Intestinal Microflora

The intestinal mucosal surface is colonised by the comensal microflora that attains very high numbers of bacterial cells in the distal intestine, more specifically in the colon. At the same time these extensive areas are the interface with the external environment, through which most pathogens initiate infectious processes in mammals. Intestinal mechanisms of defense need to discriminate accurately between comensal, symbiotic microflora, and exogenous pathogens. Today we do not fully understand the essence of the mechanism of discrimination but, probably, innate as well as adaptive immune responses participate in this process. We have explored , in in vitro models, the capacity of mucosal immunocompetent cells to discriminate amongst signals delivered by different types of bacteria. We have found at least two different patterns of innate response to gram-negative and gram-positive bacteria, and within this last group big differences are observed between species. We have only worked with non-pathogenic bacteria in what may represent the modulation of the physiological host status. The understanding of these modulatory functions could render a unique possibility for the use of food-borne bacteria to prevent or correct intestinal problems associated with food allergy, inflammatory bowel disease, and autoimmunity.

Background Animal studies have demonstrated dramatic changes in the intestinal flora during total enteral (TEN) or parenteral (TPN) nutrition. Aim of the study To assess the impact of TEN and TPN on human intestinal microflora. Methods Eight patients on fiber-free TEN, five patients on TPN, and ten controls were studied. Fecal bacteria were identified and numbered (logCFU/g feces), and fecal shortchain fatty acids (SCFAs) were measured in stool samples, by gas-liquid chromatography. Results In TEN patients, compared to controls (P<0.01), aerobes were increased (8.46±0.24) while anaerobes were decreased (5.79±0.84). In TPN patients, both aerobes and anaerobes were decreased compared to controls (5.64±0.27 and 5.31±1.09 respectively, P<0.01). Total SCFAs were lower in TPN patients than in TEN patients (48.3±16.6 vs 118.6± 24.1 mmol/kg, P<0.05). Conclusions Both TPN and TEN induce modifications in the intestinal microflora. During TPN, a homogeneous decrease occurs in both aerobic and anaerobic bacteria. TEN decreases only anaerobic bacteria, while aerobic bacteria are increased. This imbalance may play a role in the pathophysiology of TEN-induced diarrhea.

Background & aim: The addition of prebiotics to infant formula modifies the composition of intestinal microflora. Aim of the study was to test the hypothesis that prebiotics reduce the incidence of intestinal and respiratory infections in healthy infants.

Fermented foods containing probiotic bacteria have been used for many years to improve the health or treatment of some diseases. Nowadays, the Therapeutic properties of probiotics are becoming more and more obvious to everyone, insofar as in recent years, more attention has been paid to the potential relation between gut microbiota and mental health. Several studies have shown that intestinal microbiota play some roles in development and function of brain as well as psychiatric parameters such as sleep, appetite, mood and perception through production of active neural molecules. These findings, in turn had led to further research on new therapies for the resolution of mental disorders through changing and modification of intestinal microflora using a new therapeutic group called psychobiotics. Psychobiotics are probiotic bacteria that if consumed in adequate dosage, affect the function of the intestines and brain and reduce the symptoms of psychiatric illness.

The de"nition for probiotics has gradually changed with increasing understanding of the mechanisms by which they in#uence human health. Health e!ects related to changes in the intestinal micro#ora also accompany or are related to adhesion and immune system e!ects, competitive exclusion or metabolic and nutritional e!ects, with an increasing array of other potential modes of action. Most clinically documented and validated health e!ects have been studied using either fermented milks containing viable cultures or viable pure cultures. Speci"c targets for the future include controlled studies comparing foods containing viable strains to those containing non-viable strains and to assess the combined e!ects of multiple probiotics.

The effect of daily administration of oligofructose (OF) on 7-19 months old healthy children intestinal microflora, intestinal tolerance and well-being was assessed in a double blind placebo controlled study. The study comprised 8 days of observation, 21 days of supplementation, and 15 days of post-supplementation. Exclusion criteria included antibiotic use and intake of other prebiotic and probiotic at any time following enrolment. Faecal flora was analysed by culture methods, and health information was recorded daily. Bifidobacteria, tended to slightly increase with OF supplementation, but not with placebo (p = 0.095). Simultaneously, a decrease in potential pathogens, significant for clostridia (p = 0.05) but not for staphylococci (p = 0.09) was observed in the OF group. These modifications did not persist during the post-supplementation period. OF supplementation were accompanied by less flatulence, diarrhoea, vomiting (p < 0.001), and fever (p < 0.05) events.

