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PubMed2005

Antibiotic resistance in food lactic acid bacteria--a review.

Antibiotics are a major tool utilized by the health care industry to fight bacterial infections; however, bacteria are highly adaptable creatures and are capable of developing resistance to antibiotics. Consequently, decades of antibiotic use, or rather misuse, have resulted in bacterial resistance to many modern antibiotics. This antibiotic resistance can cause significant danger and suffering for many people with common bacterial infections, those once easily treated with antibiotics. For several decades studies on selection and dissemination of antibiotic resistance have focused mainly on clinically relevant species. However, recently many investigators have speculated that commensal bacteria including lactic acid bacteria (LAB) may act as reservoirs of antibiotic resistance genes similar to those found in human pathogens. The main threat associated with these bacteria is that they can transfer resistance genes to pathogenic bacteria. Genes conferring resistance to tetracycline, erythromycin and vancomycin have been detected and characterized in Lactococcus lactis, Enterococci and, recently, in Lactobacillus species isolated from fermented meat and milk products. A number of initiatives have been recently launched by various organizations across the globe to address the biosafety concerns of starter cultures and probiotic microorganisms. The studies can lead to better understanding of the role played by the dairy starter microorganisms in horizontal transfer of antibiotic resistance genes to intestinal microorganisms and food-associated pathogenic bacteria.

Anti-Bacterial Agents↗

PubMed1990

Effect of carbadox on net absorption of ammonia and glucose into hepatic portal vein of growing pigs.

Chronic cannulas were placed into the hepatic portal vein, ileal vein and carotid artery of growing pigs trained to consume their daily allowance of 1.2 kg of feed (16% protein corn-soybean meal basal diet) in a single meal. The average preoperative BW of pigs was 44.7 kg for Trial 1 (three pigs) and 35.3 kg for Trial 2 (seven pigs). In Trial 1, net absorption of ammonia (NH3) and glucose into the portal vein was determined three times at weekly intervals. The net portal absorptions were derived by multiplying the porto-arterial plasma concentration difference of NH3 and glucose by portal vein plasma flow rate estimated with the p-aminohippuric acid indicator-dilution technique. Differences in the net portal absorptions of NH3 and glucose among the three weekly measurements were small (P greater than .05). In Trial 2, the first sequence of net portal absorption measurements was conducted when pigs were fed the basal diet, and the second sequence of measurements was conducted after the pigs had been fed the diet supplemented with 55 ppm of carbadox for 7 d. Carbadox supplementation reduced (P less than .05) plasma NH3 concentration in portal plasma during the 2.5-h to 5-h postprandial period and decreased (P less than .05) net portal absorption of NH3 during the 2.5-h to 4-h postprandial period. Carbadox, however, did not affect (P greater than .05) net portal absorption of glucose. We suggest that carbadox suppresses the production of cell-toxic NH3 by intestinal microorganisms and, thus, reduces the injury and turnover of intestinal cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗

PubMedDate not supplied

[Nuclease activity of microorganisms and control of auto-microflora state of operators in hermetically sealed environment].

A study was performed to investigate biological properties of pathogenic microorganisms (Shigella, Salmonella, Staphylococcus aureus) and potentially pathogenic microorganisms which were isolated from different people, i.e. clinically healthy people with normal microflora, somatically healthy patients with intestinal dysbacteriosis, and patients with acute intestinal diseases. The most important parameters of pathogenicity typical of the basic representatives of pathogenic microflora were DNA and/or RNA forming activity. The "critical" size of depolymerization zones of nucleic acids on dense nutrient media was found to be equal to 2 mm and greater from the colony edge. The critical size was shown to be significantly different in potentially pathogenic and normal intestinal microorganisms. Maximal microbial concentrations in the major biotopes of man were estimated to be: no more than 25%, 5% and 2% for nasal mucosa, back skin, and for the large intestine of the total amount of microorganism in the test. Verification of the method gave evidence that in can be applied for an alternative evaluation of automicroflora of the large intestine of operators in an enclosed environment. It is suggested that the normal parameters characteristic of clinically healthy people need to be verified and applied in space and undersea medicine.

