Impact of Lactobacillus acidophilus supplements on the human oropharyngeal and intestinal microflora

Anti-Influenza virus effects of Enterococcus faecalis KH2 and Lactobacillus plantarum SNK12 RNA

Bacterial RNA has recently emerged as an immune-stimulating factor during viral infection. The immune response in an organism is directly related to the progression of virus infections. Lactic acid bacteria in particular have anticancer, bioprotective, and antiallergic effects by modulating immunity. Here, we aimed to demonstrate the effect of bacterial RNA on in vitro production of IL-12, a proinflammatory cytokine, and on in vivo activity against influenza A virus (IFV) infection. Oral administration of heat-killed Enterococcus faecalis KH2 (KH2) or Lactobacillus plantarum SNK12 (SNK) in IFV-infected mice suppressed viral replication and stimulated production of virus-specific antibodies. However, ribonuclease-treated KH2 or SNK abrogated the effect, reducing IL-12 production in vitro and anti-IFV effects in vivo. Taken together, KH2 or SNK showed antiviral effects in vivo when administered orally, and the RNAs of KH2 and SNK play a part in these effects, despite the phylogenetic differences between the bacteria.

Changes in the Intestinal Microbiome during a Multispecies Probiotic Intervention in Compensated Cirrhosis

Probiotics have been used in trials to therapeutically modulate the gut microbiome and have shown beneficial effects in cirrhosis. However, their effect on the microbiome of cirrhosis patients is not fully understood yet. Here, we tested the effects of a multispecies probiotic on microbiome composition in compensated cirrhosis. The gut microbiome composition of 58 patients with compensated cirrhosis from a randomized controlled trial who received a daily dose of multispecies probiotics or placebo for six months was analysed by 16S rRNA gene sequencing. Microbiome composition of patients who received probiotics was enriched with probiotic strains and the abundance of Faecalibacterium prausnitzii, Syntrophococcus sucromutans, Bacteroides vulgatus, Alistipes shahii and a Prevotella species was increased in the probiotic group compared to the placebo group. Patients who had microbiome changes in response to probiotic treatment also showed a significant increase in neopterin and a significant decrease in faecal zonulin levels after intervention, which was not observed in placebo-treated patients or patients with unchanged microbiome compositions. In conclusion, multispecies probiotics may enrich the microbiome of compensated cirrhotic patients with probiotic bacteria during a six-month intervention and beneficially change the residential microbiome and gut barrier function.

The effects of a multispecies synbiotic on microbiome-related side effects of long-term proton pump inhibitor use: A pilot study

Side effects of proton pump inhibitors (PPI) can be linked to the changes in the intestinal microbiome that occur during therapy, especially in long-term users. Therefore, the microbiome might also be a key player in the reduction of PPI side effects. We tested the effects of a three-month intervention with a multispecies synbiotic on intestinal inflammation, gut barrier function, microbiome composition, routine laboratory parameters and quality of life in patients with long-term PPI therapy. Thirty-six patients received a daily dose of a multispecies synbiotic for three months and were clinically observed without intervention for another three months. After intervention 17% of patients reached normal calprotectin levels; the overall reduction did not reach statistical significance (−18.8 ng/mg; 95%CI: −50.5; 12.9, p = 0.2). Elevated zonulin levels could be significantly reduced (−46.3 ng/mg; 95%CI: −71.4; −21.2; p < 0.001). The abundance of Stomatobaculum in the microbiome was reduced and Bacillus increased during the intervention. Furthermore, albumin, alkaline phosphatase and thrombocyte count were significantly increased and aspartate transaminase was significantly decreased during intervention. Gastrointestinal quality of life showed significant improvements. In conclusion, microbiome-related side effects of long-term PPI use can be substantially reduced by synbiotic intervention. Further studies are warranted to optimize dosage and duration of the intervention.

Fimbriae and lipopolysaccharides are necessary for co-aggregation between Lactobacilli and Escherichia coli

Cells of Lactobacilli co-aggregated with Escherichia coli K-12 cells to form co-aggregates under mixed-culture conditions at 37 °C for 24 h. Co-aggregation was inhibited by sodium dodecyl sulfate but not by protease. E. coli deletion mutants of fimbriae formation and lipopolysaccharide (LPS) formation did not co-aggregate with Lactobacilli. These results showed that fimbriae and LPS are necessary for co-aggregation between Lactobacilli and E. coli.

