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intracellular survival of enteric bacteria in cultured human enterocytes.translocating enteric bacteria have been visualized within intact intestinal epithelial cells in animal models of bacterial translocation. although the ability of the enterocyte to engulf bacteria has been well documented in both in vivo and in vitro experimental models, relatively little is known about the enterocyte's ability to degrade internalized bacteria. intracellular survival of eight strains of enteric bacteria (two strains of listeria monocytogenes, salmonella typhimurium, proteus mira ...19968828081
the use of listeriolysin o in an elisa, a skin test and a lymphocyte blastogenesis assay on sheep experimentally infected with listeria monocytogenes, listeria ivanovii or listeria innocua.purified listeriolysin o (llo) was evaluated as a specific antigen to detect both humoral and cell mediated immune responses of sheep infected with listeria monocytogenes. six sheep (two in each group) were orally inoculated with 10(10) organisms of l. monocytogenes, l. ivanovii, or l. innocua. only the l. monocytogenes inoculated sheep had an elevated temperature (> 42 degrees c) and after 15 days had anti-llo antibodies as assessed by an elisa. in a blastogenesis assay, only peripheral blood m ...19968828131
listeriosis in bone marrow transplant recipient. 19968842304
bioluminescence measurements of the antilisterial activity of nisin: comparison with ampicillin and streptomycin.the influence of nisin on intracellular atp and cell numbers of listeria monocytogenes strain scott a was determined and compared with the effect of amplicillin and streptomycin under similar conditions. in the presence of nisin (3-12 micrograms/ml), intracellular atp and cell numbers decreased rapidly during the first hour at 35 degrees c and extracellular atp increased. cell numbers and intracellular atp increased after 3 h of incubation. no effect was observed in cells treated with ampicillin ...19968844346
in vitro activities of u-100592 and u-100766, novel oxazolidinone antibacterial agents.oxazolidinones make up a relatively new class of antimicrobial agents which possess a unique mechanism of bacterial protein synthesis inhibition. u-100592 (s)-n-[[3-[3-fluoro-4-[4-(hydroxyacetyl)-1-piperazinyl]- phenyl]-2-oxo-5-oxazolidinyl]methyl]-acetamide and u-100766 (s)-n-[[3-[3-fluoro-4-(4-morpholinyl)phenyl]- 2-oxo-5-oxazolidinyl]methyl]-acetamide are novel oxazolidinone analogs from a directed chemical modification program. mics were determined for a variety of bacterial clinical isolate ...19968849237
comparison of antimicrobial susceptibilities of corynebacterium species by broth microdilution and disk diffusion methods.corynebacterium species are increasingly being implicated in foreign-body infections and in immunocompromised-host infections. however, there are no specific recommendations on the method or the criteria to use in order to determine the in vitro activities of the antibiotics commonly used to treat corynebacterium infections. the first aim of our study was to compare the susceptibilities of various species of corynebacterium to vancomycin, erythromycin, and penicillin by using a broth microdiluti ...19968849254
listeria monocytogenes in poultry and poultry products: epidemiological investigations in seven danish abattoirs.listeria monocytogenes was isolated from 11/236 (4 x 7%) caecal samples from parent flocks, providing broilers to the abattoirs investigated. caecal samples from 2078 broilers representing 90 randomly selected broiler flocks were negative for l. monocytogenes. a total of 3080 samples from seven abattoirs including poultry processing line samples, and final products were also examined for l. monocytogenes. listeria monocytogenes was isolated in 0 x 3% to 18 x 7% of the samples collected in the di ...19968849641
opsonin-independent adherence and phagocytosis of listeria monocytogenes by murine peritoneal macrophages.listeria monocytogenes adhered to and multiplied intracellularly in murine peritoneal macrophages in the absence of opsonins. the infective process in these cells was evaluated by viable bacterial cell colony counts of intracellular organisms and documented by transmission and scanning electron microscopy. adherence of listeriae to macrophages involved surface interactions of the prokaryotic cell surface and eukaryotic cell membranes. subsequent phagocytosis was seen to occur through a process i ...19968849699
[an anti-listeria seroepidemiological study in uberaba, mg].from a total of 445 individuals, 17.1% had antibodies against l. monocytogenes detected by the agglutination tube test. they were separated in seven groups: bloods donnors (n = 50), hospital visitors (n = 40), frigorific workers (n = 28), aviculture workers (n = 87), herdsman (n = 31), agriculture students (n = 60) and street-sweepers (n = 51). l1/2a serotype was predominant. individuals from urban areas (19.5%) and those who had less contact with animals (21.7%) had significantly positive serol ...19968851214
cholesterol oxidase from rhodococcus equi is likely the major factor involved in the cooperative lytic process (camp reaction) with listeria monocytogenes.the camp reaction between listeria monocytogenes and rhodococcus equi was studied by a diffusion assay. listeria monocytogenes displayed identical cooperative haemolytic effect with supernatant cultures of r. equi or with commercial cholesterol oxidase (cox). this result, even with enzymes of different sources (commercial cox is obtained from pseudomonas spp.) suggests that this enzyme secreted by r. equi has a crucial role in the synergistic haemolytic (camp) reaction with l. monocytogenes. the ...19968852354
quantitative structure activity relationship for the effect of benzoic acids, cinnamic acids and benzaldehydes on listeria monocytogenes.the inhibition of a cocktail of 18 strains of listeria monocytogenes by 24 mono-, di- and tri-substituted benzoic and cinnamic acids and 16 benzaldehydes was evaluated using the concentration (c) required to give a 50% growth inhibition under anaerobic conditions at 35 degree c and ph 6.2 as a measure of biological activity (bav). using the method of least squares, multiple regression equations were obtained which described the contribution of some physiochemical and other structural properties ...19968852677
antibacterial activity of lactobacillus plantarum ug1 isolated from dry sausage: characterization, production and bactericidal action of plantaricin ug1.lactobacillus plantarum ug1 isolated from dry sausage produced an antimicrobial substance that inhibited other strains of the genera lactobacillus and lactococcus, and some foodborne pathogens including listeria monocytogenes, bacillus cereus, clostridium perfringens and clostridium sporogenes. this antibacterial substance was inactivated by proteolytic enzymes and showed a bactericidal mode of action. consequently, it was characterized as a bacteriocin, and was designated plantaricin ug1. this ...19968854175