Fanaro S, Chierici R, Guerrini P, Vigi V. Intestinal microflora in early infancy: composition and development. Acta Paediatr 2003; Suppl 441: 48-55. Stockholm. ISSN 0803-5253 The neonatal intestinal microbiota is a complex ecosystem composed of numerous genera, species and strains of bacteria. This enormous cell mass performs a variety of unique activities that affect both the colonic and systemic physiology. Its primary activities include nutritive, metabolic, immunological and protective functions. Most studies of infants have been based on faecal samples using the classical plating techniques with culturing on specific media. The limitations of these methods must be taken into account when evaluating the varying results of the different studies. The establishment of the gut microbial population is not strictly a succession in the ecological sense; it is rather a complex process influenced by microbial and host interactions and by external and internal factors. The climax intestinal flora is attained in successive stages. The foetal intestine is sterile and bathed in swallowed amniotic fluid. Following delivery, multiple different antigens challenge the intestine of the newborn. The maternal intestinal flora is a source of bacteria for the neonatal gut. The bacterial flora is usually heterogeneous during the first few days of life, independently of feeding habits. After the first week of life, a stable bacterial flora is usually established. In full-term infants a diet of breast milk induces the development of a flora rich in Bifidobacterium spp. Other obligate anaerobes, such as Clostridium spp. and Bacteroides spp., are more rarely isolated and also enterobacteria and enterococci are relatively few. During the corresponding period, formula-fed babies are often colonized by other anaerobes in addition to bifidobacteria and by facultatively anaerobic bacteria; the development of a "bifidus flora" is unusual. In other studies the presence of a consistent number of bifidobacteria in infants delivered in large urban hospitals has not been demonstrated, whether the babies were bottle fed or exclusively breastfed. The predominant faecal bacteria were coliforms and bacteroides. According to these studies, environmental factors may be more important than breastfeeding in gut colonization after delivery. Environmental factors are indeed extremely important for the intestinal colonization of infants born by caesarean section. In these infants, the establishment of a stable flora characterized by a low incidence of Bacteroides spp. and by the isolation of few other bacteria is consistently delayed. In extremely low-birthweight infants, hospitalization in neonatal intensive care units, characterized by prolonged antibiotic therapy, parenteral nutrition, delayed oral feedings and intubation seems to affect the composition of the intestinal microbiota. The gut is colonized by a small number of bacterial species; Lactobacillus and Bifidobacteria spp. are seldom, if ever, identified. According to the few studies so far performed, the predominant species are Enterococcus faecalis, E. coli, Enterobacter cloacae, Klebsiella pneumoniae, Staphylococcus epidermidis and Staphylococcus haemolyticus. Hygienic conditions and antimicrobial procedures strongly influence the intestinal colonization pattern.

The present paper provides an overview on the use of probiotic organisms as live supplements, with particular emphasis on Lactobacillus acidophilus and Bifidobacterium spp. The therapeutic potential of these bacteria in fermented dairy products is dependent on their survival during manufacture and storage. Probiotic bacteria are increasingly used in food and pharmaceutical applications to balance disturbed intestinal microflora and related dysfunction of the human gastrointestinal tract. Lactobacillus acidophilus and Bifidobacterium spp. have been reported to be beneficial probiotic organisms that provide excellent therapeutic benefits. The biological activity of probiotic bacteria is due in part to their ability to attach to enterocytes. This inhibits the binding of enteric pathogens by a process of competitive exclusion. Attachment of probiotic bacteria to cell surface receptors of enterocytes also initiates signalling events that result in the synthesis of cytokines. Probiotic bacteria also exert an influence on commensal micro-organisms by the production of lactic acid and bacteriocins. These substances inhibit growth of pathogens and also alter the ecological balance of enteric commensals. Production of butyric acid by some probiotic bacteria affects the turnover of enterocytes and neutralizes the activity of dietary carcinogens, such as nitrosamines, that are generated by the metabolic activity of commensal bacteria in subjects consuming a high-protein diet. Therefore, inclusion of probiotic bacteria in fermented dairy products enhances their value as better therapeutic functional foods. However, insufficient viability and survival of these bacteria remain a problem in commercial food products. By selecting better functional probiotic strains and adopting improved methods to enhance survival, including the use of appropriate prebiotics and the optimal combination of probiotics and prebiotics (synbiotics), an increased delivery of viable bacteria in fermented products to the consumers can be achieved.

Metabolomics studies hold promise for the discovery of pathways linked to disease processes. Cardiovascular disease (CVD) represents the leading cause of death and morbidity worldwide. Here we used a metabolomics approach to generate unbiased small-molecule metabolic profiles in plasma that predict risk for CVD. Three metabolites of the dietary lipid phosphatidylcholine--choline, trimethylamine N-oxide (TMAO) and betaine--were identified and then shown to predict risk for CVD in an independent large clinical cohort. Dietary supplementation of mice with choline, TMAO or betaine promoted upregulation of multiple macrophage scavenger receptors linked to atherosclerosis, and supplementation with choline or TMAO promoted atherosclerosis. Studies using germ-free mice confirmed a critical role for dietary choline and gut flora in TMAO production, augmented macrophage cholesterol accumulation and foam cell formation. Suppression of intestinal microflora in atherosclerosis-prone mice inhibited dietary-choline-enhanced atherosclerosis. Genetic variations controlling expression of flavin monooxygenases, an enzymatic source of TMAO, segregated with atherosclerosis in hyperlipidaemic mice. Discovery of a relationship between gut-flora-dependent metabolism of dietary phosphatidylcholine and CVD pathogenesis provides opportunities for the development of new diagnostic tests and therapeutic approaches for atherosclerotic heart disease.

