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evaluation of antilisterial action of cilantro oil on vacuum packed ham.cilantro oil is an essential oil preparation extracted from the plant coriandrum sativium. a series of experiments were conducted to evaluate the ability of cilantro oil to control the growth of listeria monocytogenes on vacuum-packed ham. the in vitro minimal inhibitory concentration for five strains of l. monocytogenes was found to vary from 0.074% to 0.018% depending on strain. cilantro oil treatments were then tested on ham disks inoculated with a cocktail of the five l. monocytogenes strain ...200211883677
antagonistic activity of lactobacillus casei strain shirota against gastrointestinal listeria monocytogenes infection in rats.in the present study, the effect of ingested viable lactobacillus casei shirota strain yit9029 on oral infection with the enteric pathogen listeria monocytogenes in wistar rats was investigated. rats were orally infected with 10(9) viable l. monocytogenes. starting 3 days before the infection, rats received a daily dosage of 10(9) viable l. casei. it was shown that supplementation of l. casei significantly reduced the numbers of l. monocytogenes in stomach, caecum, faeces, spleen and liver, 2 da ...200211885574
salt stress proteins induced in listeria monocytogenes.the ability of listeria monocytogenes to tolerate salt stress is of particular importance, as this pathogen is often exposed to such environments during both food processing and food preservation. in order to understand the survival mechanisms of l. monocytogenes, an initial approach using two-dimensional polyacrylamide gel electrophoresis was performed to analyze the pattern of protein synthesis in response to salt stress. of 400 to 500 visible proteins, the synthesis of 40 proteins (p < 0.05) ...200211916660
cloning of rel from listeria monocytogenes as an osmotolerance involvement gene.transposon insertional mutants of listeria monocytogenes were constructed to identify genes involved in osmotolerance, and one mutant that showed reduced growth under high osmotic pressure was obtained. the cloned gene from the transposon insertion site of the mutant, named rel, was 2,214 bp in length and had very high homology to rela of bacillus subtilis, which encodes guanosine tetraphosphate (ppgpp) and guanosine pentaphosphate (pppgpp) [collectively designated (p)ppgpp] synthetase during st ...200211916666
identification of listeria monocytogenes genes expressed in response to growth at low temperature.listeria monocytogenes is a food-borne bacterial pathogen that is able to grow at refrigeration temperatures. to investigate microbial gene expression associated with cold acclimation, we used a differential cdna cloning procedure known as selective capture of transcribed sequences (scots) to identify bacterial rnas that were expressed at elevated levels in bacteria grown at 10 degrees c compared to those grown at 37 degrees c. a total of 24 different cdna clones corresponding to open reading fr ...200211916687
responses of listeria monocytogenes to acid stress and glucose availability revealed by a novel combination of fluorescence microscopy and microelectrode ion-selective techniques.fluorescence ratio imaging microscopy and microelectrode ion flux estimation techniques were combined to study mechanisms of ph homeostasis in listeria monocytogenes subjected to acid stress at different levels of glucose availability. this novel combination provided a unique opportunity to measure changes in h(+) at either side of the bacterial membrane in real time and therefore to evaluate the rate of h(+) flux across the bacterial plasma membrane and its contribution to bacterial ph homeosta ...200211916698
mechanism of murine vgamma1+ gamma delta t cell-mediated innate immune response against listeria monocytogenes infection.murine gamma delta t cells participate in innate immune response against infection of the intracellular bacterium listeria monocytogenes. in the present report, we analyzed the mechanism of the gamma delta t cell-mediated response against l. monocytogenes infection. gamma delta t cell-enriched spleen cells of l. monocytogenes-infected mice produced ifn-gamma in vitro in response to l. monocytogenes-infected spleen cells. the ifn-gamma production was abrogated by depletion of vgamma1+ gamma delta ...200211920558
listeria monocytogenes infection in israel and review of cases worldwide.listeria monocytogenes, an uncommon foodborne pathogen, is increasingly recognized as a cause of life-threatening disease. a marked increase in reported cases of listeriosis during 1998 motivated a retrospective nationwide survey of the infection in israel. from 1995 to 1999, 161 cases were identified; 70 (43%) were perinatal infections, with a fetal mortality rate of 45%. most (74%) of the 91 nonperinatal infections involved immunocompromised patients with malignancies, chronic liver disease, c ...200211927029
antimicrobial activity of individual and mixed fractions of dill, cilantro, coriander and eucalyptus essential oils.essential oils from dill (anethum graveolens l.), coriander (seeds of coriandrum sativum l.), cilantro (leaves of immature c. sativum l.) and eucalyptus (eucalyptus dives) were separated into heterogeneous mixtures of components by fractional distillation and were analyzed by gas chromatography-mass spectroscopy. minimum inhibitory concentrations against gram-positive bacteria, gram-negative bacteria and saccharomyces cerevisiae were determined for the crude oils and their fractions. essential o ...200211929164
antibacterial activity of chitosans and chitosan oligomers with different molecular weights.antibacterial activities of six chitosans and six chitosan oligomers with different molecular weights (mws) were examined against four gram-negative (escherichia coli, pseudomonas fluorescens, salmonella typhimurium, and vibrio parahaemolyticus) and seven gram-positive bacteria (listeria monocytogenes, bacillus megaterium, b. cereus, staphylococcus aureus, lactobacillus plantarum, l. brevis, and l. bulgaricus). chitosans showed higher antibacterial activities than chitosan oligomers and markedly ...200211929171
inla- but not inlb-mediated internalization of listeria monocytogenes by non-phagocytic mammalian cells needs the support of other internalins.to determine the contribution of the previously identified internalins, inla, inlb, inlc, inle, inlg, and inlh, to internalization of listeria monocytogenes by non-professional phagocytic mammalian cells, we constructed mutants with various combinations of deletions in the respective inl genes. internalization of these mutants into the epithelial-like caco-2 and the microvascular endothelial hbmec cell lines were studied. deletion of the inlghe gene cluster, or of the single genes, led to a two ...200211929515
