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At least 1,081 records · Page 60Linked to original sources
PubMed2001

Impact of gemifloxacin on the normal human intestinal microflora.

Gemifloxacin is a new fluoroquinolone that has been shown to possess a broad spectrum of antimicrobial activity against gram-positive and gram-negative microorganisms including methicillin-susceptible and methicillin-resistant staphylococci, Streptococcus pneumoniae, Haemophilus influenzae and most members of the family Enterobacteriaceae. The aim of the present study was to investigate the effect of gemifloxacin on the human intestinal microflora. Gemifloxacin was given in oral doses of 320 mg for 7 days to 10 healthy subjects and 5 subjects received a once-daily dose of matched placebo for 7 days. Faecal samples were collected prior to administration (days -8 and -6), during the administration period (days 2 and 4) and after withdrawal of administration (days 8, 11, 21, 28 and 56). In the aerobic intestinal microflora the numbers of enterobacteria were suppressed during the gemifloxacin administration and the numbers of enterococci and streptococci were also decreased. No other aerobic microorganisms were affected. In the anaerobic microflora the numbers of anaerobic cocci and lactobacilli were suppressed during the gemifloxacin administration while no other changes occurred. The microflora was normalized 49 days after the administration of gemifloxacin had stopped. No selection or overgrowth of resistant bacterial strains or yeasts occurred. The ecological impact of gemifloxacin was shown to be selective and similar to that of ciprofloxacin, levofloxacin and ofloxacin.

Adult↗
PubMed1990

Implantation and in vivo antagonistic effects of antibiotic-susceptible Escherichia coli strains administered to premature newborns.

Two antibiotic-susceptible and non-pathogenic Escherichia coli strains were administered to hospitalized premature infants in order to protect them from intestinal colonization by hospital-acquired antibiotic-resistant enteric organisms (EOs). Three groups of 16 premature newborns received respectively strain ECA, strain EMO and both strains simultaneously. A fourth group was used as a control. Resistant EOs became spontaneously established in the digestive tract of a majority of the unadministered children. Both ECA and EMO were able to colonize the digestive tract of a majority of the subjects, and reached high population numbers (greater than 10(7)/g) in the faeces. Both strains appeared as able to reduce significantly the establishment of antibiotic-resistant EOs. This effect was more prominent with EMO, which also impaired the implantation of ECA when both strains had been administered simultaneously. The use of such innocuous microorganisms could thus constitute an additional means of preventing nosocomial infections of intestinal origin.

Anti-Bacterial Agents↗
PubMed2006

Gut-trophic feed additives and their effects upon the gut structure and intestinal metabolism. State of the art in the pig, and perspectives towards humans.

The correct functional development of the gastrointestinal tract is of special importance during the neonatal and weaning phases of reared piglets. Nutrition is obviously a critical determinant in the growth of the gut in the young swine. The mucosal epithelium of the small intestine is reputed anatomically and functionally immature in neonatal pigs, a feature that appears to be exacerbated at weaning, when a colonization of the gut occurs by "new" microorganisms entering the alimentary canal with the solid feed. This frequently exposes piglets to diarrhoeic syndromes and other intestinal disturbances. Functional feed additives, also called nutraceuticals, appear as promising alternative substances to the use of chemotherapeutics as growth promoters in the rearing farm, above all considering the near banning of them by the European Parliament in the view of reducing antibiotic resistance phenomena in human therapies. Several feed additives are available that may play a role in the pig nutritional plan because of their trophic and cyto-protective effects on the gastrointestinal apparatus. Paying special attention to the quantitative consequences (histometry) upon the gut of the examined dietary supplements, this review, even if not fully exhaustive, will focus on the function (and possibly the mechanism/s of action) of certain gut-trophic nutrient substrates. This in turn will sustain the potential use of these substances in human therapy, especially the one directed at resolving intestinal diseases, both in adult and infant ages. In nutritional studies as well as in other biomedical research fields, the swine is an excellent animal model.

Animal Feed↗
PubMed1984

Studies with enterotoxigenic microorganisms: effects of candidate antidiarrhoeals in experimental animals in vivo.