mathematically modeling the repair of heat-injured listeria monocytogenes as affected by temperature, ph, and salt concentration.heat-injured cells of listeria monocytogenes were inoculated into listeria repair broth (lrb) adjusted to various ph levels (4.2, 5.0, 6.6, 8.0 and 9.6) and salt concentrations (0.5%, 2.5%, 5.0%, 7.5% and 10.0% w/v) at controlled temperatures (4, 10, 22, 37 and 43 degrees c) in a complete factorial manner (5(3)). repair of the injured microorganisms was evaluated using selective and non-selective plating media. the gompertz parameters, which were generated by fitting the equation with the bacter ...19968854177
comparison of the hydrophobic grid-membrane filter dna probe method and the health protection branch standard method for the detection of listeria monocytogenes in foods.the standard health protection branch (hpb) method for the detection of l. monocytogenes in foods involves lengthy enrichment, selection and biochemical testing, requiring up to 8 days to complete. a hydrophobic grid-membrane filter (hgmf) method employing a digoxigenin-labelled listeriolysin o probe required 5 days to complete, and included an image-analysis system for electronic data acquisition. a total of 200 food samples encompassing 8 high-risk food groups (soft and semi-soft cheeses, pack ...19968854189
functions of interleukin 1 receptor antagonist in gene knockout and overproducing mice.interleukin 1 receptor antagonist (il-1ra) is a cytokine whose only known action is competitive inhibition of the binding of interleukin 1 (il-1) to its receptor. to investigate the physiological roles of endogenously produced il-1ra, we generated mice that either lack il-1ra or overproduce it under control of the endogenous promoter. mice lacking il-1ra have decreased body mass compared with wild-type controls. they are more susceptible than controls to lethal endotoxemia but are less susceptib ...19968855299
hazard identification in swine slaughter with respect to foodborne bacteria.swine slaughter is an open process with many opportunities for the contamination of the pork carcass with potentially pathogenic bacteria; however, it does not contain any point where hazards are completely eliminated. data on the prevalence of various pathogenic bacteria (aeromonas hydrophila, campylobacter coli/jejuni, listeria monocytogenes, salmonella spp., staphylococcus aureus and yersinia enterocolitica) in pigs, their growth and survival characteristics and ability to become established ...19968856371
assessment of alimentary exposure to listeria monocytogenes.survey data on the frequency of foodborne occurrence and dietary exposure to listeria monocytogenes were used to estimate the mininmal mean per person annual rate of exposure in the united states during the late 1980s. the estimate was restricted to ready-to-eat (rte) foods because proper cooking was assumed to be listericidal. the mean amount of each food type per l. monocytogenes occurrence was calculated in about 100 sources, and dietary intake data were used to calculate the mean number of o ...19968856375
health risk assessment of listeria monocytogenes in canada.in this review, the major steps used in the formulation of a health risk assessment for listeria monocytogenes in foods are discussed. data is given on the numbers of human listeriosis cases reported in canada along with the current canadian regulatory policy on l. monocytogenes. four major steps in the health risk assessment of this organism in foods, namely, hazard identification, hazard characterization, exposure assessment and risk characterization, were examined. for hazard characterization ...19968856380
live tularemia vaccine confers protection against lethal legionella and listeria infections in experimental animals.the efficacy of a live francisella tularensis vaccine strain to cause nonspecific immunity toward experimental legionellosis and listeriosis was studied. immunisation with tularemia vaccine protected over 80% and 17% of experimental animals against subsequent lethal challenge with legionella pneumophila and listeria monocytogenes, respectively. the protection was maximal during the first month following immunisation and declined thereafter. in order to delineate the immunostimulatory moieties of ...19968861031
apoptosis of mouse dendritic cells is triggered by listeriolysin, the major virulence determinant of listeria monocytogenes.infection of a murine-spleen dendritic cell line by listeria monocytogenes was found to induce cell death through apoptosis. to characterize the bacterial product(s) involved in induction of apoptosis, dendritic cells were infected with the l. monocytogenes egd strain and several isogenic mutants deficient in the production of individual listerial virulence factors. the ability to induce cellular apoptosis was retained by all mutants tested, except the prfa and delta hly mutants, both of which a ...19968861210
inhibition of the multiplication of listeria monocytogenes in a murine hepatocyte cell line (atcc tib73) by ifn-gamma and tnf-alpha.the effects of ifn-gamma and tnf-alpha on intracellular multiplication of listeria monocytogenes in a murine enbryonic hepatocyte cell line (atcc tib 73) were investigated. neither ifn-gamma nor tnf-alpha alone (10, 25, or 100 ng/ml) significantly inhibited intracellular multiplication of l. monocytogenes. in contrast, addition of both ifn-gamma and tnf-alpha (10, 25, or 100 ng/ml) significantly inhibited intracellular listerial multiplication. the anti-listerial effects of ifn-gamma and tnf-alp ...19968861394
perinatal infection with listeria monocytogenes.listeria monocytogenes has been increasingly recognized as a cause of intrauterine sepsis with associated perinatal wastage. the condition is mostly acquired through dietary intake and appropriate advice should be given to all pregnant women. the most common presentations in pregnancy include premature labour, an influenza-like illness and reduced fetal movements. in this report, we present a series of 24 cases of perinatal listeria infection presenting to either our obstetric or neonatal units ...19968883752
identification of a clpc atpase required for stress tolerance and in vivo survival of listeria monocytogenes.we identified a new chromosomal locus involved in the virulence of the facultative intracellular pathogen listeria monocytogenes. this locus displays the same genetic organization as that of the clpc/mecb locus of bacillus subtilis. it contains a thermoregulated operon of four genes, whose transcription is upregulated at 42 degrees c. the last gene of this operon is clpc, which encodes a protein of 826 amino acid residues, identified as a clpc atpase, sharing a strong peptide sequence identity ( ...19968885268
acid tolerance in listeria monocytogenes: the adaptive acid tolerance response (atr) and growth-phase-dependent acid resistance.listeria monocytogenes acquired increased acid tolerance during exponential growth upon exposure to sublethal acid stress, a response designated the acid tolerance response (atr). maximal acid resistance was seen when the organism was exposed to ph 5.0 for 1 h prior to challenge at ph 3.0, although intermediate levels of protection were afforded by exposure to ph values ranging from 4.0 to 6.0. a 60 min adaptive period was required for the development of maximal acid tolerance; during this perio ...19968885415
