, placebo-controlled, crossover study was performed in 43 healthy volunteers to evaluate the influence of lactulose and/or S. boulardii cells either administered as a single dose or after a 4-week intake period. Urine and faeces were collected. All samples were analysed for (15)N-content by combustion-isotope ratio mass spectrometry. Real-time polymerase chain reaction was applied to determine the composition of the predominant faecal microbiota.

RESULTS

A single administration of lactulose significantly decreased urinary (15)N-excretion in a dose-dependent way. After long-term administration of lactulose, a significant reduction of the urinary (15)N-excretion was observed, which was accompanied with a significant increase in the faecal (15)N-output, more specifically more (15)N was found in the bacterial fraction. A significant rise in the Bifidobacterium population was found after lactulose intake. No significant effects were observed after S. boulardii intake.

CONCLUSION

Dietary addition of lactulose can exert a bifidogenic effect accompanied by a favourable effect on the colonic NH(3)-metabolism.

Effects of orally administered Lactobacillus casei DN-114 001 on the composition or activities of the dominant faecal microbiota in healthy humans

The composition and activities of the faecal microbiota in twelve healthy subjects analysed in a single open study were monitored before (1-week baseline step), during (10 d supplementation step) and after (10 d follow-up step) the ingestion of a fermented milk containing Lactobacillus casei DN-114 001. Fluorescent in situ hybridisation with group-specific DNA probes, real-time PCR using L. paracasei group-specific primers and temporal temperature gradient gel electrophoresis (TTGE) using group-specific primers were carried out, together with bacterial enzyme activity and metabolite analyses to monitor the structure and activities of the faecal microbiota. L. casei DNA was detected in the faeces of all of the subjects by TTGE after 10 d supplementation. Its quantification by real-time PCR showed a 1000-fold increase during the test step compared with initial levels. No major modification in either the dominant members of the faecal microbiota or their activities was observed during the trial. In conclusion, the short-term consumption of a milk product containing L. casei DN-114 001 was accompanied by a high, transient increase in the quantity of this strain in the faeces of all of the subjects without markedly affecting biochemical or bacteriological factors.

The anti-cancer effects of poi (Colocasia esculenta) on colonic adenocarcinoma cells In vitro

Hawaiians tend to have lower incidence rates of colorectal cancer and it was hypothesized that this may be due to ethnic differences in diet, specifically, their consumption of poi, a starchy paste made from the taro (Colocasia esulenta L.) plant corm. Soluble extracts of poi were incubated at 100 mg/mL in vitro for antiproliferative activity against the rat YYT colon cancer cell line. (3)H-thymidine incorporation studies were conducted to demonstrate that the poi inhibited the proliferation of these cancer cells in a dose-dependent manner. The greatest suppression of YYT colon cancer growth occurred when 25% concentration was used. When poi was incubated with the YYT cells after 2 days, the YYT cells underwent apoptotic changes as evidenced by a positive terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) stain. Poi enhanced the proliferation of normal mouse splenocyte control cells, suggesting that poi is not simply toxic to all cells but even has a positive immunostimulatory role. By flow cytometry, T cells (CD4+ and CD8+) were predominantly activated by the poi. Although numerous factors can contribute to the risk of colon cancer, perhaps poi consumption may contribute to the lower colon cancer rates among Hawaiians by two distinct mechanisms. First, by inducing apoptosis within colon cancer cells; second, by non-specifically activating lymphocytes, which in turn can lyse cancerous cells. Our results suggest for the first time that poi may have novel tumor specific anti-cancer activities and future research is suggested with animal studies and human clinical trials.

Characterisation of intestinal bacteria in infant stools using real-time PCR and northern hybridisation analyses

Real-time PCR and northern hybridisations were used to quantify bacterial populations in the large gut of infants. PCR primers for rapid, sensitive, high throughput detection of bifidobacteria, bacteroides, sulphate-reducing bacteria and Enterococcus faecalis, based on analysis of 16S rRNA genes were used. Bacterial populations were analysed in faeces from 40 infants aged 0-6, 7-12 and 13-24 months. The effects of breast versus bottle feeding was also investigated. Real-time PCR indicated that bacteroides and desulfovibrio numbers increased markedly in the 7-12 and 13-24 month age groups, and that the reverse occurred with Ent. faecalis. With the exception of desulfovibrios, this was seen with northern hybridisations, which also showed increased colonisation by the Clostridium coccoides group and Faecalibacterium prausnitzii after 6 months. Both methodologies indicated increased bifidobacteria in breast-fed babies, and higher levels of desulfovibrios in bottle-fed children.

The host response to the probiotic Escherichia coli strain Nissle 1917: specific up-regulation of the proinflammatory chemokine MCP-1

Background

The use of live microorganisms to influence positively the course of intestinal disorders such as infectious diarrhea or chronic inflammatory conditions has recently gained increasing interest as a therapeutic alternative. In vitro and in vivo investigations have demonstrated that probiotic-host eukaryotic cell interactions evoke a large number of responses potentially responsible for the effects of probiotics. The aim of this study was to improve our understanding of the E. coli Nissle 1917-host interaction by analyzing the gene expression pattern initiated by this probiotic in human intestinal epithelial cells.

Methods

Gene expression profiles of Caco-2 cells treated with E. coli Nissle 1917 were analyzed with microarrays. A second human intestinal cell line and also pieces of small intestine from BALB/c mice were used to confirm regulatory data of selected genes by real-time RT-PCR and cytometric bead array (CBA) to detect secretion of corresponding proteins.

Results

Whole genome expression analysis revealed 126 genes specifically regulated after treatment of confluent Caco-2 cells with E. coli Nissle 1917. Among others, expression of genes encoding the proinflammatory molecules monocyte chemoattractant protein-1 ligand 2 (MCP-1), macrophage inflammatory protein-2 alpha (MIP-2α) and macrophage inflammatory protein-2 beta (MIP-2β) was increased up to 10 fold. Caco-2 cells cocultured with E. coli Nissle 1917 also secreted high amounts of MCP-1 protein. Elevated levels of MCP-1 and MIP-2α mRNA could be confirmed with Lovo cells. MCP-1 gene expression was also up-regulated in mouse intestinal tissue.