Chlorpromazine or aspirin alone, when given to rats parenterally, reduced intestinal fluid secretion induced by cell-free preparations of enterotoxigenic organisms including Escherichia coli, Aeromonas hydrophila, Staphylococcus pyogenes, and Salmonella typhimurium. A combination of chlorpromazine-aspirin given parenterally caused much more marked reduction of fluid secretion. Indomethacin also had significant antisecretory effects against a range of bacterial enterotoxins, while loperamide was effective against heat-labile toxin (LT)-positive E. coli and A. hydrophila. Nicotinamide increased net fluid absorption in the presence of E. coli LT, A. hydrophila, and S. typhimurium. Of the adsorbents tested, aluminum hydroxide showed a positive effect only with E. coli LT and A. hydrophila, while cholestyramine affected net fluid flux only with E. coli ST (heat-stable toxin). Charcoal was effective against all microorganisms tested but only when premixed with the perfusate before the experiments. Aspirin and chlorpromazine probably act at multiple sites to decrease intestinal secretion, and the combination of low doses of these drugs with possibly different sites of action may have advantages over a single agent used in high dosage.

Aluminum Hydroxide↗
PubMed1994

Interactions between human defensins and lipid bilayers: evidence for formation of multimeric pores.

Defensins comprise a family of broad-spectrum antimicrobial peptides that are stored in the cytoplasmic granules of mammalian neutrophils and Paneth cells of the small intestine. Neutrophil defensins are known to permeabilize cell membranes of susceptible microorganisms, but the mechanism of permeabilization is uncertain. We report here the results of an investigation of the mechanism by which HNP-2, one of 4 human neutrophil defensins, permeabilizes large unilamellar vesicles formed from the anionic lipid palmitoyloleoylphosphatidylglycerol (POPG). As observed by others, we find that HNP-2 (net charge = +3) cannot bind to vesicles formed from neutral lipids. The binding of HNP-2 to vesicles containing varying amounts of POPG and neutral (zwitterionic) palmitoyloleoylphosphatidylcholine (POPC) demonstrates that binding is initiated through electrostatic interactions. Because vesicle aggregation and fusion can confound studies of the interaction of HNP-2 with vesicles, those processes were explored systematically by varying the concentrations of vesicles and HNP-2, and the POPG:POPC ratio. Vesicles (300 microM POPG) readily aggregated at HNP-2 concentrations above 1 microM, but no mixing of vesicle contents could be detected for concentrations as high as 2 microM despite the fact that intervesicular lipid mixing could be demonstrated. This indicates that if fusion of vesicles occurs, it is hemi-fusion, in which only the outer monolayers mix at bilayer contact sites. Under conditions of limited aggregation and intervesicular lipid mixing, the fractional leakage of small solutes is a sigmoidal function of peptide concentration. For 300 microM POPG vesicles, 50% of entrapped solute is released by 0.7 microM HNP-2. We introduce a simple method for determining whether leakage from vesicles is graded or all-or-none. We show by means of this fluorescence "requenching" method that native HNP-2 induces vesicle leakage in an all-or-none manner, whereas reduced HNP-2 induces partial, or graded, leakage of vesicle contents. At HNP-2 concentrations that release 100% of small (approximately 400 Da) markers, a fluorescent dextran of 4,400 Da is partially retained in the vesicles, and a 18,900-Da dextran is mostly retained. These results suggest that HNP-2 can form pores that have a maximum diameter of approximately 25 A. A speculative multimeric model of the pore is presented based on these results and on the crystal structure of a human defensin.

Amino Acid Sequence↗
PubMed1982

Efficacy of antibiotic prophylaxis in high risk gastroduodenal operations.

A double-blind, prospective and randomized clinical trial of the efficacy of antibiotic prophylaxis in gastroduodenal operations was studied in 39 patients over an 18 month period. All patients had clinical features that placed them at high risk for the development of postoperative wound or intraabdominal sepsis. In the placebo group of 20 patients seven gastric-related infections developed, while 1 of the 19 patients who received perioperative cefamandole had one gastric-related infection (p less than 0.01). The responsible microorganisms were those that are normal components of the oral or intestinal microflora. Nongastric-related infections and deaths did not differ significantly in the two study groups. The results of this study confirm the efficacy of the use of short-term perioperative antibiotic prophylaxis in patients undergoing gastroduodenal surgery for bleeding duodenal or gastric ulcer, obstructing duodenal ulcer, gastric ulcer or malignancy.

Anti-Bacterial Agents↗
PubMed2006

Probiotic Lactobacillus casei activates innate immunity via NF-kappaB and p38 MAP kinase signaling pathways.