Background: Probiotic microorganisms favorably alter the intestinal microflora balance, promote intestinal integrity and mobility, inhibit the growth of harmful bacteria and increase resistance to infection. Probiotics are increasingly used in nutraceuticals, functional foods or in microbial interference treatment. However, the effectiveness of probiotic organism is considered to be population-specific due to variation in gut microflora, food habits and specific host-microbial interactions. Most of the probiotic strains available in the market are of western or European origin, and a strong need for exploring new indigenous probiotic organisms is felt.

Probiotics: The Historic Milieu The term probiotic is derived from Greek and means 'for life' as opposed to antibiotics which means 'against life'. The history of probiotics began with the consumption of fermented foods. Consumption of fermented foods was fi rst observed in ancient Greeks and Romans (Gismondo et al. 1999, Guarner et al. 2005). In 1907, Ellie Metchnikoff, a Nobel Prize winner, fi rst proposed the benefi cial effects of probiotic microorganisms on human health. Metchnikoff hypothesized that Bulgarians were healthy and lived long because of the consumption of fermented milk products which consists of rod shaped bacteria (Lactobacillus spp.). These bacteria affect the gut microfl ora positively and decrease the microbial toxic activity (Gismondo et al. 1999, Chuayana et al. 2003). The fi rst documentation about health

This study investigated how lactic acid fermentation of extracted (de-oiled) soybean white flakes (WF) affected the nutritional value of the WF when fed to Atlantic salmon. WF and fermented WF (FWF) were compared with a commercial extracted (SBM) and a commercial biotechnologically processed (BPSBM) soybean meal. Lactic acid fermentation eliminated sucrose, reduced the level of raffinose, and lowered trypsin inhibitor activity in the FWF. Eight extruded diets were produced in which the soy products substituted LT-fish meal (FM) on a crude protein (CP) basis: No soy (LT-FM); 20% SBM; 20% WF; 20% FWF; 20% BPSBM; 40% WF; 40% FWF; and 40% BPSBM. Each diet was fed to triplicate groups of 188 g salmon maintained in 8.4 8C seawater for 68 days. The groups fed 40% FWF consumed slightly less feed than the other groups. The groups fed LT-FM and 20% BPSBM grew fastest, while those fed 40% WF and 40% FWF grew slowest and at similar rates. All soy products reduced the digestibility of lipid, but this effect was less severe when feeding the diets with FWF and BPSBM. Soybean meal-induced pathological changes in the intestine were less pronounced in fish fed FWF and BPSBM than in fish fed WF and SBM. The similar growth in the groups fed 40% WF and 40% FWF was attributed to higher digestibility of lipid and energy when feeding FWF. The intestinal microflora of the salmon appeared to utilise soy oligosaccharides, and also some pectin and mannan. To conclude, lactic acid fermentation improved the nutritional value of WF by partly eliminating feed allergen(s) and soy factor(s) that restrict the absorption of lipid by Atlantic salmon. D

Selected Lactobacillus casei strains were examined for their potential use in new probiotic fermented milks by evaluation of their technological performances, in vitro adhesion capacity and intestinal transit tolerance after administration to rats. Serum, tissue and faecal samples were analysed before and during treatments.

With increasing demand for environment friendly aquaculture, the use of probiotics in aquaculture is now widely accepted. However, there is clearly a need in increasing our knowledge of intestinal microbiology and of effective preparation and safety evaluation of probiotics. This review provides a summary of the status and challenges of probiotic application in aquaculture. Our review is from the perspective of digestive tract, thereby taking into account the experiences in introducing the preparation, use and safety evaluation of probiotics in aquaculture. A better understanding of rationale, preparation and safety of probiotics in aquaculture may be of interest for commercial aquaculture.

