The attachment of microorganisms to epithelial cells in the distal ileum of the mouse.
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Animals↗
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[Bacterial enterotoxin receptors].
Bacterial enterotoxin receptors. Enteric bacterial toxins display a great diversity in their structure, molecular weight and mechanism of action. The interaction of enterotoxins with the intestinal mucosa either leads to a direct effect on the cell membrane or an effect on signal transduction within eukaryotic cells. However, before a toxin can affect a cell, it must after its secretion by a microorganism, recognise and bind to a specific surface molecule, its receptor. Membrane receptors of bacterial enterotoxins have been identified as protein, glycoprotein or glycolipid in nature. The chemical nature of the molecules acting as receptors is crucial and during evolution they have been carefully selected. Some toxins, after their interaction with a receptor molecule, will transduce a signal across the cell membrane while remaining at the cell surface. Other toxins, after this initial binding step with a receptor, will be internalised. Others can form pores leading to leakage of cellular components and cell lysis. Receptors that have been identified often comprise a saccharidic chain that is directly involved in the recognition and binding of the toxin. Today, models explaining toxin-receptor interactions are more complex, including multistep events. This review summarises the knowledge of the interactions between bacterial toxins and membrane receptors present on intestinal mucosa.
Animals↗
Flow cytometric analysis for adhesion of Vibrio cholerae to human intestinal epithelial cell.
The adhesion of Vibrio cholerae O1 strains to human intestinal epithelial cell, Intestine 407, was analyzed by flow cytometer. According to positive percentages of Intestine 407 cells adhered by V. cholerae, two groups of V. cholerae strains were classified as follows: more adhesive (more than 50%), less adhesive (less than 50%) strains. In addition, the fluorescence intensity after attachment of V. cholerae was directly correlated to the number of the microorganisms. It was concluded that flow cytometry is a useful and objective method for analyzing adhesion of V. cholerae to cultured cells.
Bacterial Adhesion↗
Climatic effects on Salmonella survival in plant and soil irrigated with artificially inoculated wastewater: preliminary results.
The use of wastewater to replace other water resources for irrigation is highly dependent on whether the health risk and environmental impacts entailed are acceptable or not. Total count and species of microorganisms found in wastewater vary widely because of climatic conditions, season, population sanitary habits and disease incidence. Salmonella, one of the genera associated with waterborne diseases, lives in the intestine. Thus, it is widely accepted that they have a limited survival period under environmental conditions. Wastewater management practices and the ability of Salmonella to survival under field conditions would determine the health risk associated with its presence in wastewater. Although chlorination is widely used, there are situations in which Salmonella is able to survive the sudden stress imposed by this technique. The aim of this experiment was to contribute to the study of the climatic and soil effects on pathogen survival under agricultural field conditions in order to assess which were the best wastewater management practices from both health and economic points of view. Five pots filled with soil seeded with Medicago sativa and an automatic weather station were used. A secondary effluent was artificially inoculated with Salmonella. In addition, open plates (filled with sterilised soil) and ultraviolet radiation isolated plates (filled with non-sterilised soil) were used. As soil heat emission contributes to the environmental conditions around the bacteria, standardised meteorological temperature data had to be carefully used in the bacterial survival studies under agricultural conditions. Radiation was the main cause of Salmonella mortality as its effect was more important than natural soil bacteria competence. Higher reduction of Salmonella counts could have been associated with longer spring days. Soil was able to effectively remove Salmonella. Subsurface drip irrigation methods could provide an effective tool to prevent health risk associated with wastewater irrigation.
Agriculture↗
The role of infectious agents in Crohn's disease.
Environmental factors certainly play a role in the appearance of Crohn's disease. Wether or not those factors are infectious agents remains uncertain. Broadly, two classes of infectious hypothesis are currently under investigation. The first one, concerning specific microorganisms (such as mycobacteria and virus) dates back to the first description of the disease in 1913. The second one studies the possible involvement of compounds derived from the intestinal microflora, irrespective to speciation. It appeared more recently and receives more and more attention. These hypothesis are reviewed by the authors with regard to data obtained from epidemiology, clinical and experimental investigations.
Crohn Disease↗
[The action of the yeast preparation Perenterol (author's transl)].
This is a report on a yeast preparation of a strain of the species Saccharomyces cerevisiae, not killed as usual, but living, in a lyophilised form in gelatine capsules containing 1 x 10 9 organisms. It is possible to treat dysbiotic conditions of the gastro-intestinal tract successfully with Perenterol even without the use of chemotherapeutic agents. There is no danger that the living nonpathogenic yeast administered will increase in numbers and suppress other microorganisms.