inactivation of the srta gene in listeria monocytogenes inhibits anchoring of surface proteins and affects virulence.during infection of their hosts, gram-positive bacteria express surface proteins that serve multiple biological functions. surface proteins harbouring a c-terminal sorting signal with an lpxtg motif are covalently linked to the cell wall peptidoglycan by a transamidase named sortase. two genes encoding putative sortases, termed srta and srtb, were identified in the genome of the intracellular pathogenic bacterium listeria monocytogenes. inactivation of srta abolishes anchoring of the invasion pr ...200211929538
meningitis in the neonate.group b beta-hemolytic streptococci and escherichia coli strains account for approximately two thirds of all cases of neonatal meningitis, while bacteria that typically account for meningitis in older age groups (haemophilus influenzae type b, neisseria meningitidis, and streptococcus pneumoniae) are infrequent causes of meningitis in the neonatal population. as with other medical problems in neonates, signs and symptoms of bacterial infection of the central nervous system are generally few in n ...200211931731
antimicrobial resistance of foodborne pathogens.emergence of bacterial antimicrobial resistance has become a serious problem worldwide. while much of the resistance observed in human medicine is attributed to inappropriate use in humans, there is increasing evidence that antimicrobial use in animals selects for resistant foodborne pathogens that may be transmitted to humans as food contaminants.200211932191
application of recurrent neural network to predict bacterial growth in dynamic conditions.a combination of a factorial design and two central composite designs was used to assess quantitatively the effects of acid ph (5.6-7.0) or alkaline ph (7.0-9.5) and nacl (0-8%) variations on the growth of listeria monocytogenes in a meat broth, at 20 degrees c and lower temperature 10 degrees c. two principal phenomena were observed when bacteria were submitted to abrupt change of ph and a(w) during growth, whatever the growth temperature: (i) large environmental variations induced a lag phase ...200211934019
some examples of, and some problems with, the use of nonlinear logistic regression in predictive food microbiology.a new technique, nonlinear logistic regression, is described for modelling binomially distributed data, i.e., presence/absence data where growth is either observed or not observed, for applications in predictive food microbiology. some examples of the successful use of this technique are presented, where the controlling factors are temperature, water activity, ph and the concentration of lactic acid, a weakly dissociating organic acid. generally speaking, good-fitting models were obtained, as ev ...200211934020
proposal of a novel parameter to describe the influence of ph on the lag phase of listeria monocytogenes.predictive models for lag phase duration (lambda) have been less reliable than specific growth rate (mu) models due, in part, to the influence of the pre-growth environment on lambda. a discrete modelling approach was taken to more completely define the response of individual cells to new environments. time to detection (td) data was obtained from serial twofold dilutions of listeria monocytogenes growing in a bioscreen at 30 degrees c. comparison of the inoculum densities required to achieve ma ...200211934021
growth ph does not affect the initial physiological state parameter (po) of listeria monocytogenes.it has proven difficult to develop adequate mathematical models for the lag phase (lambda) which characterizes the adaptation period prior to the initiation of exponential growth by microorganisms. this is due, in part, to our incomplete understanding of the nature of the initial physiological state of cells (defined as h0 or p0 depending on the model), and changes taking place during adaptation. the objectives of the present study were to characterize p0 using data from growth of listeria monoc ...200211934022
utilizing luminometry for monitoring growth of listeria monocytogenes in its liquid or gelified monocultures and cocultures with "acid-only" lactococcus lactis.the light output of a bioluminescent recombinant strain of listeria monocytogenes increased parallel with its viable cell counts during the exponential phase of the growth both in aerobic monocultures and mixed cultures, but dropped significantly at the commencement of the stationary phase. suppression of l. monocytogenes by a nisin-less strain of lactococcus lactis occurred only as an early induction of the stationary state of the target organism. in low-salt cocultures, an inverse linear corre ...200211934024
combining fuzzy querying of imprecise data and predictive microbiology using category-based reasoning for prediction of the possible microbial spoilage in foods: application to listeria monocytogenes.various predictive models of microbial behavior have been created and extensive data collection has been done by numerous private or public laboratories. however, significant differences between predicted and observed values in foods have been observed and need to be stressed, understood and explained as much as possible. in this paper, we present a software tool (currently at the level of a prototype) able: (i) to store in a database all relevant information expressed on one hand as qualitative ...200211934025
modelling the growth kinetics of listeria as a function of temperature, ph and organic acid concentration.the combined effects of temperature, ph and organic acids (lactic, acetic and propionic) on the growth kinetics of listeria innocua atcc 33090 were studied. first, a multiplicative model was built assuming independent effects of all environmental factors. thus, the model was expanded by the inclusion of a novel term describing the effects of interactions on the growth/no growth limits. the proposed approach allows an accurate description of the boundary between growth and no growth of listeria.200211934031
