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trimethoprim-sulfamethoxazole salvage for refractory listeriosis during maintenance chemotherapy for acute lymphoblastic leukemia.a 5-year-old boy with acute lymphoblastic leukemia (all) and intolerance to oral trimethoprim-sulfamethoxazole (tmp/smx) had listeria monocytogenes bacteremia and meningitis develop during maintenance chemotherapy. despite prompt administration of iv amoxicillin/gentamicin and microbiologic clearance of the bloodstream, the patient had no response to therapy after a course of 7 days. intravenous tmp/smx (10 mg/kg per day of tmp) was added to the antibiotic regimen after desensitization. fever an ...200010959905
[neurological complications of renal transplant].advances in surgical procedures and new immunosuppressor therapies have improved the outcome of renal grafts. however, these changes have been accompanied by infectious, neoplastic and neurologic complications. the purpose of this study was to determine the incidence of neurologic complications among 542 patients receiving a renal transplant (from living or cadaveric donors) at cemic between 1970 and 1996. neurologic complications occurred in 43 patients (8%) as follows: 8 meningitis (1.5%), 8 a ...200010962803
a role for alpha-and beta-catenins in bacterial uptake.interaction of internalin with e-cadherin promotes entry of listeria monocytogenes into human epithelial cells. this process requires actin cytoskeleton rearrangements. here we show, by using a series of stably transfected cell lines expressing e-cadherin variants, that the ectodomain of e-cadherin is sufficient for bacterial adherence and that the intracytoplasmic domain is required for entry. the critical cytoplasmic region was further mapped to the beta-catenin binding domain. because beta-ca ...200010963665
listeria monocytogenes in faeces from clinically healthy dairy cows in sweden.faecal samples from 102 clinically healthy dairy cows, representing 34 farms in the swedish province of uppsala, were analysed for the presence of listeria spp. using an enrichment procedure. listeria monocytogenes was isolated from six (6%) and l. innocua from 2 (2%) cows. from each of the 6 samples positive for l. monocytogenes, 5 isolates were further characterised by restriction enzyme analysis using the 3 enzymes apa i, sma i, and asc i, followed by pulsed-field gel electrophoresis. three o ...200010965567
acid tolerance in listeria monocytogenes influences invasiveness of enterocyte-like cells and macrophage-like cells.clinical and food listeria monocytogenes isolates, pre-exposed to mild acidic conditions, were able to readily develop acid tolerance, irrespective of their origin. we attempted to investigate the influence of acid tolerance mechanisms, either constitutive or induced, on the invasive behaviour of this facultative food-borne pathogen. entry efficiency and intracellular growth of acid-tolerant strains were evaluated in in vitro cell models capable to mimic in vivo target cells, such as enterocytes ...200010968945
the effect of culture growth phase on induction of the heat shock response in yersinia enterocolitica and listeria monocytogenes.the effect of culture growth phase on induction of the heat shock response in yersinia enterocolitica and listeria monocytogenes, was examined. exponential or stationary preconditioned cultures were heat shocked and survivor numbers estimated using selective and overlay/resuscitation recovery techniques. the results indicate that prior heat shock induced increased heat resistance in both micro-organisms to higher heat treatments. heat-shocked cells of each micro-organism were able to survive muc ...200010971751
combined action of s-carvone and mild heat treatment on listeria monocytogenes scott a.the combined action of the plant-derived volatile, s-carvone, and mild heat treatment on the food-borne pathogen, listeria monocytogenes, was evaluated. the viability of exponential phase cultures grown at 8 degrees c could be reduced by 1.3 log units after exposure to s-carvone (5 mmol l-1) for 30 min at 45 degrees c, while individual treatment with s-carvone or exposure to 45 degrees c for 30 min did not result in a loss in viability. other plant-derived volatiles, namely carvacrol, cinnamalde ...200010971762
a small outbreak of listeriosis potentially linked to the consumption of imitation crab meat.a small outbreak of listeriosis involving two previously healthy adults occurred in ontario. food samples obtained from the refrigerator of the patients included imitation crab meat, canned black olives, macaroni and vegetable salad, spaghetti sauce with meatballs, mayonnaise and water. all of the samples except the water contained listeria monocytogenes. the three most heavily contaminated samples were the imitation crab meat, the olives and the salad which contained 2.1 x 109, 1.1 x 107 and 1. ...200010972708
selective amplification of bacterial rna: use of a dna primer containing mismatched bases near its 3' terminus to reduce false-positive signals.a reverse transcription pcr (rt-pcr) method designed to reduce false-positive results due to the co-amplification of contaminating genomic dna is reported. feasibility of the method was evaluated using 16s rrna sequences specific to bacillus cereus. a dna oligonucleotide primer, consisting of 22-bases containing three consecutive mismatched bases near its 3' terminus (primer b16rt), was used for reverse transcription and in subsequent cdna amplification. specific rrna was reverse transcribed at ...200010972726
regulation of growth inhibition at high temperature, autolysis, transformation and adherence in streptococcus pneumoniae by clpc.the clpc atpase is a subfamily of hsp100/clp molecular chaperones-regulators of proteolysis. by screening a library of loss of function mutants for the ability to survive treatment with penicillin, we identified the gene clpc. the corresponding protein was identified as a clpc atpase, sharing strong peptide sequence identity with clpc of bacillus subtilis, listeria monocytogenes and lactococcus lactis. northern blot experiments showed that expression of clpc was induced in response to high tempe ...200010972795
etiologic spectrum and pattern of antimicrobial drug susceptibility in bacterial meningitis in sokoto, nigeria.etiologic agents of meningitis were prospectively investigated among patients admitted to usman danfodio university teaching hospital, sokoto. of 1097 cerebrospinal fluid (csf) samples submitted to the microbiology laboratory from various wards of the hospital, 289 (26%) were microscopically, culturally and/or serologically proven to be bacterial meningitis. the etiologic spectrum was as follows: neisseria meningitidis (61%), streptococcus pneumoniae (18%), haemophilus influenzae (10%), staphylo ...200010976835
modulation of acta gene expression in listeria monocytogenes by iron.this study analysed the invasiveness of listeria monocytogenes into enterocyte-like caco-2 cells in which iron depletion was achieved by picolinic acid treatment. both entry and intracellular multiplication varied depending on the endogenous iron content of bacterial and eukaryotic cells. the behaviour within enterocytes was correlated with a 10-fold increased transcription of the acta gene observed in bacterial cells grown under conditions of iron stress.200010933250
