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PubMed1995

Age-associated changes in the proliferative response of rat intestinal intraepithelial leukocytes to bacterial antigens.

BACKGROUND & AIMS: Intraepithelial leukocytes (IELs) residing in the intestinal epithelium are thought to recognize bacterial antigens and play an important role in providing protection against the invasion of microorganisms through the intestinal wall. This report studies the effect of various bacterial antigens on the proliferation of cultured IELs. METHODS: Bacterial antigens mycobacterial heat shock protein (hsp) 60 or 70, staphylococcal enteroxin A (SEA), or purified protein derivative (PPD) from Mycobacterium tuberculosis were added to mixed cultures of IELs and irradiated syngeneic or allogeneic spleen cells, and the proliferative response was evaluated. Monoclonal antibodies to CD4, CD8, and major histocompatibility complex class I or class II molecules were added to assess the role of these proteins in the proliferative response. RESULTS: The proliferation of IELs isolated from mature rats in mixed culture was significantly enhanced by the addition of PPD, hsp 60, hsp 70, or SEA. The proliferation of mixed cultures of IELs isolated from young rats was enhanced only by the addition of SEA. In mixed cultures of mature rat IELs and syngeneic spleen cells containing PPD, proliferating populations were of the CD4-CD8+ and CD4+CD8+ phenotypes. Addition of anti-CD4 monoclonal antibody suppressed the proliferative response to PPD to control levels. CONCLUSIONS: IELs isolated from mature rats contain mycobacterial antigen-specific T cells, and these cells may be selected by long-term exposure to common intestinal bacterial antigens such as hsp. These cells may contain populations that recognize bacterial antigens in a CD4-dependent manner.

Age Factors↗
PubMed1988

Impact of different antimicrobial agents on the colonisation resistance in the intestinal tract with special reference to doxycycline.

The administration of antimicrobial agents has a number of effects on the intestinal microflora. One is the reduction of colonisation resistance, i.e., the resistance displayed by the host to implantation of new microorganisms in the intestinal microflora. In the present investigation, the impact of three antimicrobial agents--clindamycin, doxycycline and erythromycin--on the colonisation resistance in the intestinal human microflora was examined. Two of the agents--clindamycin and erythromycin--disturbed the colonisation resistance and caused ecological changes, while the third agent--doxycycline--better preserved the colonisation resistance. Ecological effects are difficult to foresee and clinical studies of antimicrobial agents should include investigations of the impact on the normal human intestinal microflora.

Adult↗
PubMedDate not supplied

A new simple test for evaluation of intestinal bacteria.

We investigated a newly synthesized conjugate of ursodeoxycholic acid with para-aminobenzoic acid (PABA) to determine its suitability to evaluate enteric bacteria. This compound, PABA-UDCA, is deconjugated by cholylglycine hydrolase to release free PABA whereas it is completely resistant to deconjugation by pancreatic and intestinal mucosal enzymes. In bacteriological experiments, almost all of the microorganisms which split glycocholic acid deconjugated this compound. In animal experiments, urinary excretions of PABA were measured for 6 hours following oral administration of 10 mg PABA-UDCA. Ten control rats excreted 338.5 +/- 43.8 micrograms (mean +/- SD) of PABA; 10 rats with intestinal bacterial overgrowth due to enteric stagnant loops excreted more (673.6 +/- 222.1 micrograms; p less than 0.01), whereas 10 rats in each of 8 groups with intestinal antisepsis by oral administration of various antibiotics excreted significantly less (p less than 0.001) (ampicillin + doxycycline + fradiomycin: 18.3 +/- 16.7, polymixin B + tinidazole: 14.0 +/- 8.0, polymixin B: 224.9 +/- 74.3, tinidazole: 42.7 +/- 27.3, kanamycin: 50.3 +/- 18.2, clindamycin: 57.4 +/- 23.3, vancomycin: 70.4 +/- 27.0, and paromomycin: 160.4 +/- 51.9 micrograms). These observations indicate that this compound is likely to offer a simple and rapid method for evaluation of intestinal microorganisms without the use of radioisotopes or expensive, special apparatus.