Objective: To determine the effect of consumption of milk fermented by Lactobacillus casei strain Shirota (L. casei Shirota) on the composition and metabolic activities of the intestinal micro¯ora, and immune parameters in humans. Subjects: Twenty healthy male subjects aged 40±65 years were selected. Design: A placebo-controlled trial was performed in which 10 subjects were randomly assigned to a control and 10 to a treatment group. During the ®rst and last two weeks of the 8-week study the subjects received a strictly controlled diet without fermented products. The same controlled diet was given during the intermediate 4-week test period but then the treatment group received three times daily 100 ml of fermented milk containing 10 9 CFU L. casei Shirotaaml, whereas the same amount of unfermented milk was given to the subjects in the control group. Results: In comparison to the control group, the consumption of L. casei Shirota-fermented milk resulted in an increase of the Lactobacillus count in the faeces in which the administered L. casei Shirota was predominant at the level of 10 7 CFUag wet faeces. This was associated with a signi®cant increase in Bi®dobacterium counts (P`0.05). Some shifts in the other bacterial species were found, such as a decreased number of Clostridium; however the differences were not statistically different between the treatment and the control groups.

Enterolignans are phytoestrogenic compounds derived from the conversion of dietary lignans by the intestinal microflora that may be protective against cardiovascular diseases and cancer. To evaluate the use of enterolignans as biomarkers of dietary lignan intake, we studied the relation between plasma and dietary lignans. We determined the dietary intake of 4 lignans (secoisolariciresinol (SECO), matairesinol (MAT), pinoresinol, and lariciresinol)

We present a method for the determination of the isoflavan equol in plasma and urine. This estrogenic isoflavan, which is formed by the action of the intestinal microflora, may have higher biological activity than its precursor daidzein. High urinary excretion of equol has been suggested to be associated with a reduction in breast cancer risk. The method is based on time-resolved fluoroimmunoassay, using a europium chelate as a label. After synthesis of 4 -O-carboxymethylequol the compound is coupled to bovine serum albumin (BSA), then used as antigen to immunize rabbits. The tracer with the europium chelate is synthesized using the same 4 -O-derivative of equol. After enzymatic hydrolysis (urine) or enzymatic hydrolysis and ether extraction (plasma) the immunoassay is carried out. The antiserum cross-reacted to variable extent with some isoflavonoids. For the plasma method the cross-reactivity does not seem to influence the results, which were highly specific. The overestimation of the values using the urine method (164%) compared to the results obtained by a gas chromatography-mass spectrometry (GC-MS) method is probably due to some influence of the matrix on the signal, and interference of structurally related compounds. It is suggested that plasma assays are used but if urine samples are measured a formula has to be used to correct the values making them comparable to the GC-MS results. The correlation coefficients between the time-resolved fluoroimmunoassay (TR-FIA) methods and GC-MS methods were high; r-values for the plasma and urine method, were 0.98 and 0.91, respectively. The intra-assay coefficient of variation (CV%) for the TR-FIA plasma and urine results at three different concentrations vary between 5.5-6.5 and 3.4-6.9, respectively. The inter-assay CV% varies between 5.4-9.7 and 7.4-7.7, respectively. The working ranges of the plasma and urine assay are 1.27-512 and 1.9-512 nmol/l, respectively.

Probiotics and prebiotics have been demonstrated to positively modulate the intestinal microflora and could promote host health. Although some studies have been performed on combinations of probiotics and prebiotics, constituting synbiotics, results on the synergistic effects tend to be discordant in the published works. The first aim of our study was to screen some lactic acid bacteria on the basis of probiotic characteristics (resistance to intestinal conditions, inhibition of pathogenic strains). Bifidobacterium was the most resistant genus whereas Lactobacillus farciminis was strongly inhibited. The inhibitory effect on pathogen growth was strain dependent but lactobacilli were the most effective, especially L. farciminis. The second aim of the work was to select glucooligosaccharides for their ability to support the growth of the probiotics tested. We demonstrated the selective fermentability of oligodextran and oligoalternan by probiotic bacteria, especially the bifidobacteria, for shorter degrees of polymerisation and absence of metabolism by pathogenic bacteria. Thus, the observed characteristics confer potential prebiotic properties on these glucooligosaccharides, to be further confirmed in vivo, and suggest some possible applications in synbiotic combinations with the selected probiotics. Furthermore, the distinctive patterns of the different genera suggest a combination of lactobacilli and bifidobacteria with complementary probiotic effects in addition to the prebiotic ones. These associations should be further evaluated for their synbiotic effects through in vitro and in vivo models.