Intestinal Protective Effects of Herbal-Based Formulations in Rats against Neomycin Insult

Disturbance in the gut microbial niche by antibiotics like neomycin produces gastrointestinal (GI) disorders. Here, we evaluated the impact of a mixture of extracts of three herbs (Atractylodis Rhizoma Macrocephalae, Massa Medicata Fermentata, and Dolichoris Semen) with known GI protective activities, either laboratory unfermented (herbal formulation-1 (HF-1)) or fermented/re-fermented (herbal formulation-2 (HF-2)) on neomycin-treated rats using a commercial Lactobacillus probiotic as a reference. Treatment with neomycin augmented stool water content, decreased fecal population of Lactobacillus spp., changed the histology of intestine without inducing inflammation, reduced the colonic expression of zonula occludens-1 (ZO-1) and claudin-1, and elevated the serum C-reactive protein (CRP) and interferon-gamma (IFN- γ ) levels. Coadministration of either HF-2 or probiotic, but not HF-1, restored the fecal content of Lactobacillus spp., normalized the serum CRP level, and significantly increased the colonic expression of ZO-1 and claudin-1 in neomycin-treated rats. The combined treatment with any of the above agents ameliorated the histological changes of cecum and colon in neomycin-treated rats, and the magnitude of this effect was probiotic > HF-2 > HF-1. Our study revealed the intestinal protective effect of a mixture of three herbs against neomycin insult, which is mediated through multiple mechanisms and is potentiated upon prior fermentation/refermentation of the herbs.

Antioxidant and cholesterol assimilation activities of selected lactobacilli and lactococci cultures

In present study, three strains of lactic acid bacteria (LAB) viz.Lactobacillus casei,Lactobacillus acidophilusandLactococcus lactisand milk fermented with these strains have been studied for antioxidant and cholesterol assimilation activities in-vitro and in-vivo, in addition to the effect on total lactobacilli, lactococci and coliform counts into the gut of mice fed with diets supplemented by fermented milk. All three selected strains exhibited potent 2,2-diphenyl-1-picrylhydrazyl, malonaldialdehyde and hydrogen peroxide radical scavenging abilities as well as inhibition of linoleic acid peroxidation activity. These activities were highest inLb. caseias followed byLb. acidophilusandLc. lactis. In addition, these bacterial cultures also exhibited good in-vitro cholesterol assimilation potential. Oral administration to mice of milk fermented with selected LAB strains, slightly decreased blood cholesterol, increased colonization of total lactobacilli and lactococci, and decreased coliforms in the intestinal tissues as well as faecal samples. These results indicate that, selected LAB strains have good antioxidant, hypocholesterolemic and coliform removal activities. It may suggest that, a novel functional food can be obtained by supplementation of selected LAB in milk, which may have various health beneficial properties such as antioxidant and hypocholesterolemic activities.

Live and heat-inactivated lactobacilli from feces inhibit Salmonella typhi and Escherichia coli adherence to Caco-2 cells

A quantitative approach has been proposed to evaluate the competitive inhibition of Escherichia coli and Salmonella typhi by live and heat-inactivated laboratory isolated Lactobacillus sp. on adhesion to monolayer of Caco-2 cells. Three species of Lactobacillus (L. casei, L. acidophilus, L. agilis) isolated from human neonate feces and two commercial probiotic strains (L. casei, L. acidophilus) have been compared for probiotic activity. All lactobacilli were able to attach to the Caco-2 cells, however, the degree of adhesion was bacterial strain-dependent. The adhesion indices of the two commercial probiotic strains were not significantly different from the values obtained for the other two similar fecal strains (p > 0.01). The inhibition of attachment of the pathogenic bacteria by inactivated cells of fecal L. acidophilus was examined and compared to the results of live bacteria. The inhibition pattern was similar for live and heat-inactivated L. acidophilus (p > 0.01). The number of attached pathogenic bacteria to the Caco-2 cells decreased when the number of L. acidophilus increased from 10(6) to 10(9) CFU/mL. The heat-inactivated L. acidophilus displayed similar probiotic activity compared to the live bacteria.

Are probiotics detectable in human feces after oral uptake by healthy volunteers?

GOALS

Assessment of the presence of probiotic bacteria in feces after oral ingestion.

BACKGROUND

Probiotic bacteria are said to have beneficial effects on the host. As a precondition for any effect, probiotic strains must survive passage through the gastrointestinal tract.

STUDY

The feces of seven volunteers were analyzed for the presence of probiotic strains after one week's oral ingestion of each of six commercially available products: E. coli Nissle 0.5-5 x 10(9) cells (Mutaflor), Enterococcus faecium SF 68 7.5 x 10(7) cells (Bioflorin), Lactobacillus acidophilus and Bifidobacterium infantis both 1 x 10(9) cells (Infloran), Lactobacillus gasseri and Bifidobacterium longum both 1 x 10(8) cells (Omniflora), Lactobacillus casei rhamnosus 1 x 10(9) cells (Antibiophilus), and yoghurt enriched with Lactobacillus casei Immunitas 1 x 10(10) cells (Actimel). Ten colonies were selected from each stool sample, and DNA was extracted and typed using random amplification of polymorphic DNA (RAPD). Typing patterns of the ingested probiotics and the fecal isolates were compared.