Adult↗

PubMedDate not supplied

Biosynthesis of bile acids in mammalian liver.

The biosynthesis of bile acids in mammalian liver and its regulation, together with the physiological role of bile acids, are reviewed in this article. Bile acids are biosynthesized from cholesterol in hepatocytes. Several steps are involved including epimerisation of the 3beta-hydroxyl group, reduction of the delta4 double bond to the 5beta-H structural arrangement, introduction of alpha-hydroxyl groups at C7 or C7 and C12 and, finally, oxidative degradation of the side chain by three carbon atoms. This gives the primary bile acids, cholic and chenodeoxycholic acids. Cholesterol-7alpha-hydroxylation is the rate determining step in the biosynthesis of cholic and chenodeoxycholic acids. Feedback regulation of cholesterol biosynthesis occurs by various mechanisms including termination of the synthesis of specific cytochromes P-450, modulation of specific cytosol proteins, short-term changes in the process of phosphorylation-dephosphorylation and changes in the capacity of the cholesterol pool as a substrate. Prior to being exported from the liver, bile acids are conjugated with glycine and taurine to produce the bile salts. After excretion into the intestinal tract, primary bile acids are partly converted to secondary bile acids, deoxycholic and lithocholic acids, by intestinal microorganisms. The majority of bile acids is absorbed from the intestinal tract and returned to the liver via the portal blood, so that only a small fraction is excreted in the feces. Bile acids returned to the liver can be reconjugated and reexcreted into the bile in the process of enterohepatic recycling. In addition to the physiological function of emulsifying lipids in the intestinal tract, bile acids are particularly important in respect of their ability to dissolve and transport cholesterol in the bile.

Animals↗

PubMed1982

Biosynthesis of microvillus membrane-associated glycoproteins of small intestinal epithelial cells in germ-free and conventionalized mice.

We studied the effect of intestinal microorganisms on the synthesis of membrane-associated glycoproteins in the upper small intestine by intraperitoneally administering L-[3H]fucose, D-[14C]glucosamine, or L-[3H]leucine to germ-free mice and mice exposed to microorganisms for 4 weeks (conventionalized). The incorporation of the labeled compounds into sucrase-isomaltase complex and maltase was determined by immunoprecipitating Triton X-100-solubilized microvillus membranes with their antibodies. Purified microvillus membranes from germ-free and conventionalized mice differed in the activities of some marker enzymes but not in the number and mobility of the components on SDS-polyacrylamide gel electrophoresis. Maximal incorporation of [3H]fucose and [14C]glucosamine into the microvillus membrane and two enzymes was reached 2-3 h post-injection in both groups, however, the amounts incorporated were larger in conventionalized mice. There was little difference in [3H]leucine incorporation into the total glycoproteins of microvillus membranes between the two groups. Our results suggest that the introduction of microorganisms stimulates the synthesis of sugar chains of microvillus membrane-associated glycoproteins. The enhanced in vitro fucosyltransferase activity in conventionalized mice partly supports this suggestion.

Animals↗

PubMed1996

Trauma, shock, and gut translocation.

This article reviews the scientific and clinical evidence that supports trauma and shock as potential etiologies for translocation of intestinal microorganisms and their by-products. The potential for loss of intestinal barrier function to cause the eventual septic deaths observed in such patients, as well as possible mechanisms for preventing and treating this entity is also discussed.

Animals↗

PubMed2006

Beyond diversity: functional microbiomics of the human colon.

Molecular tools have revealed wide microbial diversity in the human alimentary tract. Most intestinal microorganisms have not been cultured and the in situ functions of distinct groups of the intestinal microbiota are largely unknown but pivotal to understanding the role of these microorganisms in health and disease. Promising strategies to gain more insight into the functionality of the complex microbial communities in the human alimentary tract, including fermentation processes in the colon, are discussed. These research approaches could provide a basis for the definition of a healthy gut based on key properties of microbial functionality. This will also enable the development of direct nutritional strategies for intestinal disease prevention and health promotion.

