Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “INTESTINAL MICROORGANISMS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources
PubMed2000

[The role of the intestine in the pathogenesis of the multi-organ dysfunction syndrome in diffuse peritonitis].

Extraction of oxygen (O2), ultrastructural organization of intestinal macrophages and translocation of microorganisms were studied on 50 male rats of Wistar line in 2, 6, 12, 24 and 48 hours after the stimulation operation performance (control group) and modelling of an acute purulent peritonitis (APP)--basic group. Increase of common and lowering of intestinal extraction of O2 in early terms of the APP occurrence, accompanied by intensive reproduction of microorganisms and change of intestinal biocenosis, was noted. These infringements correlated with translocation of microorganisms through mesenteric lymphatic nodes--ductus toracicus--systemic blood flow (basic way) in term up to 24 hours and through portal vein--hepar--systemic blood flow (additional way)--up to 48 hours after the APP beginning.

Animals↗
PubMed1980

[Infectious agents in the G.I. tract diseases (author's transl)].

The distribution of normal intestinal flora changes in the different gut segments and is influenced by gastric pH, peristalsis, bactericidal activity of Immunoglobulins A (locally produced). Saprophytic bacteria prevent the growth of pathogenous microorganisms, partake in the production of vitamins (K, B group), can be responsible for the production of carcinogens and co-carcinogens by acting on bile-acids, food or drugs ingested, can affect the morphology of the intestinal mucosa. Enteroviruses are transient intestinal microorganisms, responsible for infectious disease whose highest incidence is summer and autumn, whose frequency is particularly elevated in malnourished subjects.

Child, Preschool↗
PubMedDate not supplied

[Probiotics: history, definition, requirements and possible therapeutic applications].

The ingestion of probiotics is associated with various beneficial effects on human health and modifies the physiological homeostasis of the intestinal flora. Probiotics are microorganisms with some particular characteristics: human origin, safety in human use, bile and acid resistance, survival in the intestine, at least temporary colonization of the human gut, adhesion to the mucosa and bacteriocine production. Thanks to these characteristics, probiotics block the invasion of human intestinal cells by the enteroinvasive bacteria. Furthermore, they should be able to stimulate and modulate the intestinal immune response, and to protect and stabilize the mucosal barrier. Finally, the efficacy of probiotics should be evident and documented with valid studies. All their properties should be maintained during processing and storage. Probiotics are usually used to protect the host from pathogens. With regard to this, they are useful in the prevention of antibiotic and traveler's diarrhea and they may play a role in the management of gastric Helicobacter pylori infection. Furthermore, their efficacy in the treatment of infectious diarrhea, in inflammatory bowel diseases, in pouchitis and in food allergy has been shown. Probiotics can improve the symptoms of irritable bowel syndrome and of lactose malabsorption. Finally, it has been suggested that such microorganisms may play a role in the prevention of carcinogenesis and of tumor growth.

Adult↗
PubMed2005

Probiotic alternatives to reduce gastrointestinal infections: the poultry experience.

The intestinal mucosa represents the most active defense barrier against the continuous challenge of food antigens and pathogenic microorganisms present in the intestinal lumen. Protection against harmful agents is conferred by factors such as gastric acid, peristalsis, mucus, intestinal proteolysis, and the intestinal biota. The establishment of beneficial bacterial communities and metabolites from these complex ecosystems has varying consequences for host health. This hypothesis has led to the introduction of novel therapeutic interventions based on the consumption of beneficial bacterial cultures. Mechanisms by which probiotic bacteria affect the microecology of the gastrointestinal tract are not well understood, but at least three mechanisms of action have been proposed: production/presence of antibacterial substances (e.g., bacteriocins or colicins), modulation of immune responses and specific competition for adhesion receptors to intestinal epithelium. The rapid establishment of bacterial communities has been thought to be essential for the prevention of colonization by pathogenic bacteria. Some animal models suggest that the reduction in bacterial translocation in neonatal animals could be associated with an increase in intestinal bacterial communities and bacteriocin-like inhibitory substances produced by these species. This review emphasizes the role of the intestinal microbiota in the reduction of the gastrointestinal infections and draws heavily on studies in poultry.