is amoxicillin-cotrimoxazole the most appropriate antibiotic regimen for listeria meningoencephalitis? review of 22 cases and the literature.from june 1983 to january 1994, 22 adult patients with severe listeria monocytogenes meningoencephalitis were observed in our intensive care unit. listeria monocytogenes was obtained in culture in cerebrospinal fluid or blood for every patient. seven patients were treated with the combination ampicillin-aminoglycoside (group a) and 15 patients with the combination ampicillin (or amoxicillin)-cotrimoxazole (group a + c). risk factors and gravity scores were similar in both groups. failure of the ...19968889993
the listerial exotoxins listeriolysin and phosphatidylinositol-specific phospholipase c synergize to elicit endothelial cell phosphoinositide metabolism.exotoxins such as listeriolysin (llo) and phosphatidylinositol-specific phospholipase c (pica) have been implicated in listerial infection and sepsis. employing different listeria strains, mutated in individually known virulence genes, we examined exotoxin-related induction of endothelial cell signaling. listeria monocytogenes was a potent inductor of phosphatidylinositol (ptdins) metabolism in huvec. this effect was completely absent in a llo-negative strain. using a recombinant listeria innocu ...19968892639
sodium-driven, osmotically activated glycine betaine transport in listeria monocytogenes membrane vesicles.transport of the osmoprotectant and cryoprotectant glycine betaine was investigated in membrane vesicles of listeria monocytogenes. uptake-driving transmembrane potentials ranging from 111 to 122 mv within the ph range of 5.5 to 7.5 could be generated by the electron donor system ascorbate-phenazine methosulfate but not by the electron donor system ascorbate-n,n,n',n'-tetramethyl-p-phenylenediamine. transport was dependent on both high concentrations of sodium ion and the presence of a hypertoni ...19968892806
listeriosis in 225 non-pregnant patients in 1992: clinical aspects and outcome in relation to predisposing conditions.clinical information was collected on 225 cases of listeria monocytogenes (lm) infection not associated with pregnancy occurring in france in 1992. infections affected primarily men (62%) and persons over 65 years of age. of the cases found, 81% occurred in persons with some underlying condition: 34% involved patients with severe immunosuppression; 37% were on dialysis or had diabetes mellitus, alcoholism, hepatic failure or malignancies without immunosuppressive therapy; and 10% had other under ...19968893400
development of listeriosis during vancomycin therapy in a neutropenic patient.vancomycin and aminoglycosides are widely used for fever in neutropenic patients. this combination of antibiotics has also been proposed for the treatment of listeria monocytogenes bacteremia. we report a case of fatal listeriosis in a 33-year-old man during acute lymphoblastic leukemia induction therapy in a total protective environment despite him having been on vancomycin for 8 days for treatment of staphylococcus bacteremia. vancomycin and aminoglycoside cannot be proposed for the treatment ...19968893409
significance of pre-incubation temperature and inoculum concentration on subsequent growth of listeria monocytogenes at 14 degrees c.the influence of the bacterial concentration of an inoculum (10(1) or 10(3) cfu ml-1) of two strains of listeria monocytogenes (scott a: serotype 4b and v7: serotype 1) and one strain of l. innocua (lin 11), and the time and temperature at which the inoculum was stored (cold storage: 4 degrees c for 4 weeks, or without cold storage: -20 degrees c before immediate transfer), and the temperature at which cells were pre-incubated (30 degrees c and 14 degrees c) on subsequent growth in richard's bro ...19968896354
lymphokine-activated killer cells lyse listeria-infected hepatocytes and produce elevated quantities of interferon-gamma.the bulk of listeria monocytogenes injected intravenously into mice is taken up in the liver, where hepatocytes serve as the principal site of intracellular replication. nk cells have been implicated in host defenses to a variety of intracellular pathogens. to explore the role of nk cells in resistance to listerial infections of the liver, lymphokine-activated natural killer (lak) cells were cocultured with listeria-infected hepatocytes. the aspartate aminotransferase activity in the medium (evi ...19968896511
catecholamines inhibit alpha/beta interferon production induced by lipopolysaccharide.in vitro incubation of listeria monocytogenes immune spleen cells in the presence of the catecholamines epinephrine or norepinephrine inhibited the alpha/beta-interferon (ifn alpha/beta) synthesis induced by the mitogen lipopolysaccharide, in a manner that appeared to be concentration-dependent. moreover, the inhibitory effect of both catecholamines epinephrine and norepinephrine on the synthesis of ifn alpha/beta was prevented by incubating immune spleen cells in the presence of propranolol, a ...19968897645
conversion of an extracellular cytolysin into a phagosome-specific lysin which supports the growth of an intracellular pathogen.listeria monocytogenes is a facultative intracellular pathogen which secretes a pore-forming cytolysin, listeriolysin o (llo), necessary for intracellular growth. clostridium perfringens is an extracellular pathogen which secretes a related cytolysin, perfringolysin o (pfo). when pfo is secreted by intracellular l. monocytogenes, it is toxic to the infected host cell. pfo-mediated toxicity renders the infected host cell permeable to gentamicin and leads to the death of the intracellular bacteria ...19968898390
anthrax toxin-mediated delivery of a cytotoxic t-cell epitope in vivo.the protective antigen (pa) component of anthrax toxin mediates entry of the toxin's lethal factor (lf) and edema factor into the cytosolic compartment of mammalian cells. the amino-terminal domain of lf (lfn; 255 amino acids) binds lf to pa, and when fused to heterologous proteins, the lfn domain delivers such proteins to the cytoplasm in the presence of pa. in the current study, we fused a 9-amino acid cytotoxic t-lymphocyte (ctl) epitope (llo91-99) from an intracellular pathogen, listeria mon ...19968901616
recombinant listeria monocytogenes cancer vaccines.listeria monocytogenes has recently been exploited as a vector for targeting antigens to the immune system. in the past year it has been shown to be particularly effective as a tumor antigen vector. here we set its potency as a cancer vaccine in the context of the type of immunity induced by this facultative intracellular bacterium.19968902392
human hla-b27 gene enhances susceptibility of rats to oral infection by listeria monocytogenes.germfree rats transgenic for the human genes hla-b27 and beta 2-microglobulin were colonized with hemolysin-positive (hly+) or hemolysin-negative (hly-) strains of listeria monocytogenes. hla-b27 rats were very susceptible to infection with hly+ l monocytogenes none survived beyond 6 days. conversely, nontransgenic control rats survived alimentary tract colonization with the hly+ strain, and both transgenic and nontransgenic rats survived colonization with the hly- strain of l monocytogenes. aft ...19968909262
