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PubMedDate not supplied

Antibiotic resistance of Escherichia coli in fecal samples of healthy people in two different areas in an industrialized country.

Fecal samples of 310 healthy persons, from two populations from different areas in the Netherlands, were examined for the presence of Escherichia coli resistant to ampicillin, tetracycline, sulfamethoxazole, trimethoprim and nitrofurantoin. High prevalences of resistance were found in both populations, ranging from 28% for trimethoprim to 89% for ampicillin. The percentages of the fecal samples with a dominantly resistant E. coli flora (> 50% resistance) were distinctly lower, ranging from 1% for nitrofurantoin to 21% for tetracycline. No significant differences in the level of resistance were observed between these two comparable populations in two different areas. The susceptibilities to 11 antimicrobial agents of 456 at random isolated E. coli were determined. The percentages of resistance varied widely: from 80% for chloramphenicol to 9% for nitrofurantoin. Only 19% of the isolates were susceptible to all antibiotics tested and 14% were resistant to more than four of the agents tested. Great differences in resistance rates between the two populations examined were seen for chloramphenicol (80% to 41%) and trimethoprim (16% to 36%). The results of this study underscore the presence of a human reservoir of antibiotic resistant microorganisms.

Adolescent↗
PubMed1988

Metabolism of sennosides--an overview.

The metabolism of sennosides is discussed in view of the results obtained during the last years. Rhein anthrone is to be considered as the ultimate active form produced by microorganisms in the colon. Several contributions of this senna symposium bring complementary information of utmost interest.

Animals↗
PubMed1988

Development of the gastrointestinal mucosal barrier: changes in phospholipid head groups and fatty acid composition of intestinal microvillus membranes from newborn and adult rats.

Phospholipids in microvillus membrane (MVM) prepared from the proximal small intestine of newborn (less than 24 h of age) and adult rats were characterized to determine if differences in composition existed. Our hypothesis is that developmental differences in composition of the MVM may account for mucosal barrier differences to microorganisms and antigens during the perinatal period. Lipid analysis showed that both cholesterol and total phospholipids, per mg of membrane protein, were much higher in the newborn MVM than the adult, but the molar ratio of these two lipid classes remained unchanged. Increased phosphatidylcholine and decreased phosphatidylinositol levels were found in the newborn MVM compared to the adult. In addition, the major difference in fatty acid composition of total lipid extracts and three major membrane phospholipids, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol appeared to be an increased ratio of palmitate (16:0) to stearate (18:0) and of oleate (18:1) to linoleate (18:2) in the newborn. These data suggest that changes in the proportion of phospholipid polar head groups and fatty acyl groups as well as changes in the amount of total phospholipids and cholesterol exist in the newborn MVM. These observations are consistent with differences in MVM fluidity previously noted and may help explain the increased uptake of antigens and other mucosal barrier defects in the newborn intestine.

Age Factors↗
PubMed1994

[Rheumatoid arthritis and the intestinal microbiocenosis].

Intestinal microflora was investigated by fecal bacteriological examination in 175 patients with verified rheumatoid arthritis (RA). Intestinal dysbacteriosis of different stages was detected in 75% of the RA patients on nonsteroid antiinflammatory treatment. The frequency and severity of abnormal biocenosis in RA patients were significantly greater than in subjects with osteoarthritis deformans (p < 0.01) and bronchial asthma patients (p < 0.01). Dysbacteriosis severity increased with growing RA activity (between the groups with the activity stage I and III the difference was significant, p <( 0.05). After the fecal microorganisms inoculation it became evident that RA patients carry, as a rule, Clostridium perfringens. Seven RA patients diagnosed to have dysbacteriosis received adjuvant bactisubtil (dry culture of the strain Bacillus IP 5832). The addition of bactisubtil aggravated the patients' condition, in 4 patients, moreover, the microflora got worse. Explanations of the observations on the direct participation of the intestine in RA pathogenesis are suggested.

Adjuvants, Immunologic↗
PubMed2003

Protective mucosal Th2 immune response against Toxoplasma gondii by murine mesenteric lymph node dendritic cells.