4-Aminobenzoic Acid↗
PubMed1992

[The antioxidant treatment of patients with acute intestinal infections due to gram-negative microorganisms].

It was established that administration of S. typhimurium lysate causes activation of the processes of free-radical oxidation. Introduction of unithiol in combination with magnesium sulfate returns the intensity of these processes to the initial level. Unithiol and alpha-tocopherol acetate protect the animals form lethal effects of S. sonnei lysate. Use of a combination of pharmacological agents consisting of unithiol, magnesium sulfate and alpha-tocopherol acetate in the treatment of patients with acute intestinal infections due to gram-negative pathogens (shigellae, salmonellae, proteus, klebsiellae, pseudomonas) resulted in decrease of the length of the intoxication and diarrhea syndrome, decrease of the frequency of repeat bacteria elimination and protracted forms of these infections, more rapid normalization of immune system functions.

Acute Disease↗
PubMed1990

Intestinal barriers to bacteria and their toxins.

Immunologic and nonimmunologic processes work together to protect the host from the multitude of microorganisms residing within the intestinal lumen. Mechanical integrity of the intestinal epithelium, mucus in combination with secretory antibody, antimicrobial metabolites of indigenous microorganisms, and peristalsis each limit proliferation and systemic dissemination of enteric pathogens. Uptake of microorganisms by Peyer's patches and other intestinal lymphoid structures and translocation circumvent the mucosal barrier, especially in immunosuppressed individuals. Improved understanding of the composition and limitation of the intestinal barrier, coupled with advances in genetic engineering of immunogenic bacteria, development of oral delivery systems, and immunomodulators, now make enhancement of mucosal barriers feasible.

Animals↗
PubMed2000

Disruption of the intestinal barrier and bacterial translocation in an experimental model of intestinal obstruction.

Clinical evidence and the use of experimental models in laboratory animals indicate that the intestine is a reservoir of microorganisms that can cause systemic infection in the human. The purpose of this work was to study the possible effect of intestinal obstruction (IO) on the mechanical and chemical barriers that bring protection against microorganisms crossing from the intestinal lumen towards the systemic tissues. We demonstrated that 24 hours after IO, histological and ultrastructural alterations do occur, seriously compromising the structure of the intestinal barrier in 100% of the studied animals. Likewise, it was observed that during the same period, microorganisms translocation from intestine to the peritoneal cavity and liver (100 and 80% respectively) occurred. The lungs were spared. Changes observed in the intestinal epithelium are related to a process similar to that produced by intestinal ischemia: mitochondrial destruction, with subsequent decrease of its capacity to supply energy and to preserve the equilibrium and structure of the intestinal epithelium. We propose that translocation of enteric bacteria may be the cause of the infection that brings about the death a significant group of animals at 48 hours (27%) and 72 hours (33%) post-IO.

Animals↗
PubMed1998

Simultaneous intestinal leishmaniasis and mycobacterial involvement in a patient with acquired immune deficiency syndrome.

Gastrointestinal involvement is reported in approximately 50% to 93% of patients with human immunodeficiency virus. It is frequently the result of coinfection with several microorganisms. Selective Leishmania intestinal involvement presents with atypical symptoms for visceral leishmaniasis, and may appear as a relapse or as the first manifestation of the disease. The authors present a patient with acquired immune deficiency syndrome who has a history of treated leishmaniasis and gastrointestinal infection by showed Mycobacterium avium intracellulare (MAI). After the new onset of abdominal pain, an intestinal biopsy showed the presence of both MAI and Leishmania in duodenum. Intestinal infection by Leishmania must be included in the differential diagnosis in patients with a previous history of leishmaniasis or travel to an endemic area.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

[Qualitative composition of the normal intestinal microflora in individuals from the various age groups].