in vivo cytokine production and resistance to infection after acute exposure to 3,4-dichloropropionaniline.3,4-dichloropropionaniline (propanil) is an extensively used postemergent herbicide that has been shown to produce toxic and immunotoxic effects. the present report examined if acute exposure to propanil altered in vitro or in vivo cytokine production in response to antigenic stimulation. studies to determine resistance to infection by the intracellular bacterium listeria monocytogenes after exposure to propanil were also conducted. our experiments demonstrate that in vivo exposure to propanil d ...200010933756
in vivo and in vitro assessment of the virulence of listeria monocytogenes strains.to evaluate whether the in vitro model (invasion and intracellular growth in caco-2 cells) for determining virulence is a suitable alternative to the in vivo model (50% lethal dose), we compared the levels of virulence obtained with the two models. we tested l. monocytogenes strains isolated from food and clinical samples during three episodes of listeriosis occurring in italy in the period 1993-1995. we also tested l. monocytogenes strains isolated from food during official control activities. ...200010939044
quantitative risk assessment for listeria monocytogenes in smoked or gravad salmon and rainbow trout in sweden.the objective of the present work was to develop a quantitative risk assessment model in which the exposure and risk of acquiring listeriosis from consumption of packaged smoked or gravad salmon and rainbow trout were estimated. an excel spreadsheet model was constructed in which variables were represented by distributions based on surveys of l. monocytogenes in these food products, and on demographic and consumption data. growth or inactivation was not included in the model. the model was run t ...200010939268
comparison of microbiological risk assessment studies published.the fao/who risk analysis framework and principles are in the process of being implemented in different national and international settings. the importance of a further development of international co-operation based upon agreed principles in this area is stressed in the codex alimentarius system, as well as under the wto/sps agreements. key input in this context will come from the presentation of formalised microbiological risk assessments. the number of peer-review published microbiological ri ...200010939269
mycobacterium tuberculosis h37rv comparative gene-expression analysis in synthetic medium and human macrophage.mycobacteria are intracellular pathogens that survive and grow in host macrophages. following phagocytosis, sustained intracellular bacterial growth depends on its ability to avoid destruction by macrophage-mediated host defences such as lysosomal enzymes, reactive oxygen and the reactive nitrogen intermediates. this suggests that the interaction between host cell and microbe is delicately balanced, and can be tipped in favour of either organism. the identification of mycobacterium tuberculosis ...200010940566
dithiothreitol enhances listeria monocytogenes mediated cell cytotoxicity.the hybridoma ped-2e9 based cytotoxicity assay was developed to distinguish virulent from avirulent listeria species in 6 hr. the cytotoxicity effect on ped-2e9 was reported to be primarily due the cytolytic action of listeriolysin o (llo), produced by l. monocytogenes. in this study, the effect of a reducing agent, dithiothreitol (dtt, 0-2 mm) that is known to activate llo was investigated to make the ped-2e9 based cytotoxicity assay an even more sensitive and rapid. also, we examined the effec ...200010941925
vaccination with heat-killed listeria as adjuvant reverses established allergen-induced airway hyperreactivity and inflammation: role of cd8+ t cells and il-18.asthma is a respiratory disorder characterized by airway hyperreactivity (ahr) and inflammation and is associated with high serum ige and overproduction of il-4, il-5, and il-13 by allergen-specific th2 cells. our previous studies demonstrated that heat-killed listeria monocytogenes (hkl) as an adjuvant in immunotherapy successfully reversed ongoing ag-specific th2-dominated responses toward th1-dominated responses, but it was unclear if such immune modulation could reverse ongoing, established ...200010605015
seven die in french listeria outbreak. 200010698871
bacterial pore-forming hemolysins and their use in the cytosolic delivery of macromolecules.advances in our understanding of fundamental cell biological processes have facilitated an expansion of therapeutic approaches to altering cellular physiology and phenotype. as many of these methods involve macromolecular agents that act on targets within the nucleus or cytoplasm, achieving their full potential ultimately requires the efficient delivery of these agents across the cell membrane barrier into the cytosol. various strategies have been employed to enhance cytosolic delivery. these in ...200010699316
advantage of gene gun-mediated over intramuscular inoculation of plasmid dna vaccine in reproducible induction of specific immune responses.utilizing a plasmid dna encoding a single cytotoxic t lymphocyte (ctl) epitope and that encoding ovalbumin (ova), we compared the reproducibility in the induction of immune responses by gene gun and intramuscular immunization. as compared to intramuscular inoculation, gene gun dna immunization appeared to bring about highly reproducible and reliable results in the induction of specific ctl and ifn-gamma production to the ctl epitope and production of anti-ova igg. the results obtained by intramu ...200010699319
evaluation of mini-vidas rapid test for detection of listeria monocytogenes from production lines of fresh to cold-smoked fish.this study was conducted to evaluate the efficacy of the mini-vidas listeria monocytogenes (lmo) system (biomérieux vitek, inc., missouri, usa) for detection of l. monocytogenes in environmental and fish samples from three portuguese cold-smoking plants and from their fresh fish suppliers. mini-vidas-lmo is a fully automated system that uses fluorescent elfa (enzyme linked fluorescent assay) technology for detection of listeria monocytogenes antigens in food. it can be a rapid screening method a ...200010699670
cloning, sequencing, and transcriptional analysis of the dnak heat shock operon of listeria monocytogenes.the complete dnak operon of listeria monocytogenes was isolated by chromosome walking using the previously cloned dnak gene as a probe. molecular analysis of the locus identified 6 genes in the order hrca, grpe, dnak, dnaj, orf35, and orf29. primer extension analysis revealed 3 transcription start sites-s1, s2, and s3-upstream of the hrca, grpe, and dnaj, respectively. the transcription from s1 was heat inducible. analysis of the sequences revealed the consensus promoter sequences of gram-positi ...200010701836
[changes in the virulence factor expression level in listeria monocytogenes under various environmental conditions].effects of chelators chelex-100 and activated charcoal on the production of proteins responsible for virulence of listeria monocytogenes, facultative intracellular parasite were studied. bivalent cation chelator chelex-100 stimulates the production of only thiol-dependent hemolysin listeriolysin o. the presence of activated charcoal, a nonspecific chelator, in culture medium stimulated the expression of listeriolysin o and other main virulence factors by increasing the level of their transcripti ...200010702985
