Effect of probiotic bacteria on prevalence of yeasts in oropharyngeal biofilms on silicone rubber voice prostheses in vitro.
(41/1007)
The proliferation of yeasts in the mixed bacterial and fungal biofilms colonising silicone rubber voice prostheses in laryngectomised patients is the main cause of malfunctioning of the valve mechanism on the oesophageal side of the prostheses. Indwelling voice prostheses usually have to be replaced every 3-4 months. The consumption of probiotic bacteria is largely motivated by health claims related to the urogenital and lower digestive tract, but not to the upper digestive tract. The present study examined the influence of probiotic bacteria on the prevalence of yeasts in oropharyngeal biofilms on silicone rubber voice prostheses, as formed in a modified Robbins device. Exposure of oropharyngeal biofilms on voice prostheses to suspensions of Bifidobacterium infantis 420 or Enterococcus faecium 603 did not significantly reduce the number of yeasts in the biofilm. However, suspensions of Lactobacillus fermentum B54, L. rhamnosus 744 or L. lactis cremoris SK11 led to a reduction in the number of yeasts harvested from the voice prostheses. Suspensions of L. casei Shirota and Streptococcus thermophilus B significantly reduced the number of yeasts in the biofilm to 39% and 33%, respectively. The reduction brought about in yeast prevalence in the mixed biofilm was greatest by exposure to a suspension of L. lactis 53, with yeast prevalence only 4% of the control. In conclusion, the study demonstrated that the prevalence of yeasts in oropharyngeal biofilms on silicone rubber voice prostheses might be controlled by consumption of probiotic bacteria. (+info)
Chemostat enrichments of human feces with resistant starch are selective for adherent butyrate-producing clostridia at high dilution rates.
(42/1007)
Resistant starch (RS) enrichments were made using chemostats inoculated with human feces from two individuals at two dilution rates (D = 0.03 h(-1) and D = 0.30 h(-1)) to select for slow- and fast-growing amylolytic communities. The fermentations were studied by analysis of short-chain fatty acids, amylase and alpha-glucosidase activities, and viable counts of the predominant culturable populations and the use of 16S rRNA-targeted oligonucleotide probes. Considerable butyrate was produced at D = 0. 30 h(-1), which corresponded with reduced branched-chain fatty acid formation. At both dilution rates, high levels of extracellular amylase activity were produced, while alpha-glucosidase was predominantly cell associated. Bacteroides and bifidobacteria predominated at the low dilution rate, whereas saccharolytic clostridia became more important at D = 0.30 h(-1). Microscopic examination showed that within 48 h of inoculation, one particular bacterial morphotype predominated in RS enrichments at D = 0.30 h(-1). This organism attached apically to RS granules and formed rosette-like structures which, with glycocalyx formation, agglomerated to form biofilm networks in the planktonic phase. Attempts to isolate this bacterium in pure culture were repeatedly unsuccessful, although a single colony was eventually obtained. On the basis of its 16S rDNA sequence, this RS-degrading, butyrate-producing organism was identified as being a previously unidentified group I Clostridium sp. A 16S rRNA-targeted probe was designed using this sequence and used to assess the abundance of the population in the enrichments. At 240 h, its contributions to total rRNA in the chemostats were 5 and 23% at D = 0.03 and 0.30 h(-1), respectively. This study indicates that bacterial populations with significant metabolic potential can be overlooked using culture-based methodologies. This may provide a paradigm for explaining the discrepancy between the low numbers of butyrate-producing bacteria that are isolated from fecal samples and the actual production of butyrate. (+info)
Effect of supplements with lactic acid bacteria and oligofructose on the intestinal microflora during administration of cefpodoxime proxetil.
(43/1007)
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. (+info)
Bifidobacterium strains from resident infant human gastrointestinal microflora exert antimicrobial activity.
(44/1007)
BACKGROUND AND AIMS: The gastrointestinal microflora exerts a barrier effect against enteropathogens. The aim of this study was to examine if bifidobacteria, a major species of the human colonic microflora, participates in the barrier effect by developing antimicrobial activity against enterovirulent bacteria. METHODS: Antibacterial activity was examined in vitro against a wide range of Gram negative and Gram positive pathogens. Inhibition of Salmonella typhimurium SL1334 cell association and cell invasion was investigated in vitro using Caco-2 cells. Colonisation of the gastrointestinal tract in vivo by bifidobacteria was examined in axenic C3/He/Oujco mice. Antimicrobial activity was examined in vivo in axenic C3/He/Oujco mice infected by the lethal S typhimurium C5 strain. RESULTS: Fourteen human bifidobacterium strains isolated from infant stools were examined for antimicrobial activity. Two strains (CA1 and F9) expressed antagonistic activity against pathogens in vitro, inhibited cell entry, and killed intracellular S typhimurium SL1344 in Caco-2 cells. An antibacterial component(s) produced by CA1 and F9 was found to be a lipophilic molecule(s) with a molecular weight of less than 3500. In the axenic C3/He/Oujco mice, CA1 and F9 strains colonised the intestinal tract and protected mice against S typhimurium C5 lethal infection. CONCLUSION: Several bifidobacterium strains from resident infant human gastrointestinal microflora exert antimicrobial activity, suggesting that they could participate in the "barrier effect" produced by the indigenous microflora. (+info)
Importance of intestinal colonisation in the maturation of humoral immunity in early infancy: a prospective follow up study of healthy infants aged 0-6 months.