Animals↗
PubMed1991

Kinetics of Saccharomyces cerevisiae elimination from the intestines of human volunteers and effect of this yeast on resistance to microbial colonization in gnotobiotic mice.

When healthy volunteers were given a daily dose of 3 x 10(8) life-dehydrated Saccharomyces cerevisiae cells for 5 days, the volunteers excreted 10(5) living yeast cells per g of feces at first, but the yeast cells disappeared within 5 days of the end of treatment. In gnotobiotic mice, S. cerevisiae administered alone colonized the intestinal tract but did not interfere with previous or subsequent colonization by a variety of potentially enteropathogenic microorganisms. When these microorganisms were present, the intestinal counts of S. cerevisiae were greatly reduced.

Adult↗
PubMed2002

Probiotic bacterium prevents cytokine-induced apoptosis in intestinal epithelial cells.

Probiotic bacteria are microorganisms that benefit the host by preventing or ameliorating disease. However, little information is known regarding the scientific rationale for using probiotics as alternative medicine. The purpose of this paper is to investigate the mechanisms of probiotic beneficial effects on intestinal cell homeostasis. We now report that one such probiotic, Lactobacillus rhamnosus GG (LGG), prevents cytokine-induced apoptosis in two different intestinal epithelial cell models. Culture of LGG with either mouse or human colon cells activates the anti-apoptotic Akt/protein kinase B. This model probiotic also inhibits activation of the pro-apoptotic p38/mitogen-activated protein kinase by tumor necrosis factor, interleukin-1alpha, or gamma-interferon. Furthermore, products recovered from LGG culture broth supernatant show concentration-dependent activation of Akt and inhibition of cytokine-induced apoptosis. These observations suggest a novel mechanism of communication between probiotic microorganisms and epithelia that increases survival of intestinal cells normally found in an environment of pro-apoptotic cytokines.

Animals↗
PubMed2026

Microplastics as vectors for microbial pollutants: Biofilm-associated transfer of pathogens and antibiotic resistance genes in zebrafish intestine.

As composite carriers of microorganisms and pollutants, biofilm-attached microplastics (MPs) serve as potential vectors for the environmental migration and biotransmission of antibiotic resistance genes (ARGs) and pathogens. In this study, traditional polypropylene (PP) and biodegradable polylactic acid (PLA) MPs were used to investigate the interference effects of biofilms-attached MPs on gut microbiota and ARGs transmission, through a combination of laboratory biofilm cultivation, zebrafish (Danio rerio) exposure simulations, metagenomic sequencing, and metabolomic profiling. Results showed that MP biofilms likely induced gut dysbiosis and were associated with altered diversity and abundance of pathogens and ARGs. At the phylum level, Nitrospira was transferred from PP biofilms to the gut. At the genus level, 23 genera were transferred from MP biofilms, with PLA (23 genera) showing higher transfer capacity than PP (4 genera). Notably, two human pathogens, one opportunistic pathogen, and two ARGs (adeF and oqxB) were specifically transferred from PLA biofilms, highlighting the unique dissemination risk of biodegradable MPs. Mechanistically, MPs may activate mobile genetic elements (e.g., Tn916 transposon) through metabolic remodeling and quorum sensing, thereby promoting horizontal gene transfer and ARGs dissemination within the gut. Our findings highlight the potential role of MPs as carriers of microorganisms and ARGs, underscoring the biotransmission risks of antibiotic resistance caused by composite pollution.

Animals↗
PubMed1984

Intestinal water-soluble mucins in germfree, exgermfree and conventional animals.

Water-soluble intestinal mucins were investigated in germfree (GF), exgermfree (EXG) and conventional (CONV) rats and in GF and CONV mice. After agar gel electrophoresis, all GF animals had similar specific band patterns demonstrated by PAS and Toluidine Blue. These patterns, never seen in CONV animals, disappeared in GF animals infected either with intestinal contents from CONV rats or mono-infected with a mucin converting microorganism, labelled Peptostreptococcus N. The intestinal microflora seem to have a profound influence on the water-soluble mucins, and specific microorganisms appear to be involved in the conversion of these substances. Any CONV animal with a GF mucin pattern in the faeces must be considered to have a disturbance of the normal intestinal microflora.