[listeriosis: an old or a current health problem?]. 200010703069
erratum: volume 45, number 1, january 2000the legend to the issue's cover figure was incorrectly printed. it should have read: cover micrograph: actin-comet tails induced by the bacterial pathogen listeria monocytogenes. vero cells were infected by listeria monoctyogenes. after fixation, cells were labeled with fitc-phalloidin (green) and anti-listeria antibodies (red). photo courtesy of inigo lasa and pascale cossart.200010706779
genes for the synthesis of the osmoprotectant glycine betaine from choline in the moderately halophilic bacterium halomonas elongata dsm 3043, usa.the genes involved in the oxidative pathway of choline to glycine betaine in the moderate halophile halomonas elongata dsm 3043 were isolated by functional complementation of an escherichia coli strain defective in glycine betaine synthesis. the cloned region was able to mediate the oxidation of choline to glycine betaine in e. coli, but not the transport of choline, indicating that the gene(s) involved in choline transport are not clustered with the glycine betaine synthesis genes. nucleotide s ...200010708384
human toll-like receptors 2 and 4 are targets for deactivation of mononuclear phagocytes by interleukin-4. 200010709778
does administration of infliximab increase susceptibility to listeriosis? 200010710107
infections and intoxications associated with animal feed and forage which may present a hazard to human health.animal feed or forage may be the source of a limited number of infections for farm animals that could lead to human illness. likely organisms include salmonella enterica, toxoplasma gondii, trichinella spiralis and possibly the agent of bovine spongiform encephalopathy. the risk to human health from other infectious agents which may contaminate either feed or forage appear to be either negligible, e.g. bacillus anthracis and mycobacterium bovis, or non-existent, e.g. clostridium botulinum toxin ...200010712800
single-strand conformation polymorphisms in the hly gene and polymerase chain reaction analysis of a repeat region in the iap gene to identify and type listeria monocytogenes.two novel methods that allow the powerful identification of listeria monocytogenes by polymerase chain reaction (pcr) and simultaneous differentiation by special electrophoresis formats are described. the first method involves a pcr-driven single-strand conformation polymorphism (sscp-pcr) assay using a portion of the noncoding region of the hlv gene. the assay was evaluated with 120 genetically distinct l. monocytogenes strains of either foodborne or clinical origin. distribution of listerial s ...200010716561
rapid polymerase chain reaction/dna probe membrane-based assay for the detection of listeria and listeria monocytogenes in food.we describe the development of polymerase chain reaction (pcr)/dna probe membrane-based colorimetric assays for the detection and identification of listeria and l. monocytogenes. pcr primers designed from the 16s to 23s rrna intergenic spacer region amplified products that were reverse hybridized to membrane-bound oligonucleotide probes specific for listeria and l. monocytogenes with a detection limit of 1 to 10 cfu/25 ml in inoculated raw and pasteurized milk samples. these qualitative assays h ...200010716562
development and evaluation of a 24-hour method for the detection and quantification of listeria monocytogenes in meat products.a 24-h filter monitor-based test, listeria-select, has been developed to quantify listeria monocytogenes organisms in meat samples with a sensitivity of < or = 1.0 cfu/g. the technique comprises a filter monitor-based system and a colony lift immunoassay to identify and enumerate the target organism. meat homogenates were centrifuged and the eluate was filtered to trap and immobilize the microorganisms on the filter. fraser broth was then added to the filter apparatus to allow the organisms to b ...200010716564
twenty-four-hour direct presumptive enumeration of listeria monocytogenes in food and environmental samples using the iso-grid method with lm-137 agar.a new culture medium, lm-137 agar, was developed for use with the iso-grid hydrophobic grid membrane filter system for direct presumptive enumeration of listeria monocytogenes in 24 h. the method was validated against three-replicate, three-dilution most probable number procedures based on enrichment methods specified by the u.s. department of agriculture, the association of official analytical chemists international and the u.s. food and drug administration. the study encompassed meats, dairy p ...200010716565
macrophage class a scavenger receptor-mediated phagocytosis of escherichia coli: role of cell heterogeneity, microbial strain, and culture conditions in vitro.macrophage class a scavenger receptors (sr-ai and sr-aii) contribute to host defense by binding polyanionic ligands such as lipopolysaccharide and lipoteichoic acid. sr-a knockout (sr-a(-/-)) mice are more susceptible to endotoxic shock and listeria monocytogenes infection in vivo, possibly due to decreased clearance of lipopolysaccharide and microorganisms, respectively. we have used flow cytometry to analyze the role of sr-a and other scavenger-like receptors in phagocytosis of bacteria in vit ...200010722588
purified lipopolysaccharide from francisella tularensis live vaccine strain (lvs) induces protective immunity against lvs infection that requires b cells and gamma interferon.previous results have demonstrated that nonspecific protective immunity against lethal francisella tularensis live vaccine strain (lvs) or listeria monocytogenes infection can be stimulated either by sublethal infection with bacteria or by treatment with bacterial dna given 3 days before lethal challenge. here we characterize the ability of purified lipopolysaccharide (lps) from f. tularensis lvs to stimulate similar early protective immunity. treatment of mice with surprisingly small amounts of ...200010722593
cd8(+) t-cell priming against a nonsecreted listeria monocytogenes antigen is independent of the antimicrobial activities of gamma interferon.sublethal infection of mice with recombinant listeria monocytogenes expressing a model epitope in either secreted or nonsecreted form results in similar cd8(+) t-cell priming. since nonsecreted bacterial proteins have no obvious access to the endogenous major histocompatibility complex (mhc) class i presentation pathway, presentation of these antigens requires destruction of the bacterium to reveal the nonsecreted molecules to an exogenous mhc class i presentation pathway. gamma interferon (ifn- ...200010722620
bacterial meningitis.with nearly 8,000 cases in the united states per year, and 2,000 deaths annually, bacterial meningitis continues to be a significant source of morbidity and mortality. the principal pathogens are neisseria meningitidis, streptococcus pneumoniae, group b streptococci, and hemophilus influenzae. in immunocompromised patients, listeria monocytogenes is also an important pathogen. rapid identification and evaluation of the patient with bacterial meningitis and prompt initiation of antibiotics are th ...200010725671