(45/1007)
AIM: To evaluate the role of intestinal microflora and early formula feeding in the maturation of humoral immunity in healthy newborn infants. STUDY DESIGN: Sixty four healthy infants were studied. Faecal colonisation with Bacteroides fragilis group, Bifidobacterium-like, and Lactobacillus-like bacteria was examined at 1, 2, and 6 months of age, and also the number of IgA-secreting, IgM-secreting, and IgG-secreting cells (detected by ELISPOT) at 0, 2, and 6 months of age. RESULTS: Intestinal colonisation with bacteria from the B fragilis group was more closely associated with maturation of IgA-secreting and IgM-secreting cells than colonisation with the other bacterial genera studied or diet. Infants colonised with B fragilis at 1 month of age had more IgA-secreting and IgM-secreting cells/10(6) mononuclear cells at 2 months of age (geometric mean (95% confidence interval) 1393 (962 to 2018) and 754 (427 to 1332) respectively) than infants not colonised (1015 (826 to 1247) and 394 (304 to 511) respectively); p = 0.04 and p = 0.009 respectively. CONCLUSIONS: The type of bacteria colonising the intestine of newborns and the timing may determine the immunomodulation of the naive immune system. (+info)
Acetaldehyde production and metabolism by human indigenous and probiotic Lactobacillus and Bifidobacterium strains.
(46/1007)
Many human gastrointestinal facultative anaerobic and aerobic bacteria possess alcohol dehydrogenase (ADH) activity and are therefore capable of oxidizing ethanol to acetaldehyde. We examined whether human gastrointestinal lactobacilli (three strains), bifidobacteria (five strains) and probiotic Lactobacillus GG ATCC 53103 are also able to metabolize ethanol and acetaldehyde in vitro. Acetaldehyde production by bacterial suspensions was determined by gas chromatography after a 1-h incubation with 22 mM ethanol. To determine the acetaldehyde consumption, the suspensions were incubated with 50 microM or 500 microM acetaldehyde as well as with 500 microM acetaldehyde and 22 mM ethanol, i.e. under conditions resembling those in the human colon after alcohol intake. The influence of growth media and bacterial concentration on the ability of lactobacilli to metabolize acetaldehyde and to produce acetate from acetaldehyde were determined. ADH and aldehyde dehydrogenase (ALDH) activities were determined spectrophotometrically. Neither measurable ADH nor ALDH activities were found in aerobically grown Lactobacillus GG ATCC 53103 and Lactobacillus acidophilus ATCC 4356 strains. All the lactobacilli and bifidobacteria strains revealed a very limited capacity to oxidize ethanol to acetaldehyde in vitro. Lactobacillus GG ATCC 53103 had the highest acetaldehyde-metabolizing capacity, which increased significantly with increasing bacterial concentrations. This was associated with a marked production of acetate from acetaldehyde. The type of the growth media had no effect on acetaldehyde consumption. Addition of ethanol to the incubation media diminished the acetaldehyde-metabolizing capacity of all strains. However, in the presence of ethanol, Lactobacillus GG ATCC 53103 still demonstrated the highest capacity for acetaldehyde metabolism of all strains. These data suggest a beneficial impact of Lactobacillus GG ATCC 53103 on high gastrointestinal acetaldehyde levels following alcohol intake. The possible clinical implications of this finding remain to be established in in vitro studies. (+info)
Inhibitory effect of apple pectin and culture condensate of Bifidobacterium longum on colorectal tumors induced by 1,2-dimethylhydrazine in transgenic mice harboring human prototype c-Ha-ras genes.
(47/1007)
The number and tumor score of colorectal tumors induced by 1,2-dymethylhydrazine in transgenic (Tg) mice carrying human c-Ha-ras genes were significantly reduced by ingestion of apple pectin (AP) or a culture condensate of Bifidobacterium longum (MB) when compared with a control diet. There was no statistical difference in the incidence of colorectal tumors in Tg mice between the AP or MB diet and the control diet. This study demonstrated that Tg mice are a useful tool for screening inhibition of colorectal tumors by functional foods. (+info)
Purification and identification of a growth-stimulating peptide for Bifidobacterium bifidum from natural rubber serum powder.
(48/1007)
Natural rubber serum powder, which is a by-product obtained in the production of latex rubber, has a strong growth-stimulating activity for Bifidobacterium bifidum JCM 1254. The retained fraction obtained by ultrafiltration (molecular weight cutoff 1000) showed a growth-stimulating activity in a dose-dependent manner on B12 assay medium with ammonium sulfate. One of the growth stimulators was purified from the retained fraction by acetone precipitation, solid-phase extraction with a hydrophobic pretreatment column, and multistage reversed-phase HPLC. An increase of 53-fold in the specific activity, and a recovery of 1.3% were obtained. The amino acid composition and N-terminal sequence analysis of this growth stimulator provided the structure of Ala-Thr-Pro-Glu-Lys-Glu-Glu-Pro-Thr-Ala. The molecular mass was 1075 by MALDI-TOF MS analysis. These results showed that this growth stimulator was a decapeptide with the sequence shown above. This is the first report that clarified the structure of an active peptide for the growth of Bifidobacterium. (+info)