Animals↗
[The degradation of lactose in the intestines of rats on human and cow's milk diets].
Female lactose adapted rats were kept for 10 days on human milk (HM), a milk diet adapted to human milk (MD1), and a milk diet rich in protein and phosphate (MD2), the lactose supply being always the same. In the caecum, colon and faeces, the pH value, the phosphorus content, the buffer capacity and the numbers of microorganisms with proteolytic activity (Bacteroides, Klebsiella, Proteus) were lower and the lactose concentration and the beta-galactosidase activity were higher on HM and MD1 than on MD2.
Animals↗
Microbial purification technique of mineral dressing plants reject waters.
Earlier investigations on laboratory and pilot plant scale have shown the resort to microorganisms to be a practicable approach to the problem of purifying mineral dressing plant reject waters from residual flotation reagents and/or metal ions. In spite of the proven effectiveness of this method, one major drawback, namely the pathogenicity of some microorganisms, has so far hampered its application on a commercial scale. A research programme, aimed at developing a microbial reject water purification technique utilizing non-pathogenic strains was thus drawn up and is currently being implemented. Strains such as Bacillus subtilis, Saccharomyces cerevisiae, Bifidobacterium bifidum, Lactobacillus acidophilus and Acinetobacter calcoaceticus, which are not harmful to human health, some of them being commonly found in the human intestine, have been successfully tested for removing alkylsulphates, alkylamines and fatty acids from solutions simulating flotation plant tailings waters. Removals as high as 90% in less than 48 h can be easily achieved with no nutrient requirements, since in most cases the flotation reagent residue to be removed is metabolized by the microorganisms themselves.
Acinetobacter calcoaceticus↗
D-Lactic acidosis in children: an unusual metabolic complication of small bowel resection.
Acidosis caused by intestinal bacterial D-lactate production occurs in ruminants engorged with carbohydrate. A similar phenomenon was identified in two children who developed recurrent episodes of metabolic acidosis and peculiar neurologic symptoms in response to increased dietary carbohydrate after major small bowel resections. Both children were found to have elevated plasma concentrations of D-lactic acid at the time of each episode. Acid base and neurologic abnormalities responded immediately to neomycin therapy. Among a number of microorganisms isolated from stool cultures of these patients, one anaerobic Lactobacillus acidophilus species produced large amounts of D-lactate in vitro. Reduction in carbohydrate intake in one patient tested led to a fall in D-lactate generation. We believe that excessive D-lactate production by intestinal bacteria, from malabsorbed carbohydrate, may produce metabolic acidosis and neurologic symptoms in children with small bowel resections.
Acidosis↗
[Vulvar lymphedema: unusual manifestation of metastatic Crohn's disease].
Cutaneous-mucosal lesions constitute one of the most frequent extraintestinal manifestations of Crohn's disease and in some cases may be the first symptom of intestinal disease. We describe the case of a 45-year-old female patient who sought medical help for genital tumefaction of 20 years' evolution. For the previous 15 years, she had been experiencing digestive symptomatology attributed to irritable bowel syndrome. Two months before the consultation, and coinciding with aggravation of the condition, the patient had been diagnosed with colonic Crohn's disease. Skin biopsy of the labia minora revealed sarcoid granulomas. The results of microbiological studies (staining for microorganisms and cultures) were negative. A diagnosis of metastatic vulvar Crohn's disease was made and, treatment with metronidazole was started, which improved the genital edema after 2 months. Genital lymphedema is an exceptionally rare manifestation of metastatic Crohn's disease that may appear several years before intestinal symptomatology develops. Treatment with metronidazole seems to be a good therapeutic option.
Crohn Disease↗
Bacterial contamination of the small bowel evaluated by breath tests, 75Se-labelled homocholic-tauro acid, and scanning electron microscopy.
Eighty-one patients with diarrhoea due to suspected bacterial contamination of the small intestine were investigated with the bile acid breath test (BABT) and 75Se-labelled homocholic-tauro acid (SeHCAT). The impact of bile acid malabsorption due to dysfunction of the terminal ileum on BABT was evaluated. The group of patients with abnormal BABT, notably the 6-h accumulated value, showed a high frequency of reduced SeHCAT values (p less than 0.01), indicating that a reliable test for bile acid malabsorption is indispensable for interpreting the BABT in the investigation of small-intestinal bacterial overgrowth. The results of the 14C-D-xylose breath test were compared with the outcome of the combined SeHCAT-BABT in 44 patients. In contrast to previous findings no correlation between the two breath tests was found. On the contrary, a significant negative correlation was encountered (p less than 0.01) for patients in whom either breath test was abnormal. Scanning electron microscopy for demonstration of adherent microorganisms was included in the investigations. No correlations were found with the outcomes of the different breath tests. The effect of antibiotic treatment was evaluated with regard to symptoms and breath tests. The results of the investigation indicate that different tests are needed for the diagnosis of bacterial overgrowth of the small intestine, because of the different metabolic characteristics of the contaminating bacteria.