novel bacterial systems for the delivery of recombinant protein or dna.on the basis of attenuated intracellular bacteria, we have developed two delivery systems for either heterologous proteins or dna vaccine vectors. the first system utilizes attenuated strains of gram-negative bacteria which are engineered to secrete heterologous antigens via the alpha-hemolysin secretion system of escherichia coli. the second system is based on attenuated suicide strains of listeria monocytogenes, which are used for the direct delivery of eukaryotic antigen expression vectors in ...200010727885
oral delivery of dna vaccines using attenuated salmonella typhimurium as carrier.the efficacious delivery of eukaryotic expression plasmids to inductive cells of the immune system constitutes a key prerequisite for the generation of effective dna vaccines. here, we have explored the use of bacteria as vehicles to orally deliver expression plasmids. attenuated salmonella typhimurium aroa harbouring eukaryotic expression plasmids that encoded virulence factors of listeria monocytogenes were administered orally to balb/c mice. strong cytotoxic and helper t cell responses as wel ...200010727890
osmoprotectants and cryoprotectants for listeria monocytogenes.listeria monocytogenes is a foodborne pathogen that can grow in high osmotic strength environments and at refrigeration temperatures. glycine betaine, proline betaine, acetylcarnitine, carnitine, gamma-butyrobetaine and 3-dimethylsulphoniopropionate all acted as osmoprotectants, as evidenced by an increase in growth rate of l. monocytogenes 10403s and scott a when provided with these compounds, while being stressed in defined medium containing 0.7 m nacl. these same compounds exhibited cryoprote ...200010728555
ctsr controls class iii heat shock gene expression in the human pathogen listeria monocytogenes.stress proteins play an important role in virulence, yet little is known about the regulation of stress response in pathogens. in the facultative intracellular pathogen listeria monocytogenes, the clp atpases, including clpc, clpp and clpe, are required for stress survival and intracellular growth. the first gene of the clpc operon of l. monocytogenes encodes a homologue of the bacillus subtilis ctsr repressor of stress response genes. an l. monocytogenes ctsr-deleted mutant displayed enhanced s ...200010692157
growing an actin gel on spherical surfaces.inspired by the motility of the bacteria listeria monocytogenes, we have experimentally studied the growth of an actin gel around spherical beads grafted with acta, a protein known to be the promoter of bacteria movement. on acta-grafted beads f-actin is formed in a spherical manner, whereas on the bacteria a "comet-like" tail of f-actin is produced. we show experimentally that the stationary thickness of the gel depends on the radius of the beads. moreover, the actin gel is not formed if the ac ...200010692348
rapid determination of listeria monocytogenes by automated enzyme-linked immunoassay and nonradioactive dna probe.a rapid and reliable analytical method was developed to detect and confirm the presence of listeria monocytogenes in raw and partially processed foods. forty-nine food samples (25 mixed cut vegetable salad, 12 smoked salmon, and 12 sterile smoked salmon) were individually inoculated with high levels [10-100 colony forming units (cfu)/25 g sample] and low levels (1-10 cfu/25 g sample) of l. monocytogenes, and were screened using the vitek immuno diagnostic assay (vidas) listeria monocytogenes (vi ...200010693007
ribotype analysis of strain distribution in listeria monocytogenes.changes in the temporal and spatial patterns of strain distribution for the foodborne pathogen listeria monocytogenes were studied by ribotyping using the qualicon riboprinter system. ribotype patterns were obtained by using the restriction enzymes ecori and pvuii for 72 isolates of l. monocytogenes recovered from smoked salmon samples over a period of 3 years. each pattern was classified both by comparison to a pattern library and by comparison among the 72 isolate patterns. eleven ecori-based ...200010678421
incidence and characterization of listeria monocytogenes from domestic and imported foods in korea.a total of 1,537 domestic and imported food products were examined for the incidence of listeria monocytogenes between 1993 and 1997 in korea. l. monocytogenes was detected using the u.s. department of agriculture isolation method. isolated l. monocytogenes was confirmed by polymerase chain reaction with hly1 and hly2 primers designed from the listeriolysin o. overall, 122 samples (7.9%) contained l. monocytogenes. the rate of isolation was 4.3% for beef, 19.1% for pork, 30.2% for chicken, 1.2% ...200010678422
listeria monocytogenes as a short-lived delivery system for the induction of type 1 cell-mediated immunity against the p36/lack antigen of leishmania major.listeria monocytogenes has been used as an experimental live vector for the induction of cd8-mediated immune responses in various viral and tumoral experimental models. susceptibility of balb/c mice to leishmania major infection has been correlated to the preferential development of th2 cd4 t cells through an early production of interleukin 4 (il-4) by a restricted population of cd4 t cells which react to a single parasite antigen, lack (stands for leishmania homologue of receptors for activated ...200010678966
interaction between burkholderia pseudomallei and acanthamoeba species results in coiling phagocytosis, endamebic bacterial survival, and escape.burkholderia pseudomallei causes melioidosis, a potentially fatal disease whose clinical outcomes include rapid-onset septicemia and relapsing and delayed-onset infections. like other facultative intracellular bacterial pathogens, b. pseudomallei is capable of survival in human phagocytic cells, but unlike mycobacteria, listeria monocytogenes, and salmonella serovar typhimurium, the species has not been reported to survive as an endosymbiont in free-living amebae. we investigated the consequence ...200010678988
novel approaches to monitor bacterial gene expression in infected tissue and host.elucidating the complex and dynamic host-microbe interactions during infection requires, among other things, detailed knowledge of microbial gene expression in vivo. recently, advances in fluorescence and bioluminescence detection techniques, as well as recombinase-based in vivo expression technology, have rendered monitoring virulence gene expression in vivo a feasible task. these techniques have been adapted by several laboratories to study the spatial and temporal patterns of virulence gene e ...200010679414
bacterial replication in the host cell cytosol.intracellular bacteria in mammalian host cells can either live in a membrane-bound vacuole modified to support bacterial growth, or escape from the primary phagosome into the host cell cytoplasm. phagosomal escape is best studied in listeria monocytogenes in which a pore-forming cytolysin and two phospholipases are involved in the lysis of the phagosomal membrane. the mechanisms of and requirements for cytoplasmic growth are less clear but there is growing evidence that proficient replication of ...200010679420