the tandem repeat domain in the listeria monocytogenes acta protein controls the rate of actin-based motility, the percentage of moving bacteria, and the localization of vasodilator-stimulated phosphoprotein and profilin.the acta protein is responsible for the actin-based movement of listeria monocytogenes in the cytosol of eukaryotic cells. analysis of mutants in which we varied the number of proline-rich repeats (prr; consensus sequence dfpppptdeel) revealed a linear relationship between the number of prrs and the rate of movement, with each repeat contributing approximately 2-3 microns/min. mutants lacking all functional prrs (generated by deletion or point mutation) moved at rates 30% of wild-type. indirect ...19968909540
who international multicenter listeria monocytogenes subtyping study--rationale and set-up of the study. 19968913798
who-sponsored international collaborative study to evaluate methods for subtyping listeria monocytogenes: restriction fragment length polymorphism (rflp) analysis using ribotyping and southern hybridization with two probes derived from l. monocytogenes chromosome.seven laboratories participated in a who-sponsored international collaborative study, to evaluate methods for subtyping listeria monocytogenes, by performing restriction fragment length polymorph sm (rflp) analysis-based subtyping of an international study set of 80 strains of l. monocytogenes that included 22 epidemiologically related groups. the rflp analysis was done by southern hybridization with one of two types of probes found in multiple copies on the chromosome of l. monocytogenes. six l ...19968913799
serotyping of 80 strains from the who multicentre international typing study of listeria monocytogenes.serotyping was carried out on 80 coded strains, distribute to all laboratories taking part in the who l. monocytogenes multicenter subtyping study. all six laboratories used the method recommended by their coordinator. all 80 strains were typeable. there was complete agreement between the six laboratories on 49 (61.3%) strains (21 serovar 1/2a and 28 serovar 4b strains) which in turn were identical to the expected serovars, known only after decoding. the intralaboratory reproducibility carried o ...19968913800
who study on subtyping listeria monocytogenes: results of phage-typing.a multi-centered study on phage typing of listeria monocytogenes was carried out using 80 cultures sent under code and tested in six different laboratories. phage typing was performed using an international phage set in five laboratories and phage sets unique to two laboratories. testing of cultures sent in duplicate showed similar levels of reproducibility to that previously reported. analysis of results from groups of epidemiologically related cultures showed a high level of agreement in all l ...19968913801
multilocus enzyme electrophoresis for characterization of listeria monocytogenes isolates: results of an international comparative study.multilocus enzyme electrophoresis (mee) is a standard technique that is used to elucidate the epidemiology of a variety of bacterial species. recently, the method has been employed by several laboratories for investigations of clinical and foodborne isolates of listeria monocytogenes. to assess the sensitivity and reproducibility of mee in characterising l. monocytogenes isolates for epidemiological purposes and, ultimately, to agree on a standard protocol, seven laboratories participated in a b ...19968913802
high-frequency endonuclease (rea) typing: results from the who collaborative study group on subtyping of listeria monocytogenes.eighty isolates of listeria monocytogenes were typed by high-frequency restriction endonuclease analysis. two laboratories participated in the study with two restriction enzymes each. the enzymes used were ecori, hae1ii, hhai. and its isoschizomer cfo1. ecori was less discriminatory than the other enzymes. the profiles generated by hha1 and cfoi were not fully stable for some closely related isolates. the size and the number of restriction bands generated by hha1 in one laboratory and its isosch ...19968913803
the who multicenter study on listeria monocytogenes subtyping: random amplification of polymorphic dna (rapd).as part of a who multicenter study on listeria monocytogenes subtyping methods the random amplification of polymorphic dna (rapd)-technique was evaluated. six participants were asked to use a standard protocol to analyse a set of 80 l. monocytogenes strains. this set contained 22 groups of epidemiologically linked isolates and 11 pairs of duplicate strains. using three different 10-mer primers the median reproducibility of the rapd-results obtained by the six participants was 86.5% (range 0-100% ...19968913804
genomic fingerprinting of 80 strains from the who multicenter international typing study of listeria monocytogenes via pulsed-field gel electrophoresis (pfge).an international multicenter typing study of listeria monocytogenes was initiated by the world health organization (food safety unit, geneva) in order to evaluate the usefulness of various phenotypic and genotypic typing methods for l. monocytogenes, to select and standardize the most appropriate methods to define common nomenclature of varieties and to select specific reference strains. pulsed-field gel electrophoresis was used in four laboratories for molecular characterization of a set of 80 ...19968913805
effect of multiplicity of infection on listeria monocytogenes pathogenicity for hela and caco-2 cell lines.the significance of multiplicity of infection (moi) for invasiveness and intracellular multiplication of listeria monocytogenes in caco-2 and hela cell monolayers was investigated. a low moi (1:1) resulted in recovery of significantly more l. monocytogenes when these bacteria were used to infect either cell line. at high moi (100:1), the percentage recovery of bacteria was comparatively low, even after extensive invasion and intracellular multiplication. microscopic analysis of giemsa- and immun ...19968918946
exploitation of a chromosomally integrated lactose operon for controlled gene expression in lactococcus lactis.lactococcus lactis mg5267 is a plasmid-free strain in which the lactose operon is integrated in the bacterial chromosome. the chromosomal lacg gene which encodes phospho-beta-galactosidase was inactivated by a double cross-over integration event. unexpectedly, the resultant mutant was shown to retain a lac-positive phenotype. the lysin gene from listeria monocytogenes bacteriophage lm-4 was subsequently integrated into the chromosome of this strain such that expression of the heterologous gene w ...19968919450
construction of luciferase reporter bacteriophage a511::luxab for rapid and sensitive detection of viable listeria cells.specific transfer and expression of bacterial luciferase genes via bacteriophages provides an efficient way to detect and assay viable host cells. listeria bacteriophage a511 is a genus-specific, virulent myovirus which infects 95% of listeria monocytogenes serovar 1/2 and 4 cells. we constructed recombinant derivative a511::luxab, which carries the gene for a fused vibrio harveyi luxab protein inserted immediately downstream of the major capsid protein gene (cps). efficient transcription is ini ...19968919773