modelling the competitive growth of listeria monocytogenes and listeria innocua in enrichment broths.the overgrowth of listeria innocua in enrichment broths designed for the isolation of listeria monocytogenes is believed to result from two factors: a selective growth advantage of l. innocua, and/or an inhibitory interspecies interaction. the generation times of 13 isolates of l. innocua and l. monocytogenes were determined in brain heart infusion (bhi) and a variety of enrichment media. no significant differences were found in growth characteristics between either species in the various media, ...200211934034
modeling the lag phase of listeria monocytogenes.an estimate of the lag phase duration is an important component for predicting the growth of a bacterium and for creating process models and risk assessments. most current research and data for predictive modeling programs initiated growth studies with cells grown to the stationary phase in a favorable ph, nutrient and temperature environment. in this work, listeria monocytogenes scott a cells were grown in brain heart infusion (bhi) broth at different temperatures from 4 to 37 degrees c to the ...200211934036
predictive modelling for packaging design: equilibrium modified atmosphere packages of fresh-cut vegetables subjected to a simulated distribution chain.the impact of temperature fluctuations in a simulated cold distribution chain, typical of commercial practice, was investigated on both the microbial and sensorial quality of equilibrium modified atmosphere (ema) packaged minimally processed vegetables. the internal o2 concentration of the designed packages could be predicted for the different steps of the simulated distribution chain by applying an integrated mathematical system. the internal atmosphere in the packages remained in its aerobic r ...200211934040
pediocin pa-1, a wide-spectrum bacteriocin from lactic acid bacteria.pediocin pa-1 is a broad-spectrum lactic acid bacteria bacteriocin that shows a particularly strong activity against listeria monocytogenes, a foodborne pathogen of special concern among the food industries. this antimicrobial peptide is the most extensively studied class ila (or pediocin family) bacteriocin, and it has been sufficiently well characterized to be used as a food biopreservative. this review focuses on the progress that have been made in the elucidation of its structure, mode of ac ...200211934133
foodborne infectious risks: do we need a wide system of data collection and survey? the lessons learned from the study of infectious intestinal disease in england.in 2000, the united kingdom government's food standards agency published "a report of the study of infectious intestinal disease in england". this report was the result of over a decade's endeavour and cost well in excess of 2 million pound sterling (approximately 3.3 million euros). the study originated in 1989. in response to national epidemics of foodborne infection with salmonella enteritidis phage type 4 and listeria monocytogenes, the government set up the committee on the microbiological ...200211938120
cerebellar abscess due to listeria monocytogenes.brain abscess due to listeria monocytogenes mainly involves the cerebral hemispheres. cerebellar abscess is an infrequent event, which could lead to rapid neurological deterioration if unrecognized. we present a case of multiple brain stem and cerebellar abscesses in a previously healthy individual exposed to unpasteurized milk. this is the 2nd case of cerebellar abscess due to listeria monocytogenes reported in the english literature. the diagnosis of listeria monocytogenes was made in the surg ...200211938402
tissue-level regulation of th1 and th2 primary and memory cd4 t cells in response to listeria infection.ag-specific th1 and th2 cytokine-producing cd4 t cells were quantitated in secondary lymphoid and tertiary tissues following oral listeria monocytogenes infection. although the response to listeria was previously believed to be predominantly th1 like, cd4 t cells producing il-4 or il-5 comprised a substantial proportion of the overall primary and memory response. the frequency of ifn-gamma-, il-4-, or il-5-producing primary effector or memory cd4 t cells was significantly higher in lung, liver, ...200211970995
mitogen-activated protein kinase-activated protein kinase 2-deficient mice show increased susceptibility to listeria monocytogenes infection.mitogen-activated protein kinase-activated protein kinase 2 (mk2) is one of several kinases activated through direct phosphorylation by p38 mitogen-activated protein kinase. mk2 regulates lps-induced tnf mrna translation, and targeted mutation of the mk2 gene renders mice more resistant to d-galactosamine plus lps-induced liver damage. in the present study, we investigated the role of mk2 in immune defense against listeria monocytogenes infection. mk2-deficient mice displayed diminished resistan ...200211971016
mip-1alpha, mip-1beta, rantes, and atac/lymphotactin function together with ifn-gamma as type 1 cytokines.we analyzed for the first time the expression of chemokines in subpopulations of the murine immune system at the single-cell level. we demonstrate in vitro and in a model of murine listeriosis that macrophage inflammatory protein (mip)-1alpha, mip-1beta, regulated on activation normal t cell expressed and secreted (rantes), and activation-induced, t cell-derived, and chemokine-related cytokine (atac)/lymphotactin are cosecreted to a high degree with ifn-gamma by activated individual natural kill ...200211972057
t-cell activation, proliferation and apoptosis in primary listeria monocytogenes infection.listeria monocytogenes infection of mice leads to a rapid expansion of activated t cells, followed by a decline in specific cells once the bacteria are eliminated. in order to define the relationship between t-cell proliferation and activation, and to investigate the role of apoptosis in limiting the expansion, the expression of activation markers, uptake of 5-bromo-2'-deoxyuridine (brdu) in vivo and the incidence of apoptosis was investigated. increased numbers of t cells expressing the activat ...200211972636
autolytic phenotype of lactococcus lactis strains isolated from traditional tunisian dairy products.to evaluate the autolytic properties of lactococcus lactis strains isolated from artisan tunisian dairy products, their peptidoglycan hydrolase content and their activity spectrum.200211972683