rapid neutrophil response controls fast-replicating intracellular bacteria but not slow-replicating mycobacterium tuberculosis.being one of the first cells to invade the site of infection, neutrophils play an important role in the control of various bacterial and viral infections. in the present work, the contribution of neutrophils to the control of infection with different intracellular bacteria was investigated. mice were treated with the neutrophil-depleting monoclonal antibody rb6-8c5, and the time course of infection in treated and untreated mice was compared by using intracellular bacterial species and strains va ...200010669354
recombinant human interleukin-11 has anti-inflammatory actions yet does not exacerbate systemic listeria infection.to determine whether recombinant human (rh) interleukin (il)-11 disrupts the clearance of microbial pathogens, mice were challenged with listeria monocytogenes after receiving high-dose rhil-11, anti-tumor necrosis factor (tnf) monoclonal antibody (mab), anti-il-11 mab, or saline control. the ld50 was not affected by rhil-11 but was 10-fold lower in the anti-tnf mab group (p<.001). plasma il-6, il-1beta, and tnf-alpha levels were not different between rhil-11-treated animals and the control grou ...200010669370
transient expression of bacterial gene fragments in eukaryotic cells: implications for cd8(+) t cell epitope analysis.cd8(+) t cells are potent effectors of acquired immunity against some viruses and intracellular bacterial pathogens. antigens recognized by cd8(+) t cells are small, 8-9 amino acid peptides derived from proteins produced by the pathogen. these peptides are presented by mhc class i molecules on the surface of the infected cell. when characterizing the cd8(+) t cell response to a bacterial or viral pathogen, it is often necessary to express an antigenic protein in a eukaryotic host cell that is ca ...200010669778
disease patterns in field and bank vole populations during a cyclic decline in central finland.declining field vole (microtus agrestis) and bank vole (clethrionomys glareolus) populations were sampled (117 field voles and 34 bank voles) in south-central finland during the winter of 1988-89. the last surviving field voles were caught in april and bank voles in february. a subsample (16) of the april field voles were taken live to the laboratory for immunosuppression. the histopathology of the main internal organs and the presence of aerobic bacteria and certain parasites were studied. in t ...200010670697
th1-biased immune responses induced by dna-based immunizations are mediated via action on professional antigen-presenting cells to up-regulate il-12 production.the efficacy of dna-based immunization in conferring protective immunity against certain microbial pathogens including human immunodeficiency virus type 1 (hiv-1) has been described. the potential advantage of dna-based immunization over the traditional vaccines largely results from its capacity to efficiently induce th1-biased immune responses against an encoded antigen. we describe how th1-biased immune responses are induced by dna-based immunization, using a dna vaccine construct encoding hiv ...200010606974
sequence variations within prfa dna binding sites and effects on listeria monocytogenes virulence gene expression.reporter gene fusions were used to investigate the contributions of prfa dna binding sites to listeria monocytogenes virulence gene expression. our results suggest that the dna sequence of prfa binding sites determines the levels of expression of certain virulence genes, such as hly and mpl. other virulence genes, such as acta and plcb, may depend upon additional factors for full regulation of gene expression.200010633124
identification and characterization of immunoglobulin g in blood as a major inhibitor of diagnostic pcr.a major inhibitor of diagnostic pcr in human plasma was identified and the mechanism of inhibition was characterized. human blood was divided by centrifugation into buffy coat, plasma, platelets, and erythrocytes. all these blood fractions were found to be highly inhibitory to a standardized pcr mixture containing the thermostable dna polymerase amplitaq gold. pcr inhibitors in human plasma were purified by chromatographic procedures and were characterized by a process of elimination, so that th ...200010618113
listeria monocytogenes acta protein interacts with phosphatidylinositol 4,5-bisphosphate in vitro.the n-terminal region of the listeria monocytogenes acta protein, in conjunction with host cell factors, is sufficient for actin polymerization at the bacterial surface. previous data suggested that acta could protect barbed ends from capping proteins. we tested this hypothesis by actin polymerization experiments in the presence of the acta n-terminal fragment and capping protein. acta does not protect barbed ends from capping protein. in contrast, this polypeptide prevents pip(2) from inhibitin ...200010618167
molecular grouping of listeria monocytogenes based on the sequence of the inib gene.the major part of the gene inlb was sequenced in 24 strains of listeria monocytogenes belonging to serovars 1/2a, 1/2b, 1/2c, 3b and 4b. a phylogenetic analysis based on the inlb nucleotide sequences showed that strains of serovars 1/2a and 1/2c were closely related, as well as those of serovars 1/2b and 3b. strains sharing serovar 4b could be divided into two distinct groups. there were differences in amino-acid sequence between all serovars except between serovars 1/2b and 3b. differences in a ...200010628828
comparative in vitro activity of moxifloxacin against gram-positive clinical isolates.the in vitro activity of moxifloxacin was compared with that of 15 antibacterial agents against 513 gram-positive microorganisms. the mic(90) (mg/l) of moxifloxacin was 0.06 for quinolone-susceptible staphylococcus aureus and staphylococcus epidermidis, 0.12 for streptococcus pyogenes and streptococcus agalactiae; 0.25 for streptococcus pneumoniae, streptococcus mitis, streptococcus bovis, streptococcus anginosus and actinomyces pyogenes; 0.5 for streptococcus sanguis and listeria monocytogenes, ...200010629010
electron paramagnetic resonance studies of the membrane fluidity of the foodborne pathogenic psychrotroph listeria monocytogenes.listeria monocytogenes is a foodborne psychrotrophic pathogen that grows at refrigeration temperatures. previous studies of fatty acid profiles of wild-type and cold-sensitive, branched-chain fatty acid deficient mutants of l. monocytogenes suggest that the fatty acid 12-methyltetradecanoic (anteiso-c(15:0)) plays a critical role in low-temperature growth of l. monocytogenes, presumably by maintaining membrane fluidity. the fluidity of isolated cytoplasmic membranes of wild-type (slcc53 and 1040 ...200010631292
pathogen-specific loss of host resistance in mice lacking the ifn-gamma-inducible gene igtp.interferon-gamma (ifn-gamma) is critical for defense against pathogens, but the molecules that mediate its antimicrobial responses are largely unknown. igtp is the prototype for a family of ifn-gamma-regulated genes that encode 48-kda gtp-binding proteins that localize to the endoplasmic reticulum. we have generated igtp-deficient mice and found that, despite normal immune cell development and normal clearance of listeria monocytogenes and cytomegalovirus infections, the mice displayed a profoun ...200010639151