RESULTS

Fingerprints identical to the ingested probiotic strains were recovered from fecal samples of 4/7 volunteers after one week of Mutaflor, from 4/6 after taking Bioflorin, and from 1/6 after Infloran. Cultivation of strains of the same species from fecal specimens was negative after consumption of Antibiophilus, Omniflora and Actimel.

CONCLUSIONS

After oral consumption of probiotics, E. coli and enterococci could be detected in stool samples (57% and 67%, respectively). In contrast, with only one exception, ingested lactobacilli and bifidobacteria could not be detected in human feces.

Fermented milks, probiotic cultures, and colon cancer

Colorectal cancer (CRC) is a major cause of death from cancer in the Western world. Approximately 70% of CRC is associated with environmental factors, probably mainly the diet. There is interest in the potential protective role of fermented milks containing probiotic cultures against CRC. This article analyzes the existing data from human, animal, and in vitro studies that explore whether consumption of milks fermented with probiotic cultures could play a role in colon cancer risk reduction. Cohort studies have failed to detect significant effects, but most case-control studies favor a protective role of fermented milks against colon cancer. Interventional studies have shown a shift of intermediate markers of CRC risk in human subjects from a high- to low-risk pattern after ingestion of fermented milks or probiotics. Animal studies consistently show a reduction in chemically induced colorectal tumor incidence and aberrant crypt formation accompanying probiotic administration. In vitro studies also provide evidence of protection, and permit a better understanding of active compounds involved, and of the mechanisms underlying their anticarcinogenic effects. Probiotics may beneficially modulate several major intestinal functions: detoxification, colonic fermentation, transit, and immune status, which may accompany the development of colon cancer. Although the evidence is not conclusive and much further research is required, the data reviewed constitute a promising body of evidence supporting the protective role of milks fermented with probiotic cultures in colon cancer risk reduction.

Effect of Ampicillin on the kinetics of colonization of Streptococcus pneumoniae and Lactobacillus fermentum in the respiratory tract of mice

Ampicillin was selected to further study the effect of this antibiotic on the colonization capability of S. pneumoniae and L. fermentum intranasally inoculated in a mice experimental model. The sensitivity of S. pneumoniae and L. fermentum to antibiotics was evaluated by different "in vitro" techniques. The results showed that both microorganisms have a typical pattern of sensitivity to antibiotics in these assays. The "in vivo" experiments showed that the treatment with Ampicillin increased the number of lactobacilli and neumococci in the groups of mice treated only with one of the microorganisms. In those mice treated with Lactobacillus, challenged later with neumococci and treated with Ampicillin, the pathogen in lung decreased on the 4th day, disappearing completely after on. The histological studies showed that the antibiotic treatment decreased the inflammatory response produced by the pathogen at the lung and trachea levels.

Dietary influence of kefir on microbial activities in the mouse bowel

AIMS

In this work the microflora present in kefir, a fermented milk product, was studied together with the effect of kefir administration on different groups of indigenous bacteria of mouse bowel.

METHODS AND RESULTS

Kefir microflora was composed of lactic acid bacteria, acetic acid bacteria and yeasts. Yeast population was composed of Saccharomyces cerevisiae, S. unisporus, Candida kefir, Kluyveromyces marxianus and K. lactis. The streptococci levels in kefir treated mice increased by 10-fold and the levels of sulfite-reducing clostridia decreased by 100-fold. The number of lactic acid bacteria increased significantly.

CONCLUSIONS

The administration of kefir significantly increased the lactic acid bacteria counts in the mucosa of the bowel. Ingestion of kefir specifically lowered microbial populations of Enterobacteriaceae and clostridia.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first long-term study about the effects of the kefir administration on the intestinal microflora of mice.

Biotherapeutic agents and disease in infants

Human milk contains many factors that act synergistically or with redundancy in protecting suckling infants from infectious diseases. The rigorous application of the scientific method has shown significant beneficial effects of these specific factors. The beneficial effects of biotherapeutic agents, including prebiotics and probiotics, on the alteration of intestinal microflora and modulation of the local and systemic immune response of infants have been shown. The beneficial effects of these compounds on preventing diarrhea and possibly other infectious diseases in infants serves as a model for the development and use of biotherapeutic agents to treat and prevent infectious diseases in persons of all ages.