Probiotic bacteria are microorganisms that benefit the host through improvement of the balance of intestinal microflora and possibly by augmentation of host defense systems. We examined the mechanisms for the up-regulation of innate immune responses by a probiotic Lactobacillus casei ATCC27139, in vivo. Using mouse models of systemic Listeria monocytogenes infection and MethA fibrosarcoma tumorigenesis in combination with BALB/c and SCID mice, we found that parenteral administration of L. casei ATCC27139 confers a protective effect against L. monocytogenes infection and anti-tumor activity against MethA fibrosarcoma by activation of innate immunity, while L. casei ATCC27139-J1R strains, which are J1 phage-resistant strains that have been selected from MNNG-treated clones, lacked these activities. Substantial differences between ATCC27139 and ATCC27139-J1R strains were observed in the capacity to induce innate cytokines such as TNF-alpha, IL-12, IL-18, and IFN-gamma, and pathogen-associated molecular pattern receptors, TLR2 and Nod2, by spleen cells. In addition, although phosphorylation of NF-kappaB p65 in spleen was equally enhanced in the ATCC27139- and the ATCC27139-J1R-treated groups, phosphorylation of both p38 MAPK and MAPKAPK-2 was significantly induced only by ATCC27139. Furthermore, inhibitors of NF-kappaB (sulfasalazine) and p38 MAPK (SB203580) significantly reduced cytokine production by the spleen cells of the mice treated with L. casei ATCC27139, suggesting that both NF-kappaB and p38 MAPK signaling pathways play important roles in the augmentation of innate immunity by the probiotic L. casei.

Animals↗
PubMed2007

Defensins and cathelicidins in gastrointestinal infections.

PURPOSE OF REVIEW: To review recently published studies presenting novel and relevant information on antimicrobial peptides in gastrointestinal infections. RECENT FINDINGS: Defensins and cathelicidins are important antimicrobial peptides expressed by the gastrointestinal epithelium. Their localization and regulation have been the focus of current research establishing the relevance of these peptides both in counteracting an attack by pathogens as well as in controlling the endogenous bacterial flora. In the small intestine, Paneth cell alpha-defensins maintain a low level of microorganisms and regulate the composition of the bacterial flora. In contrast, a constitutive beta-defensin can be found in nearly all gastrointestinal tissues. Other relevant beta-defensins as well as human cathelicidin are inducible by inflammation or infections. Thus Helicobacter pylori enhances defensin expression in the gastric mucosa and Campylobacter jejuni and Salmonella provoke a similar response in the colon. Other pathogenic bacteria may suppress the antimicrobial peptide response as an escape strategy. Notably, the therapeutic induction of cathelicidins alleviates experimental shigellosis, suggesting a future role of endogenous antibiotics in medical therapy. SUMMARY: These recent findings together with a better understanding of underlying mechanisms involved in the regulation and biology of antimicrobial peptides will open up new therapeutic avenues to battle infections.

Antimicrobial Cationic Peptides↗
PubMed2005

Irritable bowel syndrome in developing countries--a disorder of civilization or colonization?

While irritable bowel syndrome (IBS) is common in the West, early studies suggest that the prevalence is low in developing countries. However, recent studies point to increasing prevalence in newly developed Asian economies. The presentation appears to differ from the West, with a lack of female predominance, a greater frequency of upper abdominal pain and defecatory symptoms perceived as being less bothersome. This difference, together with the preoccupation with organic disease, could explain why we may be missing IBS in Asia and also why excess surgery has been observed in some Asian countries. While a recent study from China, consistent with western studies, support an important role for infection and inflammation, early studies from India reporting no association between amoebic infection and IBS appear to dispute this observation. To reconcile these seemingly contradictory observations, an hygiene hypothesis model is proposed. Exposure to a variety of microorganisms early in life could result in the colonization of the intestine with microflora that can respond more efficiently to an episode of gastroenteritis. Together with the changes with evolution of Asian economies such as westernization of the diet and increased psychosocial stress, it is proposed that loss of this internal protective effect, could give rise to a more uniform worldwide prevalence of IBS.

Culture↗
PubMed1996

Inhibition of adhesion of Clostridium difficile to Caco-2 cells.

