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PubMed2004

Initiation and resolution of mucosal inflammation.

Antigens entering the body through the mucosal surface are screened by a highly developed immune system comprised not only of traditional lymphoid cells but also epithelial cells, fibroblasts, and antigen-presenting cells (APCs). For example, in the intestinal tract, gut-associated lymphoid tissue (GALT) is tolerant to the approx 400 separate commensal strains residing mainly in the colon, but also retains the capacity to detect and remove virulent bacteria before they infect systemically. This review summarizes recent work characterizing the molecular mechanisms involved in acute and chronic intestinal inflammation. We will also describe a natural murine pathogen, Citrobacter rodentium, which is being used to explore the host response to enteric pathogens and the resulting immunopathology.

Animals↗
PubMedDate not supplied

[Using antibiotics in urinary tract infection in a first level of attention health care unit in Bogotá, Colombia].

OBJECTIVES: Describing using antibiotics for urinary tract infection in a first level of attention health care unit. METHODS: This was an observational and descriptive study of a cohort of register-based patients attending the Universidad Nacional de Colombia's Health Service Unit (UNISALUD) diagnosed as suffering urinary tract infection between July 2002 and June 2003. RESULTS: 6,3 % urinary tract infection incidence was found, especially affecting women (84,4 %). The signs and symptoms were the same as those usually found in this disease. 58% corresponded to lower tract infection, 36 % to non-specific infection, 4 % to infection during pregnancy and 2 % to upper tract infection. The following uropathogens were isolated: E. coli (88.9%), Proteus spp. (5,1%), Klebsiella spp. (3,7 %), Enterobacter spp. (1%), Citrobacter spp. (1 %) and Staphylococcus saprophyticus (0,3 %). There was great variability in the antibiotic schemes being prescribed. Nitrofurantoin, Trimethoprim-sulfamethoxizole and Fluoroquinolones were the most prescribed, per defined daily dose; these antibiotics presented low susceptibility for the uropathogens so isolated. There was a 4:1 ratio of empirical treatment respecting confirmed ones. 98 % of the cases corresponded to patients suffering from a single event or having just 1 to 2 recurrences. DISCUSSION The urinary tract infection studied here presented a similar epidemiological profile to that usually found in the general population. The isolated microorganism's low susceptibility to the prescribed antibiotics could reflect inappropriate use of antibiotics by the health service, inducing selective pressure on bacterial resistance.

Adolescent↗
PubMed2001

Use of an ALFexpress DNA sequencer to analyze protein-nucleic acid interactions by band shift assay.

Gel retardation analysis, or band shift assay, is technically the simplest method to investigate protein-nucleic acid interactions. In this report, we describe a nonradioactive band shift assay using a fluorescent DNA target and an ALFexpress automatic DNA sequencer in place of the current method that utilizes radioactively end-labeled DNA target and a standard electrophoresis unit. In our study, the dsDNA targets were obtained by annealing two synthetic oligonucleotides or by PCR. In both cases, a molecule of indodicarbocyanine (CY5) was attached at the 5' OH end of one of the two synthetic oligonucleotides, with a ratio of one molecule of fluorescent dye per molecule of dsDNA. To demonstrate the feasibility of this new band shift assay method, the DNA-binding proteins selected as models were the BlaI and AmpR repressors, which are involved in the induction of the Bacillus licheniformis 749/I and Citrobacter freundii beta-lactamases, respectively. The results show that the use of an automatic DNA sequencer allows easy gel retardation analysis and provides a fast, sensitive, and quantitative method. The ALFexpress DNA sequencer has the same limit of detection as a laser fluorescence scanner and can be used instead of a FluorImager or a Molecular Imager.

Autoanalysis↗
PubMed1993

Spontaneous bacterial peritonitis in an adult patient with nephrotic syndrome.

Most cases of spontaneous bacterial peritonitis (SBP) in association with nephrotic syndrome are children. The complication of SBP in adults with nephrotic syndrome is extremely rare. Herein, we report a 25-year-old man with nephrotic syndrome and chronic renal failure who suffered from SBP. Citrobacter freundii was isolated from ascites. Irreversible deterioration of renal function followed the development of SBP, though the peritonitis was cured with antibiotic treatment. This case suggests that SBP is a rare, but serious complication of adult nephrotic syndrome with ascites.