Biodiversity↗

PubMed1976

[Local effectiveness of surgical preparation using a chemically defined diet in colon surgery].

A report is given about the advantages of Vivasorb and BSD for patients who must undergo surgery of the colon. By extensive reduction of the intestinal microorganisms a preoperative medication of antibiotics which are not resorbed in the intestines becomes superfluous. The rate of postsurgical complications is enormously reduced. Clamps will not be required in surgery of the colon, the advantage of which becomes evident and important when resecting a very low situated carcinoma of the rectum, the narrowness of the operation area being an impediment for the handling of clamps. By using Vivasorb, the posterior rectotomy (for polyps which cannot be removed per rectoscopiam) can be done without a temporary colostomy, meaning two operations less for the patient (colostomy and its closure). Finally the positive results of Vivasorb in relation to resection of the colon, necessary because of sealed perforated diverticuli and the results of BSD in connection with internal drainage of the small bowels are reported.

Aged↗

PubMed1980

Mutagenic activation of an antischistosomal drug by enteric Streptococcus sps in vitro and in vivo.

Previous studies have shown that a new antischistosomal drug, 4-isothiocyano-4'-nitro diphenylamine (CGP 4540, amoscanate), is not mutagenic in vitro, but the urines of animals treated with this drug have mutagenic activity. Mutagenicity can be eliminated by coadministration of some antibacterial agents and is not demonstrable in germ-free animals. The present study describes attempts to isolate and identify intestinal microorganisms responsible for the mutagenic activation of amoscanate. Streptococcus equinus, isolated from the intestinal tract of mice, as well as some other species of Streptococcus, were found to produce mutagenic activation of amoscanate when introduced into animals pretreated with antibacterial agents. Similarly, incubation of these strains with amoscanate in vitro resulted in the formation of a mutagenic product.

Aniline Compounds↗

PubMed1984

Epimerization of the four 3,7-dihydroxy bile acid epimers by human fecal microorganisms in anaerobic mixed cultures and in feces.

The conversion of 3,7-dihydroxy bile acids by anaerobic mixed cultures of intestinal microorganisms was studied in fecal samples from eight healthy adult males. Incubations using substrate chenodeoxycholic acid (CDCA) and ursodeoxycholic acid (UDCA) were performed simultaneously in separate microbial suspensions from the same fecal samples. A time course study was done on four samples, chosen randomly from the eight. In the incubation of CDCA, substrate CDCA always decreased rapidly in amount; UDCA increased in amount, as did 3 beta, 7 beta-dihydroxy-5 beta-cholanoic acid (3 beta, 7 beta) and 3 beta, 7 alpha-dihydroxy-5 beta-cholanoic acid (3 beta, 7 alpha). In the incubation of UDCA, UDCA gradually decreased in amount; (3 beta, 7 beta), CDCA, and (3 beta, 7 alpha) increased gradually in amount. All reactions involved four epimers. After 48-72 hr UDCA was predominant and the reactions appeared to have reached equilibrium. In cultures from all eight samples, after 72-96 hr, a predominance of beta-hydroxy configurations at 7-position and alpha-hydroxy configurations at 3-position was observed. To compare these bile acid compositions to those in feces, an in vivo study using nine subjects was carried out. Concurrent with the collection of feces, transit time of food through the gut was measured. In samples from five subjects, in which amounts of lithocholic acid (LCA) was small, four 3,7-dihydroxy epimers were found. In samples from the other four, however, CDCA, the predominant epimer in bile, had apparently been converted to LCA by 7-dehydroxylation, and four epimers were not always found. In contrast to the incubation study, UDCA was not always the predominant 3,7-dihydroxy epimer in the fecal study. This may have been due to the transit times, which averaged 26.4 +/- 8.9 SD hr, being much shorter than the time it took for the incubation reactions to reach equilibrium.