Background & aims: In a previous study, we have found that glutamine supplementation decreased the infection rate in very low birth weight (VLBW) infants. In this study, we investigated whether this beneficial effect originated from increased number of bifidobacteria and lactobacilli in the intestinal microflora of these infants. Methods: In a randomized controlled trial, VLBW infants (gestational age o32 weeks and/ or birth weight o1500 g) received enteral glutamine supplementation (0.3 g/kg/day) or isonitrogenous placebo supplementation between d3 and d30 of life. Faecal microflora was determined by fluorescent in situ hybridization o48 h, at d7, d14 and d30 of life. Results: In 43/52 (glutamine group) and 43/50 (control group) infants, X2 samples were analyzed. Baseline characteristics were not different between groups. The prevalence of bifidobacteria, lactobacilli, Escheria coIi, streptococci and clostridia was not different between groups (p40.05). In both groups, colonization with bifidobacteria was delayed, whereas potentially pathogenic bacteria such as E. coli, appeared rapidly after birth. Antibiotic treatment decreased the prevalence of all faecal bacteria (po0.05). Conclusions: Decreased infectious morbidity in VLBW infants that received glutamine supplementation was not associated with alterations in the prevalence of bifidobacteria,

The birth process allows the progressive formation of complex intestinal microflora composed of myriad bacteria, leading to this recently identified host-bacterial mutualism in the human intestine. This kind of cross-talk originating from birth is opportunistically used by the young host to initiate its own immune system. Recent epidemiogical data support the hypothesis that some increasing immune deviances observed in the last 2 decades could have originated from a modification of the bacterial environment in young populations. Our modern approach to perinatal care may, to some extent, have modified inadequately the overall quality of this bacterial-host interface. The international medical community has to be made aware of the increasing importance that initial colonising intestinal microflora could have on the health and well-being of the host later in life. It is of great concern to decrease these possible negative influences and to discover in the near future the possible means...

Adding prebiotics or probiotics to infant formula to improve the intestinal flora of formula-fed infants is considered to be a major innovation. Several companies have brought relevant formulations onto the market. However, comparative data on the effects of pre- and probiotics on the intestinal microflora of infants are not available. The present study aimed to compare the effects of infant

Reutericyclin is an inhibitory compound produced by sourdough isolates of Lactobacillus reuteri that is structurally but not functionally related to naturally occurring tetramic acids. It is bacteriostatic or bactericidal to gram-positive bacteria based on its activity as a protonionophore, and a broad range of food-related spoilage organisms and pathogens is inhibited by reutericyclin. Gram-negative bacteria are resistant to reutericyclin because of the barrier properties of their outer membrane, and resistance of beer-spoiling lactobacilli towards hop bitter acids provides cross-protection to reutericyclin. Remarkably, reutericyclin-producing strains were shown to persist for a period of 10 years in an industrial sourdough fermentation, and reutericyclin was shown to be produced in concentrations active against competitors during growth of L. reuteri in sourdough. Based on the known properties of reutericyclin and L. reuteri, reutericyclin-producing strains may have applications in the biopreservation of foods. Furthermore, these strains were shown to colonize reconstituted lactobacilli-free mice at high levels. Therefore, they could serve as a suitable model system to evaluate a possible impact of antimicrobial compounds on the intestinal microflora of humans and animals.

This study evaluated the potential of silver nanoparticles (AgNano) as an antimicrobial growth-promoting supplement for broiler chickens. One hundred forty-four seven-day-old broiler chicks were distributed randomly to AgNano treatments at 0, 10 and 20 mg/kg (Control, Group AgNano10, and Group AgNano20, respectively) provided via the drinking water from day 7 to 36 post-hatching. Body weight and feed consumption were measured weekly. In addition, balance and respiration experiments were carried out to determine nitrogen (N) utilisation and energy retention. At days 22 and 36, blood samples and intestinal content were collected to evaluate the effects of AgNano on plasma concentration of immunoglobulins and the intestinal microflora, respectively. The provision of water solutions containing different concentrations of AgNano had no effect on postnatal growth performance and the energy metabolism of broiler chickens. However, in Group AgNano10 N intake (p = 0.05) and retention (p = 0....

The aim of the study was to investigate the metabolic function of intestinal microflora in children with celiac disease (CD) in order to find out if there is a deviant gut flora in CD patients compared to healthy controls. The study group comprised children with CD, consecutively diagnosed according to current criteria given by the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition. Thirty-six children were studied at presentation, i.e., on a normal gluten-containing diet, with clinical symptoms and signs indicative of CD, positive celiac serology markers, and a small bowel biopsy showing severe enteropathy. Forty-seven patients were studied when they had been on a gluten-free diet (GFD) for at least 3 months. For comparison, a group of 42 healthy controls (HC) were studied. The functional status of the intestinal microflora was evaluated by gas-liquid chromatography of short chain fatty acids (SCFAs) in fecal samples. There was a significant difference betw...