c-terminal domains of listeria monocytogenes bacteriophage murein hydrolases determine specific recognition and high-affinity binding to bacterial cell wall carbohydrates.listeria monocytogenes phage endolysins ply118 and ply500 share a unique enzymatic activity and specifically hydrolyse listeria cells at the completion of virus multiplication in order to release progeny phage. with the aim of determining the molecular basis for the lytic specificity of these enzymes, we have elucidated their domain structure and examined the function of their unrelated and unique c-terminal cell wall binding domains (cbds). analysis of deletion mutants showed that both domains ...200211972774
surface proteins and the pathogenic potential of listeria monocytogenes.on the basis of the recently determined genome sequence of listeria monocytogenes, we performed a global analysis of the surface-protein-encoding genes. only proteins displaying a signal peptide were taken into account. forty-one genes encoding lpxtg proteins, including the previously known internalin gene family, were detected. several genes encoding proteins that, like inlb and ami, possess gw modules that attach them to lipoteichoic acids were also identified. additionally, the completed geno ...200211973158
identification of a salt-induced primary transporter for glycine betaine in the methanogen methanosarcina mazei gö1.the salt adaptation of the methanogenic archaeon methanosarcina mazei gö1 was studied at the physiological and molecular levels. the freshwater organism m. mazei gö1 was able to adapt to salt concentrations up to 1 m, and the addition of the compatible solute glycine betaine to the growth medium facilitated adaptation to higher salt concentrations. transport studies with cell suspensions revealed a salt-induced glycine betaine uptake activity in m. mazei gö1, and inhibitor studies argue for a pr ...200211976081
role of acetate in production of an autoinducible class iia bacteriocin in carnobacterium piscicola a9b.carnobacterium piscicola strain a9b isolated from cold smoked salmon inhibits growth of the food-borne pathogen listeria monocytogenes partly due to the production of a proteinaceous compound (l. nilsson, l. gram, and h. h. huss. j. food prot. 62:336-342, 1999). the purpose of the present study was to purify the compound and describe factors affecting its production, with particular emphasis on food-relevant factors. amino acid sequencing showed that the compound is a class iia bacteriocin with ...200211976095
bets is a major glycine betaine/proline betaine transporter required for early osmotic adjustment in sinorhizobium meliloti.hybridization to a pcr product derived from conserved betaine choline carnitine transporter (bcct) sequences led to the identification of a 3.4-kb sinorhizobium meliloti dna segment encoding a protein (bets) that displays significant sequence identities to the choline transporter bett of escherichia coli (34%) and to the glycine betaine transporter opud of bacillus subtilis (30%). although the bets protein shows a common structure with bcct systems, it possesses an unusually long hydrophilic c-t ...200211976294
engineered listeria monocytogenes as an aids vaccine.listeria monocytogenes (lm) is an attractive vector to elicit t cell immunity because it infects antigen-presenting cells and because infection originates at the mucosa. lm expressing hiv gag elicits sustained high levels of gag-specific ctl in mice. since lm causes disease in immunocompromised hosts, a highly attenuated strain of lm that requires d-ala for viability was produced. attenuated bacteria expressing hiv-1 gag (lmdd-gag) are as efficient as wild-type recombinants at stimulating gag-sp ...200211983264
monoassociation of scid mice with helicobacter muridarum, but not four other enterics, provokes ibd upon receipt of t cells.recently, a number of animal models for different aspects of inflammatory bowel disease (ibd) have been developed. the aim of this study was to use one of these to determine whether particular, ostensibly innocuous, intestinal bacteria could provoke or exacerbate ibd.200211984521
lung dendritic cells are primed by inhaled particulate antigens, and retain mhc class ii/antigenic peptide complexes in hilar lymph nodes for a prolonged period of time.intratracheal (it) administration of heat-killed listeria monocytogenes (hkl) results in an influx of macrophage and dendritic cell (dc) precursors into the lung interstitium. low-density, fcr+, interstitial lung cells isolated from rats instilled 24 hr before with hkl or vehicle alone, were > 90% mar1+. after culturing with granulocyte-macrophage colony-stimulating factor (gm-csf) for 3 days, up to 24% of the loosely adherent cells were dc that stimulated allogeneic t-cell proliferation in an m ...200211985669
targeted gene transfer to liver using protein-dna complexes. 200211987775
evaluation of two commercial methods for the detection of listeria sp. and listeria monocytogenes in a chicken nugget processing plant.this study measures the detection performances of two rapid test systems (listeria rapid test clearview and bax system) for the screening of listeria sp. and listeria monocytogenes, respectively. a total of 413 samples from different sources (product from (i) different stages of processing, (ii) different environments, and (iii) different food handlers), collected from a chicken nugget processing plant, were analysed by both rapid methods and a cultural method consisting of pre-enrichment, enric ...200211989773
method extension study to validate applicability of aoac official method 996.14 assurance polyclonal enzyme immunoassay for detection of listeria monocytogenes and related listeria spp. from environmental surfaces: collaborative study.test portions from 3 environmental surface types, representative of typical surfaces found in a food production facility, were analyzed by the assurance listeria polyclonal enzyme immunoassay (eia) and the u.s. department of agriculture/food safety and inspection service (usda/fsis) culture method for listeria monocytogenes and related listeria species. in all cases, naturally contaminated environmental test samples were collected from an actual food production facility by sponge or swab. test s ...200211990033
method extension study to validate applicability of aoac official method 997.03 visual immunoprecipitate assay (vip) for listeria monocytogenes and related listeria spp. from environmental surfaces: collaborative study.test portions from 3 environmental surface types, representative of typical surfaces found in a food production facility, were analyzed by the visual immunoprecipitate assay (vip) and the u.s. department of agriculture/food safety and inspection service (usda/fsis) culture method for listeria monocytogenes and related listeria species. in all cases, naturally contaminated environmental test samples were collected from an actual food production facility by sponge or swab. test samples from concre ...200211990034