Adult↗

PubMed2005

Accumulation of intestinal intraepithelial lymphocytes in association with lack of polymeric immunoglobulin receptor.

Immunoglobulin A (IgA) is transported by the polymeric immunoglobulin receptor (pIgR) through epithelial cells of the gut, the airways, the tear and salivary glands, and the lactating mammary gland, and IgA accumulates in serum and the intestinal lamina propria of pIgR-deficient (pIgR(-/-)) mice. Intraepithelial lymphocytes (IEL) increased in number and Thy-1(+)CD8alphabeta(+)TCRalphabeta(+) IEL preferentially expanded in the small intestine (SI) of pIgR(-/-) mice. Cytotoxic activity of SI-IEL was comparable in pIgR(+/+) and pIgR(-/-) mice. Accumulation and cytotoxic activity of SI-IEL was attenuated in germ-free pIgR(-/-) mice. Furthermore, Thy-1(+)CD8alphabeta(+) IEL did not expand in pIgR(-/-)TCRbetadelta(-/-) mice compared with TCRbetadelta(-/-) mice, and SI-IEL from pIgR(-/-)TCRbetadelta(-/-) mice as well as TCRbetadelta(-/-) mice expressed perforin and granzyme B mRNA and serine esterase. The proliferative status of SI-IEL from pIgR(+/+) and pIgR(-/-) mice was similar, but adoptive transfer experiment showed that SI-IEL from pIgR(-/-) mice might have a stronger tendency to migrate into the intestinal epithelia than those from pIgR(+/+) mice. These results demonstrate that the accumulation of Thy-1(+)CD8alphabeta(+)TCRalphabeta(+) IEL in pIgR(-/-) mice triggered by intestinal microorganisms needed the expression of functional TCR and might be caused by lymphocyte migration into the intestinal epithelia.

Animals↗

PubMedDate not supplied

The metabolic and pharmacokinetic disposition of mebendazole in the rat.

The metabolism and pharmacokinetics of mebendazole was studied in rats using [2'-3H]-mebendazole (biologically stable; specific activity 383.9 (mCi/mMol) and [2-14C]-mebendazole (specific activity 2.57 mCi/mMol). Analyses were performed by high pressure liquid chromatography and liquid scintillation spectrometry. About 85% of an intravenous dose was eliminated with the bile and the remainder with the urine. The majority of the dose was recovered as conjugated metabolites. The major metabolite (methyl-5(6)-(alpha-hydroxybenzyl)-2-benzimidazole carbamate) accounted for about 77% of the total recovered and 99% of it was conjugated. Anaerobic metabolism studies conducted in vitro with intestinal microorganisms obtained from rats indicated that metabolism of mebendazole did not occur in the gut, but that the intestinal microflora was able to hydrolyse conjugated metabolites which were eliminated with the bile. Mebendazole was found to have a biphasic elimination profile after intravenous administration. Its terminal plasma elimination half-life was 3.2 hours and its re-distribution half-life was 0.4 hour. After oral administration, as a solution in aqueous dimethyl sulphoxide, a bioavailability of 53% was obtained.

Administration, Oral↗

PubMed1997

Crohn's disease and Escherichia coli. A new approach in therapy to maintain remission of colonic Crohn's disease?