For many microorganisms, including Clostridium difficile, mucosal association is an important factor influencing intestinal colonisation and subsequent infection. Inhibition of adhesion of C. difficile to intestinal mucosa could be a new promising strategy for prevention and treatment of antibiotic-associated diarrhoea. We investigated the possibilities of influencing the adhesion of C. difficile by xylitol and bovine colostrum whey. Caco-2 cells and C. difficile cells were incubated with 1%, 5% and 10% solutions of xylitol and colostrum. Our study revealed that both xylitol and colostrum inhibited the adhesion of C. difficile to Caco-2 cells. Inhibition by xylitol was dose-dependent. When compared to the control, the count of adherent C. difficile decreased 3.4 times when treated with 1% xylitol, 12 times when 5% xylitol was applied, and 18.7 times when treated with 10% xylitol. The inhibition of adherence by colostrum was partially dose-dependent: 3.1 times in the case of 1%, and 5.5 times in the cases of 5% and 10% colostrum. Further experimental and clinical studies are needed for the application of xylitol and colostrum in the treatment and prophylaxis of pseudomembraneous colitis.

Animals↗
PubMed1970

Formation of "photodieldrin" by microorganisms.

Photodieldrin, previously reported as the major conversion product of dieldrin by sunlight, was found among the metabolic products of dieldrin among microorganisms isolated from various environments including soil, water (Lake Michigan), rat intestines, and rumen stomach contents of a cow.

Animals↗
PubMed2005

Pseudospirochaetosis of the urinary bladder.

This report describes an elderly patient with urinary symptoms who showed surface colonisation of the transitional mucosa of the bladder by an unusual haematoxophilic microorganism superficially resembling the "blue fuzz" seen in colonic biopsies showing intestinal spirochaetosis. Special stains showed that the organisms were Gram and Giemsa positive, weakly argyrophilic, and Ziehl-Nielsen negative. Immunostains were negative for Helicobacter pylori and electron microscopy revealed curious curved bodies, which were difficult to classify. Therefore, this condition was described as pseudospirochaetosis of the urinary bladder. The urinary symptoms regressed on treatment with ciprofloxacin. The clinicopathological relevance of these findings is discussed in the report.

Aged↗
PubMed2006

The bacterial weaponry: lessons from Shigella.

Shigella, a Gram-negative bacterial species of the family Enterobacteriaceae, causes bacillary dysentery in humans, an acute rectocolitis that reflects the capacity of the microorganism to disrupt, invade, and cause the inflammatory destruction of the intestinal epithelium. Here, the pathogenesis of Shigella infection is analyzed in the context of the disruption of the homeostatic balance that protects the gut against inflammation in the presence of its commensal flora. Thus a unified view by which enteroinvasive pathogens allow identification of key signalling molecules and pathways involved in the regulation of intestinal inflammation, thereby providing keys to understand inflammatory bowel diseases (IBDs) such as Crohn's disease and ulcerative colitis.

Dysentery, Bacillary↗
PubMed2001

[Metabolic disorders in nonspecific inflammatory bowel diseases].

The primary function of the gastrointestinal system is to assist the intake and further processing of food and liquids. Besides that, it forms an anatomical barrier between the external environment and internal milieu. It is also highly important for its paracrine and endocrine function. Inflammatory bowel diseases, which frequently cause a gastrointestinal failure, form a specific group. Most frequently it is the ulcerative colitis and Crohn's disease. Impaired integrity of the gastrointestinal mucosa and failure of protective mechanisms lead to the increased permeability of the intestinal wall for antigens derived from food, saprophytic bacteria and pathogenic microorganisms. When the gastrointestinal failure is threatening, factors determining its residual function become more important. As decisive reveals the severity and location of the primary disease. Previous surgeries and adaptation of the residual part of the gastrointestinal system are important, as well as the possibility of peroral or enteral nutrient intake. Depending on the presence of risk factors and the degree of residual gut function, some complications can be expected: dehydration, mineral disorders, symptoms of protein and energy depletion, infection, and multiple organ dysfunction syndrome. It is highly important to decide whether the gastrointestinal system will be included into or excluded from the process of realimentation. Critically ill patients with inflammatory bowel diseases should be treated at an intensive care unit.

Deficiency Diseases↗
PubMed1998

A cluster of equine granulomatous enteritis cases: the link with aluminium.

A cluster of 6 cases of equine granulomatous enteritis is described. Aluminium was demonstrated in the tissues and lesions of these horses and in the intimal bodies of intestinal vessels. The relationship between granulomatous lesions, aluminium, acidity and invading microorganisms, particularly parasites, is presented and discussed.