influence of environmental parameters on phosphatidylcholine phospholipase c production in listeria monocytogenes: a convenient method to differentiate l. monocytogenes from other listeria species.the ability to produce phosphatidylcholine phospholipase c (lecithinase) is associated with virulence in pathogenic species of listeria. levels of production vary greatly among members of the genus, and this virulence factor is not readily detectable in many members of the pathogenic species on conventional agar media containing egg yolk, a common substrate for the enzyme. in this study, the influence of a variety of environmental parameters, including temperature, ph, and salt concentration, on ...19968919785
characterization of listeria monocytogenes isolates by esterase electrophoresis.multiple bands of alpha-naphthyl-propionyl esterase (alpha npe) activity observed following starch gel electrophoresis of cell extracts allowed 219 listeria monocytogenes isolates from milk, nondairy foods, and clinical and veterinary sources to be assigned to 17 different alpha npe types. multilocus enzyme electrophoresis (mee) analysis was used to obtain electrophoretic mobility data for alpha npes and nine other metabolic enzymes; on the basis of these data, the 219 strains were assigned to 5 ...19968919813
listeria monocytogenes joint infection in a patient with psoriatic arthritis. 19968923390
expression of the inlab operon by listeria monocytogenes is not required for entry into hepatic cells in vivo.listeria monocytogenes injected intravenously into mice is taken up in the liver, where hepatocytes serve as the principal site of intracellular replication. the factors effecting entry of l. monocytogenes into hepatic cells remain to be determined. others have shown that the protein products of the inlab (internalin) operon are required for maximum entry of l. monocytogenes into a number of cell lines in vitro. likewise, we report here that expression of the inlab operon was required for maximu ...19968926058
differences in virulence and in expression of prfa and prfa-regulated virulence genes of listeria monocytogenes strains belonging to serogroup 4.listeria monocytogenes isolates belonging to serogroup 4 (subtypes 4a, 4ab, 4b, 4c, 4d, and 4e) exhibit different levels of virulence in mice. molecular studies indicate that in comparison with the control strain egd (serotype 1/2a), these strains differ in the expression of the prfa-regulated virulence genes, including prfa itself. strains of serotypes 4c, 4d, 4e, and especially 4a show a low level of invasiveness in caco-2 cells, which correlates in part with the low level of expression of the ...19968926062
adsorption of bacteriocins by ingestible silica compounds.bacteriocins including nisin, pediocin po2, brevicin 286 and piscicolin 126 were adsorbed from culture supernates by various food-grade porous silica anti-caking agents and the food colourant, titanium dioxide. all the porous silica (calcium silicate or silicon dioxide) materials showed substantial capacity in adsorbing bacteriocin activities from the culture supernate and biological activity was recovered in the adsorbents. in contrast, the food colourant titanium dioxide adsorbed most of the b ...19968926221
[septic infection of hip joint prosthesis with listeria monocytogenes].a case of listeria monocytogenes septicaemia and infection of a prosthetic hip joint is presented in a patient with non-insulin-dependent diabetes mellitus. the patient developed the infection five and a half years after primary alloplastic operation. the prosthesis was removed and a temporary prosthesis with gentamicin was placed ("spacer"). the antibiotic treatment included ampicillin, pivampicillin and sulfamethoxazole-trimetroprim. six weeks after removal of the prosthesis an un-cemented pro ...19968928284
internalin a can mediate phagocytosis of listeria monocytogenes by mouse macrophage cell lines.listeria monocytogenes internalin a (inla) is a surface protein that mediates the attachment of listeria to, and invasion of, hepatocytes, epithelial, and endothelial cells. in this study, we tested whether inla could also mediate phagocytosis of l. monocytogenes by the non-listericidal mouse macrophage cell lines j774a.1 and h36.12j. recombinant inla (rinla) was used to derive mouse monoclonal anti-inla antibodies (mab) and rabbit anti-inla antibodies. fluorescence microscopy demonstrated that ...19968929551
in vivo bioluminescence to detect the attachment of l-forms of listeria monocytogenes to food and clinical contact surfaces.a bioluminescent phenotype of listeria monocytogenes was employed to study the adhesion and biofilm formation of both classical and l-forms to relevant food and clinical contact surfaces. attachment of both parental (cell-walled) and l-forms to intravenous tubing and stainless steel was compared using viable counts and bioluminescence. both cell types attached themselves to intravenous tubing and stainless steel. parental cell numbers attached to intravenous tubing were 1 log higher than l-form ...19968930702
antimicrobial activity of hop extracts against listeria monocytogenes in media and in food.growth of listeria monocytogenes was inhibited in culture media and in certain foods by four hop extracts (i-iv) containing varying concentrations of alpha-and beta-acids. extracts (ii and iii) containing the highest concentrations of beta-acids were inhibitory at 0.01 mg/l in trypticase soy broth. in food, these hop extracts showed varying magnitudes of inhibition. in coleslaw, hop extract iii at 1 mg/g enhanced the rate of inactivation of l. monocytogenes scott a. hop extract ii was inhibitory ...19968930705
isolation and characterization of bacteriocin-producing lactic acid bacteria from ready-to-eat food products.lactic acid bacteria isolated from a range of foods sold in ready-to-eat form were screened for bacteriocin production. twenty-two bacteriocin-producing cultures were isolated from 14 of the 41 foods sampled. bacteriocin-producing isolates from meat, fish and dairy products were lactobacillus and leuconostoc species typically found associated with these products. most of these isolates gave only a narrow inhibitory spectrum although two showed activity against listeria monocytogenes. fruit and v ...19968930706
multiplex pcr assay for the routine detection of listeria in food.the development and validation of a multiplex pcr assay for the detection of listeria that can be employed in routine investigation of food samples are described. the assay, which employs a short culture enrichment step followed by isolation of bacterial cells and detection by multiplex pcr reaction, is highly sensitive and specific for the detection of listeria monocytogenes and all other listeria species. over 350 food samples were tested in parallel by standard cultural procedures and the pcr ...19968930713