The effects of an extract of the brown seaweed Ascophyllum nodosum (AN) in grower-finisher pigs are reported. In Experiment 1, the effect of dietary supplementation with increasing levels of AN extract (ANE) on growth performance, carcass characteristics and gastrointestinal microflora was investigated. A total of 360 pigs were randomly allocated, based on initial live-weight and sex, to one of four experimental treatments as follows; control diet (no ANE), control diet plus 3 g ANE/kg, control diet plus 6 g ANE/kg and control diet plus 9 g ANE/kg. These diets were fed ad libitum up to slaughter. In Experiment 2, eight male pigs were allocated to a control diet (no ANE) or the control diet plus 2.5 g ANE/kg to determine effects of ANE on coefficient of total tract apparent digestibility (CTTAD) of nutrients and nitrogen (N) balance. Supplementation with increasing levels of ANE in Experiment 1 resulted in reduced daily gain, carcass weight and kill-out yield during the combined grower-finisher period (P<0.05); however, there were no effects of treatment on feed intake, feed conversion ratio or carcass characteristics. Increasing levels of dietary ANE resulted in decreased ileal coliform counts (P<0.05). Increasing dietary ANE also tended to increase adherent lactobacilli in the colon (P=0.080) but caecal bifidobacteria declined (P<0.05). There were trends towards a linear reduction in colonic bifidobacteria (P=0.077) and towards a quadratic effect on rectal lactobacilli (P=0.077). Intestinal pH was unaffected by ANE supplementation (P>0.05). In Experiment 2, the CTTAD was unaffected by the inclusion of ANE (P>0.05). Overall, the intestinal coliform reductions obtained suggest that ANE may provide a dietary means to improve gut health and potentially reduce pathogen carriage in finishing pigs. However, the negative effects on growth performance observed in healthy animals will most likely limit the commercial use of dietary ANE as a feed additive.

The influence of route of administration on the absolute bioavailability and GI tract absorption of nitrofurantoin was investigated in rabbits. The disposition of nitrofurantoin was described by a one-compartment model with simultaneous first-order and Michaelis-Menten type elimination kinetics, and bioavailability was estimated by nonlinear assessment. The plasma levels following oral administration were significantly lower than those after intravenous administration, and absolute Fvalues for oral administration were approximately 0.3. However, Fvalues following intraduodenal administration and portal vein infusion were nearly unity, and it was concluded that the reduction of bioavailability following oral administration could not be attributed to metabolism by intestinal microflora or to the hepatic first-pass effect. Thus, reduction of Fvalues following oral administration is probably due to gastric degradation of the drug. The effects of factors influencing bioavailability, such as water volume taken with the drug, change of gastric emptying rate and effect of particle size, were also investigated. Increase of volume of water administered tended to improve the bioavailability, and a particle size dependency was also observed.

The aim of this study was to prepare Se/Zn-enriched probiotics and investigate their effect on blood Se and Zn concentrations, blood antioxidant capacities, and intestinal microflora in canine. The preparation was performed in a single-factor experiment. The optimal culture conditions were as follows: the initial concentrations of Se(4+) and Zn(2+) were 5 and 150 µg/ml, respectively; the inoculation volume was 5%; and the liquid volume of the medium was 50 ml in a 250-ml flask. The medium was then cultured at 32°C for 36 h. The biomass of the final product was 26.83 g/l, organic Se concentration was 173.35 µg/g, organic Zn concentration was 4.38 mg/g, Candida utilis biomass was 8.69 lg colony-forming units (CFU)/ml, and Lactobacillus biomass was 9.61 lg CFU/ml. In vivo, 20 indigenous dogs were randomly assigned to two dietary treatment groups for a 35-day study and fed a basal diet or a diet supplemented with 2.0 g of Se/Zn-enriched probiotics. Blood and fecal samples were collected...

Objective: Faecal bifidobacteria and lactobacilli, perceived as exerting health-promoting properties, may be increased by ingestion of high-dose lactulose in humans. The effects of low and well-tolerated doses of lactulose are not well known. The aim of the study was to assess the effects of prolonged low-dose lactulose administration on faecal bifidobacteria and selected metabolic indexes potentially involved in colonic carcinogenesis. Subjects and methods: In all, 16 healthy volunteers were included in this controlled, randomised, double-blind, parallel group trial. Participants ingested lactulose or placebo (sucrose) at a dose of 5 g b.i.d. for 6 weeks. Stools were regularly collected at baseline (d0), and after 3 (d21) and 6 (d42) weeks of sugar ingestion. Tolerance was evaluated using a daily chart. Results: Faecal bifidobacterial counts were higher in lactulose than in sucrose group (P ¼ 0.03). Lactulose ingestion led to a significant increase in faecal bifidobacteria counts from d0 to d21 and d42 ((m7s.e.m.) 8.2570.53, 8.9670.40 and 9.5470.28 log colony-forming units/g wet wt (CFU/g), respectively (P ¼ 0.048)). Placebo ingestion did not lead to any faecal bifidobacterial count change. Total anaerobes, Lactobacillus and pH were not significantly changed throughout the study in the two groups. Neither faecal bile acids nor neutral sterols were modified by lactulose. Excess flatus was more common in the lactulose group (P ¼ 0.03), but was very mild. Bloating and borborygmi did not differ between both the groups. Conclusions: A measure of 10 g lactulose/day increases faecal bifidobacterial counts, and lactulose fulfils the criteria requested to be considered as a prebiotic.