Protective effect of intranasally inoculated Lactobacillus fermentum against Streptococcus pneumoniae challenge on the mouse respiratory tract

Lactic acid bacteria are increasingly used to restore the ecological equilibrium of different mucosal areas in humans and/or animals. Likewise, they can be used to potentially protect against pathogenic microorganisms. In the present paper, the preventive effect of intranasally inoculated Lactobacillus fermentum against challenge with Streptococcus pneumoniae was studied, using a mouse experimental model. L. fermentum inoculated four times at a dose of 10(7) colony forming units per mouse was able to decrease the number of S. pneumoniae throughout the respiratory tract. The L. fermentum treatment increased the number of activated macrophages in lung slices, and a higher lymphocyte population in the tracheal lamina propria. S. pneumoniae challenge showed a typical response against pathogen with a higher non-specific immune response. Preventive treatment, i.e. L. fermentum administration prior to S. pneumoniae challenge, showed a response close to that of L. fermentum. Anti-S. pneumoniae antibodies increased in lactobacilli-treated animals compared to the non-treated lactobacilli mice. The increase in the antibody levels suggests that the mucosal immune system could be involved in the protective effect, accomplished with competitive exclusion, nutrient competition and production of inhibitory substances. This paper will be the basis for further studies of the protective effect of lactobacilli against S. pneumoniae in the respiratory tract.

Establishment of orally-administered Lactobacillus gasseri SBT2055SR in the gastrointestinal tract of humans and its influence on intestinal microflora and metabolism

AIMS

To investigate the fate of a streptomycin-rifampicin-resistant variant of Lactobacillus gasseri SBT2055 (LG2055SR) and the influence of its oral administration on the composition and metabolism of the intestinal microflora.

METHODS AND RESULTS

Intestinal passage of LG2055SR was monitored by a combination of selection with antibiotics and identification by a randomly amplified polymorphic DNA (RAPD)-PCR METHOD: Composition of intestinal microflora was analysed by the method developed by Mitsuoka et al. (1965, 1974). Establishment of orally-administered LG2055SR in the human intestine was confirmed in this study. LG2055SR ingestion specifically lowered faecal populations of Staphylococcus and faecal contents of p-cresol.

CONCLUSION

LG2055SR and its parent strain, LG2055, are considered to be appropriate candidates for probiotics.

SIGNIFICANCE AND IMPACT OF THE STUDY

It is clarified that LG2055SR has the ability to establish in the human gastrointestinal tract and alters the composition and metabolism of the intestinal microflora and physical characteristics of faeces.

Effect of supplements with lactic acid bacteria and oligofructose on the intestinal microflora during administration of cefpodoxime proxetil

Thirty healthy volunteers in three groups participated in a study of the effect on the intestinal microflora of oral supplementation with Bifidobacterium longum, Lactobacillus acidophilus and oligofructose, an indigestible oligosaccharide, during oral administration of cefpodoxime proxetil bd for 7 days. Those in group A also received an oral supplement with c.1011 cfu of B. longum BB 536 and L. acidophilus NCFB 1748 and 15 g oligofructose daily, those in group B received a supplement with oligofructose only and those in group C received placebo, for 21 days. In all three groups there was a marked decrease in aerobic microorganisms, involving mainly a rapid and almost complete disappearance of Escherichia coli (P: < 0.05) during antimicrobial administration and, thereafter, an overgrowth of enterococci (P: < 0.05). The number of intestinal yeasts also increased significantly (P: < 0.05) in groups A and B over the same period. There was a dramatic decrease in anaerobic microorganisms on day 4 of administration, mainly caused by loss of bifidobacteria (P: < 0.05) in all groups. The number of lactobacilli also decreased but was significantly higher in group A than in group C at the end of cefpodoxime proxetil administration. Clostridium difficile was found in only one person from group A, but six persons each in groups B and C. Of the bifidobacterial strains isolated from the faecal samples in group A, one was similar to the strain of B. longum administered, but most volunteers were colonized by several different strains of B. longum during the investigation period. The administered strain of L. acidophilus was recovered from six patients in group A.

Quantitative approach in the study of adhesion of lactic acid bacteria to intestinal cells and their competition with enterobacteria

To describe the phenomena of bacterial adhesion to intestinal cells and the competition for adhesion between bacteria, mathematical equations based on a simple dissociation process involving a finite number of bacterial receptors on intestinal cell surface were developed. The equations allow the estimation of the maximum number of Lactobacillus sp. and Escherichia coli cells that can adhere to Caco-2 cells and intestinal mucus; they also characterize the affinity of the bacteria to Caco-2 cells and intestinal and fecal mucus and the theoretical adhesion ratio of two bacteria present in a mixed suspension. The competition for adhesion between Lactobacillus rhamnosus GG and E. coli TG1 appeared to follow the proposed kinetics, whereas the competition between Lactobacillus casei Shirota and E. coli TG1 may involve multiple adhesion sites or a soluble factor in the culture medium of the former. The displacement of the adhered Lactobacillus by E. coli TG1 seemed to be a rapid process, whereas the displacement of E. coli TG1 by the Lactobacillus took more than an hour.