treatment of an acute bacterial infection with a combination of acetylsalicylic acid/ibuprofen and interferon gamma.the bacterial infection with listeria monocytogenes is associated with an inhibition of the macrophage function, the first-line defense against bacterial infection. we studied the effect of acetylsalicylic acid (asa, cas 50-78-2) and ibuprofen (cas 15687-21-1) alone and in combination with a suboptimal dose of recombinant interferon gamma. (ifn gamma) on the acute infection with listeria monocytogenes in the balb/c mouse. animals were intravenously infected with a sublethal dose of listeria mono ...19968931897
effect of medium-chain fatty acids in mould ripened cheese on the growth of listeria monocytogenes.listeria monocytogenes and list. innocua were isolated from commercial soft ripened and blue-veined cheeses manufactured in france, mainly from brie cheese made from unpasteurized milk. five isolates were list. monocytogenes serotype 1/2 and two were list. innocua. examination of bleu d'auvergne cheese with the cryoscanning electron microscope showed that many conidia spores were present in the blue veins in close contact with the cheese surface. there were few conidia spores in the brie, mostly ...19968933308
bacteriophage receptors on listeria monocytogenes cells are the n-acetylglucosamine and rhamnose substituents of teichoic acids or the peptidoglycan itself.different approaches were used to examine the function of teichoic acids (ta) as phage receptors among selected listeria strains, and to identify and characterize specific receptor structures of host cells belonging to different serovars. this included successive removal of cell wall constituents, preparation and purification of ta, and glc analysis of ta components. adsorption of listeria monocytogenes bacteriophages could be inhibited by polyvalent antisera, specific lectins and addition of pu ...19968936325
the effect of temperature and growth rate on the susceptibility of listeria monocytogenes to environmental stress conditions.the effect of growth temperature and growth rate on the susceptibility to heat and ph stress were investigated in listeria monocytogenes grown in continuous culture where these two growth variables could be varied independently of each other, and in batch culture. after growth at 30 degrees c or 10 degrees c at constant growth rate, or at 30 degrees c at different growth rates, cells did not differ in their resistance to heat at 55 degrees c. cells grown at 30 degrees c were more resistant to ac ...19968936371
polymerase chain reaction (pcr) detection of listeria monocytogenes in diluted milk and reversal of pcr inhibition caused by calcium ions.dna from listeria monocytogenes was used as the model system from this investigation, with pcr primers based on the listeriolysin o gene. under standard polymerase chain reaction (pcr) conditions and with no prior treatment, amplification failed in the presence of more than 5% milk. since inhibition of the pcr occurred at the same milk concentrations with full fat, half fat and fat-free milk, inhibition was not attributed to the fat content of the milk. calcium ions were, however, identified as ...19968936376
effects of growth conditions on the resistance of some pathogenic and spoilage species to high pressure homogenization.the effects of chemico-physical growth conditions such as ph, temperature and water activity (aw) on lethal high homogenization pressure effects on listeria monocytogenes, staphylococcus aureus, escherichia coli and yarrowia lipolytica were investigated. the results, though based on standard media, emphasize the importance of food system composition and its thermal history on the high pressure tolerance of the microbial population.19968936378
induced illness in interleukin-6 (il-6) knock-out mice: a causal role of il-6 in the development of the low 3,5,3'-triiodothyronine syndrome.interleukin-6 (il-6) administration to human subjects or experimental animals induces changes in thyroid hormone metabolism resembling those in the sick euthyroid syndrome. furthermore, the decrease in serum t3 during illness is significantly related to serum il-6 concentrations. these findings suggest, but do not prove, a causal role for il-6 in the development of the low t3 syndrome. the aim of the present study was to evaluate the role of il-6 in the development of the sick euthyroid syndrome ...19968940342
genus- and species-specific detection of listeria monocytogenes using polymerase chain reaction assays targeting the 16s/23s intergenic spacer region of the rrna operon.in this study, the 16s/23s rrna intergenic spacer (igs) regions of six listeria species were examined. dna bands of 590 and 340 bp were observed following polymerase chain reaction (pcr) amplification of dna from listeria monocytogenes, listeria innocua, listeria seeligeri, listeria welshimeri, and listeria ivanovii strains with generic rrna igs oligonucleotide primers. for strains of listeria grayi subspp. grayi and murrayi, dna band sizes of 550 and 340 bp were observed with this primer pair. ...19968941989
il-4 neutralization or tnf-alpha treatment ameliorate disease by an intracellular pathogen in ifn-gamma receptor-deficient mice.successful control of infectious disease depends on aquisition of an appropriate protective immune response. ifn-gamma, first produced by nk cells and then by th1 cells, is central to acquired resistance against intracellular bacteria, including listeria monocytogenes. in contrast, il-4 is not generated to a measurable degree. here we show that il-4 is produced during listeriosis by ifn-gamma receptor gene disruption (ifn-gammar(-/-)) mutant mice. production of tnf was diminished, whereas il-12 ...19968943375
magnetic resonance imaging of abscesses of the brain stem and cerebellum complicating listeria monocytogenes rhombencephalitis. 19968943914
prolonged gastric acid suppression therapy: a significant risk factor for listeria monocytogenes infection? 19968944366
increased prevalence of listeria monocytogenes in the faeces of patients receiving long-term h2-antagonists.human listeriosis is an uncommon infection caused by the gram-positive organism listeria monocytogenes.19968944368
secretion of type ii phospholipase a2 and cryptdin by rat small intestinal paneth cells.we examined the secretion of antimicrobial proteins and peptides into surgically isolated and continuously perfused segments of rat small intestine. up to nine discrete antimicrobial molecules appeared in the intestinal perfusates following intravenous administration of bethanechol, a cholinergic agonist, or intralumenal instillation of lipopolysaccharide (lps). among them were three markers of paneth cell secretion: lysozyme; type ii (secretory) phospholipase a2; and at least one intestinal def ...19968945560
antibodies to the leucine-rich repeat region of internalin block entry of listeria monocytogenes into cells expressing e-cadherin.internalin, a surface protein essential for entry of listeria monocytogenes egd into epithelial cells, was used as an antigen to raise nine monoclonal antibodies. these monoclonal antibodies recognized seven distinct epitopes which were located in three different regions of the protein. three of them inhibited internalin-mediated entry and recognized the amino-terminal leucine-rich repeat region of the protein, suggesting that this region is essential for entry.19968945603