Thesis Wageningen University-with references -with summary in Dutch ISBN 90-8504-152-X 70 Chapter 5 Faecal SIgA secretion in infants fed on pre-or probiotic infant formula. 86 Chapter 6 General Discussion 104 Summary Samenvatting Dankwoord Curriculum Vitae Opleidingstraject 130 138 146 149 152 List of abbreviations 9 List of abbreviations Cfu Colony forming units CS Caecarean Section DP Degree of polymerization FOS Fructo-oligosaccharides GALT Gut associated lymphoid tissue GOS Galacto-oligosaccharides SCFA Short chain fatty acids SIgA Secretory immunoglobulin A.

In this study we investigated the presence of the cfxA gene (encoding a class A β-lactamase) in 73 strains of the Bacteroides fragilis group belonging to the species B. distasonis (34), B. vulgatus (14), B. thetaiotaomicron (8), B. merdae (6), B. caccae (9) and B. ovatus (2) isolated from human intestinal microflora of healthy children and adults. Employing specific primers to the cfxA gene, a 312-bp amplified fragment was obtained in 2 strains of B. vulgatus and 9 strains, the majority from children, of B. distasonis. The expression of this enzyme was analysed by determining the MICs to cefoxitin and cefotaxime and values varied from 2 to >256 µg/ml of both cefoxitin and cefotaxime. Sequence analysis of the amplicons corresponding to the cfxA gene from B. distasonis and B. vulgatus revealed identical sequences between these isolates and high similarity with other β-lactamase genes of anaerobes such as cfxA of B. vulgatus (99%) and cfxA2 of Prevotella intermedia (99%), both sequences of which deposited in Genbank under accession numbers U38243 and AF118110, respectively. However, a fragment obtained from a B. distasonis strain (EC17-4) showed a unique RFLP profile and 87% nucleotide similarity with cfxA and cfxA2 genes. These results seem to suggest a dissemination of these resistance determinants among Bacteroides species.

Septic complications represent frequent causes of morbidity in liver diseases and following hepatic operations. Most infections are caused by the individual own intestinal microflora. The intestinal microflora composition is important in physiological and pathophysiological processes in the human gastrointestinal tract, but their influence on liver in different situations is unclear. We therefore studied the effect of different Lactobacillus strains and a Bifidobacterium strain on the extent of liver injury, bacterial translocation and intestinal microflora in an acute liver injury model.

Background: Improved hygiene has altered early microbial exposure by reducing childhood infections, which has been suggested as a cause for the continuously rising prevalence of atopic diseases. On the basis of both intensity and timing of stimulus, it has been hypothesized that exposure to commensal microflora may represent another key protective modulator of immunity against atopy and subsequent atopic diseases. Objective: We sought to investigate whether differences in early gut microflora precede the later development of atopic sensitization. Methods: Intestinal microflora from 76 infants at high risk of atopic diseases were analyzed at 3 weeks and 3 months of age by using conventional bacterial cultivation and 2 culture-independent methods, gas-liquid chromatography of bacterial cellular fatty acids and quantitative fluorescence in situ hybridization of bacterial cells. Infants evincing at least one positive skin prick reaction at 12 months were grouped as atopic subjects, and those without positive reactions were grouped as nonatopic subjects. Results: Atopic sensitization was observed in 22 (29%) of 76 children. At 3 weeks, the bacterial cellular fatty acid profile in fecal samples differed significantly between infants in whom atopy was and was not developing (P = .005). By using fluorescence in situ hydridization, atopic subjects had more clostridia (geometric mean [95% confidence interval]: 9.3 × 10 7 [3.8-22.9 × 10 7 ] vs 3.3 × 10 7 [1.8-6.1 × 10 7 ], P = .04) and tended to have fewer bifidobacteria (1.8 × 10 9 [0.4-7.6 × 10 9 ] vs 6.1 × 10 9 [2.5-14.6 × 10 9 ], P = .11) in their stools than nonatopic subjects, resulting in a reduced ratio of bifidobacteria to clostridia (P = .03). The differences were not detected by bacterial cultivation. Conclusion: Differences in the neonatal gut microflora precede the development of atopy, suggesting a crucial role of the balance of indigenous intestinal bacteria for the maturation of human immunity to a nonatopic mode. (J Allergy Clin Immunol 2001;107:129-34.)