Conclusion

Thus, probiotic E. coli Nissle 1917 specifically upregulates expression of proinflammatory genes and proteins in human and mouse intestinal epithelial cells.

The use of enteral nutrition in the management of Crohn's disease in adults

Crohn's disease is a chronic, relapsing disease and none of the treatments developed so far can cure it. Artificial nutrition is effective to both treat malnutrition when present and induce remission. However, striking advances in anti-inflammatory and immunomodulating therapies (including infliximab) and low compliance to treatment in the first trials have limited its place in the management of adults to drug-resistant patients. Randomized controlled trials show that artificial nutrition is effective in >50% of the cases in this selected population. Significant progress has recently been made to improve the palatability (and thus acceptability) of some enteral solutions, which can be consumed by the oral route and as pharmaconutrition. We reviewed the literature on enteral nutrition in adults with Crohn's disease. We present herein the results of the studies performed with antioxidants, glutamine, short-chain fatty acids, prebiotics, probiotics, low microparticle diets, and a TGFbeta2 enriched formulation.

Invasive Saccharomyces infection: a comprehensive review

BACKGROUND

Saccharomyces cerevisiae (also known as "baker's yeast" or "brewer's yeast") is mostly considered to be an occasional digestive commensal. However, since the 1990s, there have been a growing number of reports about its implication as an etiologic agent of invasive infection. A particular feature of such infections is their association with a probiotic preparation of Saccharomyces boulardii (a subtype of S. cerevisiae) for treatment various diarrheal disorders.

METHODS

We collected published case reports, through May 2005, of invasive Saccharomyces infection by use of a Medline query. Epidemiological and clinical charts and therapeutic strategies were analyzed.

RESULTS

We found 92 cases of Saccharomyces invasive infection. Predisposing factors were similar to those of invasive candidiasis, with intravascular catheter and antibiotic therapy being the most frequent. Blood was the most frequent site of isolation (for 72 patients). S. boulardii accounted for 51.3% of fungemias and was exclusively isolated from blood. Compared with patients infected with S. cerevisiae, patients infected with S. boulardii were more frequently immunocompetent and had a better prognosis. Saccharomyces invasive infection was clinically indistinguishable from an invasive candidiasis. Overall, S. cerevisiae clinical isolates exhibited low susceptibility to amphotericin B and azole derivatives. However, global outcome was favorable in 62% of the cases. Treatment with intravenous amphotericin B and fluconazole, in combination with central vascular catheter removal, were effective therapeutic options.

CONCLUSION

Saccharomyces organisms should now be added to the growing list of emerging fungal pathogens. Special caution should be taken regarding the use of S. boulardii probiotic preparations.

Study of adhesion and survival of lactobacilli and bifidobacteria on table olives with the aim of formulating a new probiotic food

With the aim of developing new functional foods, a traditional product, the table olive, was used as a vehicle for incorporating probiotic bacterial species. Survival on table olives of Lactobacillus rhamnosus (three strains), Lactobacillus paracasei (two strains), Bifidobacterium bifidum (one strain), and Bifidobacterium longum (one strain) at room temperature was investigated. The results obtained using a selected olive sample demonstrated that bifidobacteria and one strain of L. rhamnosus (Lactobacillus GG) showed a good survival rate, with a recovery of about 10(6) CFU g(-1) after 30 days. The Lactobacillus GG population remained unvaried until the end of the experiment, while a slight decline (to about 10(5) CFU g(-1)) was observed for bifidobacteria. High viability, with more than 10(7) CFU g(-1), was observed throughout the 3-month experiment for L. paracasei IMPC2.1. This strain, selected for its potential probiotic characteristics and for its lengthy survival on olives, was used to validate table olives as a carrier for transporting bacterial cells into the human gastrointestinal tract. L. paracasei IMPC2.1 was recovered from fecal samples in four out of five volunteers fed 10 to 15 olives per day carrying about 10(9) to 10(10) viable cells for 10 days.

Bifidobacterium-selective isolation and enumeration from chicken caeca by a modified oligosaccharide antibiotic-selective agar medium

AIMS

To determine the efficacy and selectivity of an acidified, antibiotic-selective, oligosaccharide-containing media for enumerating Bifidobacterium spp. from chicken caeca samples.

METHODS AND RESULTS

Transoligosaccharide propionate agar medium (TOS) modified by addition of mupirocin (50 microg ml-1) and glacial acetic acid (1%, v/v), did not inhibit the growth of bifidobacteria compared with the control media yet inhibited the growth of Lactobacillus acidophilus, Lactobacillus gallinarum, Lactobacillus helveticus and Streptococcus gordonii.

CONCLUSIONS

Addition of mupirocin (50 microg ml-1) and glacial acetic acid (1%, v/v) to TOS (TOS-AM50), is an effective selective medium for isolation and enumeration of Bifidobacterium spp. from chicken caeca samples.

SIGNIFICANCE AND IMPACT OF THE STUDY

The development of an intestinal bifidobacteria-selective media contributes to the study of probiotics and prebiotics in poultry and potentially other species.

Efficacy of Saccharomyces boulardii for treatment of horses with acute enterocolitis

OBJECTIVE

To evaluate the viability of Saccharomyces boulardii after PO administration in clinically normal horses and its efficacy as a treatment for horses with acute enterocolitis.

DESIGN

Prospective study.

ANIMALS

5 clinically normal horses and 14 horses with acute enterocolitis.

PROCEDURE

Feces were collected from 5 clinically normal horses and submitted for microbial culture for 2 days prior to administration of a lyophilized form of S. boulardii (25 or 50 g, PO, q 12 h) for 10 days. Feces were collected for microbial culture 5 and 10 days after treament initiation and 10 days after treatment was discontinued. Fourteen horses with acute enterocolitis were randomly allocated to receive a placebo or S. boulardii (25 g), PO, every 12 hours for 14 days.

RESULTS

S. boulardii was not detected in feces of clinically normal horses. After administration, yeast survived within the gastroinestinal tract but did not permanently colonize it. In horses with acute enterocolitis, the severity and duration of gastrointestinal tract disease during hospitalization were significantly decreased in horses receiving S. boulardii, compared with horses receiving the placebo.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of S. boulardii may help decrease the severity and duration of clinical signs in horses with acute enterocolitis.