either b7-1 or b7-2 is required for listeria monocytogenes-specific production of gamma interferon and interleukin-2.listeria infection results in the induction of gamma interferon (ifn-gamma)-producing t lymphocytes. blocking of the costimulatory molecule b7 in vivo led to a marked decrease in antigen-specific production of ifn-gamma and interleukin-2 by lymphocytes. blocking of both b7-1 (cd80) and b7-2 (cd86) was required in order to inhibit cytokine production, indicating that either molecule could act alone. although ifn-gamma production by cultured spleen cells was significantly suppressed by b7 blocking ...19968945605
specific binding of the listeria monocytogenes transcriptional regulator prfa to target sequences requires additional factor(s) and is influenced by iron.the prfa protein, which is a member of the crp/fnr family of prokaryotic transcription activators, regulates the virulence genes of listeria monocytogenes. in this work, specific binding of prfa to its target dna was determined by electrophoretic mobility-shift assays (emsas) using cell-free extracts from the two l. monocytogenes strains egd and nctc 7973. prfa-specific binding differs between the two strains, even when the concentration of prfa was adjusted to similar levels. both strains exhib ...19968951812
listeria meningitis during treatment of a meningococcal meningitis in an immunocompetent infant.a case report of a listeria meningitis 5 days after diagnosis of meningococcal meningitis in a immunocompetent child of 2 years is presented. the infection occurred during hospital admission. culture results of cerebrospinal fluid (csf) were confirmed by a listeria-specific polymerase chain reaction in 2 csf specimens. the listeria meningitis quickly responded to antimicrobial treatment with intravenous amoxicillin combined with tobramycin.19968953686
production of pediocin ach by lactobacillus plantarum whe 92 isolated from cheese.among 1,962 bacterial isolates from a smear-surface soft cheese (munster cheese) screened for activity against listeria monocytogenes, six produced antilisterial compounds other than organic acids. the bacterial strain whe 92, which displayed the strongest antilisterial effect, was identified at the dna level as lactobacillus plantarum. the proteinaceous nature, narrow inhibitory spectrum, and bactericidal mode of action of the antilisterial compound produced by this bacterium suggested that it ...19968953710
purification and amino acid sequences of piscicocins v1a and v1b, two class iia bacteriocins secreted by carnobacterium piscicola v1 that display significantly different levels of specific inhibitory activity.two bacteriocins produced by carnobacterium piscicola v1 were purified and characterized. piscicocin v1a (molecular mass = 4,416 da) and piscicocin v1b (molecular mass = 4,526 da) are nonlantibiotic, small, heat-stable antibacterial peptides. piscicocin v1b is identical to carnobacteriocin bm1, while piscicocin v1a is a new bacteriocin. its complete sequence of 44 amino acid residues has been determined. piscicocin v1a belongs to the class iia bacteriocins having the consensus ygngv motif. these ...19968953713
purification of the bacteriocin bavaricin mn and characterization of its mode of action against listeria monocytogenes scott a cells and lipid vesicles.bavaricin mn was purified from lactobacillus sake culture supernatant 135-fold with a final yield of 11%. sequence analysis revealed bavaricin mn to be a 42-amino-acid peptide having a molecular weight of 4,769 and a calculated pi of 10.0. computer analysis indicated that the c-terminal region may form an alpha-helical structure with an amphipathic nature deemed important in the interaction of bacteriocins with biological membranes. bavaricin mn rapidly depleted the membrane potential (delta p) ...19968953724
immune function and host defense in rodents exposed to 60-hz magnetic fields.this study was conducted to evaluate the influence of subchronic exposure to pure, linearly polarized 60-hz magnetic fields (mf) on the host immune response in mice. the experimental design was as follows: three groups were exposed continuously (18.5 hr/day) to mf at field strengths of 0.02, 2, or 10 gauss (g), one group was exposed intermittently (1 hr on/1 hr off) to mf at a field strength of 10 g, and one group served as a sham control. experimental endpoints included spleen and thymus weight ...19968954752
development of antigen-delivery systems, based on the escherichia coli hemolysin secretion pathway.we describe the development of plasmid vectors carrying the expression sites, an hlya cassette and the secretion genes of escherichia coli hemolysin. these allow the synthesis and secretion of heterologous microbial antigens in e. coli and attenuated salmonella aroa strains. genes or gene fragments encoding microbial antigens are inserted in-frame into a residual part of the hlya gene which essentially encodes the hlya secretion signal (hlyas). in general, the fused genes, carrying the hlyas seq ...19968955639
neutrophils are involved in the non-specific resistance to listeriosis induced by mycobacterial infections.a major role has been recently ascribed to the neutrophil in the resistance to infection by listeria monocytogenes (l. monocytogenes). here we evaluated whether such neutrophils played a role in the non-specific resistance to listeriosis that develops in hosts infected by mycobacteria. we found that the depletion of neutrophils completely abrogated the resistance conferred by the activated macrophages induced during the mycobacterial infection. the lack of killing by activated kupffer cells and ...19968958060
interleukin-12 as an adjuvant in the generation of protective immunity to an intracellular pathogen. 19968958971
a method to recover, enumerate and identify lymphomyeloid cells present in an inflammatory dermal site: a study in laboratory mice.we describe a new method to recover and study cells present in the dermis of mouse ear at homeostasis or after intradermal injection of disturbing agents (lipopolysaccharide or listeria monocytogenes). the ears either left untreated or inoculated were handled and processed as culture explants of the dorsal and ventral leaflets, their dermal sides being spread on a buffered medium. within this medium emigrate/sediment, with different kinetics: neutrophils, mononuclear phagocytes, dendritic leucoc ...19968960094
occurrence of listeria monocytogenes and other listeria spp. in raw caprine milk.samples of caprine milk from bulk tanks of 405 farms in central spain were analyzed for listeria spp. once per season over a 1-yr period. listeria monocytogenes and listeria innocua were detected in 2.56 and 1.73% of the 1445 samples, respectively. listeria ivanovii (0.21% samples) and listeria seeligeri (0.07% samples) were rarely isolated. only 6 milk samples were contaminated by more than one listeria species. most farms (92.59%) produced milk that was apparently free from l. monocytogenes th ...19968961100
[extensive serositis caused by listeria monocytogenes]. 19968962898