The study of the microflora of the large intestine in healthy adult volunteers of different age groups (25-36, 55-68 and 88-94 years old), living in Switzerland, has been carried out. As revealed by the analysis of the result obtained in this study, normal intestinal microflora in adults has different qualitative and quantitative characteristics at different periods of their life. The greatest diversity of intestinal microflora is observed at a mature age (55-68 years old), while the poorest microflora is observed in people more advanced in age. The amount of microorganisms inhabiting the intestine reaches its maximum in people of mature age and is low in elderly people. Changes in normal intestinal microflora are probaly linked with morpho-functional transformations in the host body at different periods of life. It is expedient to work out the criteria of norm for the microflora of different age groups with a view to use these criteria for the evaluation of the microbial status of the intestine in persons of different age.

Adult↗
PubMed2001

The Lactobacillus and Bifidobacterium microflora of the human intestine: composition and succession.

Lactobacillus and bifidobacterial cultures are increasingly used as probiotics in pharmaceuticals and in foods. The selection of strains is performed often for technological rather than for microecological reasons. Detailed reports about species and strains composition of these microorganisms in the intestinal microflora of man are rare. Our investigations were performed with samples originating from infants and adults, taken from faeces and from upper sections of the intestinal tract including mouth and stomach, and from caecum and colon. Post mortem cases as well as test subjects under physiological conditions were analyzed using an automatic capsule system sampling at defined times in different parts of the intestinal tract. The fate of selected strains after oral intake was studied, too. Furthermore, influences of the microflora originating from food were considered. The identification of autochthonous (indigenous) and allochthonous (transient) species could be achieved with descriptions of new species in the genera Lactobacillus and Bifidobacterium. L. gasseri and L. reuteri proved to be predominant autochthonous Lactobacillus species in infants as well as in adults. Both species were occasionally present even in the stomach. This was also the case with an anaerobic lactic acid bacterium, previously named Catenabacterium catenaforme, later classified as L. ruminis, a non-motile variant of this species. The bifidobacterial microflora differed in composition between infants and adults and in different stages of the host's life. Up to 5 species or special strains of bifidobacteria could be present in different, individually fixed, combinations. Species typical for infants were B. bifidum, B. infantis, B. breve, and B. parvulorum. Typical for adults were 4 different variants of B. adolescentis. B. bifidum and B. longum could often be found in both groups, but in lower numbers. B. longum showed some oxygen tolerance whereas B. bifidum and B. adolescentis required strict anaerobic and fastidious conditions for cultivation. The autochthonous Lactobacillus and Bifidobacterium microflora in man will remain stable life-long. With lactobacilli, however, some successions may be caused by transient species derived from food or from the oral cavity, thus giving the impression of an altered microflora. Nevertheless L. gasseri, L. reuteri, L. ruminis, and to some degree, L. salivarius, may be present as autochthonous species all of the time. With bifidobacteria, a decreasing tendency in counts and in multiple composition in elderly people exists. Furthermore, this microflora is also influenced by consumption habits, which are probably caused by geographical circumstances.

Adolescent↗
PubMed1977

Development of intestinal host defense mechanisms and the passive protective role of human milk.

In this review of development of host defense mechanisms of the gastrointestinal tract, I have attempted to develop the concept of a mucosal barrier to the uptake of intestinal antigens and microorganisms. Alterations in development of immunologic defense and non-immunologic defenses results in an increased vulnerability for clinical disease in the newborn (premature) infant. The passive role of human milk in promoting intestinal maturation and protecting the newborn gut from pathologic penetration of macromolecules is discussed. It was predicted that many, as yet undiscovered factors, will be reported in future years to further underscore the importance of human milk in perinatal host defense. Immediate and delayed disease states resulting from an altered defense were considered.

Animals↗
PubMed1987

[Determination of the inhibitory effect of a biologically active preparation on the reproduction of micro-organisms from the intestines of ruminants].

A procedure for the production of biologically active substances from pine and spruce needles was worked out within the research project Utilization of Tree Verdure. The product was referred to as a biologically active preparation. The fields of its possible uses include agriculture (animal production-feeding), cosmetics (production of pastes, soaps, etc.), pharmaceutical industry (after additional conditioning the product can be used for manufacturing medicinal drugs for the control of inflammatory diseases and the like). The biologically active preparation, i. e. the pine needle extract, was studied as to its effect on some of the most numerous microorganisms in the intestines of ruminants. As found, this preparation has a partial inhibitive action on the growth and reproduction of microorganisms. The biologically active preparation is an extract isolated from the needles by means of 0.3% sodium hydroxide. Besides extractive substances it also contains the residues of organellae of cellular nature (which got into the extract through the filter during the process of preparation) and a small amount of fibre (0.33%). The chemical composition of the biologically active preparation is varied: until now about 220 substances, many of which are biologically active, have been found to be present in the product.