Toxoplasma gondii, an obligate intracellular parasite pathogen which initially invades the intestinal epithelium before disseminating throughout the body, may cause severe sequelae in fetuses and life-threatening neuropathy in immunocompromised patients. Immune protection is usually thought to be performed through a systemic Th1 response; considering the route of parasite entry it is important to study and characterize the local mucosal immune response to T. gondii. Despite considerable effort, Toxoplasma-targeted vaccines have proven to be elusive using conventional strategies. We report the use of mesenteric lymph node dendritic cells (MLNDCs) pulsed ex vivo with T. gondii antigens (TAg) as a novel investigation approach to vaccination against T. gondii-driven pathogenic processes. Using a murine model, we demonstrate in two genetically distinct mouse strains (C57BL/6 and CBA/J) that adoptively transferred TAg-pulsed MLNDCs elicit a mucosal Toxoplasma-specific Th2-biased immune response in vivo and confer strong protection against infection. We also observe that MLNDCs mostly traffic to the intestine where they enhance resistance by reduction in the mortality and in the number of brain cysts. Thus, ex vivo TAg-pulsed MLNDCs represent a powerful tool for the study of protective immunity to T. gondii, delivered through its natural route of entry. These findings might impact the design of vaccine strategies against other invasive microorganisms known to be delivered through digestive tract.

Adoptive Transfer↗
PubMed1992

[Natural and experimental infection of rodents (Rattus norvegicus) with Salmonella gallinarum].

Thirty five (35) rats (Rattus norvegicus) were trapped in the area of four egg producing poultry farms and were examined for Salmonella spp., micro-biologically. The samples were taken from liver, spleen and intestinal content. Cultures were made directly in MacConkey Agar, in Selenite broth and Rappaport Vassiliadis at 37 degrees C and 43 degrees C. Five strains of S. gallinarum and one strain of Salmonella subgroup II were isolated from the intestinal content of six rats. An experimental study was also carried out. Ten rats Rattus norvegicus were trapped near poultry farms of N. Greece. No Salmonella could be detected in their feces when examined three times by the Selenite 37 degrees C and Rappaport-Vassiliadis 37 degrees C methods. The rats were orally infected with an 18 hours culture of S. gallinarum (1 x 10(9)/ml microorganisms). One hundred and sixty samples of feces were periodically collected and examined for the isolation of the microorganism by the methods mentioned above. Although not any clinical sign of a disease was noticed, S. gallinarum was isolated from their feces up to 121 days post infection.

Animals↗
PubMed2005

Escherichia coli F4 fimbriae specific llama single-domain antibody fragments effectively inhibit bacterial adhesion in vitro but poorly protect against diarrhoea.

Oral administration of polyclonal antibodies directed against enterotoxigenic Escherichia coli (ETEC) F4 fimbriae is used to protect against piglet post-weaning diarrhoea. For cost reasons, we aim to replace these polyclonal antibodies by recombinant llama single-domain antibody fragments (VHHs) that can be produced efficiently in microorganisms. Six F4 fimbriae specific VHHs were isolated. The VHH that was produced at the highest level by yeast, K609, was further analysed. 3.8 mg/L K609 inhibited 90% of bacterial attachment to intestinal brush borders in vitro. Perfusion of a jejunal segment with at least 4 mg/L K609 reduced the ETEC-induced fluid loss, but only to 30%. Preventive administration of a high K609 dose (150 mg/(piglet day)) to piglets that were challenge infected with ETEC resulted in less severe diarrhoea only at 4 and 5 days post-infection, but did not improve average daily weight gain, ETEC shedding and piglet survival. Thus, we have shown that an antibody fragment that effectively inhibited in vitro ETEC adhesion to intestinal brush borders poorly protected piglets against experimental ETEC infection.

Administration, Oral↗
PubMed1993

The friendly anaerobes.

Anaerobic bacteria include the most pathogenic of microorganisms. Their primary function, however, is hardly to cause illness. They rarely are involved in epidemics or in clinically significant infections. Some organisms, e.g. lactobacilli, control the normal vaginal ecosystem, and the intestinal anaerobes probably are instrumental in restraining the growth of Clostridium difficile in human carriers. The main role of anaerobes appears to be the provision of catabolic enzymes for organic compounds that cannot be digested by enzymes of eukaryotic origin. They are needed for the catabolism of cholesterol, bile acids, and steroid hormones; they hydrolyze a number of flavonoid glycosides to anticarcinogens; and they detoxify certain carcinogens. Anaerobic enzymes are used industrially in the production of cheese; the conversion of starch to sweeteners; and the transformation of sawdust, wood chips, and waste paper to fuel. Indeed, the anaerobes may well be the gene bank on which future generations of eukaryotic organisms will rely to adapt successfully to an ever-changing world.