Adult↗
PubMed2005

Retrievable Günther Tulip filter complicated by sepsis and retroperitoneal hemorrhage: successful management by filter retrieval.

We encountered complications of septic shock and retroperitoneal hemorrhage which occurred after implantation of a retrievable Günther Tulip filter. A 79-year-old woman was diagnosed as right femoral vein thrombosis, and a retrievable Günther Tulip filter was deployed prior to a total knee replacement surgery. However, the patient developed septicemia due to Citrobacter freundii, followed by thrombocytopenia and retroperitoneal hemorrhage. A large hematoma was formed along the lateral side of the filter struts. We considered that the filter should be removed to control retroperitoneal hemorrhage and prevent secondary infection of the hematoma. Removal of the retrievable filter was effective in managing these complications.

Aged↗
PubMed1976

Incidence and identification of phospholipase C-producing bacteria in fresh and spoiled homogenized milk.

Bacteria which produced phospholipase C were isolated from 13 of 34 fresh and 15 of 35 spoiled samples of homogenized milk. No single off flavor was assigned consistently to samples with phospholipase producers, but 75% of them were bitter. Pseudomonads constituted 62% of the isolates. Other phospholipase C-producing genera and their numbers were Acinetobacter, two; Alcaligenes, three; Bacillus, two; Citrobacter, one; Enterobacter, three; and Flavobacterium, two. Two unidentified yeasts also were isolated.

Acinetobacter↗
PubMed1978

Distribution of enterobacteriaceae in recycled manure bedding on California dairies.

The distribution of coliform organisms on three California dairies which use a system of automatic flushing of alley ways and composted, recycled manure solids as free stall bedding for utilization of waste was studied. There was a wide distribution of Escherichia coli, Klebsiella, and Enterobacter and to less extent Citrobacter organisms. Klebsiella were not commonly in bovine feces. Composting manure solids effectively reduced coliform counts to few or to zero. However, if given proper conditions of moisture and temperature, coliforms could multiply to large numbers again in composted solids whether from survivors or from external contamination. Dried composted manure was satisfactory material for bedding of free stalls provided it was dried properly before application.

Animal Feed↗
PubMed2004

Protective role of arginase in a mouse model of colitis.

Arginase is the endogenous inhibitor of inducible NO synthase (iNOS), because both enzymes use the same substrate, l-arginine (Arg). Importantly, arginase synthesizes ornithine, which is metabolized by the enzyme ornithine decarboxylase (ODC) to produce polyamines. We investigated the role of these enzymes in the Citrobacter rodentium model of colitis. Arginase I, iNOS, and ODC were induced in the colon during the infection, while arginase II was not up-regulated. l-Arg supplementation of wild-type mice or iNOS deletion significantly improved colitis, and l-Arg treatment of iNOS(-/-) mice led to an additive improvement. There was a significant induction of IFN-gamma, IL-1, and TNF-alpha mRNA expression in colitis tissues that was markedly attenuated with l-Arg treatment or iNOS deletion. Treatment with the arginase inhibitor S-(2-boronoethyl)-l-cysteine worsened colitis in both wild-type and iNOS(-/-) mice. Polyamine levels were increased in colitis tissues, and were further increased by l-Arg. In addition, in vivo inhibition of ODC with alpha-difluoromethylornithine also exacerbated the colitis. Taken together, these data indicate that arginase is protective in C. rodentium colitis by enhancing the generation of polyamines in addition to competitive inhibition of iNOS. Modulation of the balance of iNOS and arginase, and of the arginase-ODC metabolic pathway may represent a new strategy for regulating intestinal inflammation.

Animals↗
PubMed2004

Impaired immunity to intestinal bacterial infection in stromelysin-1 (matrix metalloproteinase-3)-deficient mice.