nonspecific modification of cellular immunity by yersinia enterocolitica.an isogenic pair of virulent and avirulent yersinia enterocolitica o9 strains was used to examine the influence of the virulence plasmid on the non-specific modification of the cellular immunity in balb/c mice after experimental infection with yersiniae. the modification of contact hypersensitivity response to dinitrofluorobenzene, resistance to the syngeneic lymphoma lstra, and resistance to listeria monocytogenes was heavily influenced by the presence of the virulence plasmid. as a general rul ...19968964610
cell motility driven by actin polymerization.certain kinds of cellular movements are apparently driven by actin polymerization. examples include the lamellipodia of spreading and migrating embryonic cells, and the bacterium listeria monocytogenes, that propels itself through its host's cytoplasm by constructing behind it a polymerized tail of cross-linked actin filaments. peskin et al. (1993) formulated a model to explain how a polymerizing filament could rectify the brownian motion of an object so as to produce unidirectional force (peski ...19968968574
the inla gene required for cell invasion is conserved and specific to listeria monocytogenes.the gram-positive bacterium listeria monocytogenes can actively induce its own uptake by epithelial cells and fibroblasts through a surface-exposed 80 kda protein, internalin (inia), encoded by inia. we studied the distribution and the dna polymorphism of inia sequences in a wide variety of wild strains of l. monocytogenes as compared to other listeria species. this was done by pcr-amplifying inia sequences encoding the fifteen repeats a and the three repeats b of inia. inia-repeated sequences w ...19968581163
intracellular pathogenesis of listeriosis. 19968592552
physiochemical characterization of the nisin-membrane interaction with liposomes derived from listeria monocytogenes.mechanistic information about the bacteriocin nisin was obtained by examining the efflux of 5(6)-carboxy-fluorescein from listeria monocytogenes-derived liposomes. the initial leakage rate (percentage of efflux per minute) of the entrapped dye was dependent on both nisin and lipid concentrations. at all nisin concentrations tested, 5(6)-carboxyfluorescein efflux plateaued before all of the 5(6)-carboxyfluorescein was released (suggesting that pore formation was transient), but efflux resumed whe ...19968593036
use of molecular typing methods to trace the dissemination of listeria monocytogenes in a shrimp processing plant.molecular typing of bacteria has been widely used in epidemiological studies but not as extensively for tracing the transmission of pathogenic bacteria in food plants. this study was conducted to examine the potential use of two molecular typing methods, random amplified polymorphic dna (rapd) analysis and pulsed-field gel electrophoresis (pfge), to trace listeria monocytogenes contamination in a shrimp processing plant. ribotyping and phase typing were also performed on a select number of strai ...19968593073
recognition of two classes of oligoproline sequences in profilin-mediated acceleration of actin-based shigella motility.the gram negative rod shigella flexneri uses it surface protein icsa to induce host cell actin assembly and to achieve intracellular motility. yet, the icsa protein lacks the oligoproline sequences found in acta, the surface protein required for locomotion of the gram positive rod listeria monocytogenes. microinjection of a peptide matching the second acta oligoproline repeat (fefpppptde) stops listeria locomotion (southwick, f.s., and d.l. purich. 1994a. proc. natl. acad. sci. usa. 91:5168-5172 ...19968601612
intramolecular inhibition of human defensin hnp-1 by its propiece.we examined mechanisms that protect host defense cells from their cytotoxic effector molecules. human neutrophil peptides (hnp) 1-3 are microbicidal and cytotoxic defensins, initially synthesized as 94-amino acid preprohnp(1-94), cotranslationally proteolyzed to prohnp(20-94), then converted by removal of the anionic propiece to mature hnp(65-94)(hnp-1 and -3) and hnp(66-94) (hnp-2). we hypothesized that during synthesis and subcellular sorting the anionic propiece inhibits the cytotoxicity of t ...19968601627
acquired resistance against a secondary infection with listeria monocytogenes in mice is not dependent on reactive nitrogen intermediates.during an infection, inflammatory mediators can induce the production of nitric oxide, a reactive nitrogen intermediate (rni) which plays a role in antimicrobial activity against a wide variety of pathogens. in vitro experiments have shown that release of rni by macrophages is mediated by tumor necrosis factor alpha (tnf). since tnf is essential for acquired resistance during a secondary listeria monocytogenes infection in mice, the aim of the present study was to determine whether rni are also ...19968606078
endogenous interleukin-4, but not interleukin-10, is involved in suppression of host resistance against listeria monocytogenes infection in interferon-depleted mice.the production and roles of endogenous interleukin-4 (il-4) and il-10 in a sublethal infection with listeria monocytogenes were studies in normal mice and anti-gamma interferon (ifn-gamma) monoclonal antibody (mab)-pretreated mice. in normal mice, the expression of mrnas for il-4 and il-10, which was amplified by reverse transcription-pcr, was induced in the spleens and livers either early or late in infection, although the serum il-4 and il-10 were not detectable by enzyme-linked immunosorbent ...19968606087
effect of cell polarization and differentiation on entry of listeria monocytogenes into the enterocyte-like caco-2 cell line.the entry of listeria monocytogenes into the enterocyte-like caco-2 cell line was studied as a function of cell polarization and differentiation. l. monocytogenes entered through the entire surface of nonpolarized cells and, predominantly, through the basolateral surface of polarized cells based on the following observations: (i) sites of l. monocytogenes invasion paralleled the distribution of the transferrin receptor, a well-known basolateral marker of polarization; (ii) numbers of internalize ...19968606093
early pathogenesis of listeria monocytogenes infection in the mouse spleen.histological observations suggested that in the spleen, blood-borne listeria monocytogenes bacteria were preferentially ingested by two morphologically distinct mononuclear phagocyte populations present in the marginal zone of the white pulp. the morphologies of these phagocytes corresponded to those of marginal zone macrophages or marginal zone dendritic cells. moreover, during the first day of infection, the same phagocytes containing listeria apparently translocated from the marginal zone int ...19968606358
differential effects of viable and killed bacteria on il-12 expression of macrophages.listeria monocytogenes-specific, ifn-gamma-producing cd4+ t cells are induced in 5-day in vitro cultures of naive spleen cells with viable l. monocytogenes (vlm) but are not induced in cultures with heat killed l. monocytogenes (hklm). anti-il-12 abs abrogated the induction of the ifn-gamma-producing cd4+ t cells by vlm, suggesting an importance of il-12 in the induction of ifn-gamma-producing cd4+ t cells. accordingly, il-12p40 was expressed by macrophages (m phi) from the cultures of whole spl ...19968609419
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