detection and isolation of listeria monocytogenes from food samples: implications of sublethal injury.detection of l. monocytogenes is often limited by the performance of the enrichment media used to support bacterial growth to detectable levels. because listeria may exist at extremely low levels in foods, sample enrichment protocols must amplify these low initial populations to detectable limits. listeria may also exist in an injured state in food products as a result of processing treatments such as heating, freezing, exposure to acids, or exposure to sanitizing compounds. selective agents in ...200211990037
optimized, one-step, recovery-enrichment broth for enhanced detection of listeria monocytogenes in pasteurized milk and hot dogs.a one-step, recovery-enrichment broth, optimized penn state university (opsu) broth, was developed to consistently detect low levels of injured and uninjured listeria monocytogenes cells in ready-to-eat foods. the opsu broth contains special selective agents that inhibit growth of background flora without inhibiting recovery of injured listeria cells. after recovery in the anaerobic section of opsu broth, listeria cells migrated to the surface, forming a black zone. this migration separated viab ...200211990038
polymerase chain reaction-based methods for detection of listeria monocytogenes: toward real-time screening for food and environmental samples.a review is presented of nucleic acid amplification-based methodology, specifically polymerase chain reaction (pcr)-based assays, for the detection of listeria monocytogenes in food and environmental samples. until recently, developmental challenges including poor sensitivity, due in part to reaction inhibition by components of the sample matrix, and the potential for false-positive reactions have limited routine application of pcr-based screening assays. commercial assays address these challeng ...200211990039
virulence testing of listeria monocytogenes.a major problem in understanding foodborne listeriosis from both the basic science and regulatory perspectives revolves around the role played by virulence factors of listeria monocytogenes and how these interact with host susceptibility to result in the observed incidence of disease. from a mechanistic perspective, this problem has been well investigated, and many virulence components of l. monocytogenes have been discovered. deletion of these genes results in large reductions in virulence func ...200211990040
molecular subtyping methods for listeria monocytogenes.conventional, phenotypic, and dna-based subtyping methods allow differentiation of listeria monocytogenes beyond the species and subspecies level. bacterial subtyping methods not only improve our ability to detect and track human listeriosis outbreaks, but also provide tools to track sources of l. monocytogenes contamination throughout the food system. the use of subtyping methods also provides an opportunity to better understand the population genetics, epidemiology, and ecology of l. monocytog ...200211990041
identification and characterization of genes encoding sex pheromone cam373 activity in enterococcus faecalis and staphylococcus aureus.the sex pheromone cam373 of enterococcus faecalis and the related staph-cam373 of staphylococcus aureus were found to correspond to heptapeptides located within the c-termini of the signal sequences of putative prelipoproteins. the deduced mature forms of the lipoproteins share no detectable homology and presumably serve unrelated functions in the cells. the chromosomally encoded genetic determinants for production of the pheromones have been identified and designated came (encoding cam373) and ...200211994160
a hypermutator phenotype attenuates the virulence of listeria monocytogenes in a mouse model.the integrity of the genetic material of bacteria is guaranteed by a set of distinct repair mechanisms. the participation of these repair systems in bacterial pathogenicity has been addressed only recently. here, we study for the first time the participation in virulence of the mutsl mismatch repair system of listeria monocytogenes. the muts and mutl genes, which are contiguous in the l. monocytogenes chromosome, were identified after in silico analysis. the deduced muts shares 62% identity with ...200211994166
[listeria monocytogenes and ulcerative colitis]. 200211996775
elevated carnitine accumulation by listeria monocytogenes impaired in glycine betaine transport is insufficient to restore wild-type cryotolerance in milk whey.listeria monocytogenes accumulates low molecular weight compounds (osmolytes, or compatible solutes) in response to chill stress. this response has been shown to be responsible, in part, for the chill tolerance of the species. among the osmolytes tested to date, glycine betaine, gamma-butyrobetaine and carnitine display the strongest cryoprotective effect. these osmolytes are not synthesized in the cell and must be transported from the medium. in this study, the compatible solute accumulation pr ...200211999105
microbiological analysis of seed sprouts in norway.as part of larger survey of microbial contamination of fruits and vegetables in norway, four different sprouted seed products were analysed for bacterial and parasitic contaminants (n = 300 for bacterial analyses and n = from 17 to 171 for parasite analyses, depending on parasite). escherichia coli o157, salmonella, listeria monocytogenes, cyclospora oocysts, ascaris eggs and other helminth parasites were not detected in any of the sprout samples. thermotolerant coliform bacteria (tcb) were isol ...200211999108
responses of listeria monocytogenes to acid stress and glucose availability monitored by measurements of intracellular ph and viable counts.physiological aspects of the response of listeria monocytogenes to acidic conditions and effect of glucose availability were studied by fluorescence ratio-imaging microscopy (frim) as compared with traditional viable counts. three types of experiments were conducted: (i) static with measurements of intracellular ph (phi) at extracellular ph (pho) values ranging from ph 3.0 to 6.0 at 0.5 ph unit intervals; (ii) kinetic with monitoring of bacterial responses to changes in the pho from the value of ...200211999120