Infection of mice with the intestinal bacterial pathogen Citrobacter rodentium results in colonic mucosal hyperplasia and a local Th1 inflammatory response similar to that seen in mouse models of inflammatory bowel disease. Matrix metalloproteinases (MMPs) have been shown to mediate matrix remodeling and cell migration during tissue injury and repair in the intestine. We have previously shown enhanced pathology in infected TNFRp55-/-, IL-12p40-/-, and IFN-gamma-/- mice, and here we show that this is associated with an increase in stromelysin-1 (MMP3) transcripts in colonic tissues. We have therefore investigated the role of MMP3 in colonic mucosal hyperplasia and the local Th1 responses using MMP3-/- mice. In MMP3-/- mice, similar mucosal thickening was observed after infection as in wild-type (WT) mice. Colonic tissues from MMP3-/- mice showed a compensatory increase in the expression of other MMP transcripts, such as MMP7 and MMP12. However, MMP3-/- mice showed delayed clearance of bacteria and delayed appearance of CD4+ T lymphocytes into intestinal lamina propria. CSFE-labeled mesenteric lymph node CD4+ T lymphocytes from infected WT mice migrated in fewer numbers into the mesenteric lymph nodes and colon of MMP3-/- mice than into those of WT mice. These studies show that mucosal remodeling can occur in the absence of MMP3, but that MMP3 plays a role in the migration of CD4+ T lymphocytes to the intestinal mucosa.

Animals↗
PubMed2005

Cathelicidin mediates innate intestinal defense against colonization with epithelial adherent bacterial pathogens.

Cathelicidin-related antimicrobial peptide (mCRAMP), the sole murine cathelicidin, is encoded by the gene Cnlp. We show that mCRAMP expression in the intestinal tract is largely restricted to surface epithelial cells in the colon. Synthetic mCRAMP had antimicrobial activity against the murine enteric pathogen Citrobacter rodentium, which like the related clinically important human pathogens enteropathogenic Escherichia coli and enterohemorrhagic E. coli, adheres to the apical membrane of intestinal epithelial cells. Colon epithelial cell extracts from Cnlp+/+ mice had significantly greater antimicrobial activity against C. rodentium than those of mutant Cnlp-/- mice that lack mCRAMP. Cnlp-/- mice developed significantly greater colon surface and crypt epithelial cell colonization, surface epithelial cell damage, and systemic dissemination of infection than Cnlp+/+ mice after oral infection with C. rodentium. Moreover, Cnlp+/+ mice were protected from oral infections with C. rodentium inocula that infected the majority of Cnlp-/- mice. These results establish cathelicidin as an important component of innate antimicrobial defense in the colon.

Animals↗
PubMed2006

Helminth-primed dendritic cells alter the host response to enteric bacterial infection.

To examine whether intestinal helminth infection may be a risk factor for enteric bacterial infection, a murine model was established using the intestinal helminth Heligomosomoides polygyrus and a murine pathogen Citrobacter rodentium, which causes infectious colitis. Using this model we recently have shown that coinfection with the Th2-inducing H. polygyrus and C. rodentium promotes bacterial-associated disease and colitis. In this study, we expand our previous observations and examine the hypothesis that dendritic cells (DC) stimulated by helminth infection may play an important role in the regulation of the intestinal immune response to concurrent C. rodentium infection as well as in the modulation of the bacterial pathogenesis. We show that H. polygyrus infection induces DC activation and IL-10 expression, and that adoptive transfer of parasite-primed DC significantly impairs host protection to C. rodentium infection, resulting in an enhanced bacterial infection and in the development of a more severe colonic injury. Furthermore, we demonstrate that adoptive transfer of parasite-primed IL-10-deficient DCs fails to result in the development of a significantly enhanced C. rodentium-mediated colitis. Similarly, when the DC IL-10 response was neutralized by anti-IL-10 mAb treatment in mice that received parasite-primed DC, no deleterious effect of the parasite-primed DC on the host intestinal response to C. rodentium was detected. Thus, our results provide evidence to indicate that the H. polygyrus-dependent modulation of the host response to concurrent C. rodentium infection involves IL-10-producing DCs.

Adoptive Transfer↗
PubMed2000

Improvement of mannitol lysine crystal violet brilliant green agar for the selective isolation of H2S-positive Salmonella.