Aluminum↗
PubMed2004

Intra-abdominal, retroperitoneal, and visceral abscesses in children.

This review describes the microbiology, diagnosis, and management of intra-abdominal abscesses (including subphrenic, hepatic, splenic, and retroperitoneal abscesses) in children. They often occur as a complication of local or generalized peritonitis, commonly secondary to appendicitis, necrotizing enterocolitis, pelvic inflammatory disease, and tubo-ovarian infection, surgery or trauma. The original infection generally occurs because of the entry of enteric microorganisms into the peritoneal cavity through a defect in the wall of the intestine or other viscus as a result of obstruction, infarction, or direct trauma. Mixed aerobic and anaerobic flora can be recovered from most abscesses. The predominant aerobic isolates are Escherichia coli, Staphylococcus aureus, and Enterococcus spp. and the main anaerobic bacteria are Bacteroides fragilis group Peptostreptococcus spp., Fusobacterium spp., and Clostridium spp. The treatment of intraabdominal abscesses includes drainage, surgical correction of pathology, and administration of antimicrobials effective against both aerobic and anaerobic microorganisms.

Abdomen↗
PubMed2003

How not to get bugged by bugs: mechanisms of cellular tolerance to microorganisms.

PURPOSE OF REVIEW: Advances in the characterization of the receptors and signaling pathways involved in the response to infection have led to a more detailed understanding of cellular tolerance to endotoxin and other microbial components. This review summarizes recent progress in the field, particularly in relation to the molecular mechanisms that underlie the development of tolerance to microorganisms. RECENT FINDINGS: The identification of Toll-like receptors as major sensors of microbial molecules has led to numerous studies of their function in tolerant cells. Decreased Toll-like receptor expression, altered interactions between the Toll-like receptors and intracellular signal transducers, and decreased expression or activity of downstream signaling molecules have all been implicated. Upregulation of specific proteins that inhibit Toll-like receptor signaling has also been described. Apart from these general mechanisms, special features of the intestinal microenvironment and its resident cells also contribute to making the gut hyporesponsive to microorganisms. SUMMARY: The application of gene knockout technology has highlighted the importance of macrophage tolerance in regulating innate immunity to microbial infection. Such studies have indicated that the failure of tolerance can lead to exaggerated inflammatory responses to intestinal bacteria, raising the possibility that defects in tolerance may be linked to conditions such as inflammatory bowel disease. Further characterization of this link will help in elucidating the pathogenesis of such conditions and in devising new approaches to treatment.

Journal Article↗
PubMed2001

Nerve-driven immunity: neuropeptides regulate cytokine secretion of T cells and intestinal epithelial cells in a direct, powerful and contextual manner.

Throughout the body, immune cells of various types, both classical (such as T-cells) and less recognized (such as intestinal epithelial cells) are exposed to a variety of neurotransmitters secreted from local nerve fibers. Moreover, immune cells express specific neurotransmitter receptors. Based on the above we asked whether neurotransmitters. by direct interaction with their receptors, can either evoke or block immune functions in general, and cytokine secretion in particular. We found that several neuropeptides (SOM, Sub P, CGRP and NPY), in nM concentration and in the absence of any additional stimulatory molecules, induced a significant secretion of cytokines from Th0, Th1 and Th2 antigen specific T-cells. Moreover, some neuropeptides surprisingly drove committed Thl and Th2 populations to a 'forbidden' cytokine secretion: secretion of Th2 cytokines from Th1 cells, and vice versa. We further found that SOM by itself markedly affected the secretion of proinflammatory cytokines from intestinal epithelial cells, which play a major role in the gut immunity in the mucosal defense against invading microorganisms. Thus, somatostatin, through its specific receptor, inhibits (> 90%) of the spontaneous, TNF-alpha or bacteria (Salmonella)-induced secretion of IL-8 and IL-1beta from two intestinal epithelial cell lines. Taken together, these observations suggest that neuropeptides can by themselves induce both typical and atypical cytokine secretion from T-cells and intestinal epithelial cells. Since a myriad of immune reactivities are mediated by, and dependent on, specific cytokines secreted from immune cells, the neuropeptide-induced effects may have important implications for numerous physiological and pathological conditions, including autoimmune diseases, chronic inflammation and neoplasias.

Autoimmune Diseases↗