Bacterial Infections↗
Blastocystosis in preschool children from bolivar city, venezuela
To evaluate the prevalence of Blastocystis hominis and its clinical relevance, 169 preschool children from the 'Los Coquitos' nursery school living in Bolivar City, Venezuela, were studied. Stool samples were obtained and examined by direct microscopic examination, and the Faust and Willis concentration techniques. Some 72 of the children had intestinal parasites, of whom 32 (29.09%) had B. hominis. Prevalence for the latter was 18.93 % +/- 5.93 %. No differences were observed by sex or age (X(2) = 1.84 DF= 3; p > 0. 05). In the majority (53.13%) of the children, B. hominis was the only parasite. Giardia lamblia was the parasite most frequently identified with B. hominis (39.13%). In 1994, in 12% of the cases more than five microorganisms per microscopic field were observed. Clinical manifestations were observed in 70.58% of the preschool children. Presence of parasites was not correlated with symptomatology, but only with severity. Proper clinical and parasitological response to treatment was observed in 80% and 90% of patients, respectively. The conclusion was that B. hominis is a relatively frequent intestinal parasite among the preschool children evaluated.
Journal Article↗
[Dynamics of the establishment of intestinal microflora in healthy full-term newborns].
A study was made of the dynamics of establishment of the intestinal microflora in 79 healthy mature neonates born of healthy mothers. A total of 223 bacteriological examinations were conducted. A stable prevalence of bifidobacteria over the aerobic portion of the intestinal biocenosis occurred in all the children from the 8th day after birth. Along with this the following bacteria were continuously present in the intestine: lactic bacilli and streptococci E. coli, enterococci and staphylococci; however, their portion in the biocenosis was not great. Bacteroids, microbes of the Proteus genus, and yeast-like fungi were found in the cultures only before the establishment of a high bifidobacteria level. Conditionally pathogenic microorganisms and their associations were continuously revealed in 19.8% of healthy mature neonates. Apparently the qualitative prevalence of bifidobacteria prevented the clinical expression of dysbacteriosis in these children.
Age Factors↗
Influence of intestinal bacterial desulfation on the enterohepatic circulation of dehydroepiandrosterone sulfate.
Selective association of germ-free (GF) rats with dehydroepiandrosterone sulfate (DHEAS) desulfating bacteria allowed us to assess the exact impact of intestinal bacterial desulfation on the excretion and enterohepatic circulation of orally administered DHEAS. Germ-free rats selectively associated with the DHEAS-desulfating strain Peptococcus niger H4 (H4 rats) excreted 50% of the total label recovered within 17 h vs 21 h in GF rats and 13 h 23 min in conventional (CV) rats. Germ-free rats excreted 30% of the total label recovered via their urine. However, association of GF rats with the desulfating microorganism increased urinary excretion to 46%, comparable to the 45.5% found in CV rats. Fractionation of fecal label yielded 70% sulfoconjugated DHEAS and 2% unconjugated dehydroepiandrosterone in GF rats vs 5 and 77% in CV rats, and 55 and 14% in H4 rats, respectively. Our results demonstrate that the intestinal bacterial desulfation of DHEAS stimulated the enterohepatic circulation of DHEAS. This in turn increased the urinary excretion of label resulting in an accelerated elimination of labeled DHEAS from the body.
Animals↗
Towards understanding molecular modes of probiotic action.
The possibility that certain microorganisms might be beneficial to human health is highlighted by the numerous consumer products containing probiotic bacteria. Probiotics are typically administered in food that, following entry into the gastro-intestinal tract, results in measurable health-promoting effects. Although there is a growing list of health benefits provided by the consumption of probiotics, their precise mechanisms of action remain largely unknown. Recent molecular- and genomics-based studies are starting to provide insight into the ways probiotic bacteria sense and adapt to the gastro-intestinal tract environment. Complementary approaches using host cell in vitro systems together with animal models and human volunteers are revealing specific intestinal cell responses to probiotics. These studies should ultimately disclose the molecular mechanisms and pinpoint the bacterial and host effector molecules and pathways by which probiotics are able to modulate human health.