Animals↗
PubMed1984

Effect of various metals and calcium metabolism inhibitors on the growth of Bifidobacterium bifidum var. pennsylvanicus.

In view of the facts that the normal intestinal flora exerts beneficial effects and that bifidobacteria are a more important component in the breast-fed than in the bottle-fed infant, factors affecting the growth of the latter microorganisms are of interest. A series of transition and other metals were shown to be growth inhibitors of Bifidobacterium bifidum var. pennsylvanicus. Such inhibition could be reversed fully or partially by 0.5-1.0 mM Fe2+ in the case of Zn2+, Cu2+, Au3+, Pt4+, La3+, Cr3+, Mn2+, Ni2+, and Cd2+, but not with Ag+, Hg2+, and VO2+. In addition, 2-4 mM Ca2+ substantially relieved the inhibitory effects of Zn2+, Mn2+, and La3+, and partially relieved the effects of Cd2+. Mg2+ was ineffective in relieving Zn2+ inhibition, but Ba2+ and Sr2+ could replace Ca2+ to some extent. The calcium metabolism antagonists verapamil, ruthenium red, 2-chloroadenosine, lasalocid, Ca-ionophore A-23187, and calmodulin inhibitors W-5 and W-7 inhibited microbial growth. Inhibition could be relieved fully or partially with 0.5-1 mM Fe2+. Mg2+ relieved the inhibition by lasalocid, Ca-ionophore A-23187, and verapamil, whereas Ca2+ was effective only in the case of Ca-ionophore A-23187. We conclude that calcium and magnesium fluxes play an important role in the physiology of the bifidobacteria and that several metal growth inhibitors interfere with iron metabolism.

Bifidobacterium↗
PubMed1991

Role of Neisseria gonorrhoeae and Chlamydia trachomatis in intraabdominal abscess formation in the rat.

Our concept of the pathogenesis of acute salpingitis and advanced pelvic infection, such as tuboovarian abscess, is evolving. Although Neisseria gonorrhoeae and Chlamydia trachomatis are thought to play a significant role in acute pelvic inflammatory disease, other microorganisms, such as aerobes and anaerobes, have repeatedly been reported to play a significant role, also, particularly in the patient with advanced disease. A study was designed to evaluate the pathogenesis, and particularly any synergistic role, of some aerobes and anaerobes with N gonorrhoeae and C trachomatis abscess formation. Using the rat model developed by Weinstein and Onderdonk, the study demonstrated that N gonorrhoeae and C trachomatis alone do not produce abscesses. However, when combined with facultative or anaerobic bacteria, synergism with abscess formation is noted frequently. The data support the hypothesis that N gonorrhoeae and C trachomatis initiate infection and that aerobic and anaerobic bacteria act synergistically to produce abscesses. In addition, microorganisms not inoculated were found to be recruited into the infectious process. The organisms may gain access to the peritoneal cavity via the lower genital tract or from transmucosal migration from the intestinal flora.

Abscess↗
PubMedDate not supplied

[Clinico-pathogenetic basis for using crystalline lysozyme in the combined therapy of food toxinfections].

In food toxinfections caused by various microorganisms (Staphylococcus, Escherichia, Klebsiella, Proteus, Citrobacter, etc.) a decrease of lysozyme debit and an increase of pH of gastric juice were found. One third of patients exhibited lactose deficiency of the small intestine. Treatment with furazolidone contributed to the development of lactase deficit and delayed stools normalization. Crystalline lysozyme shortened duration of febrile reaction and diarrhea, its intake facilitated lactose hydrolysis.

Administration, Oral↗
PubMed1976

[Biological characteristics of enteropathogenic escherichia of serologic group 015:K].

A study was made of 239 strains of enteropathogenic escherichia 0151:K-- isolated in various regions of the USSR from patients with the clinical diagnosis of dysentery, gastroenteritis, intestinal coli-infection: a standard strain of the international collection of escherichia belonging to the given serological group was also studied. There was shown an increase in the role of these microorganisms among the enteropathogenic escherichia recorded at the territory of the USSR; they occupied the third place by the frequency of isolation after the serological group 0124:K72 and 0111:K58. There was established a common nature of the enzymatic characteristics of escherichia 0151:K--with shigellae by the absence of lactose, sucrose, inosite, adonite fermentation, the presence of gasless, immobile variants containing no lysin decarboxylase, and a possibility of rapid differentiation from shigellae in the use of acetate medium. Among the escherichia 0151:K--there was revealed the presence of 5 biotypes by the capacity to gas-formation in glucose, arabinose, sorbit, dulcit fermentation, and decarboxylation of lysin and ornithin; three biotypes are described for the first time. Industrial issue of the agglutinating serum 0151:K--is necessary to provide the diagnosis of these microorganisms at the territory of the USSR.