Animals↗
PubMed1999

[General infection prevention in abdominal surgery with special reference to intestinal decontamination].

In surgery prophylaxis for infection is necessary, because patients are immunocompromised due to the underlying disease and the operation while at the same time being increasingly exposed to potentially pathogenic germs. Prophylaxis is based on the control of endogenous and exogenous microorganisms. For this purpose either systemic or locally active topical agents may be employed. Systemically active substances are applied with the aim to kill and eliminate invasive microorganisms in deep tissue levels, either by their own biological activity or by stimulating specific or unspecific host immune reactions. Local topical measures in contrast are to prevent the primary contact between microorganisms and host. The central pillar of systemic measures is the perioperative systemic antibiotic prophylaxis, immunonutrition is beginning to gain importance, and in the future possibly substances such as G-CSF, which directly stimulate the immune system, may be employed. Standard topical measures are sterilization and desinfection while decontamination of the digestive tract has until now not found a wide spread acceptance. For certain indications especially high risk surgical resections with anastomoses at the level of the oesophagus or the lower rectum it is possible to eliminate endogenous intestinal microorganisms effectively using topical decontamination in combination with systemic antibiotics and improve the surgical results, especially anastomotic healing.

Abdomen↗
PubMed1981

Transit time of epithelial cells in the small intestines of germfree mice and ex-germfree mice associated with indigenous microorganisms.

Germfree mice housed in isolators under controlled environmental and nutritional conditions were associated with an intestinal microflora. These associated animals and germfree mice drawn from the same population were tested for the rate at which the epithelial cells transited from the crypts of Lieberkuhn to the tips of the villi in their small intestines. The method for estimating the rate of transit of epithelial cells involved the use of liquid scintillation counting to determine the amount of radioactivity entering the cells while the animals were being injected with [3H]thymidine and statistical analysis of th data with a computer program developed for the purpose. As estimated by that method, the cells transited from the crypts to the villous tips in germfree mice in about 115 h and in the associated animals in about 53 h. In monoassociated mice, a strain of a Lactobacillus sp. had no effect on the transit time of the epithelial cells. A strain of Torulopsis pintolopesii stimulated uptake of 3[H]thymidine by the small bowel mucosae in mice monoassociated with the organisms for 5 weeks. In animals monoassociated with the yeast fo 3, 4, and 6 weeks, however, the radioactive compound was incorporated into the bowel mucosae to the same extent as the mucosae of germfree mice. Therefore, similarly to the Lactobacillus strain, T. pintolopesii has no obvious influence on the transit rate of small bowel epithelial cells.

Animals↗
PubMed1996

The Escherichia coli K-12 gntP gene allows E. coli F-18 to occupy a distinct nutritional niche in the streptomycin-treated mouse large intestine.

Escherichia coli F-18 is a human fecal isolate that makes type 1 fimbriae, encoded by the fim gene cluster, and is an excellent colonizer of the streptomycin-treated mouse intestine. E. coli F-18 fimA::tet, lacking type 1 fimbriae, was constructed by bacteriophage P1 transduction of the fim region of the E. coli K-12 strain ORN151, containing the tetracycline resistance gene from Tn10 inserted in the fimA gene, into E. coli F-18. E. coli F-18 fimA::tet was found to occupy a distinct niche in the streptomycin-treated mouse intestine when fed in small numbers (10(4) CFU) to mice, along with large numbers (10(10) CFU) of E. coli F-18, as defined by the ability of the E. coli F-18 fimA::tet strain to grow and colonize only 1 order of magnitude below E. coli F-18. The same effect was observed when mice already colonized with E. coli F-18 were fed small numbers of E. coli F-18 fimA::tet. Experiments which show that the E. coli K-12 gene responsible for this effect is not fim::tet but gntP, which maps immediately downstream of the fim gene cluster, are presented. gntP encodes a high-affinity gluconate permease, suggesting that the distinct niche in the mouse large intestine is defined by the presence of gluconate. The data presented here support the idea that small numbers of an ingested microorganism can colonize the intestine as long as it can utilize an available nutrient better than any of the other resident species can.