Survival of probiotic lactobacilli in acidic environments is enhanced in the presence of metabolizable sugars

Lactobacillus rhamnosus GG is an industrially significant probiotic strain with proven health benefits. In this study, the effect of glucose on L. rhamnosus GG survival was analyzed in simulated gastric juice at pH 2.0. It was found that the presence of 19.4 mM glucose resulted in up to 6-log10-enhanced survival following 90 min of exposure. Further work with dilute HCl confirmed that glucose was the sole component responsible. Comparative analysis with other Lactobacillus strains revealed that enhanced survival was apparent in all strains, but at different pH values. The presence of glucose at concentrations from 1 to 19.4 mM enhanced L. rhamnosus GG survival from 6.4 to 8 log10 CFU ml(-1) in simulated gastric juice. The mechanisms behind the protective effect of glucose were investigated. Addition of N',N'-dicyclohexylcarbodiimide to simulated gastric juice caused survival to collapse, which was indicative of a prominent role in inhibition of F0F1-ATPase. Further work with neomycin-resistant mutants that exhibited 38% to 48% of the F0F1-ATPase activity of the parent confirmed this, as the survival in the presence of glucose of these mutants decreased 3 x 10(6)-fold compared with the survival of the wild type (which had a viability of 8.02 log10 CFU ml(-1)). L. rhamnosus GG survival in acidic conditions occurred only in the presence of sugars that it could metabolize efficiently. To confirm the involvement of glycolysis in the glucose effect, iodoacetic acid was used to inhibit glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity. The reduction in GAPDH activity caused survival to decrease by 8.30 log10 CFU ml(-1) in the presence of glucose. The data indicate that glucose provides ATP to F0F1-ATPase via glycolysis, enabling proton exclusion and thereby enhancing survival during gastric transit.

Isomaltooligosaccharide increases cecal Bifidobacterium population in young broiler chickens

A newly developed compound derived by fermentation, isomaltooligosaccharide (IMO), was hypothesized to enrich cecal bifidobacterial populations and reduce colonization levels of Salmonella in the ceca of broiler chickens. Broiler starter diets were prepared with final IMO concentrations of 1% (wt/wt), 2% (wt/wt), and 4% (wt/wt) and a control diet without IMO supplementation. Chickens were divided into 4 groups and challenged with 10(8) cell of Salmonlella enterica ser. Typhimurium with 200 microg/mL nalidixic acid resistant (S. Typhimurium Nalr) after 7 d of placement. The experiment was done in 3 replications. IMO-supplemented diets resulted in significantly higher cecal bifidobacteria compared with the control diet (P < 0.05). However, there was no significant difference in bifidobacteria counts among the treatment groups. Chickens fed diets with 1% IMO had a significant 2-log reduction in the level of inoculated S. Typhimurium Nalr (P < 0.05) present in, the ceca compared with the control group, but no differences were found between the control group and the groups fed 2 or 4% IMO for S. Typhimurium Nalr. No differences in feed consumption, feed conversion, or feed efficiency compared with the control group were observed; however, the result showed a significant reduction in weight for birds fed 1% IMO diet compared with those fed the control diet.

Update in traveler's diarrhea

TD has not proved as preventable as hoped, despite knowing that it is transmitted mainly through food. Travelers have little ability to select restaurants based on the kitchen hygiene. The rates of TD in travelers to developing countries have not changed in the past 50 years, either because the dietary precautions they are taught are not effective or they cannot be adhered to in the course of a pleasurable vacation. Nonantibiotic prophylaxis with bismuth subsalicylate has the potential to prevent 40% to 60% of TD episodes in short-term travelers, and is probably underused. Antibiotic prophylaxis can prevent up to 90% of infections, but is not routinely recommended. Empiric treatment of TD has been the best approach to dealing with this problem, but its usefulness is being undermined by growing antibiotic resistance in many parts of the world. Fluoroquinolones are still the most useful agents where Campylobacter is not a predominant pathogen. Rifaximin may prove to be a useful addition to the options for treatment and prophylaxis. If used for treatment, it may require a backup antibiotic in areas where Campylobacter and Shigella are prominent pathogens.

Nonpathogenic Escherichia coli strain Nissle1917 prevents murine acute and chronic colitis

BACKGROUND

Nonpathogenic Escherichia coli strain Nissle1917 has been used as a probiotics in human inflammatory bowel disease; however, there are few reports examining its therapeutic effect on animal colitis models, and its therapeutic mechanisms remain unknown. The aim of this study was to elucidate the therapeutic effect and mechanism of Nissle1917 using murine acute and chronic colitis models.

METHODS

Two models were used. (1) Acute model: colitis was induced by administration of 1.3% dextran sodium sulfate for 7 days. Nissle1917 or phosphate-buffered saline were orally administered for 10 days. Mice were killed at day 10, and the colonic lesions were assessed macro- and microscopically. (2) Chronic model: IL-10 mice were treated with Nissle1917 or phosphate-buffered saline for 8 weeks. After 8 weeks of treatment, mice were killed to assess the colonic lesions macro- and microscopically. In the acute dextran sodium sulfate colitis model, viable, heat-killed, or genomic DNA of Nissle1917 was orally administered for 10 days, and the therapeutic effect was assessed.

RESULTS

In the acute model, Nissle1917 ameliorated body weight loss, disease activity index, and macro- and microscopic damage. In the chronic model, it also suppressed the mucosal inflammatory findings and histologic damages. Moreover, heat-killed Nissle1917 or its genomic DNA alone also ameliorated the acute DSS colitis and viable bacteria macro- and microscopically.

CONCLUSIONS

Nonpathogenic E. coli strain Nissle1917 prevents both acute and chronic colitis, and its anti-inflammatory effect is exhibited not only by viable bacteria but also by heat-killed bacteria or its DNA.

Characterization of a bacteriocin produced by Enterococcus faecium GM-1 isolated from an infant

AIM

To partially characterize the bacteriocin produced by the GM-1 strain of Enterococcus faecium, isolated from the faeces of a newborn human infant.