Behaviour of Saccharomyces boulardii in recurrent Clostridium difficile disease patients

BACKGROUND

Despite recent interest in therapeutic microorganisms taken orally, little is known about the pharmacodynamics of these agents in a target population of patients with disease. The present study reports the stool concentrations of Saccharomyces boulardii in a patient population with Clostridium difficile disease (CDD) and correlates stool concentrations with efficacy.

METHODS

Patients with recurrent CDD all received a 10-day standard antibiotic regimen together with 28 days of S. boulardii or placebo. Stool samples were collected from patients at various time points and assayed for S. boulardii.

RESULTS

The mean concentration of S. boulardii of patients who recurred was 2.5 x 104 CFU/g compared to 1 x 106 CFU/g in patients that did not recur (P=0.02). Patients with low yeast concentrations in their stools (<104/g) recurred more often (14/15, 93%) compared with patients with higher levels (19/35, 54%, P=0.007). Clearance of S. boulardii was rapid; only 4% had positive stools 3 days after stopping dosing.

CONCLUSIONS

After chronic dosing of S. boulardii, patients with low stool concentrations had a higher likelihood of recurrence of CDD. Stool concentrations were also lower during periods of diarrhoea. These results show the importance of characterizing the dynamics of a therapeutic microorganism in patients with disease, as kinetic studies in healthy volunteers may not give a true reflection of the disturbed microecology in the disease state.

Microbial flora variations in the respiratory tract of mice

A stable microbial system in the respiratory tract acts as an important defense mechanism against pathogenic microorganisms. Perturbations in this system may allow pathogens to establish. In an ecological environment such as the respiratory tract, there are many diverse factors that play a role in the establishment of the indigenous flora. In the present work we studied the normal microbial flora of different areas of the respiratory tract of mice and their evolution from the time the mice were born. Our interest was to know which were the dominant groups of microorganisms in each area, which were the first capable of colonizing and which dominated over time to be used as probiotic microorganisms. Our results show that Gram negative facultatively anaerobic bacilli and strict anaerobic microorganisms were the last ones to appear in the bronchia, while aerobic and Gram positive cocci were present in all the areas of the respiratory tract. The number of facultative aerobes and strict anaerobes were similar in the nasal passage, pharynx instilled and trachea, but lower in bronchia. The dominant species were Streptococcus viridans and Staphylococcus saprophyticcus, followed by S. epidermidis, Lactobacilli and S. cohnii I which were present on every studied days but at different proportions. This paper is the first part of a research topic investigating the protective effect of the indigenous flora against pathogens using the mice as an experimental model.

Effect of propionibacteria supplementation on fecal bifidobacteria and segmental colonic transit time in healthy human subjects

BACKGROUND

Some strains of Propionibacterium have bifidogenic properties and enhance gut motility in the animal. However, they are not part of the indigenous fecal flora. This study was designed to assess the digestive survival of ingested propionibacteria, their bifidogenic properties, and the resulting changes in colonic transit time in healthy humans.

METHODS

Eighteen subjects were given 5 . 10(10) CFU propionibacteria/day during 2 weeks. Fecal concentrations of propionibacteria and bifidobacteria were counted before (day -8, day -1), during (day 7, day 14), and after (day 21, day 28) the supplementation. Colonic transit time was measured before and at the end of the 1st week of supplementation.

RESULTS

Basal counts of propionibacteria were less than 5 log CFU/ml stools. They increased in 15 subjects to (mean+/-1 standard deviation) 5.63+/-0.71 and 6.37+/-0.89 on day 7 (P < 0.01) and day 14 (P < 0.01) and returned to basal levels on day 21. Basal counts of bifidobacteria (mean, 7.94+/-0.71) increased to 8.39+/-0.97 on day 7, 8.36+/-0.86 on day 14, and 8.70+/-0.95 on day 21 (P < 0.05 from mean basal count) and returned to pretreatment levels on day 28 (7.88+/-1.38). Mean counts of propionibacteria during supplementation and bifidobacteria levels on day 14 were significantly correlated (P = 0.01). Transit time did not change in the right colon (17.4+/-8.1 h versus 17.3+/-8.3 h) or in the rectosigmoid area(12.8+/-8.5 versus 13.3+/-0.2 h); left colon transit was significantly slowed (7.0+/-5.0 h versus 11.9+/-9.4 h; P < 0.05).