mutants of listeria monocytogenes defective in in vitro invasion and cell-to-cell spreading still invade and proliferate in hepatocytes of neutropenic mice.listeria monocytogenes mutants defective in the acta gene, the plcb gene, and the inla and inlb genes were less virulent when injected intravenously into balb/c mice. the growth of these strains as well as of the virulent wild-type strains was increased by treating mice with a neutrophil-specific depleting monoclonal antibody, rb6-8c5. histologic examination of the livers of the treated animals showed intrahepatocytic proliferation of the listeriae in all cases. our data show that more than one ...200010639462
role of listeriolysin o in cell-to-cell spread of listeria monocytogenes.listeria monocytogenes is a facultative intracellular bacterial pathogen that escapes from a host vacuolar compartment and grows rapidly in the cytosol. listeriolysin o (llo) is a secreted pore-forming protein essential for the escape of l. monocytogenes from the vacuole formed upon initial internalization. however, its role in intracellular growth and cell-to-cell spread events has not been testable by a genetic approach. in this study, purified six-his-tagged llo (hisllo) was noncovalently cou ...200010639481
determination of natural resistance of mice fed dietary lipids to experimental infection induced by listeria monocytogenes.current understanding based on the effect of dietary lipid manipulation upon immune system function indicates that fatty acids are involved in the modulation of the immune response through different and complex pathways. reduction of several immune parameters by fatty acid action may be applied in the treatment of diseases characterised by an overactivation of the immune system. as a consequence, a reduction of host resistance against infectious agents has been reported in animals fed dietary li ...200010640607
bactericidal activity of isothiocyanate against pathogens on fresh produce.the bactericidal activity of allyl and methyl isothiocyanate (aitc and mitc) was tested with a rifampicin-resistant strain of salmonella montevideo and streptomycin-resistant strains of escherichia coil o157:h7 and listeria monocytogenes scott a. iceberg lettuce inoculated with high (10(7) to 10(8) cfu/g) and low (10(3) to 10(4) cfu/g) concentrations of bacterial pathogens was treated with aitc and mitc in sealed containers at 4 degrees c for 4 days. aitc showed stronger bactericidal activity th ...200010643765
survival of listeria monocytogenes scott a on vacuum-packaged raw beef treated with polylactic acid, lactic acid, and nisin.low-molecular-weight polylactic acid (lmw-pla) and lactic acid (la) were used to inhibit growth of listeria monocytogenes scott a on vacuum-packaged beef. nisin was also used simultaneously as an additional hurdle to the growth of this pathogen. inoculated beef cubes were immersed in a solution of 2% lmw-pla, 2% la, 400 iu/ml of nisin, or combinations of each acid and nisin for 5 min and drip-dried for 15 min. the cubes were then vacuum-packaged and stored at 4 degrees c for up to 42 days. surfa ...200010643784
p45, an extracellular 45 kda protein of listeria monocytogenes with similarity to protein p60 and exhibiting peptidoglycan lytic activity.a monoclonal antibody obtained by immunization of mice with heat-killed cells of listeria monocytogenes serotype 4d showed reactivity towards a protein (p45) from l. monocytogenes with an apparent molecular mass of 45 kda. this protein was detected in the culture supernatant and at the cell surface of l. monocytogenes. proteins cross-reacting with the monoclonal antibody were present in all listeria strains investigated, except l. grayi. the structural gene was cloned in escherichia coli and seq ...200010648100
synergistic effects of nisin and thymol on antimicrobial activities in listeria monocytogenes and bacillus subtilis.nisin z and thymol were tested, alone and in combination, for antibacterial activity against listeria monocytogenes atcc 7644 and bacillus subtilis atcc 33712. the antibacterial effect of nisin z, produced by lactococcus lactis ke3 isolated from the traditional moroccan fermented milk, was greatly potentiated by sub-inhibitory concentrations of thymol in both bacterial strains. our data showed that the concentration of nisin required for effective control of food-borne pathogenic bacteria could ...200010650225
ph-regulated activation and release of a bacteria-associated phospholipase c during intracellular infection by listeria monocytogenes.listeria monocytogenes grows in the cytosol of mammalian cells and spreads from cell to cell without exiting the intracellular milieu. during cell-cell spread, bacteria become transiently entrapped in double-membrane vacuoles. escape from these vacuoles is mediated in part by a bacterial phospholipase c (pc-plc), whose activation requires cleavage of an n-terminal peptide. pc-plc activation occurs in the acidified vacuolar environment. in this study, the ph-dependent mechanism of pc-plc activati ...200010652090
generalized transduction of serotype 1/2 and serotype 4b strains of listeria monocytogenes.this is the first report of generalized transduction in the gram-positive, food-borne pathogen listeria monocytogenes. bacteriophages were isolated from the environment and from lysogens, or were obtained from other laboratories. of the 59 bacteriophages tested, 34 proved to be capable of transduction. we exploited the ability of l. monocytogenes to grow at room temperature and isolated bacteriophages that were incapable of growth at 37 degrees c. transductions at this temperature therefore elim ...200010652092
complete nucleotide sequence, molecular analysis and genome structure of bacteriophage a118 of listeria monocytogenes: implications for phage evolution.a118 is a temperate phage isolated from listeria monocytogenes. in this study, we report the entire nucleotide sequence and structural analysis of its 40 834 bp dna. electron microscopic and enzymatic analyses revealed that the a118 genome is a linear, circularly permuted, terminally redundant collection of double-stranded dna molecules. no evidence for cohesive ends or for a terminase recognition (pac) site could be obtained, suggesting that a118 viral dna is packaged via a headful mechanism. p ...200010652093
recent advances with recombinant bacterial vaccine vectors.bacille calmette-guerin (bcg), listeria monocytogenes, salmonellae and shigellae have shown promise as vaccine vectors in experimental animal models. although disappointing results in humans and non-human primates stalled the development of this vaccination strategy, interest in this approach was reinvigorated recently by the development of bacterial dna-vaccine-vectors. the purpose of this review is to highlight the strengths and weaknesses of bacterial vaccine vectors, and to discuss the futur ...200010652479
carbon dioxide and nisin act synergistically on listeria monocytogenes.this paper examines the synergistic action of carbon dioxide and nisin on listeria monocytogenes scott a wild-type and nisin-resistant (nis(r)) cells grown in broth at 4 degrees c. carbon dioxide extended the lag phase and decreased the specific growth rate of both strains, but to a greater degree in the nis(r) cells. wild-type cells grown in 100% co(2) were two to five times longer than cells grown in air. nisin (2.5 microg/ml) did not decrease the viability of nis(r) cells but for wild-type ce ...200010653749