biocide use in the food industry and the disinfectant resistance of persistent strains of listeria monocytogenes and escherichia coli.the aims of the project were threefold: to survey the use of disinfectants in the uk food industry; to assess the product and environmental microflora of selected food factories for the persistence of listeria monocytogenes and escherichia coli; and to determine the disinfectant resistance of any persistent strains.200212000620
factors affecting the adsorption of buchnericin lb, a bacteriocin produced by lactobacillus [correction of lactocobacillus] buchneri.buchnericin-lb adsorbs to gram-positive but not to gram-negative bacteria. the tested gram-positive bacteria were species of lactobacillus, pediococcus, leuconostoc, enterococcus, lactococcus, listeria, bacillus, staphylococcus; gram-negative bacteria belonged to the genera salmonella, escherichia, yersinia and pseudomonas. buchnericin-lb adsorption depended on ph but not on time and temperature. also some anions of salts and lipoteichoic acid reduced or inhibited its adsorption. treatment of ce ...200212002398
experimental mixed infection of rabbits with yersinia enterocolitica and listeria monocytogenes.experimental mixed infection was reproduced in rabbits after per os infection with yersinia enterocolitica serotype 0:3 cells. four days later some of animals were re-infected orally with listeria monocytogenes serotype 4b cells. a third group of healthy rabbits was also infected per os with listeria monocytogenes. the infectious process was followed dynamically from days 1-28. the experimental animals were examined for clinical, paraclinical and morphological findings. augmentation of body temp ...200212002426
listeriolysin o-liposome-mediated cytosolic delivery of macromolecule antigen in vivo: enhancement of antigen-specific cytotoxic t lymphocyte frequency, activity, and tumor protection.cytotoxic t lymphocytes (ctls) are primed by peptide antigens that are endogenously processed in the cytosol and presented in the context of major histocompatibility complex i (mhc i) molecules of antigen-presenting cells (apcs). exogenous soluble protein antigens do not gain efficient entry into the cytosol of apcs, and therefore requires a special cytosolic delivery method. we have developed such a delivery strategy adopting the well-elucidated cytosol-invading listerial endosomal escape mecha ...200212007619
inducible nitric oxide synthase and nitrotyrosine in listeric encephalitis: a cross-species study in ruminants.listeria monocytogenes (lm) is a gram-positive facultative intracellular bacterium that causes fatal meningoencephalitis in humans and ruminants. a current paradigm predicts that intracellular bacteria are controlled by nitric oxide (no) whose synthesis is catalyzed by inducible nitric oxide synthase (inos). the ability of macrophages (mphi) to express inos shows extreme interspecies variability. here the expression of inos and synthesis of no was studied in listeric encephalitis of cattle, shee ...200212009057
listeria monocytogenes: a model system to study invasion and spread of bacteria in the central nervous system. 200212014191
the dynamics of actin-based motility depend on surface parameters.in cells, actin polymerization at the plasma membrane is induced by the recruitment of proteins such as the arp2/3 complex, and the zyxin/vasp complex. the physical mechanism of force generation by actin polymerization has been described theoretically using various approaches, but lacks support from experimental data. by the use of reconstituted motility medium, we find that the wiskott aldrich syndrome protein (wasp) subdomain, known as vca, is sufficient to induce actin polymerization and move ...200212015607
[dealing with microbes]. 200212018150
swift and definite serotyping for isolated listeria monocytogenes strains.the serotype is most important for molecular epidemiological analysis of listeria monocytogenes (l.m.) contaminating marketed meats. an improvement on the traditional method was thus attempted in the present study because of the requirement of swift and definite serotyping. in the determination of o-antigen, definite judgement was allowed by an immediate cooling at 80 degrees c after autoclaving the bacteria. in the determination of h-antigen, use of a culture plate without craigie's tube yielde ...200212019722
effect of tumor necrosis factor alpha, interferon gamma, and interleukin-4 on bacteria-enterocyte interactions.little is known about the mechanisms involved in bacterial translocation from the intestinal lumen to extraintestinal sites. because the cytokine cascade associated with sepsis, inflammation, and trauma has been shown to affect intestinal epithelial permeability, experiments were designed to clarify the effects of selected cytokines on bacterial adherence to and internalization by cultured ht-29 and caco-2 enterocytes.200212020125
comparison of protein patterns of listeria monocytogenes grown in biofilm or in planktonic mode by proteomic analysis.the proteome of a listeria monocytogenes strain isolated from a food plant was investigated to study the differential protein pattern expressed by biofilms and planktonic bacteria. the approach used in this study was a combination of two-dimensional electrophoresis, matrix-assisted laser desorption ionization-time of flight and database searches for the protein identification. thirty-one proteins varied significantly between the two growth conditions. twenty-two and nine proteins were up- and do ...200212023073
multiple mechanisms compensate to enhance tumor-protective cd8(+) t cell response in the long-term despite poor cd8(+) t cell priming initially: comparison between an acute versus a chronic intracellular bacterium expressing a model antigen.we evaluated cd8(+) t cell responses against the dominant ctl epitope, ova(257-264), expressed by an acute (listeria monocytogenes (lm) ova) vs a chronic pathogen (mycobacterium bovis bacillus calmette-guérin (bcg) ova) to reveal the influence on cd8(+) t cell memory and consequent protection against a challenge with ova-expressing tumor cells. infection with lower doses of both pathogens resulted in stronger bacterial growth but weaker t cell memory indicating that memory correlates with pathog ...200212023374
listeriolysin o secreted by listeria monocytogenes induces nf-kappab signalling by activating the ikappab kinase complex.listeriolysin o (llo) is a pore-forming cytolysin secreted by the pathogen listeria monocytogenes and is required for its intracellular survival. we recently demonstrated that in endothelial cells, llo activates the nf-kappab signalling pathway. in this work, we studied the llo-induced molecular cascade of nf-kappab activation with a cellular model extensively used to analyse the signalling pathway of nf-kappab activation, i.e. the human embryonic kidney hek-293 cell line and its derivatives (tr ...200212028384