Animals↗
PubMedDate not supplied

New trends in non-absorbable antibiotics in gastrointestinal disease.

Numerous antibiotics have been used for several years in the treatment of intestinal diseases, the majority belonging to the class of aminoglycosides. These are effective against gram-positive and some gram-negative bacteria, above all aerobes, and do not therefore cover the entire range of microorganisms responsible for intestinal infections. With these antibiotics, moreover, it is not possible to exclude intestinal absorption which can lead to serious side effects. Other intestinal antibiotics, however, such as Vancomycin, have a restricted spectrum of action which limits their use. This study analyzes the pharmacological characteristics of a new non-absorbable antibiotics with particularly interesting properties from a clinical pharmacokinetic and pharmacodynamic point of view: Rifaximin. This drug has an extremely broad spectrum of action covering all intestinal germs, and its absorption is practically zero. The results of some controlled clinical studies in gastrointestinal diseases are examined, such as the treatment of infectious diarrhoea, of acute or chronic portal-caval encephalopathy and of diverticular disease of the colon. The possible role of Rifaximin in some intestinal diseases, such as small bowel bacterial overgrowth and Crohn's disease and ulcerative colitis, is also analyzed.

Bacterial Infections↗
PubMed2000

[Shigella: from the rupture to the invasion and to the destruction of the colonic epithelium].

CROSSING THE EPITHELIAL BARRIER: Shigella acts on the immune system in order to cross the intestinal epithelial barrier which is normally impermeable to intestinal flora. Among the effectors of the immune system of the colonic mucosa are translocation sites corresponding to lymphatic follicles carrying a follicular epithelium in the presence of M cells. These cells capture molecules, particles and microorganisms from the intestinal barrier that they translocate to immune competent cells present in the follicles (antigen presenting cells including resident macrophages and then B and T lymphocytes). MACROPHAGE APTOTOSIS AND ITS CONSEQUENCES: The first cell infected by Shigella appears to be the macrophage once the translocation has been made via the M cells. This infection rapidly leads to apoptotic death of the macrophage allowing the Shigella to infect the laterobasal epithelial cells and the development of an inflammatory response. This response in turn facilitates the invasion, rupture and permeability of the intestinal epithelium and the initiation, by Shigella, of a cell-to-cell invasion pathway.

Apoptosis↗
PubMed1985

Ultrastructural study of ehrlichial organisms in the large colons of ponies infected with Potomac horse fever.

Potomac horse fever is characterized by fever, anorexia, leukopenia, profuse watery diarrhea, dehydration, and high mortality. An ultrastructural investigation was made to search for any unusual microorganisms in the digestive system, lymphatic organs, and blood cells of ponies that had developed clinical signs after transfusion with whole blood from horses naturally infected with Potomac horse fever. A consistent finding was the presence of rickettsial organisms in the wall of the intestinal tract of these ponies. The organisms were found mostly in the wall of the large colon, but fewer organisms were found in the small colon, jejunum, and cecum. The organisms were also detected in cultured blood monocytes. In the intestinal wall, many microorganisms were intracytoplasmic in deep glandular epithelial cells and mast cells. Microorganisms were also found in macrophages migrating between glandular epithelial cells in the lamina propria and submucosa. The microorganisms were round, very pleomorphic, and surrounded by a host membrane. They contained fine strands of DNA and ribosomes and were surrounded by double bileaflet membranes. Their ultrastructure was very similar to that of the genus Ehrlichia, a member of the family Rickettsiaceae. The high frequency of detection of the organism in the wall of the intestinal tract, especially in the large colon, indicates the presence of organotrophism in this organism. Infected blood monocytes may be the vehicle for transmission between organs and between animals. The characteristic severe diarrhea may be induced by the organism directly by impairing epithelial cell functions or indirectly by perturbing infected macrophages and mast cells in the intestinal wall or by both.