effect of flagella on initial attachment of listeria monocytogenes to stainless steel.at 22 degrees c a flagellin mutant of listeria monocytogenes was found to attach to stainless steel at levels 10-fold lower than wild-type cells, even under conditions preventing active motility. at 37 degrees c, when flagella are not produced, attachment of both strains was identical. therefore, flagella per se facilitate the early stage of attachment.200010653766
reconstitution of listeria motility: implications for the mechanism of force transduction.listeria monocytogenes and some other infectious bacteria polymerize their host cell's actin into tails that propel the bacteria through the cytoplasm. here we show that reconstitution of this behavior in simpler media resolves two aspects of the mechanism of force transduction. first, since dilute reconstitution media have no cytoskeleton, we consider what keeps the tail from being pushed backward rather than the bacterium being propelled forward. the dependence of the partitioning of motion on ...200010656971
eta-1 (osteopontin): an early component of type-1 (cell-mediated) immunity.cell-mediated (type-1) immunity is necessary for immune protection against most intracellular pathogens and, when excessive, can mediate organ-specific autoimmune destruction. mice deficient in eta-1 (also called osteopontin) gene expression have severely impaired type-1 immunity to viral infection [herpes simplex virus-type 1 (kos strain)] and bacterial infection (listeria monocytogenes) and do not develop sarcoid-type granulomas. interleukin-12 (il-12) and interferon-gamma production is dimini ...200010657301
human toll-like receptor 2 mediates monocyte activation by listeria monocytogenes, but not by group b streptococci or lipopolysaccharide.human toll like receptor (tlr) 2 has been implicated as a signaling receptor for lps from gram-negative bacteria and cell wall components from gram-positive organisms. in this study, we investigated whether tlr2 can signal cell activation by the heat-killed group b streptococci type iii (gbs) and listeria monocytogenes (hklm). hklm, but not gbs, showed a time- and dose-dependent activation of chinese hamster ovary cells transfected with human tlr2, as measured by translocation of nf-kappab and i ...200010657659
expression and use of the green fluorescent protein as a reporter system in legionella pneumophila.the gene encoding the green fluorescent protein (gfp) was used as a reporter gene in legionella pneumophila. to analyze gfp expression in legionella, transcriptional fusions of gfp with the legionella-specific mip (macrophage infectivity potentiator) promoter (p(mip)) and the sod (superoxide dismutase) promoter (p(sod)) derived from listeria monocytogenes were constructed. following transformation into the virulent l. pneumophila strain jr 32, strong gfp-mediated fluorescence was detected with b ...200010660067
intracellular staining for tnf and ifn-gamma detects different frequencies of antigen-specific cd8(+) t cells.cd8(+) t lymphocytes are important mediators of adaptive immunity against certain viral, protozoan and bacterial pathogens. activated cd8(+) t cells are able to induce cytolysis of infected cells (perforin and cd95-cd95l mediated pathways) and also elaborate cytokines, including ifn-gamma and tnf after appropriate mhc class i-peptide recognition. new technologies for the detection of antigen-specific cd8(+) t cells, including tetrameric mhc class i-peptide complexes, intracellular ifn-gamma stai ...200010758241
the clpp serine protease is essential for the intracellular parasitism and virulence of listeria monocytogenes.we identified the stress-induced clpp of listeria monocytogenes and demonstrated its crucial role in intracellular survival of this pathogen. clpp is a 21.6 kda protein belonging to a family of proteases highly conserved in prokaryotes and eukaryotes. a clpp-deleted mutant enabled us to demonstrate that clpp is involved in proteolysis and is required for growth under stress conditions. intramacrophage survival of this mutant was strongly restricted, thus resulting in loss of virulence for the mo ...200010760131
substantial in vivo proliferation of cd4(+) and cd8(+) t lymphocytes during secondary listeria monocytogenes infection.in mice listeria monocytogenes infection induces a strong t cell response. in an attempt to quantitatively analyze the magnitude and kinetics of the cd4(+) and cd8(+) t cell response during l. monocytogenes infection in vivo we used a t cell transfer system that is independent of in vitro cell culture techniques and information about the identity of immunogenic t cell epitopes. our results demonstrate substantial expansion of the in vivo primed and transferred t cell populations in response to l ...200010760793
osmotic and chill activation of glycine betaine porter ii in listeria monocytogenes membrane vesicles.listeria monocytogenes is a foodborne pathogen known for its tolerance to conditions of osmotic and chill stress. accumulation of glycine betaine has been found to be important in the organism's tolerance to both of these stresses. a procedure was developed for the purification of membranes from l. monocytogenes cells in which the putative atp-driven glycine betaine permease glycine betaine porter ii (gbu) is functional. as is the case for the l. monocytogenes sodium-driven glycine betaine uptak ...200010762257
modeling microbial survival during exposure to a lethal agent with varying intensity.traditionally, the efficacy of preservation and disinfection processes has been assessed on the basis of the assumption that microbial mortality follows a first-order kinetic. however, as departures from this assumed kinetics are quite common, various other models, based on higher-order kinetics or population balance, have also been proposed. the database for either type of models is a set of survival curves of the targeted organism or spores determined under constant conditions, that is, consta ...200010770273
development of a simple recovery-enrichment system for enhanced detection of heat-injured listeria monocytogenes in pasteurized milk.a simple anaerobic recovery-enrichment system, semisolid penn state university (sspsu) broth, that enhances recovery of heat-injured listeria monocytogenes, was rapidly achieved in 10-ml screw-capped tubes by adding bacto-agar (2.5 g/liter) and l-cysteine (0.5 g/liter) to penn state university broth. glucose was removed from the formulation for sspsu broth to prevent the growth of thermoduric lactobacilli. ferric ammonium citrate was added to sspsu broth to detect esculin hydrolysis and to indic ...200010772211
a combined discrete-continuous model describing the lag phase of listeria monocytogenes.food microbiologists generally use continuous sigmoidal functions such as the empirical gompertz equation to obtain the kinetic parameters specific growth rate (mu) and lag phase duration (lambda) from bacterial growth curves. this approach yields reliable information on mu; however, values for lambda are difficult to determine accurately due, in part, to our poor understanding of the physiological events taking place during adaptation of cells to new environments. existing models also assume a ...200010777067