Animals↗
PubMed1997

An intestinal mucin is the target substrate for a baculovirus enhancin.

An invertebrate intestinal mucin (IIM) was identified from a lepidopterous insect, Trichoplusia ni. The IIM is a major protein constituent of the peritrophic membrane that facilitates the digestive process, as well as protecting invertebrate digestive tracts from microbial infections. The IIM demonstrated biochemical characteristics similar to vertebrate mucins, but exhibited strong association with the chitin-containing peritrophic membrane matrix. We have demonstrated that a baculovirus enhancin, which is encoded and carried by specific baculoviruses, has mucin-degrading activity both in vitro and in vivo. The in vivo degradation of IIM by enhancin was correlated with the enhancement of baculovirus infections in insects. These findings have shown that viruses have evolved a novel strategy to overcome intestinal mucinous barriers against microorganisms by utilizing a mucin-degrading enzyme.

Animals↗
PubMed2001

The synergistic effect of lactic acid bacteria and alkylglycerols on humoral immunity in mice.

Investigations on immune suppression and reconstitution of immune functions dependent on the presence of physiological microflora allow us to conclude that symbiotic microorganisms such as Lactobacillus sp. are essential for adequate activity of the defense system in humans. In addition to their beneficial influence on the intestinal microbial balance, these microorganisms exert a variety of immunomodulatory effects on the host immune system. On the other hand, immunostimulatory animal-derived substances rich in alkylglycerols have been shown to enhance lactic acid bacteria proliferation. Therefore, the aim of the present study was to evaluate the effects on murine humoral response of the combined administration of lyophilized combination of three lactic acid bacteria: L. acidophilus, L. bulgaricus and Bifidobacterium bifidum together with alkylglycerol-rich shark liver oil. The lactic acid bacteria mixture induced markedly stronger enhancement of the humoral response than alkylglycerols did. A significant synergistic stimulatory effect of lactic acid bacteria and alkylglycerols was observed in both treatment schedules: post- as well as in preimmunization with sheep red blood cells. However, their concomitant administration exerted stronger immunomodulatory effect than did the alternative route of treatment.

Animals↗
PubMed1983

Activation of cycasin to a mutagen for Saccharomyces cerevisiae by rat intestinal flora.

Genetic test systems involving microorganisms and liver enzyme preparations may be insufficient to detect compounds that require breakdown by enzymes provided by the microbial flora of the intestinal tract. A method is described for providing such activation and for simultaneously testing the potential genetic activity of breakdown products in an indicator organism. Parabiotic chambers containing Saccharomyces cerevisiae genetic test organisms in one chamber were separated by a membrane filter from rat cecal organisms and test chemical contained in the other chamber. The genetic activities of cycasin breakdown products for mutation, gene conversion, and mitotic crossing-over in samples incubated aerobically are reported. Samples containing cycasin alone had a small but clearly increased frequency of genetic damage. Samples containing rat cecal organisms without cycasin showed no increase in genetic activity. Anaerobic incubation resulted in no increase in genetic activity in any of the samples.

Aerobiosis↗
PubMed2006

[Gut barrier in the critically ill patient: facts and trends].

The disturbances of gut barrier in critically ill patients may influence their outcome and prognosis. Experiments in animals show that fasting and stress collaborate to produce intestinal atrophy and translocation of microorganisms and toxins. This fact is one of the main arguments to promote the use of early enteral feeding in critically ill patients. However, the intestinal barrier behaves differently in humans than in animals. The human enteral cells have a good tolerance to fasting and stress, mucosal atrophy is mild and it is not always associated with changes in intestinal permeability. Moreover, the relationship between intestinal permeability with sepsis and bacterial translocation is controversial. This last phenomenon also happens in normal subjects and may be a mechanism to build immunological memory. One of the most important factors that influence bacterial translocation is the microorganism, that under stress conditions can adhere to the intestinal cell and penetrate the intestinal barrier. Splanchnic ischemia and reperfusion is one of the main pathogenic factors in the failure of intestinal barrier. Finally, the fact that the small bowel is an inflammatory target of extra intestinal injuries, explains several clinical situations. The pathophysiology of the intestinal barrier definitely requires more research.