Animals↗
PubMed1999

Inhibition of pathogenic Salmonella enteritidis growth mediated by Escherichia coli microcin J25 producing strains.

For the first time, microcin-producing strains showing inhibitory activities against enteropathogen Salmonella enteritidis were isolated from poultry intestinal contents. Among the numerous strains isolated, two strains of Escherichia coli, named J02 and J03, showing the greatest activities against S. enteritidis, were studied. Biochemical tests and purification identified the main antagonist compound produced as microcin J25. In order to evaluate the protective potential of E. coli J02 and J03 against S. enteritidis infection, the ability of these strains to inhibit growth of S. enteritidis was investigated in mixed culture. A strong antagonist activity was obtained with a preculture phase of the active strain in minimal medium before incubation with S. enteritidis. In a bioreactor experiment simulating the chicken gastric and intestinal tract environment, a mixture of the two strains E. coli J02 and J03, provided an enhanced inhibitory effect. Microcinogenic strain activities were not affected by bile, pancreatic enzymes addition, or acidic conditions. These results suggest the relevant role of microcin-producing microorganisms in microbial intestinal ecology. To conclude, this study shows that microcin J25 strains could exert a beneficial protective effect against S. enteritidis growth in situ.

Animal Husbandry↗
PubMed2000

Diagnosis of small intestinal bacterial overgrowth in patients with cirrhosis of the liver: poor performance of the glucose breath hydrogen test.

BACKGROUND/AIMS: Small intestinal bacterial overgrowth is known to occur in association with cirrhosis of the liver and studies are needed to assess its pathophysiological role. The glucose breath hydrogen test as an indirect test for small intestinal bacterial overgrowth has been applied to patients with cirrhosis but has not yet been validated against quantitative culture of jejunal secretion in this particular patient population. METHODS: Forty patients with cirrhosis underwent glucose breath hydrogen test and jejunoscopy. Jejunal secretions were cultivated quantitatively for aerobe and anaerobe microorganisms. RESULTS: Small intestinal bacterial overgrowth was detected by culture of jejunal aspirates in 73% of patients, being associated with age and the administration of acid-suppressive therapy. The glucose breath hydrogen test correlated poorly with culture results, sensitivity and specificity ranging from 27%-52% and 36%-80%, respectively. CONCLUSIONS: In patients with cirrhosis, the glucose breath hydrogen test correlates poorly with the diagnostic gold standard for small intestinal bacterial overgrowth. Until other non-invasive tests have been validated, studies addressing the role of small intestinal bacterial overgrowth in patients with cirrhosis should resort to microbiological culture of jejunal secretions.

Adult↗
PubMed1984

[Systems of membrane transport, genetics and nutrition; the example of congenital anomalies of intestinal transport in children].

As the plasma membrane of the cell, the intestinal epithelium ensures the selective functions of the entry and exit of nutriments or metabolites. These functions are controlled genetically by structural genes and eventually by regulatory genes which direct the expression of the former. The influence of some essential nutriments also plays a role. These aspects are illustrated for microorganisms. Selective, congenital intestinal malabsorptions, which are hereditary, occur in humans; their study leads to a better understanding of the genetic and nutritional control of transport mechanisms. Known anomalies of the intestinal transport of basic amino acids have been studied by showing the probable relationships with selective reabsorption deficiencies in the renale tubule and possible disorders of the urea cycle. Amino acid transport through the intestinal epithelium may be under a dual genetic control i.e. at the brush border (co-transport with sodium) as well as at the basal-lateral membrane (diffusion). It is emphasized that small peptides must be present in dietary solutions of enteral origin for amino acid absorption to be optimal. Selective malabsorption of glucose and galactose due to loss of the co-transport systems of glucose-sodium and galactose-sodium at the brush border is discussed. A comparison is made with anomalies of glucose reabsorption in the renal tubule. The digestive consequences (watery diarrhea) of the absence of sodium co-transports has been underlined. A generalization is proposed.

Amino Acids↗