METHODS AND RESULTS

The bacteriocin produced by E. faecium GM-1 showed a broad spectrum of activity against indicator strains of Escherichia coli, Staphylococcus aureus, Vibrio spp., Salmonella typhimurium, Listeria monocytogenes, Lactobacillus acidophilus, and Streptococcus thermophilus. Treatment of the GM-1 bacteriocin with proteolytic enzymes reduced its inhibitory activities. The bacteriocin was stable at 100 degrees C for 20 min and displayed inhibitory activity at neutral pH. The optimal production of bacteriocin from E. faecium GM-1 was obtained when the culture conditions were pH 6.0-6.5 and 35-40 degrees C. The inhibitory activity of the bacteriocin was not substantially changed by the use of different carbon sources in the media, except when galactose was substituted for glucose. The use of a sole nitrogen source caused a decrease in inhibitory activity. A bacteriocin gene similar to enterocin P was identified from the total DNA of E. faecium GM-1 by PCR and direct sequencing methods.

CONCLUSION

E. faecium GM-1, which was isolated from the faeces of a newborn baby, produces an enterocin P-like bacteriocin with inhibitory activity against Gram-positive and Gram-negative bacteria, including food-borne pathogens.

SIGNIFICANCE AND IMPACT OF THE STUDY

E. faecium GM-1, isolated from infant faeces, produces a new bacteriocin that is similar to enterocin P. This bacteriocin is heat stable and has a broad antibacterial spectrum that includes both Gram-positive and Gram-negative bacteria.

Effect of Lactobacillus gasseri PA 16/8, Bifidobacterium longum SP 07/3, B. bifidum MF 20/5 on common cold episodes: a double blind, randomized, controlled trial

BACKGROUND & AIMS

The aim of this study was to investigate whether the consumption of Lactobacillus gasseri PA 16/8, Bifidobacterium longum SP 07/3, B. bifidum MF 20/5 (5 x 10(7) cfu/tablet) during at least 3 months influences the severity of symptoms and the incidence and duration of the common cold.

METHODS

A randomized, double-blind, placebo-controlled intervention study was performed over at least 3 months during two winter/spring periods. Four hundred and seventy nine healthy adults (aged 18-67) were supplemented daily with vitamins and minerals with or without the probiotic bacteria. Cellular immune parameters were evaluated in a randomly drawn subgroup of 122 volunteers before and after 14 days of supplementation. During common cold episodes, the participants recorded symptoms daily. Stool samples were collected before and after 14 days of probiotic supplementation to quantify fecal Lactobacilli and Bifidobacteria using qRT-PCR.

RESULTS

The total symptom score, the duration of common cold episodes, and days with fever during an episode were lower in the probiotic-treated group than in the control group: 79.3+/-7.4 vs. 102.5+/-12.2 points (P = 0.056), 7.0+/-0.5 vs. 8.9+/-1.0 days (P = 0.045), 0.24+/-0.1 vs. 1.0+/-0.3 days (P = 0.017). A significantly higher enhancement of cytotoxic plus T suppressor cells (CD8+) and a higher enhancement of T helper cells (CD4+) was observed in the probiotic-treated group. Fecal lactobacilli and bifidobacteria increased significantly after probiotic supplementation.

CONCLUSIONS

The intake of probiotic bacteria during at least 3 months significantly shortened common cold episodes by almost 2 days and reduced the severity of symptoms.

Selective expression of detoxifying glutathione transferases in mouse colon: effect of experimental colitis and the presence of bacteria

Glutathione transferases (GSTs) play a central role in the cellular defense against harmful endogenous compounds and xenobiotics in mouse and man. The gastrointestinal channel is constantly exposed to bacteria, bacterial products, and xenobiotics. In the present study the distribution of alpha, mu, and pi class GSTs was examined immunohistologically in the colon of conventional and germ-free (GF) mice subjected to experimental colitis. The tissues samples were from conventional mice with and without colitis induced by dextran sulfate sodium (DSS); GF mice treated with DSS or carrageenan; and GF mice inoculated with normal mouse bacterial flora as well as with Lactobacillus GG. In conventional as well as in GF mice the mu and pi class GSTs showed reduced intestinal expression when colitis was induced. In con-rast, the level of GSTs reacting with antibodies directed against the alpha class, in particular mGST A4-4, was elevated after induction of inflammation. Of special interest is mGST A4-4 because of its high catalytic activity with toxic products of lipid peroxidation. In the colon of conventionalized GF mice that were given mouse intestinal flora, the mGST A4-4 expression was increased with time for several weeks, but then showed a decrease to a normal level. Additionally, the inoculation of GF mice with Lactobacillus GG induced all the intestinal GSTs studied.

Sporadic colorectal cancer – role of the commensal microbiota

There are vast numbers of bacteria present within the human colon that are essential for the host's well being in terms of nutrition and mucosal immunity. While certain members of the colonic microbiota have been shown to promote the host's health there are also numerous studies that have implicated other members of the colonic microbiota in the development of colorectal cancer, a prominent malignancy within the western world. In this review we consider the evidence for the role of bacteria in colorectal cancer from molecular and animal model studies. We focus on some of the mechanisms by which the colonic microbiota drives the progression towards colorectal malignancy including generation of reactive metabolites and carcinogens, alterations in host carbohydrate expression and induction of chronic mucosal inflammation.

Effects of Saccharomyces boulardii in children with acute diarrhoea

AIM

Certain probiotic agents, e.g. Lactobacillus GG, have shown efficacy in clinical trials for the treatment of acute childhood diarrhoea, but few studies have examined the effect of Saccharomyces boulardii. We evaluated the effect of S. boulardii in children with acute diarrhoea.

METHODS

Two hundred children were randomized to receive S. boulardii in a granulated form in a daily dose of 250 mg (S. boulardii group) or placebo (placebo group) for 5 d. Clinical and demographic characteristics on admission were similar between the study groups.

RESULTS

The medians of the average stool frequency after the second day of the treatment were significantly lower in the S. boulardii group than in the placebo group (p = 0.003). The duration of diarrhoea significantly reduced in the S. boulardii group compared with the placebo group (4.7 vs 5.5 d, p = 0.03). The effect of S. boulardii on watery diarrhoea became apparent after the second day of the treatment. The duration of hospital stay was shorter in the S. boulardii group than in the placebo group (2.9 vs 3.9 d, p < 0.001). Four children from the placebo group versus only one child from the S. boulardii group had persisting diarrhoea.