Mannitol lysine crystal violet brilliant green agar (MLCB) is widely used in Japan for Salmonella isolation because the medium has been commercially available. Colonies of Salmonella on MLCB appear colorless with black centers due to H2S gas production; however, most Citrobacter freundii also produce H2S gas. In order to distinguish H2S-positive Salmonella from C. freundii we have improved MLCB. To MLCB was added 1% lactose (L-MLCB). The relation for pH and black center colony formation was examined. The pH of MLCB and L-MLCB inoculated with Salmonella species was slightly acid after 7 h, but the pH of L-MLCB inoculated with C. freundii did not become acid for 24 h. The colony of C. freundii did not have a black center because the production of acid from lactose lowers the pH below 10 where it is needed for H2S to react with iron to produce black pigments. Of 99 Salmonella strains including 13 serotypes tested, all strains had the same colony morphologies on MLCB and L-MLCB. When MLCB and L-MLCB were evaluated with 36 C. freundii strains isolated from foods, only colonies on MLCB had black centers. We conclude that L-MLCB is useful for detection of nonlactose-fermenting, H2S-positive Salmonella in food samples.

Agar↗
PubMed2000

Prevalence of Salmonella spp. in poultry broilers and shell eggs in Korea.

This study was conducted to determine the presence of Salmonella spp. in raw broilers and shell eggs in Korea. In total, 135 dozen shell eggs and 27 raw broilers were tested. None of the egg yolks were found to contain Salmonella organisms but Escherichia coli, Escherichia hermanii, and Citrobacter freundii were isolated from egg shells. Salmonella spp. were detected in 25.9% of raw broilers, and Salmonella serotypes isolated from raw broilers were Salmonella Enteritidis, Salmonella Virchow, and Salmonella Virginia. D-values and antibiotic resistance of Salmonella isolates were also investigated. D-values of Salmonella enteritidis, Salmonella Virginia, and Salmonella Virchow in tryptic soy broth at 55 degrees C were 2.36, 2.13, and 0.70 min and 0.53, 0.37, and 0.20 min at 60 degrees C, respectively. All Salmonella isolates showed multiple antibiotic resistance patterns and were resistant to penicillin and vancomycin. One strain of Salmonella Enteritidis showed resistance to 12 antibiotics used in this study.

Animals↗
PubMed2003

Prophylactic feeding of Lactobacillus acidophilus NCFM to mice attenuates overt colonic hyperplasia.

The objective of this project was to determine if the probiotic Lactobacillus acidophilus NCFM would protect mice from developing transmissible murine colonic hyperplasia (TMCH) caused by Citrobacter rodentium. Our hypothesis was that the oral administration of L. acidophilus NCFM to mice would mitigate colonic hyperplasia and modulate the host immune response. A concurrent administration (CA) study was performed by feeding mice phosphate-buffered saline (PBS), C. rodentium only, L. acidophilus NCFM only, or C. rodentium and NCFM concurrently on the same day. The mice in the CA study were not protected by the probiotic, since their mean colon sample weights (0.109 g) were significantly higher than those of the PBS controls (0.0774 g), and the hematoxylin and eosin-stained samples showed histological changes typically associated with TMCH. A prophylactic feeding (PF) study was performed by orally feeding mice PBS or NCFM once daily for 20 consecutive days; in addition, on day 7, mice were challenged with either PBS or C. rodentium. Mice in the PF study were protected when they consumed the probiotic prior to the pathogen challenge, since their mean colon sample weights (0.0812 g) were not significantly higher than those of the controls (0.0753 g). The hematoxylin and eosin-stained samples appeared similar to the control samples, and the intestinal interleukin (IL)-15 and gamma interferon (IFN-gamma) mRNA levels were reduced. L. acidophilus NCFM did attenuate overt colonic hyperplasia when fed to mice prior to challenge with C. rodentium. The mouse model used in this study enabled us to investigate the efficacy of the L. acidophilus NCFM in preventing gastrointestinal disease and is a valid model for future probiotic research.

Administration, Oral↗
PubMed1979

The bacterial outer-membrane permeability of beta-lactam antibiotics.