Animals↗
Mucosal immunity: implications for vaccine development.
The mucosal surfaces in e.g. the gastrointestinal, respiratory and urogenital tracts represent a very large exposure area to exogenous agents including microorganisms. Not surprising, therefore, those mucosal tissues are defended by a local immune system with properties and functions that in many respects are separate from the systemic immune system. The intestine is the largest immunological organ in the body. It comprises 70-80% of all immunoglobulin-producing cells and produces more secretory IgA (SIgA) (50-100 mg/kg body weight/day) than the total production of IgG in the body (ca. 30 mg/kg/day). The local immune system of the gut has two main functions: to protect against enteric infections, and to protect against uptake of and/or harmful immune response to undergraded food antigens. The best known entity providing specific immune protection for the gut is the SIgA system. The resistance of SIgA against normal intestinal proteases makes antibodies of this isotype uniquely well suited to protect the intestinal mucosal surface. The main protective function of SIgA antibodies is the "immune exclusion" of bacterial and viral pathogens, bacterial toxins and other potentially harmful molecules. SIgA has also been described to mediate antibody-dependent T cell-mediated cytotoxicity (ADCC), and to interfere with the utilization of necessary growth factors for bacterial pathogens in the intestinal environment, such as iron. It is now almost axiomatic that in order to be efficacious, vaccines against enteric infection must be able to stimulate the local gut mucosal immune system, and that this goal is usually better achieved by administering the vaccines by the oral route rather than parenterally. Based on the concept of a common mucosal immune system through which activated lymphocytes from the gut can disseminate immunity also to other mucosal and glandular tissues there is currently also much interest in the possibility to develop oral vaccines against e.g. infections in the respiratory and urogenital tracts. It has previously been widely assumed that only live vaccines would efficiently stimulate a gut mucosal immune response. However, an oral cholera vaccine, composed of the nontoxic B subunit of cholera toxin in combination with killed whole cell (WC) cholera vibrios has been shown to stimulate a strong intestinal SIgA antibody response associated with long-lasting protection against cholera. We have used this new cholera subunit vaccine and developed ELISPOT methods for examining at the clonal B and T cell level the dynamics of intestinal and extra-intestinal immune responses in humans after enteric immunizations.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Chagasic megacolon and proximal jejunum microbiota.
BACKGROUND: Among other factors, control of jejunal microflora depends on intestinal emptiness, and it can be impaired by Chagas disease. This study was developed to identify the microecology of the proximal jejunum in chagasic megacolon. Our objective was to characterize both the jejunal microbial stasis before surgery and the microflora after surgical treatment in patients with chagasic megacolon. METHODS: The intestinal fluids were collected, and the proximal jejunum microflora was analyzed. RESULTS: Preoperative microflora had shown an increase in bacteria compatible with bacterial overgrowth syndrome, mainly facultative and strict anaerobes microorganisms and fungi. The microflora had changed in the postoperative period in 83% of these patients, with significant decrease in the number of transient microorganisms. CONCLUSIONS: Chagasic megacolon was related to an increase in jejunal microflora. By removing the impairment of the colon there was a transient decrease in the proximal jejunum microflora.
Adult↗
Review of epidemiological studies on health effects from exposure to recreational water.
BACKGROUND: In order to facilitate the setting of guidelines, this review article evaluates the health risks caused by poor microbiological quality of recreational natural water. METHODS: Studies on uncontrolled waters, such as sea, lakes and rivers were considered in this review through MEDLINE and WHO resources. Out of the 37 studies identified, 22 were reviewed because they addressed associations of interest and fulfilled the validity criteria. RESULTS: Most studies reported a dose-related increase of health risk in swimmers with an increase in the indicator-bacteria count in recreational waters. Relative risk (RR) values for swimming in polluted water versus clean water were often significant (usually 1.0 < RR < 3.0). The indicator microorganisms that correlate best with health outcomes were enterococci/faecal streptococci for both marine and freshwater, and Escherichia coli for freshwater. In both marine and freshwater, increased risk of gastro-intestinal symptoms was reported for water quality values ranging from only a few indicator counts/100 ml to about 30 indicator counts/100 ml. These values are low compared with the water qualities frequently encountered in coastal recreational waters. Studies which showed a higher threshold for increased risk and case-rate values in some countries may suggest immunity due to endemicity or a lower pathogen-to-indicator ratio in the natural waters. CONCLUSIONS: The review strongly suggests a causal dose-related relationship between gastrointestinal symptoms and recreational water quality measured by bacterial indicator counts.
Adolescent↗