Escherichia coli↗
PubMed1993

Impact of cefpodoxime proxetil and amoxicillin on the normal oral and intestinal microflora.

Ten healthy volunteers were given 200 mg cefpodoxime proxetil tablets every 12 h and ten volunteers received 500 mg amoxicillin tablets every 8 h for seven days and the impact of the agents on the oral and intestinal microflora was studied. In the oral microflora, only minor alterations were observed in both groups. In subjects receiving cefpodoxime proxetil, the numbers of streptococci, enterobacteria and clostridia were strongly reduced in the faecal flora, while there was an overgrowth of enterococci, yeasts and Clostridium difficile. Amoxicillin administration induced somewhat smaller alterations in the faecal microflora, although all subjects had overgrowth of new colonizing amoxicillin resistant microorganisms, mainly Escherichia coli, Klebsiella and Enterobacter. Beta-lactamase activity was detected in the flora of six volunteers from each group.

Adult↗
PubMed2005

Rifaximin, a poorly absorbed antibiotic: pharmacology and clinical potential.

Rifaximin (4-deoxy-4'-methylpyrido[1',2'-1,2]imidazo- [5,4-c]-rifamycin SV) is a synthetic antibiotic designed to modify the parent compound, rifamycin, in order to achieve low gastrointestinal (GI) absorption while retaining good antibacterial activity. Both experimental and clinical pharmacology clearly show that this compound is a nonsystemic antibiotic with a broad spectrum of antibacterial action covering Gram-positive and Gram-negative organisms, both aerobes and anaerobes. Being virtually nonabsorbed, its bioavailability within the GI tract is rather high with intraluminal and fecal drug concentrations that largely exceed the minimal inhibitory concentration values observed in vitro against a wide range of pathogenic organisms. The GI tract represents, therefore, the primary therapeutic target and GI infections the main indication. The appreciation of the pathogenic role of gut bacteria in several organic and functional GI diseases has increasingly broadened its clinical use, which is now extended to hepatic encephalopathy, small intestine bacterial overgrowth, inflammatory bowel disease and colonic diverticular disease. Potential indications include the irritable bowel syndrome and chronic constipation, Clostridium difficile infection and bowel preparation before colorectal surgery. Because of its antibacterial activity against the microorganism and the lack of strains with primary resistance, some preliminary studies have explored the rifaximin potential for Helicobacter pylori eradication. Oral administration of this drug, by getting rid of enteric bacteria, could also be employed to achieve selective bowel decontamination in acute pancreatitis, liver cirrhosis (thus preventing spontaneous bacterial peritonitis) and nonsteroidal anti-inflammatory drug (NSAID) use (lessening in that way NSAID enteropathy). This antibiotic has, therefore, little value outside the enteric area and this will minimize both antimicrobial resistance and systemic adverse events. Indeed, the drug proved to be safe in all patient populations, including young children. Although rifaximin has stood the test of time, it still attracts the attention of both basic scientists and clinicians. As a matter of fact, with the advancement of the knowledge on microbial-gut interactions in health and disease novel indications and new drug regimens are being explored. Besides widening the clinical use, the research on rifaximin is also focused on the synthesis of new derivatives and on the development of original formulations designed to expand the spectrum of its clinical use.

Animals↗
PubMed2004

Disassembly of F-actin cytoskeleton after interaction of Bacillus cereus with fully differentiated human intestinal Caco-2 cells.

In the present study, the role of direct procaryote-eucaryote interactions in the virulence of Bacillus cereus was investigated. As a model of human enterocytes, differentiated Caco-2 cells were used. Infection of fully differentiated Caco-2 cells with B. cereus in the exponential phase of growth, in order to minimize the concentration of spores or sporulating microorganisms, shows that a strain-dependent cytopathic effect develops. Interestingly, addition of 3-h-old cultures of some strains resulted in complete detachment of the cultured cells after a 3-h infection whereas no such effect was found after a 3-h infection with 16-h-old cultures. Infection of enterocyte-like cells with B. cereus leads to disruption of the F-actin network and necrosis. Even though the effect of secreted factors cannot be ruled out, direct eucaryote-procaryote interaction seems to be necessary. In addition, we observed that some B. cereus strains were able to be internalized in Caco-2 cells. Our findings add a new insight into the mechanisms of virulence of B. cereus in the context of intestinal infection.