Bacterial Infections↗
PubMed1975

Nutritional consequences of the Maillard reaction. The absorption of fructose-L-tryptophan in the large intestine of the rat.

The absorption of fructose-L-tryptophan, an early Maillard reaction product formed from tryptophan and glucose, in the large intestine of the rat was examined. The possible involvement of cecal microflora of the rat in the absorption of fructose-L-tryptophan was investigated. Fructose-L-tryptophan was degraded by the cecal microflora (in vitro) after a 12-hour incubation at 37 degrees. Experiments with rat colonic rings and everted sacs indicated that a passive diffusion of this compound occurs in vitro in the colon of the rat. In vivo absorption was determined by introducing fructose-L-[3-14C]tryptophan directly into the cecum. Twenty percent of the total radioactivity injected was recovered in the urine after 24 hours. Fructose-L-tryptophan was detected in the urine, which suggested that this compound was absorbed by the large intestine but excreted without being metabolized. Approximately 1% of the total radioactivity was recovered in the expired air within 24 hours after injection. The small recovery of fructose-L-tryptophan in feces might indicate that this compound was degraded by the action of microorganisms in the large intestine of the rat.

Animals↗
PubMed1978

Intestinal enzyme activities in germfree, conventional, and gnotobiotic rats associated with indigenous microorganisms.

Various enzyme activities involved in the active transport system, glycolysis, and digestion were assayed in various parts of the gastrointestinal tracts of germfree, conventional, and gnotobiotic rats associated with indigenous bacteria. The activity levels of alkaline phosphatase, glucose 6-phosphatase, adenosine triphosphatase, and disaccharidases in the upper small intestine were highest in all parts of the gastrointestinal tracts of various kinds of gnotobiotic, conventional, and germfree rats. Alkaline phosphatase, glucose 6-phosphatase, and adenosine triphosphatase activities in the upper small intestine of germfree rats were, respectively, 2.3-, 2.9-, and 1.7-fold higher than those in conventional rats. Similar to the results of these enzymes, sucrase, maltase, trehalase, and lactase activities in the upper small intestine of germfree rats were, respectively, 1.6-, 1.5-, 2.3-, and 1.8-fold higher than those in conventional rats. In various gnotobiotic rats, enzyme activity levels were intermediate between those in germfree and conventional rats. These findings suggest that those enzymatic activities are strongly depressed by the association with the indigenous microorganisms in the epithelial mucosa of the upper small intestine of rats. The levels of pyruvate kinase, hexokinase, and lactate dehydrogenase activities were highest, respectively, in the stomach, cecum, and the upper small intestine and cecum in all parts of the gastrointestinal tracts in various kinds of gnotobiotic, conventional, and germfree rats. It was also shown that six kinds of gastrointestinal bacteria, including lactobacilli, significantly depressed the enzyme activity levels to levels between those of the germfree and conventional rats in the upper small intestine of gnotobiotic rats.

Adenosine Triphosphatases↗
PubMed1993

The largest bacterium.

The large, morphologically peculiar microorganism Epulopiscium fishelsoni inhabits the intestinal tract of Acanthurus nigrofuscus, a brown surgeonfish (family Acanthuridae) from the Red Sea. Similar microorganisms have been found in surgeonfish species from the Great Barrier Reef. As these microorganisms have only been seen in surgeonfish and no free-living forms have been found, they are considered to be specific symbionts of surgeonfish, although the nature of the symbiosis is unclear. Initial reports considered them to be eukaryotic protists, based primarily on their size, with individuals being larger than 600 microns by 80 microns. But their cellular morphology in the electron microscope is more like that of bacterial than eukaryotic cells. To resolve the nature of these symbionts, we have isolated the genes encoding the small subunit ribosomal RNA from two morphotypes and used them in a phylogenetic analysis. In situ hybridization with oligonucleotide probes based on the cloned rRNA sequences confirmed the source of the rRNA genes. Our result identify the symbionts as members of the low-(G+C) Gram-positive group of bacteria. They are therefore the largest bacteria to be described so far.

Animals↗