CONCLUSION

The placebo-controlled study suggested that S. boulardii significantly reduced the duration of acute diarrhoea and the duration of hospital stay. S. boulardii seems to be a promising agent for the amelioration of the course of acute diarrhoea in children when used therapeutically.

Effect of Bifidobacterium longum ingestion on experimental salmonellosis in mice

AIMS

The effect of lactic acid bacteria on the immune system is well established under normal conditions and generally by in vivo determinations, but few data are available, in vivo, during an infectious challenge. The objective of this study was to obtain data on the putative protective role of bifidobacteria upon challenge with an intestinal pathogen.

METHODS AND RESULTS

The effect of oral treatment with Bifidobacterium longum Bb46 on intragastric challenge with Salmonella Typhimurium was studied. Faecal bacterial levels were determined in gnotobiotic (GN) mice and mortality, histopathology (intestines, liver), immunoglobulin levels (IgM, IgG, IgG1, IgG2a) and cytokine production (IFN-gamma, IL-10) were determined in conventional (CV) mice. Conventional mice received 0.1 ml probiotic milk (10(8) CFU) daily, 10 days before the oral pathogenic challenge (10(2) CFU). Then, probiotic treatment was continued until the end of the experiment. Probiotic treatment in germ-free mice consisted of a single dose at the beginning of the experiment. Control groups were treated with sterile skim milk and submitted to the same procedure. A higher survival (40%) was observed for probiotic-treated animals when compared with the control group (0%). This protective effect was confirmed by the histopathological and morphometric data. However, S. Typhimurium population levels in the faeces were similar among control and probiotic-treated groups. During the challenge with S. Typhimurium, a decrease in IFN-gamma and IgG2a productions was observed in probiotic-treated mice.

CONCLUSIONS

The protective effect against the pathogenic challenge may be due to a reduced inflammatory response, mediated by the probiotic treatment, but not to a population antagonism.

SIGNIFICANCE AND IMPACT OF THE STUDY

Results suggest that dietary supplementation with B. longum could provide benefits against enteric infection.

Transition of the probiotic bacteria, Lactobacillus casei strain Shirota, in the gastrointestinal tract of a pig

The transition of probiotic bacteria Lactobacillus in the gastrointestinal tract was investigated in pigs that received commercially available fermented milk prepared with Lactobacillus casei strain Shirota (LCS). Three female pigs fistulated at the cecum were fed 130 ml of fermented milk that contained over 10(10) (cfu) LCS with their daily meal for 8 days. Cecal contents were sampled through a fistula every 2 h for 24 h after marker dosing. The viable cell number (log cfu/g) of LCS and the concentrations of transit markers in each sample were determined. The viable number of LCS cells ranged from 3.56 to 6.58. The number of LCS in the cecum was not stable in pigs and varied with the flow of the cecal content. The viable number of LCS cells was significantly correlated with the relative concentration of the marker. These results indicated that most LCS moved with the liquid component. The level of LCS reached the maximum (6.38) 6 h after dosing. Four doses every 6 h may be required to maintain the maximum level of LCS at the cecum.

Toxicity evaluation for an Enterococcus faecium strain TM39 in vitro and in vivo

Previously, we have screened lactic acid bacteria (LAB) strains from infant feces and evaluated their functional properties. We found a strain of Enterococcus faecium termed as TM39 which is acid and bile tolerant, able to adhere to the intestinal epithelium and with antagonistic activity against Helicobacter pylori. In this study, we demonstrate that strain TM39 is not vancomycin resistant, not invasive to human gastric carcinoma cell line TSGH 9201 and human intestinal epithelial cell line Int-407 in vitro. In addition, we have conducted the in vivo study to evaluate the toxicity of this E. faecium strain TM39 in Wistar rats. For such study, cells of strain TM39 were daily oral administrated with dose of 1 x 10(12), 5 x 10(11) and 2 x 10(10) CFU/kg of body weight, respectively, to the rats for 28 consecutive days. There were no adverse effects on the general condition, behavior, growth, feed and water consumption, hematology, clinical chemistry values, organ weights and histopathologic analysis of the rats. Results of this study demonstrate that consumption of strain E. faecium TM39, even in large quantities, is not associated with any obvious signs of toxicity in Wistar rats.

Live Lactobacillus rhamnosus [corrected] is essential for the inhibitory effect on tumor necrosis factor alpha-induced interleukin-8 expression

The mechanism of the apparent anti-inflammatory action of probiotic organisms is unclear. Lactobacillus reuteri is effective in inhibiting colitis in interleukin-10 (IL-10)-deficient mice. Nerve growth factor (NGF), in addition to its activity on neuronal cell growth, has significant anti-inflammatory effects in several experimental systems in vitro and in vivo, including a model of colitis. Our experiments were designed to explore the mechanism of effect of L. reuteri in the human epithelial cell lines T84 and HT29 on cytokine and NGF synthesis and IL-8 response to tumor necrosis factor alpha (TNF-alpha). Epithelial cells were cultured for various times with live and killed L. reuteri and examined by reverse transcription-PCR for NGF, IL-10, and TNF-alpha-induced IL-8 expression. An enzyme-linked immunosorbent assay was used to quantitate intracellular IL-8 and secreted product. Western blotting and confocal microscopy were used to determine the effects on IkappaB and NF-kappaB, respectively. Live but not heat-killed or gamma-irradiated L. reuteri upregulated NGF and dose dependently inhibited constitutive synthesis by T84 and HT29 cells of IL-8 and that induced by TNF-alpha in terms of mRNA and intracellular and secreted protein. Similarly, L. reuteri inhibited IL-8 synthesis induced by Salmonella enterica serovar Typhimurium. L. reuteri required preincubation and adherence for effect, inhibited translocation of NF-kappaB to the nuclei of HeLa cells, and prevented degradation of IkappaB. Neither cellular lysates nor media supernatants had any effect on TNF-alpha-induced IL-8. The conclusion is that L. reuteri has potent direct anti-inflammatory activity on human epithelial cells, which is likely to be related to the activity of ingested probiotics. L. reuteri also upregulates an unusual anti-inflammatory molecule, NGF, and inhibits NF-kappaB translocation to the nucleus.