CONCLUSIONS

Part of the ingested propionibacteria were able to survive the digestive transit. This supplementation was associated with changes in segmental colonic motility, yet the mechanisms involved in these changes remain unknown.

The effect of probiotic strains on the microbiota of the Simulator of the Human Intestinal Microbial Ecosystem (SHIME)

The aim of the present work was to study five potential probiotic strains (Lactobacillus plantarum, two strains of L. paracasei subsp. paracasei, L. rhamnosus and Bifidobacterium sp.) comparatively in the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) in vitro model, and to evaluate this model as a tool in the screening and selection of probiotic bacteria. The impact of the strains on the composition of microbiota and its metabolic activities (production of lactic acid and short-chain fatty acids) was studied. Changes in composition of the microbiota become apparent as a result of probiotic treatment. A marked, but temporary, increase was noted in the number of lactic acid bacteria and bifidobacteria. The profiles of D(-) and L(+) isomers of lactic acid detected in the SHIME after addition of probiotic strains corresponded well to those that are produced in pure culture conditions. The numbers of enterobacteriaceae decreased markedly and those of clostridia detectably during the intervention, while the enterococci tended to increase after the treatment. This pattern was similar in the reactors representing both the small and large intestine in the model. The changes in short-chain fatty acids were small, and no definite trend was observed.

In vitro lactose fermentation by human colonic bacteria is modified by Lactobacillus acidophilus supplementation

Adaptation of the colonic flora to lactose may contribute to lactose digestion in lactose maldigesters, and supplementation with Lactobacillus acidophilus may modify colonic fermentation of lactose and short-chain fatty acid production. We evaluated the capability of colonic bacteria to ferment lactose and the ability of L. acidophilus to modify lactose fermentation by the colonic microflora in vitro. An anaerobic continuous culture was established and inoculated with fresh samples of human feces. Lactose infusion was maintained at 25 g/d and pH at 6.7. L. acidophilus strain LA-1 (1.5 x 10(10) cells) was introduced into the fermenter on d 0 or added daily on d 0 through 4. The control was the continuous culture without the addition of lactobacilli. Rapid adaptation of colonic bacteria to lactose occurred within 1-2 d, with a significant decrease in lactose concentration and increase in beta-galactosidase activity, and lactose concentrations fell below 3 mmol/L by d 7. Supplementation with strain LA-1 resulted in a significantly greater decrease in lactose concentration and greater increase in acetate and propionate production within the first day compared with the control group. However, there was no significant difference between the fermentation treated with L. acidophilus daily and the control after the first day. These data suggest that the colonic bacteria adapt quickly to lactose, causing efficient utilization of lactose. L. acidophilus supplementation may enhance lactose fermentation during early periods when the adaptation is not established in this model.

Lactobacillus reuteri as a therapeutic agent in acute diarrhea in young children

BACKGROUND

Certain strains of lactobacilli may promote recovery from acute diarrhea. Lactobacillus reuteri is of human origin and is a natural colonizer of gastrointestinal tract. In this trial, exogenously administered L. reuteri was studied as a therapeutic agent in acute diarrhea.

METHODS

Forty patients between 6 and 36 months of age hospitalized with acute diarrhea (75% rotavirus) were studied. After parental consent, the patients were randomized to one of two treatment groups to receive either 10(10) to 10(11) colony-forming units of L. reuteri or a matching placebo daily for the length of hospitalization or up to 5 days. The clinical outcome of diarrhea and colonization of L. reuteri were evaluated.

RESULTS

The mean (SD) duration of watery diarrhea after treatment was 1.7 (1.6) days in the L. reuteri group and 2.9 (2.3) days in the placebo group (p = 0.07). On the second day of treatment only 26% of patients receiving L. reuteri had watery diarrhea, compared with 81% of those receiving placebo (p = 0.0005). Cultures of lactobacilli from stool samples demonstrated that administration of L. reuteri resulted in colonization of the gastrointestinal tract. Lactobacillus reuteri accounted for > 75% of the total lactobacilli found in children fed with this product.

CONCLUSIONS

Lactobacillus reuteri is effective as a therapeutic agent in acute rotavirus diarrhea in children. Further studies are warranted to confirm the present finding and to explore the full therapeutic potential of L. reuteri in acute viral diarrhea.