the use of immuno-magnetic separation (ims) as a tool in a sample preparation method for direct detection of l. monocytogenes in cheese.a sample preparation procedure was developed for direct detection of l. monocytogenes in cheese. the sample preparation protocol consisted of a 10-fold dilution and homogenization, a centrifugation step to precipitate large food particles, passage of the supernatant over a sieve and through a separatory funnel to further eliminate food particles and fat, a centrifugation step to recover the bacterial pellet and finally enzymatic digestion of the suspension to degrade the remaining small food par ...200010777071
specific binding of recombinant listeria monocytogenes p60 protein to caco-2 cells.the listeria monocytogenes p60 is a major extracellular protein, which is believed to be involved in the invasion of these bacteria into their host cells. so far the mechanism by which p60 participates in the internalization or penetration of l. monocytogenes is still veiled. to determine the possibility of a direct interaction of p60 with the host cell surface, the iap gene was recombinantly expressed in escherichia coli and used for binding studies with the enterocyte-like caco-2 cells. fluore ...200010779709
smoking decreases alveolar macrophage function during anesthesia and surgery.smoking changes numerous alveolar macrophage functions and is one of the most important risk factors for postoperative pulmonary complications. the current study tested the hypothesis that smoking impairs antimicrobial and proinflammatory responses in alveolar macrophages during anesthesia and surgery.200010781271
an outbreak of febrile gastroenteritis associated with corn contaminated by listeria monocytogenes.on may 21, 1997, numerous cases of febrile gastrointestinal illness were reported among the students and staff of two primary schools in northern italy, all of whom had eaten at cafeterias served by the same caterer.200010781619
listeria meningitis in children: report of two cases.we report two cases of meningitis caused by listeria monocytogenes in children. the first patient was a healthy 14-month-old boy and the second patient a 3-year-old girl with byler disease which, however, is not reported as a predisposing factor for listeriosis. we present these cases because listeria infection, although common in neonates, is extremely infrequent during infancy and childhood.200010782402
[investigation of listeria monocytogenes in soft cheeses].listeria monocytogenes has been recognized as a bacteria that produces severe illness in animals and humans. considering the importance of the presence of l. monocytogenes in soft paste cheeses, a study of diverse cheeses from supermarkets of direct sale to the public was carried out. from the 35 analyzed cheeses, 4 strains were isolated (11.4%). the result of the serological study showed that all the strains corresponded to the serotype 4. the proteic profiles of the isolated strains showed sim ...200010785944
immobilization with metal hydroxides as a means to concentrate food-borne bacteria for detection by cultural and molecular methods.the application of nucleic acid amplification methods to the detection of food-borne pathogens could be facilitated by concentrating the organisms from the food matrix before detection. this study evaluated the utility of metal hydroxide immobilization for the concentration of bacterial cells from dairy foods prior to detection by cultural and molecular methods. using reconstituted nonfat dry milk (nfdm) as a model, two food-borne pathogens (listeria monocytogenes and salmonella enterica serovar ...200010788338
acid responses of listeria monocytogenes.the acid response and the correlated protein synthesis in listeria monocytogenes were studied. the lowest ph value which l. monocytogenes could resist was dependent on the strain and the kind of acid used. previous adaptation to an intermediary ph augmented bacterial resistance to a subsequent lethal acidic ph. the acid tolerance was also growth phase dependent. organic volatile acids exerted a more deleterious effect on l. monocytogenes than inorganic acids, because weak acids infer a lower int ...200010791729
mechanism of action of pulsed high electric field (phef) on the membranes of food-poisoning bacteria is an 'all-or-nothing' effect.salmonella typhimurium (cra 1005) was more sensitive than listeria monocytogenes (nctc 11994) to pulsed high electric field (phef) treatment in distilled water (10, 15 and 20 kv/cm), 10 mm tris-maleate buffer ph 7.4 (15 kv/cm) and model beef broth (0.75% w/v: 15 kv/cm). sublethal injury could not be detected using a selective medium plating technique, indicating that bacterial inactivation by phef may be an 'all-or-nothing' event. phef-induced membrane permeabilization resulted in increased uv-l ...200010791731
proteins variations in listeria monocytogenes exposed to high salinities.listeria monocytogenes scott a grown in the minimal chemically defined medium m6lt was challenged to a concentration of either 35 or 65 g l(-1) of nacl for 1 h in the presence of a [35s]cysteine-[35s]methionine labelling mix. the protein patterns were analysed by 2d-electrophoresis in the two conditions and isoosmotic condition (5 g l(-1) of nacl in m6lt). a great number of proteins which were synthesized under isoosmotic conditions were either completely repressed or expressed at a reduced leve ...200010791735
modelling the growth of listeria monocytogenes in dynamic conditions.a recurrent neural network for the prediction of listeria monocytogenes growth under ph and a(w) variable conditions was developed. the use of this model offered the possibility to take into account the consequences of the variations of the factors on l. monocytogenes growth. the effects of solutions, such as nacl, acetic acid and naoh, and their interactions on the response of l. monocytogenes cells were studied. furthermore, the results showed the capacity of the recurrent neural network to pr ...200010791744
production of a nisin-like bacteriocin by lactococcus lactis subsp. lactis a164 isolated from kimchi.lactococcus lactis subsp. lactis a164 was isolated from kimchi (korean traditional fermented vegetables). the bacteriocin produced by strain a164 was active against closely related lactic acid bacteria and some food-borne pathogens including staphylococcus aureus, listeria monocytogenes and salmonella typhimurium. the antimicrobial spectrum was nearly identical to that of nisin. bacteriocin activity was not destroyed by exposure to elevated temperatures at low ph values, but the activity was los ...200010792514
limitation of adhesion and growth of listeria monocytogenes on stainless steel surfaces by staphylococcus sciuri biofilms.the adhesion and subsequent development of listeria monocytogenes on stainless steel was studied in the absence and in the presence of a staphylococcus sciuri biofilm. in the three growth media studied, the percentage of adherent cells was reduced to nearly the same extent by the presence of 1-day biofilms of staph. sciuri for the two strains of l. monocytogenes studied. one-day biofilms of staph. sciuri exhibited the same exopolysaccharide content per square centimetre, although they colonized ...200010792517
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