I, 5. Treatment of viral gastroenteritis

Viral gastroenteritis (mainly after rotavirus infection) directly causes death through dehydration. Thus, the treatment and prevention of dehydration are the primary goals in caring for infants with gastroenteritis. Viral gastroenteritis can also inflict considerable nutritional insult on children because of anorexia, vomiting, malabsorption, and traditional therapies in which nutritionally poor diets are offered. This chapter discusses the treatment of the deficiencies of fluids, electrolytes, and nutrients. While there are already very good cost-effective strategies for correcting the sequelae of viral gastroenteritis, there is little yet available to effectively treat the acute symptoms of vomiting and diarrhea. The chapter discusses several potential modes of symptomatic therapy for viral gastroenteritis including probiotics, antivirals, passive immunotherapy, and antidiarrheals. The first major advance in the treatment of dehydration was the development of effective intravenous rehydration therapy.

Lactobacillus GG bacteria ameliorate arthritis in Lewis rats

Probiotic bacteria have beneficial effects in infectious and inflammatory diseases, principally in bowel disorders. In the case of chronic progressive autoimmune arthritides, a major goal of treatment is to reduce inflammation. We hypothesized that probiotic bacteria would ameliorate inflammation found in arthritis models. To assess this effect, Lewis rats were injected with 50 microg bovine alpha-tropomyosin (TRM) or complete Freund's adjuvant (CFA) to induce tropomyosin arthritis (TA) or adjuvant arthritis (AA), respectively. In both models, the rats were divided into 6 groups and fed 0.5 mL/d of the following suspensions: 1) heat-killed Lactobacillus GG (LGG) bacteria; 2) live LGG, both 10(11) colony-forming units (cfu)/L; 3) sterilized milk; 4) plain yogurt; 5) yogurt containing 10(11) cfu/L LGG; or 6) sterilized water. In the disease-prevention experiments, feeding started 1 wk before or after disease induction. In the therapeutic experiments, feeding was initiated at the onset of clinical arthritis. In all experiments, there were significant interactions between time and treatment (P < 0.001), except for milk, which had no effect in the therapeutic experiment. Histologically, rats fed yogurt containing LGG had a milder inflammation in all experiments (P < 0.05), whereas rats fed plain yogurt exhibited a moderate inflammatory score only in the prevention experiments. Anti-TRM antibody titers were not affected by any of the treatments in any of the experiments. Ingestion of live or heat-killed human LGG had a clinically beneficial effect on experimental arthritis. Our observation of the remarkable preventive and curative effect on arthritis using commercial yogurts containing lactobacilli, especially LGG, suggests the need for investigation of these agents in arthritic patients.

Comparative survival of probiotic lactobacilli spray-dried in the presence of prebiotic substances

AIMS

Probiotic milk-based formulations were spray-dried with various combinations of prebiotic substances in an effort to generate synbiotic powder products.

METHODS AND RESULTS

To examine the effect of growth phase and inclusion of a prebiotic substance in the feed media on probiotic viability during spray-drying, Lactobacillus rhamnosus GG was spray-dried in lag, early log and stationary phases of growth in reconstituted skim milk (RSM) (20% w/v) or RSM (10% w/v), polydextrose (PD) (10% w/v) mixture at an outlet temperature of 85-90 degrees C. Stationary phase cultures survived best (31-50%) in both feed media and were the most stable during powder storage at 4-37 degrees C over 8 weeks, with 30-140-fold reductions in cell viability at 37 degrees C in RSM and PD/RSM powders, respectively. Stationary phase Lact. rhamnosus GG was subsequently spray-dried in the presence of the prebiotic inulin in the feed media, composed of RSM (10% w/v) and inulin (10% w/v), and survival following spray-drying was of the order 7.1-43%, while viability losses of 20,000-90,000-fold occurred in these powders after 8 weeks' storage at 37 degrees C. Survival of the Lactobacillus culture after spray-drying in powders produced using PD (20% w/v) or inulin (20% w/v) as the feed media was only 0.011-0.45%. To compare different probiotic lactobacilli during spray-drying, stationary phase Lact. rhamnosus E800 and Lact. salivarius UCC 500 were spray-dried using the same parameters as for Lact. rhamnosus GG in either RSM (20% w/v) or RSM (10% w/v) and PD (10% w/v). Lact. rhamnosus E800 experienced approx. 25-41% survival, yielding powders containing approximately 10(9) CFU g(-1), while Lact. salivarius UCC 500 performed poorly, experiencing over 99% loss in viability during spray-drying in both feed media. In addition to the superior survival of Lact. rhamnosus GG after spray-drying, both strains experienced higher viability losses (570-700-fold) during storage at 37 degrees C over 8 weeks compared with Lact. rhamnosus GG.

CONCLUSIONS

Stationary phase cultures were most suitable for the spray-drying process, while lag phase was most susceptible. The presence of the prebiotics PD and inulin did not enhance viability during spray-drying or powder storage.

SIGNIFICANCE AND IMPACT OF THE STUDY

High viability (approximately 10(9) CFU g(-1)) powders containing probiotic lactobacilli in combination with prebiotics were developed, which may be useful as functional food ingredients for the manufacture of probiotic foods.

Effects of the probiotic yeast Saccharomyces boulardii on the neurochemistry of myenteric neurones in pig jejunum

We studied the effects of food supplementation with Saccharomyces boulardii (S. boulardii; synonym S. cerevisiae HANSEN CBS 5926; 1 g per day for 9 days) on the presence and co-localization patterns of neuronal markers in myenteric neurones of the pig jejunum. The pan neuronal marker Hu revealed no change in the number of neuronal cell bodies per ganglion (37 +/- 7 in control vs 34 +/- 9 in the S. boulardii group). Ranked by size the following cell populations were identified: choline acetyltransferase (ChAT), calbindin-28k (CALB), substance P (SP), neurofilament 160 kD (NF-160), vasoactive intestinal polypeptide (VIP), nitric oxide synthase (NOS), calcitonin gene-related peptide (CGRP), calretinin (CALRET). We found a significant decrease in the number of CALB myenteric neurones in animals which received S. boulardii supplemented diet. None of the other neuronal markers revealed any difference between controls and S. boulardii treated animals. The study reports transmitter-localization patterns in the myenteric plexus of the pig jejunum and provides evidence that changes in the neurochemistry of enteric neurones occur with S. boulardii supplemented diet. Although only CALB expression was altered and the functional significance of this finding remains unknown, our study identified a possible new effector level of probiotics in the gut.