application of a multiplex polymerase chain reaction assay for the simultaneous confirmation of listeria monocytogenes and other listeria species in turkey sample surveillance.a multiplex polymerase chain reaction was developed to simultaneously identify listeria monocytogenes and species of the genus listeria. two sets of primers were used, with the first amplifying a 938-bp region of the 16s rrna gene that is highly conserved in all listeria species and the second amplifying a 174-bp region of the listeriolysin (hlya) gene of l. monocytogenes. thus, isolates of listeria spp. yield a single 938-bp product, whereas l. monocytogenes isolates yield both the 938-bp produ ...200212030288
comparison of the cell surface properties and growth characteristics of listeria monocytogenes and listeria innocua.growth kinetics and physicochemical surface properties were compared for three listeria strains with differing degrees of virulence: l. monocytogenes lo28; its isogenic, nonhemolytic mutant l. monocytogenes bof415; and a nonvirulent species, l. innocua (strain lin9). the influences of growth stage (mid-exponential phase, early stationary phase, and mid-stationary phase) and culture temperature (20 and 37 degrees c) were assessed by determining the electrical properties and the hydrophobic-hydrop ...200212030289
effect of selected generally recognized as safe preservative sprays on growth of listeria monocytogenes on chicken luncheon meat.the ability of selected generally recognized as safe (gras) chemical preservatives to reduce populations or inhibit growth of listeria monocytogenes on chicken luncheon meat was evaluated. slices of luncheon meat were treated by evenly spraying onto their surfaces 0.2 ml of a solution of one of four preservatives (sodium benzoate, sodium propionate, potassium sorbate, and sodium diacetate) at one of three different concentrations (15, 20, or 25% [wt/vol]). each slice was then surface inoculated ...200212030290
behavior of listeria monocytogenes and staphylococcus aureus in yogurt fermented with a bacteriocin-producing thermophilic starter.streptococcus salivarius subsp. thermophilus b producing a bacteriocin active against listeria monocytogenes atcc 7644 and staphylococcus aureus sad 30 was isolated from bakery yeast. the bacteriocin was partially purified by an adsorption/desorption technique, and its spectrum of action was compared to that of a neutralized cell-free supernatant (cfs). although the cfs inhibited a number of gram-positive and -negative bacteria of health and spoilage significance, the spectrum of action of the p ...200212030291
influence of poultry carcass skin sample site on the effectiveness of trisodium phosphate against listeria monocytogenes.the aim of this study was to determine the influence of skin sample site on the efficacy of trisodium phosphate (tsp) solutions in reducing listeria monocytogenes populations on chicken carcasses during refrigerated storage. chicken skin samples from the legs, the breasts, and the dorsal area inoculated with l. monocytogenes (10(8) cfu/ml) were dipped for 15 min in sterile tap water (control) or in 8, 10, or 12% tsp. l. monocytogenes counts and surface ph values were determined after 0, 1, 3, an ...200212030300
effect of lauric acid and nisin-impregnated soy-based films on the growth of listeria monocytogenes on turkey bologna.research in development of antimicrobial packaging applications for further processed meats has become more common with recent outbreaks of contamination of these products. in this present study, lauric acid (8%, wt/wt) and 2.5% pure nisin (4%, wt/wt) were incorporated singly and together into thermally compacted soy films. biocide-impregnated films were compared to control films containing no biocide for inhibition of listeria monocytogenes in liquid medium and on turkey bologna surface. l. mon ...200212033424
effect of intragastric and intraperitoneal immunisation with attenuated and wild-type lack-expressing listeria monocytogenes on control of murine leishmania major infection.stable chromosomal constructs of attenuated deltaacta and wild-type listeria monocytogenes expressing the leishmania major protein lack were tested as live vaccine vectors in the th2-orientated chronic l. major murine infection model. these vectors, either by intraperitoneal (i.p.) or intragastric (i.g.) route, were able to induce a strong cd4 th1 immune response that was correlated with slower parasite growth in the infected footpad. significant protection against l. major infection was observe ...200212034096
genetic homogeneity among listeria monocytogenes strains from infected patients and meat products from two geographic locations determined by phenotyping, ribotyping and pcr analysis of virulence genes.thirty listeria monocytogenes isolates from human patients and foods originated from two different geographic locations without any epidemiological relations were analyzed for their genotypic and phenotypic virulence gene expressions and genetic relatedness. all strains contained virulence genes, inla, inlb, acta, hlya, plca and plcb, with expected product size in pcr assay except for the acta gene. some strains produced acta gene product of 268 and others 385 bp. phenotypically, all were hemoly ...200212038565
application of nontraditional meat starter cultures in production of hungarian salami.listeria monocytogenes and escherichia coli o111 have been implicated in several outbreaks of food-borne disease linked to smallgoods products. traditional meat starter cultures, containing a mixture of lactic acid bacteria (lab) and staphylococci, are used to maintain safety and sensory properties of hungarian salami. the present study investigated if nontraditional meat starter (ntms) cultures can be used for improving the safety of hungarian salami. salami batter was inoculated with list. mon ...200212038580
identification of opuc as a chill-activated and osmotically activated carnitine transporter in listeria monocytogenes.the food-borne pathogen listeria monocytogenes is notable for its ability to grow under osmotic stress and at low temperatures. it is known to accumulate the compatible solutes glycine betaine and carnitine from the medium in response to osmotic or chill stress, and this accumulation confers tolerance to these stresses. two permeases that transport glycine betaine have been identified, both of which are activated by hyperosmotic stress and one of which is activated by low temperature. an osmotic ...200212039715