Effect of oral supplementation of lactobacilli on bacterial translocation in acute liver injury induced by D-galactosamine

BACKGROUND/AIM

Bacterial infections and sepsis are frequent complications of acute liver injury, with a high share in the mortality and morbidity of this condition. Bacterial translocation from the gut may play an important role in the high rate of infections observed. In this experiment the effect of different oral supplementation on bacterial translocation was evaluated in acute liver injury induced by D-galactosamine in the rat.

METHODS

Rats were given oral supplements of lactulose, neomycin, Lactobacillus reuteri R2LC, and Lactobacillus plantarum DSM 9843 for 1 week. Liver injury was induced by intraperitoneal administration of 1.1 g/kg D-galactosamine. Twenty-four hours later, rats were sacrificed and liver enzymes and histology, intestinal bacterial count and microflora, intestinal mucosal histology, DNA and RNA content, bacterial translocation to blood, mesenteric lymph nodes, and liver, and serum endotoxin were studied or measured.

RESULTS

Lactulose was highly effective in prevention of liver injury and bacterial translocation. Neomycin and Lactobacillus plantarum DSM 9843 showed a moderate effect in prevention of liver injury and bacterial translocation. Intestinal bacterial count and microflora were affected by different treatment modalities. No endotoxin concentration was found in any of the experimental groups. Both lactobacilli could significantly improve the mucosal proliferative state.

CONCLUSIONS

Oral supplementation of lactulose with anti-endotoxin effect could successfully prevent the liver injury and the subsequent bacterial translocation in acute liver injury induced by administration of D-galactosamine in the rat. This effect was irrespective of the intestinal bacterial alteration or mucosal proliferative state.

Oral supplementation with lactic acid-producing bacteria during intake of clindamycin

OBJECTIVE: To study the effect of administration of clindamycin with or without supplementation of the intestinal microflora with Bifidobacterium bifidum and Lactobacillus acidophilus. METHODS: Twenty-three healthy subjects received clindamycin by mouth for 7 days. Eleven of the subjects also received capsules containing lyophilized L. acidophilus and B. bifidum for 14 days. The other 12 subjects received placebo. RESULTS: There was a marked decrease in total numbers of anaerobic bacteria during the administration of clindamycin. In the lactic acid bacteria-supplemented group, a tendency towards delayed reduction and earlier increase in bifidobacteria was observed, and two of 11 subjects (18%) were colonized with Clostridium difficile, in comparison with five of 12 (41%) in the placebo group. The total number of microorganisms was significantly higher in the lactic acid bacteria-supplemented group than in the placebo group (p=0.02) 4 days after the end of clindamycin administration. The difference was mainly due to higher counts of Escherichia coli and enterococci. Mean levels of other enterobacteria increased less in the lactic acid bacteria-supplemented group than in the placebo group between days 0 and 14. CONCLUSIONS: The recolonization with aerobic and anaerobic microorganisms was faster in the lactic acid bacteria-supplemented group than in the placebo group. This may be of importance in preventing colonization with C. difficile.

Effect of administration of milk fermented with Lactobacillus acidophilus LA-2 on fecal mutagenicity and microflora in the human intestine

To demonstrate the antimutagenic effect of fermented milk in the human intestine, fecal mutagenicity and bacterial composition of six healthy subjects consuming their regular diet were investigated before and during the administration of milk fermented with Lactobacillus acidophilus LA-2. The administration of the fermented milk caused a remarkable decrease (71.9% on the average; range of 19.4 to 90.6%) in fecal mutagenicity compared with that before the administration; Lactobacillus spp. and Bifidobacterium spp. population increased in the feces of all subjects. The suppression of fecal mutagenicity appeared to be due to the change in fecal microflora caused by the presence of strain LA-2 in the human intestine.

The role of oral administration of oatmeal fermented by Lactobacillus reuteri R2LC on bacterial translocation after acute liver failure induced by subtotal liver resection in the rat

BACKGROUND

Previous experimental studies showed that a disturbed ecology of the enteric bacterial population might contribute to the occurrence of bacterial translocation from the gut in acute liver failure (ALF).

METHODS

In the present study the effects of oral administration of exogenous Lactobacillus reuteri R2LC and oat fiber on bacterial overgrowth and translocation and on enterocyte protein contents were investigated in rats with ALF induced by subtotal liver resection. The oatmeal soup base was anaerobically inoculated with L. reuteri R2LC and fermented for 15 h. The animals were then fed with fermented or unfermented oatmeal or saline daily for 6 days before the experimental procedure.