Actins↗
PubMed2003

Intestinal adherent bacteria and bacterial translocation in breast-fed and formula-fed rats in relation to susceptibility to infection.

The barrier function of the intestinal mucosa is immature in the newborn mammal, and is strengthened by breast milk. We investigated this effect of breast milk by comparing the susceptibility to infection assessed in terms of adherent bacterial colonization of the intestinal tissue (AdC) and bacterial translocation (BT) between breast-fed and formula-fed newborn rats. Three-day-old rat pups were assigned to one of three groups: mother-reared (MR), pseudo-cannulated (sham), and artificially reared (AR). AR rats were infused with formula through an intragastric cannula, under the control of a computer-regulated pumping machine. MR and sham rat pups were reared with their respective dams and received breast milk until weaning in a specially designed cage. In 10-d-old rats, there was no significant difference in the fecal or cecal flora between the AR and MR groups, whereas the AdC and the BT to the liver were greater in the AR than MR group. Enterobacteriaceae, Streptococcus and/or Enterococcus, and Staphylococcus were dominantly detected as microorganisms in AdC flora and BT. The AdC flora did not directly reflect the bacterial colonization flora. These findings suggest that AR rat pups mature normally, although there is a greater colonization of Enterobacteriaceae and BT in AR than MR pups. Consequently, the intestinal barrier function of the pups reared by artificial feeding may become susceptible to BT, and AdC may be more indicative than bacterial colonization of the susceptibility to BT.

Animals↗
PubMedDate not supplied

[Scanning electronic microscopy of the small intestine in persistent diarrhea].

Persistent diarrhea very often leads children to malnutrition. It has become the major cause of death resulting from acute diarrhea episodes in developing countries. In order to determine the ultrastructural alterations of the small bowel that occur in the syndrome, 16 infants with severe persistent diarrhea were studied, utilizing light microscopy and the scanning electron microscope. Stool and jejunal fluid samples were collected for culture, rotavirus, ova and parasite search. Enteropathogenic agents were isolated in stools from 11 (68.7%) patients and bacterial proliferation in the small bowel was detected in 11 (68.7%) patients. EPEC strains were the most frequent enteropathogenic agent isolated both from stool and jejunal fluid cultures. The stool cultures revealed the presence of the following enteropathogenic microorganisms: EPEC 0111 in four, EPEC 0119 in one, EAggEC in five, Shigella flexneri in two, and Shigella sonnei in one; mixed infections due to EAggEC associated with EPEC 0111 were seen in two patients. The light microscopic analysis revealed that 56.2% of the patients suffered moderate villous atrophy most frequently associated with effacement of the microvilli, intracytoplasmatic vacuolization, increased number of multivesicular bodied and increased lymphocytic and eosinophylic infiltration in the lamina propria. The scanning electron microscopic analysis revealed in all cases shortening of the villi and enterocyte derangements; very often there was a total lack and/or effacement of the microvilli; in half of the patients there was a mucoid material covering the enterocytes tightly adhered to the apical epithelium surface. The scanning ultrastructural alterations observed in these patients are probably due to an association of factors brought about by the presence of enteropathogenic microorganisms and the resulting food intolerance that is responsible for perpetuation of diarrhea.

Diarrhea, Infantile↗
PubMedDate not supplied

Microbially controlled drug delivery to the colon.

The human gastrointestinal tract consists of a highly complex ecosystem of aerobic and anaerobic microorganisms that plays a significant role in the metabolism of nutrients as well as drugs. In the colon, bacteria ferment various types of substrates that are not susceptible to digestion in the small intestine. This arouses interest in specific drugs, drug delivery systems, and prodrugs that escape small bowel digestion, arrive intact, and are absorbed or degraded in the large bowel. For the past forty years, experience has been gained with the azo prodrug of 5-amino salicylic acid, salazopyrine, which is cleaved by colonic bacteria to its parent drug. Some laxative drugs were also reported to degrade into active metabolites in the colon. Lately equally interesting and more sophisticated microbial controlled delivery systems, have been developed based on similar principles.

Animals↗