Involvement of pathogenic or potentially pathogenic bacteria in the pathogenesis of inflammatory bowel disease has long been suggested because, among other reasons, the inflammatory response resembles that in infectious bowel diseases. Elevated antibody levels to pathogen antigens and a changed metabolic activity of the intestinal microflora have been detected in patients with Crohn's disease. Several studies have revealed a possible etiologic link between intestinal microorganisms and inflammatory bowel disease. Therefore, several therapeutic strategies, including reduction or dilution of bacterial components in the intestine by antibiotics or intestinal lavage, respectively, inactivation of inflammatory bacterial products, and reconstitution of intestinal microflora have been employed, substantiating the idea that dysfunction of the intestinal mucosal barrier and an alteration of bacterial composition contribute to the inflammatory disease. However, the beneficial effect of restoration of the physiologic intestinal microflora in colonic inflammation by exogenous administration of a viable nonpathogenic bacterium has not been investigated before in a placebo-controlled study. Promising results came from the present pilot study in which the nonpathogenic Escherichia coli strain Nissle 1917 was tested for efficacy and tolerance in maintaining remission in patients with colonic Crohn's disease. Application of the physiologic bacteria reduced the risk for relapse and minimized the need for glucocorticoids. Therefore we are convinced that in Crohn's disease parts of the intestinal microflora, including the host's immune response toward indigenous flora or an impairment of the gut flora's metabolic activity are involved in the development or at least in the onset of relapse from remissive of colonic Crohn's disease. However, more data are necessary to prove the benefit of E. coli strain Nissle 1917 as a new therapy to maintain remission of colonic Crohn's disease.

Biological Therapy↗

PubMed1979

Investigation of the immune response to aerobic and anaerobic intestinal bacteria in a patient with Crohn's disease.

The immune response to aerobic and anaerobic intestinal bacteria in a patient with Crohn's disease with an intestinal fistula was investigated with various serological techniques. Two aerobic bacterial species, E. dispar and P. mirabilis, and four strict anaerobic bacterial species, B. fragilis ss. fragilis, F. varium and two different strains of C. perfringens, were isolated from fistula secretion of the patient. These strains were used as antigens for tube agglutination, passive hemagglutination, indirect immunofluorescence and immune hemolysis assays with serum specimens obtained before and after operation of the patient. Immune responses were demonstrated to the aerobic as well as to the anaerobic bacterial strains isolated from the patient's fistula. In connection with the operation an active immune response was demonstrated to the aerobic and anaerobic bacterial isolates. Antibodies belonging to IgG and IgA took part in the active immune response while IgM was very little involved. Antibodies responsible for passive hemagglutination reactions were resistant to treatment with beta-mercaptoethanol. Antibodies to aerobic and anaerobic Gram-negative rods were shown to have complement fixing activity. The importance of the demonstrated antibodies for the host's defence against normal intestinal microorganisms and the inflammatory reaction as a consequence of chronic antigenic stimulation in the diseased part of the intestine in patients with Crohn's disease is discussed.

Adult↗

PubMed2000

Bifidobacteria and lactobacilli in human health.

The gastrointestinal microflora is a complex ecological system, normally characterized by a flexible equilibrium. The most important role of the microflora, from the point of view of the host, is probably to act in colonization resistance against exogenous, potentially pathogenic, microorganisms. Bifidobacteria and lactobacilli are Gram-positive lactic acid-producing bacteria constituting a major part of the intestinal microflora in humans and other mammals. Administration of antimicrobial agents may cause disturbances in the ecological balance of the gastrointestinal microflora with several unwanted effects such as colonization by potential pathogens. To maintain or reestablish the balance in the flora, supplements of intestinal microorganisms, mainly bifidobacteria and lactobacilli, sometimes called probiotics, have been successfully used. This article reviews the role of bifidobacteria and lactobacilli in human health.

Animals↗

PubMed1985

Ventricular sepsis and abdominally related complications in children with cerebrospinal fluid shunts.