RESULTS

The incidence of bacterial translocation to the systemic circulation was nil and 17% in rats subjected to sham operation with saline or 90% hepatectomy with fermented oatmeal, respectively, and 80-90% and 34-50% in rats subjected to hepatectomy with saline or unfermented oatmeal. One rat treated with fermented oatmeal had positive bacterial growth in mesenteric lymph nodes (MLN), which was significantly lower than in hepatectomized rats with saline or unfermented oatmeal (80-100% and 50-67%). No significant differences was demonstrable between hepatectomized animals with oral administration of fermented or unfermented oatmeal as compared with sham-operated rats. The number of anaerobic bacteria, Gram-negative anaerobes, and Lactobacillus decreased significantly, and the number of Escherichia coli increased in the distal small intestine and colon in hepatectomized animals with saline or unfermented oatmeal, as compared with animals subjected to sham operation or hepatectomy with fermented oatmeal.

CONCLUSIONS

The occurrence of bacterial translocation from the gut in 90% hepatectomy-induced ALF could be prevented by fermented oatmeal, which implies possibilities for biologically balancing the enteric bacterial ecology.

Microbiological evaluation of jejunal aspirates and faecal samples after oral administration of bifidobacteria and lactic acid bacteria

A double-blind placebo controlled investigation was carried out to study the effect of peroral colonization. Human volunteers were given mixtures of bifidobacteria and lactic acid bacteria. Measurements were made over a 1 week treatment period and for another week after the end of the treatment. Two different bacteriological preparations were used, one consisted of Enterococcus faecium and Bifidobacterium longum (a total of 6.4 x 10(8) cfu d-1); the other consisted of Lactobacillus acidophilus, Bif. bifidum, Lact. delbrueckii ssp. bulgaricus, and Streptococcus thermophilus (a total of 9 x 10(9) cfu d-1). Together with a placebo preparation, they were given to 24 healthy controls (eight in each group). Microbiological examinations of jejunal aspirates showed that viable counts of most species were below the detection limit. However, the test preparation containing Ent. faecium and Bif. longum significantly reduced the anaerobe: aerobe ratio in faeces by a factor of three during treatment (P = 0.03), and increased it by a factor of 30 during the following week (P < 0.02). This study shows that peroral administration of certain bacterial cultures may affect the distal intestinal microflora.

Potential of using lactic acid bacteria for therapy and immunomodulation in man

There is in 1993 no proven medical indication of lactic acid bacteria (LAB) for therapy or immunomodulation in man. However, within the bulk of publications, rigorous trials have now opened rational fields of research on beneficial effects of LAB. These include lactose digestion, cholesterol metabolism, diarrheal disorders, prophylaxis of intestinal or urogenital infections, immunomodulation or even oral vaccination. We try here to analyse these studies, considering LAB as pharmacological agents, and conclude that pursuit of research could be promising for ecological therapy of mucosal diseases, and for development of original and flexible vectors for targeting in the gastrointestinal tract.

Numerical taxonomy of Lactobacillus spp. associated with healthy and diseased mucosa of the human intestines

Two-hundred and fifty Lactobacillus strains isolated from healthy and diseased mucosa of human intestines of 75 individuals and 49 reference strains were phenotypically classified using 49 unit characters. Data were processed by the Jaccard (SJ) and Simple Matching (SSM) coefficients, and unweighted pair group algorithm with arithmetic averages. Seventeen major clusters were defined at the 76% SJ-similarity level which approximately correspond to the SSM-level of 91%. Seven clusters could be identified: Lactobacillus plantarum (isolates recovered from 5% of the patients), Lact. casei subsp. rhamnosus (17% of the patients), Lact. casei subsp. pseudoplantarum (5% of the patients), Leuconostoc mesenteroides subsp. mesenteroides (3% of the patients), Lact. buchneri (4% of patients), Lact. reuteri (4% of the patients) and Lact. salivarius subsp. salivarius (9% of the patients). Unassigned clusters 1 and 3 both contained homofermentative Lactobacillus strains. Cluster 1 included the type strains of Lact. crispatus, Lact. acidophilus, Lact. jensenii and Lact. gasseri, and cluster 3, the type strains of Lact. delbrueckii subsp. lactis, Lact. agilis and Lact. casei subsp. tolerans. Clusters 1 and 3 were found in 15% and 25% of the patients, respectively. Unassigned clusters 2, 6, 7, 8 and 10 contained homofermentative Lactobacillus strains but no reference strains. Clusters 11, 12, 15 and 17 were made up of heterofermentative Lactobacillus strains but no reference strains. Phenotypical characteristics of the clusters are given. No obvious trends in species (cluster) composition between different intestinal locations could be noted. Most clusters contained isolates from both diseased and healthy mucosa. Exceptions were cluster 15 and cluster 17 which only included isolates from healthy mucosa, and cluster 11 which only included isolates from diseased mucosa. Cluster 15 was isolated in 12% of the patients, and cluster 11 in 8%.