Probiotiques et maladies inflammatoires chroniques de l’intestin : essais contrôlés et perspectives

Probiotics may modulate intestinal flora and immunity and are therefore studied in an attempt to modulate experimental colitis or human inflammatory bowel disease. We analysed randomised controlled trials performed using probiotics in humans with Crohn's disease, ulcerative colitis and pouchitis. Perspectives include the use of genetically modified micro-organisms to deliver anti-inflammatory agents to the gastrointestinal tract.

Commensal anaerobic gut bacteria attenuate inflammation by regulating nuclear-cytoplasmic shuttling of PPAR-gamma and RelA

The human gut microflora is important in regulating host inflammatory responses and in maintaining immune homeostasis. The cellular and molecular bases of these actions are unknown. Here we describe a unique anti-inflammatory mechanism, activated by nonpathogenic bacteria, that selectively antagonizes transcription factor NF-kappaB. Bacteroides thetaiotaomicron targets transcriptionally active NF-kappaB subunit RelA, enhancing its nuclear export through a mechanism independent of nuclear export receptor Crm-1. Peroxisome proliferator activated receptor-gamma (PPAR-gamma), in complex with nuclear RelA, also undergoes nucleocytoplasmic redistribution in response to B. thetaiotaomicron. A decrease in PPAR-gamma abolishes both the nuclear export of RelA and the anti-inflammatory activity of B. thetaiotaomicron. This PPAR-gamma-dependent anti-inflammatory mechanism defines new cellular targets for therapeutic drug design and interventions for the treatment of chronic inflammation.

Safety aspects of enterococci from the medical point of view

Enterococci occur in a remarkable array of environments. They can be found in soil, food, and water, and make up a significant portion of the normal gut flora of humans (10(5)-10(7)/g of stool) and animals. As other bacteria of the gut flora, enterococci can also cause infectious diseases. Most clinical isolates are Enterocococus faecalis, which account for 80-90% of clinical strains. Enterocococus faecium accounts for 5-10% of such isolates. Typical enterococcal infections occur in hospitalised patients with underlying conditions representing a wide spectrum of severity of illness and immune modulation. Enterococci today rank second to third in frequency among bacteria isolated from hospitalised patients. They are isolated from urinary tract infections, intra-abdominal and pelvic infections, bacteremias, wound and tissue infections, and endocarditis--often as part of a polymicrobial flora. Surprisingly, little is known about the factors that contribute to the ability of enterococci to cause infections. Many strains of E. faecalis produce a cytolysin (haemolysin) exhibiting tissue-damaging capacity. Further extracellular products often observed in clinical isolates are a proteinase (gelatinase), hyaluronidase, and extracellular superoxide. Furthermore, many of the clinical isolates possess the aggregation substance on the surface and an extracellular surface protein, both contributing to the adherence to eucaryotic cells. Some strains of E. faecalis, and many E. faecium strains are resistant to multiple antimicrobials. The ultimate role of all these factors in enterococcal pathogenicity remains to be determined. It was previously thought that enterococcal infections were endogenously acquired from the patient's own gut flora. A rather new concept that has emerged is that enterococcal disease is a two-stage process. There is an initial colonisation of the gastrointestinal tract by enterococcal strains possessing virulence traits and/or antibiotic resistance. Subsequently, this population spreads, often facilitated by antibiotic elimination of competitors. For a selected number of patients, there is subsequent tissue invasion from the gastrointestinal tract reservoir. From this concept, it can be deduced that enterococcal strains without virulence traits and antibiotic resistances exogenously transferred into the human gut via food products or probiotics will not represent any risk for immunocompetent individuals. In very severely immunocompromised patients, however, a risk for enterococcal disease by such strains cannot completely be excluded.

Probiotics: what are they? What are their effects on gut physiology?

Probiotics can be defined as microbial cells that have a beneficial effect on the health and well-being of the host. Since the gastrointestinal mucosa is the surface of contact with probiotics, it seems evident that the first effects of probiotics relate to digestive function. A brief review of the literature indicates that probiotics have very few effects on the main physiological functions of the gastrointestinal tract, which are digestion, absorption and propulsion. The main action of probiotics can be summarised as a reinforcement of the intestinal mucosal barrier against deleterious agents. Experimental data indicate that some probiotics reduce pathological alterations in paracellular permeability to large molecules or bacteria, stimulate mucosal immunity, display a trophic action on the mucosa, reduce mucus degradation and interact with mediators of inflammation. Yoghurt may help lactose digestion, and some data needing confirmation indicate a stimulation of water absorption and an acceleration of intestinal transit by some bacteria.

Proposed nutrient composition for fortified complementary foods

A proposed nutrient composition for fortified processed complementary foods (FPCF) is developed based on the other papers in this publication, which consider a number of factors such as age range, daily ration size, recommended nutrient requirements, contribution of human milk to these requirements, macronutrient interactions, compound bioavailability, methods of production and overage. The proposed fortification levels are based on a daily ration size of 40 g for infants aged 6-12 mo and 60 g for children aged 12-23 mo. A desired protein-energy ratio of 6-10% is used to estimate energy from protein. The desired percentage of energy from lipid is estimated at 24% for infants aged 6-11 mo and 28% for children aged 12-23 mo, with the remaining energy to be supplied from carbohydrate. An FPCF should provide a quantity of iron sufficient to meet the Recommended Dietary Allowance in the form of dried ferrous sulfate of small particle size. Ascorbic acid, 70-140 mg for infants aged 6-11 mo and 50-100 mg for children aged 12-23 mo, will enhance iron absorption. Because of the lower bioavailability of zinc in cereal-based diets in developing countries, 4-5 mg of zinc in the form of zinc oxide is recommended. Proposed fortification levels are also provided for copper, calcium, vitamin D, magnesium, phosphorus, vitamin A, the B vitamins and iodine. To prevent micronutrient losses, it is recommended that the FPCF be precooked. The knowledge base to develop an FPCF is quite limited, and much additional research is needed before an optimal formulation can be recommended.