Human milk is an important factor in the initiation, development and/or composition of the neonatal gut microflora. Bacteria commonly isolated from this biological fluid include staphylococci, streptococci, micrococci, lactobacilli and enterococci, which should be considered as components of the natural microflora of human milk, rather than as mere contaminant bacteria. These bacterial groups contain strains with potential to be used as bacteriotherapeutic or probiotic agents. The origin of the bacteria found in human milk is debated and it is suggested that, at least, some species may be endogenously delivered from the maternal gut to the mammary gland. Although such hypothesis can be a subject of controversy, it should stimulate further research in this fascinating area. If this hypothesis is verified, it would imply that modulation of the intestinal microflora of mothers can have a direct effect on the health of infants and, therefore, would open new perspectives for bacteriotherapy and probiotics.

The experiment was conducted to determine the individual and combined effects of oregano and garlic essential oils on performance, carcase, organ and blood characteristics and intestinal microflora of broilers. Four starter and grower diets were formulated to provide a similar nutrient profile with the exception of using two feed additives or a combined addition of these additives. The diets were

Advances in science and medicine as well as improved living standards have led to a steady increase in life expectancy Yet ageing is associated with increased susceptibility to degenerative or infectious diseases, which may be exacerbated by a poor nutritional status. The intestinal microflora will mediate crucial events towards the protection or degradation of health. It is hence essential and timely that strategies of preventive nutrition aimed at maintaining or improving the quality of life of the ageing population be developed. 'CROWNALIFE" is a newly funded EuropeanUnion project, so called because of its emphasis on the preservation of the period of independence of the elderly recognised as the "crown of life". The project aims at assessing agerelated alterations and exploring strategies to restore and maintain a balanced healthy intestinal environment. Current knowledge on the composition and function of the human intestinal microflora is still improving with the use of better methodologies and yet their evolution with ageing has not been investigated in detail. There have been a few reports that putatively protective lactic acid bacteria, in general, and bifidobacteria, in particular: seem less represented in the elderly faecal flora. We have also observed an increase in species diversity of the dominant faecal microflora with ageing. This certainly warrants confirmation and is being addressed by the investigation of age-related changes in the structure and function of the intestinal flora of the elderly in countries across Europe. Ensuing results will constitute a baseline for functional-food based strategies aimed at providing health benefits for the elderly

Cow's milk allergy (CMA) continues to be a growing health concern for infants living in Western countries. The long-term prognosis for the majority of affected infants is good, with about 80% naturally acquiring tolerance by the age of four years. However, recent studies suggest that the natural history of CMA is changing, with an increasing persistence until later ages. The pathogenesis of CMA, as well as oral tolerance, is complex and not completely known, although numerous studies implicate gut-associated immunity and enteric microflora, and it has been suggested that an altered composition of intestinal microflora results in an unbalanced local and systemic immune response to food allergens. In addition, there are qualitative and quantitative differences in the composition of gut microbiota between patients affected by CMA and healthy infants. These findings prompt the concept that specific beneficial bacteria from the human intestinal microflora, designated probiotics, could restore intestinal homeostasis and prevent or alleviate allergy, at least in part by interacting with the intestinal immune cells. The aim of this paper is to review what is currently known about the use of probiotics as dietary supplements in CMA.

ATCC 4356 T ATCC NA b L. acidophilus NA NA L. agilis DSM 20509 T DSM NA b NA NA NA L. brevis ATCC 14869 T ATCC NA b NA NA NA L. casei ATCC 334 ATCC NA b L. casei NA NA L. casei/L. zeae ATCC 393 T ATCC NA b L. zeae NA NA L. casei ATCC 4684 ATCC NA b L. casei NA NA L. crispatus ATCC 33820 T ATCC NA b L. crispatus NA NA L. delbrueckii subsp. bulgaricus ATCC 11842 T ATCC NA b NA NA NA L. fermentum ATCC 14869 T ATCC NA b L. fermentum NA NA L. gasseri ATCC 33323 T ATCC NA b L. gasseri NA NA L. helveticus ATCC 15009 T ATCC NA b NA NA NA L. johnsonii ATCC 33200 T ATCC NA b L. johnsonii NA NA L. paracasei subsp. paracasei ATCC 25302 ATCC NA b L. casei NA NA L. plantarum ATCC 1988 ATCC NA b L. plantarum NA NA L. plantarum ATCC 14917 T ATCC NA b L. plantarum NA NA L. rhamnosus ATCC 8530 ATCC NA b L. rhamnosus NA NA L. rhamnosus DSM 20021 T DSM NA b L. rhamnosus NA NA L. reuteri DSM 20016 T DSM NA b L. reuteri NA NA L. ruminis ATCC 27780 T ATCC NA b NA NA NA L. salivarius subsp. salicinius ATCC 11742 T ATCC NA b NA NA NA L. salivarius subsp. salivarius ATCC 11741 T ATCC NA b NA NA NA L. sharpeae DSM 20505 T DSM NA b L. sharpeae NA NA L. vitulinus ATCC 27783 T ATCC NA b NA NA NA L. zeae DSM 20178 T DSM NA b L. zeae NA NA GTP5 Pig