In a retrospective study of 300 children who underwent placement or revision of cerebrospinal fluid (CSF)-peritoneal shunts during a 10-year period, 15 (5%) developed shunt-related abdominal complications with ventricular sepsis and two developed acute perforated appendicitis. Abdominal complications and associated shunt infections suggested two potential modes of development: (1) descent of contaminated CSF from an infected shunt into the abdomen (CSF ascites--four patients, CSF pseudocysts--four patients, and shunt-induced abscess/peritonitis--five patients); and (2) ascent of bacteria into the shunt from an abdominal source (visceral perforation by the shunt catheter--two patients and acute perforated appendicitis--two patients). Three types of shunt systems were placed during the study period; five of the seven (71%) most serious septic complications were associated with the use of Raimondi spring-reinforced catheters. Bacteria isolated in this series were associated with differing modes of sepsis: those involving descent of bacteria into the abdomen from an infected shunt were predominantly gram-positive, cutaneous microorganisms, whereas those associated with ascent of bacteria from the abdomen into the shunt were mixed, gram-negative intestinal microorganisms. Appendicitis did not result in shunt infections. Aggressive treatment resulted in no operative or complication-related deaths. Removal of the shunt catheter from the abdomen and intravenous antibiotics were essential for eradication of sepsis; laparatomy was required only for cases with suspected peritonitis. In eight of the 17 (47%) patients, reestablishment of CSF-peritoneal shunts was performed after resolution of shunt-related complications. In recent years improved shunting materials and supportive care have reduced the incidence of the most serious of these complications.

Abdomen↗

PubMed1981

Dosage form design for improvement of bioavailability of levodopa IV: Possible causes of low bioavailability of oral levodopa in dogs.

Several potential mechanisms for reduced levodopa bioavailability following oral administration to dogs and humans were investigated by studying the influence of the administration route on plasma levodopa levels after intravenous, hepatoportal, and duodenal administrations to dogs. The observed average areas under the plasma concentration-time curves (AUC) of levodopa following hepatoportal injection and intravenous injection were virtually identical; but following duodenal administration a decrease in the AUC of levodopa was observed with a concomitant increase in the AUC of total dopamine. The possible involvement of intestinal microorganisms in levodopa metabolism was explored in dogs that had been administered a combination of paromomycin and kanamycin to reduce intestinal microflora. Similar patterns of plasma level profiles and urinary excretion were observed between control and treated dogs. As measured by the release of [14C]carbon dioxide from [14C]levodopa, the distribution of levodopa decarboxylase enzyme activity in various parts of the intestine was studied in homogenates prepared from isolated intestinal segments of the duodenum and upper, middle, and lower parts of the jejunum and ileum. The jejunum showed the highest decarboxylase activity followed by the ileum and duodenum. These data indicate that the reduced bioavailability of orally administered levodopa occurs as a result of metabolism by levodopa decarboxylase enzyme in the gut wall.

Administration, Oral↗

PubMed1997

Dissimilatory amino Acid metabolism in human colonic bacteria.

The abilities of slurries of human faecal bacteria to ferment 20 different amino acids were investigated in batch culture incubations. Ammonia, short chain fatty acids, and in some cases, amines, were the principal products of dissimilatory metabolism. The types of SCFA produced were dependent on the chemical compositions of the test substrates. Thus, acetate and butyrate were formed from the acidic amino acid glutamate, while acetate and propionate predominated in aspartate fermentations. Breakdown of the basic amino acids lysine and arginine was rapid, and yielded butyrate and acetate, and ornithine and citrulline, respectively. The major products of histidine deamination were also acetate and butyrate. However, fermentation of sulphur-containing amino acids was slow and incomplete. Acetate, propionate and butyrate were formed from cysteine, whereas the main products of methionine metabolism were propionate and butyrate. The simple aliphatic amino acids alanine and glycine were fermented to acetate, propionate and butyrate, and acetate and methylamine, respectively. Branched-chain amino acids were slowly fermented by colonic bacteria, with the main acidic products being branched-chain fatty acids one carbon atom shorter than the parent amino acid. Low concentrations of amines were also detected in these fermentations. Aliphatic-hydroxy amino acids were rapidly deaminated by large intestinal microorganisms. Serine was primarily fermented to acetate and butyrate, while threonine was mainly metabolised to propionate. Proline was poorly utilized by intestinal bacteria, but hydroxyproline was efficiently fermented to acetate and propionate. The aromatic amino acids tyrosine, phenylalanine and tryptophan were broken down to a range of phenolic and indolic compounds.

Journal Article↗