Inflammatory bowel disease and irritable bowel syndrome: separate or unified?

Both irritable bowel syndrome and inflammatory bowel diseases share symptoms of altered bowel habits associated with abdominal pain or discomfort. Irritable bowel syndrome has been referred to as a functional bowel disorder, which is diagnosed by a characteristic cluster of symptoms in the absence of detectable structural abnormalities. Inflammatory bowel disease is a heterogeneous group of disorders characterized by various forms of chronic mucosal and/or transmural inflammation of the intestine. In this review, the authors discuss recent evidence suggesting several potential mechanisms that might play a pathophysiologic role in both syndromes. Possible shared pathophysiologic mechanisms include altered mucosal permeability, an altered interaction of luminal flora with the mucosal immune system, persistent mucosal immune activation, alterations in gut motility, and a role of severe, sustained life stressors in symptom modulation. It is proposed that similarities and differences between the two syndromes can best be addressed within the framework of interactions between the central nervous system and the gut immune system. Based on recent reports of low-grade mucosal inflammation in subpopulations of patients meeting current diagnostic criteria for irritable bowel syndrome, therapeutic approaches shown to be effective in inflammatory bowel disease, such as probiotics, antibiotics, and antiinflammatory agents, have been suggested as possible therapies for certain patients with irritable bowel syndrome.

Structural and ultrastructural studies of the urinary tract of mice inoculated with Lactobacillus fermentum

OBJECTIVE

To assess, using structural and ultrastructural studies of the urinary tract, the effects of the intraurethral inoculation of lactobacilli (probiotic treatment) as lactobacilli are the predominant micro-organisms of the urogenital tract of humans, monkeys and mice.

MATERIALS AND METHODS

Previous work showed the protective effect of Lactobacillus fermentum CRL 1058 intraurethrally inoculated against the challenge of uropathogenic Escherichia coli. There was also an effect of oestrogens and antibiotics in the kinetics of colonization of both micro-organisms in mice. In the present study L. fermentum was inoculated with agarose beads (107 colony-forming units) and the number of micro-organisms determined by plating in selective media, giving a high degree of colonization in all the organs studied. The urinary tract organs were processed by histological and electron microscopy techniques standardized in our laboratory.

RESULTS

The intraurethral inoculation of lactobacilli produced no adverse effects or significant changes in any of the organs assessed (kidney, ureter, bladder or urethra), when evaluated by histological and ultrastructural techniques.

CONCLUSION

The use of lactobacilli as a probiotic treatment is probably safe.

Isolation and biochemical characterisation of enterocins produced by enterococci from different sources

AIMS

Comparison of enterocins produced by six Enterococcus faecium strains and one Ent. faecalis strain isolated from different origin with regard to their microbiological and biochemical characteristics in view of their technological potential and practical use.

METHODS AND RESULTS

The seven enterococci were sensitive to the glycopeptide antibiotics vancomycin and teicoplanin and did not show haemolytic activity. The absence of the glycopeptide-resistant genotypes and the genes involved in the production of the lantibiotic cytolysin was confirmed by PCR. The enterocins were active towards Listeria innocua and other lactic acid bacteria. Their temperature stability was dependent on the pH and their activity was higher at acidic pH. A bactericidal and bacteriolytic effect was shown. PCR analyses revealed that the gene of enterocin A was present in the genome of Ent. faecium CCM 4231, Ent. faecium 306 I.2.20 and Ent. faecalis Y; both enterocin A and B genes were present in the genome of Ent. faecium LMG 11423T, Ent. faecium RZS C5 and Ent. faecium RZS C13. Enterocin P was detected in the genome of Ent. faecium RZS C5 and Ent. faecium RZS C13. No signal was found for Ent. faecium SF 68. Enterocins from Ent. faecium RZS C5, Ent. faecium RZS C13 and Ent. faecium SF 68 were purified to homogeneity.

CONCLUSIONS

Ent. faecium RZS C5 and Ent. faecium RZS C13 produced an enterocin with a molecular mass of 5460 and 5477 Da, respectively, which was in the range of that of enterocin B. The amino acid sequence analysis of the enterocin from Ent. faecium RZS C13 revealed 24 N-terminal residues, which were identical to those of enterocin B. The enterocin from Ent. faecium SF 68 had a molecular mass of 4488 Da, which did not correspond to any enterocin known so far.

SIGNIFICANCE AND IMPACT OF THE STUDY

The number of characterized enterocins is increasing. As this type of work is tedious and time-consuming, it may be interesting to include PCR as a first step to know if the Enterococcus strain in study produces either a known or a new enterocin. Also, it is important to check the absence of cytolysin and resistance to vancomycin for a further application of the Enterococcus strain in food or health applications.

Effect of Lactobacillus rhamnosus GG on ileal pouch inflammation and microbial flora

BACKGROUND

Preliminary trials of probiotics in preventing recurrent chronic pouchitis have been encouraging.

AIM

To investigate the efficacy of Lactobacillus GG supplementation as primary therapy for ileal pouch inflammation, and its effect on the microbial flora.

METHODS

Twenty patients, with a previous history of pouchitis and endoscopic inflammation, were recruited for a prospective, randomized, double-blind, placebo-controlled trial of Lactobacillus GG supplementation (10 LGG, 10 placebo) in two gelatine capsules [(0.5-1) x 10(10) colony-forming units/capsule] b.d. for 3 months. Quantitative bacterial culture of fresh faecal samples and biopsies taken from the pouch and afferent limb was performed before and after supplementation.

RESULTS

Lactobacillus GG supplementation changed the pouch intestinal flora by increasing the ratio of total faecal lactobacilli to total faecal anaerobes (P = 0.03) and enhancing the frequency of lactobacilli-positive cultures in the pouch and afferent limb mucosal biopsy samples. However, only 40% of patients were colonized with Lactobacillus GG. No differences were observed between the groups with regard to the mean pouchitis disease activity index or the total anaerobes or aerobes of faecal or tissue biopsy samples.

CONCLUSIONS

A single-strain probiotic bacterium supplement of Lactobacillus GG changed the pouch intestinal bacterial flora, but was ineffective as primary therapy for a clinical or endoscopic response. More clinical trials are needed to evaluate the right placement and dosage of probiotics within a treatment regimen for pouchitis.