Two penicillins and 5 cephalosporins were evaluated for their ability to pass through the outer-membranes of Proteus morganii, Citrobacter freundii and Escherichia coli. Cefazolin, ceftezole and cephaloridine showed high permeability through the outer-membranes of these Gram-negative bacteria. Benzylpenicillin and cephalothin, on the contrary, showed low permeability. The outer-membrane permeability of ampicillin and cephalexin varied from species to species. C. freundii was found to have the highest barrier against both the penicillins and the cephalosporins, and E. coli appeared to have a low barrier against the cephalosporins. The hydrophobic character of the beta-lactam antibiotics, which was estimated by a reversed-phase thin-layer chromatography was closely related to the outer-membrane permeability. In general, the more hydrophilic antibiotic showed the higher outer-membrane permeability. However, cephaloridine, the most lipophilic compound among the antibiotics tested, showed good permeability.

Anti-Bacterial Agents↗
PubMed1980

Cefoxitin resistance by a chromosomal cephalosporinase in Escherichia coli.

Cefoxitin resistance, an unique property found in clinical isolates of Escherichia coli was investigated. Cefoxitin resistant strains, 255 and GN206, produced cephalosporinase constitutively. The cephalosporinase was located in the periplasm, and its production was considered to be mediated by chromosomal gene(s). Cephalosporinase-less mutants from both strains were susceptible to cefoxitin as well as other beta-lactam antibiotics, suggesting that the cephalosporinase was responsible for the resistance to beta-lactam antibiotics including cefoxitin. The cephalosporinases from the E. coli strains were partially purified and their enzymological properties were compared with those of cephalosporinases of Citrobacter freundii and Proteus morganii. Although the cephalosporinases of E. coli, as well as other cephalosporinases, showed little activity for cefoxitin-hydrolysis, the E. coli cephalosporinases exhibited a significantly higher affinity for cefoxitin than other cephalosporinases. It was assumed that the E. coli enzyme located around the targets of cefoxitin protected the targets from the antibiotic by its high affinity for the antibiotic.

Cefoxitin↗
PubMed1988

Cephalosporinase interactions and antimicrobial activity of BMY-28142, ceftazidime and cefotaxime.

Cephalosporinases of Enterobacter cloacae and Citrobacter freundii were responsible for resistance to newer cephalosporins such as cefotaxime and ceftazidime but not BMY-28142. Interaction of these cephalosporins including hydrolysis, binding, inhibition, and inactivation with cephalosporinases from E. cloacae GN7471 and C. freundii GN7391 were studied. BMY-28142 was much more stable against the both enzymes than cephalothin, but more hydrolyzable than cefotaxime and ceftazidime at higher concentration such as 100 microM. Because of low affinity for the enzymes, i.e. large Km and Ki, the calculated hydrolysis rate of BMY-28142 at 0.1 microM was smaller than those of cefotaxime and ceftazidime, that explained the difference in activity against cephalosporinase-producing strains between BMY-28142 and cefotaxime or ceftazidime. The effects of cephalosporinase production on susceptibility of Escherichia coli omp mutants were examined using a plasmid having cephalosporinase gene of C. freundii GN346. Decrease in susceptibility of E. coli by cephalosporinase production was larger in the strain lacking outer membrane proteins (Omp) F and C, and smaller in the strain producing OmpF constitutively.

Cefepime↗
PubMed1990

Characteristics of aztreonam as a substrate, inhibitor and inducer for beta-lactamases.

Aztreonam was investigated as to its characteristics as a substrate, inhibitor and inducer for the well-defined beta-lactamases of Gram-negative bacteria, and its antibacterial efficacy as to bacterial cells producing eight types of beta-lactamases was also evaluated. Aztreonam was hydrolyzed at measurable rates by class A beta-lactamases, a TEM-2 type penicillinase and the Proteus vulgaris cephalosporinase with a broad substrate range. However, the affinity of aztreonam for the class A enzymes was low, this property being well reflected by its high antibacterial activity toward producers of class A beta-lactamases. Aztreonam was extremely stable as to the typical class C cephalosporinase of Citrobacter freundii, and acted as a competitive and progressive inhibitor for the beta-lactamase. While the MICs of aztreonam in the cases of the constitutive producers of class C beta-lactamases were evidently affected by enzyme production. An experiment involving aztreonam as a inhibitor in combination with a hydrolyzable beta-lactam gave ambiguous results, however, a strong synergistic effect was found in combination with mecillinam. Using Pseudomonas aeruginosa, aztreonam was confirmed to be a poor inducer of beta-lactamases.

Amdinocillin↗