variation of branched-chain fatty acids marks the normal physiological range for growth in listeria monocytogenes.the fatty acid composition of listeria monocytogenes scott a was determined by close-interval sampling over the entire biokinetic temperature range. there was a high degree of variation in the percentage of branched-chain fatty acids at any given temperature. the percentage of branched c17 components increased with growth temperature in a linear manner. however, the percentages of iso-c15:0 (i15:0) and anteiso-c15:0 (a15:0) were well described by third-order and second-order polynomial curves, r ...200212039736
combined ribotyping and random multiprimer dna analysis to probe the population structure of listeria monocytogenes.to improve our understanding of the genetic links between strains originating from food and strains responsible for human diseases, we studied the genetic diversity and population structure of 130 epidemiologically unrelated listeria monocytogenes strains. strains were isolated from different sources and ecosystems in which the bacterium is commonly found. we used rrna gene restriction fragment length polymorphism analysis with two endonucleases and random multiprimer dna analysis with seven oli ...200212039742
ability of the listeria monocytogenes strain scott a to cause systemic infection in mice infected by the intragastric route.listeriosis is an important food-borne disease that causes high rates of morbidity and mortality. for reasons that are not clear, most large outbreaks of human listeriosis involve listeria monocytogenes serotype 4b. relatively little is known about the pathogenesis of listeriosis following gastrointestinal exposure to food-borne disease isolates of l. monocytogenes. in the present study, we investigated the pathogenesis of systemic infection by the food-borne isolate scott a in an intragastric ( ...200212039747
microtiter plate assay for assessment of listeria monocytogenes biofilm formation.listeria monocytogenes has the ability to form biofilms on food-processing surfaces, potentially leading to food product contamination. the objective of this research was to standardize a polyvinyl chloride (pvc) microtiter plate assay to compare the ability of l. monocytogenes strains to form biofilms. a total of 31 coded l. monocytogenes strains were grown in defined medium (modified welshimer's broth) at 32 degrees c for 20 and 40 h in pvc microtiter plate wells. biofilm formation was indirec ...200212039754
molecular characterization of the genes encoding dna gyrase and topoisomerase iv of listeria monocytogenes.the genes encoding subunits a and b of dna gyrase and subunits c and e of topoisomerase iv of listeria monocytogenes, gyra, gyrb, parc and pare, respectively, were cloned and sequenced. compared with the sequences of quinolone-susceptible bacteria, such as escherichia coli and bacillus subtilis, the quinolone resistance-determining region (qrdr) of dna gyrase subunit a was altered; the deduced amino acid sequences revealed the substitutions ser-84-->thr and asp/glu-88-->phe, two amino acid varia ...200212039883
dietary calcium phosphate promotes listeria monocytogenes colonization and translocation in rats fed diets containing corn oil but not milk fat.most gram-positive bacteria are susceptible to the bactericidal action of fatty acids and bile acids. because dietary calcium phosphate (cap(i)) lowers the intestinal concentration of these antimicrobial agents, high cap(i) intake may enhance intestinal colonization of gram-positive pathogens and the subsequent pathogenesis. in this study, we tested this hypothesis in a rat model using listeria monocytogenes. rats were fed diets containing low (20 micromol/g diet) or high (160 micromol/g diet) a ...200212042445
[opportunistic bacteria detected in cultivated mussels].as many as 8 listeria monocytogenes strains, 12 pseudomonas aeruginosa strains and 5 staphylococcus aureus strains were isolated from mussels mytilus edulis, grown on special installations in the trinity bay of the gulf of peter the great, the sea of japan. the isolated cultures proved to be highly resistant to a number of antibiotics. many strains displayed dnaase and haemolytic activity. the cultures of l. monocytogenes, s. aureus and p. aeruginosa also had high lipase, protease and lecithinas ...200212043163
ecology of listeria monocytogenes in the environment of raw poultry meat and raw pork meat processing plants.the zoonotic listeria monocytogenes is mainly transmitted to humans by the food-borne route. this bacterium was often found in the environment of food processing plants. therefore the aims of this study were (i) the identification of environmental factors associated with l. monocytogenes contamination on working and non-working surfaces in poultry or pork processing plants and (ii) the understanding of its survival in such environments. the physicochemical risk profiles showed that a surface in ...200212044686
[cervicovaginal infection as a risk factor for premature labor].to identify the possible association between cervicovaginal infections (cvi) and preterm delivery.200212050955
[prosthetic hip joint infection caused by listeria monocytogenes].the authors report an unusual case of prosthetic hip joint infection caused by listeria monocytogenes. the patient, an 87-year-old lady who had undergone a right total hip replacement 10 years previously, presented with pain and restriction of hip motion three weeks after an episode of abdominal pain. aspiration of the joint yielded a dark fluid, from which listeria monocytogenes type 4-b was isolated. blood cultures remained negative. after prolonged antibiotic therapy, symptoms gradually resol ...200212051008
enhanced antimicrobial effects of combination of lactate and diacetate on listeria monocytogenes and salmonella spp. in beef bologna.the antimicrobial activities of salts of organic acids such as lactate and acetate are well documented, but there is limited information on their effect when used in combination. we previously reported enhanced inhibition of listeria monocvtogenes and salmonella enterica serovar enteritidis in sterile comminuted beef at 5 and 10 degrees c by combinations of sodium lactate (sl) (2.5%) and sodium diacetate (sda) (0.2%). the present study was undertaken to evaluate the inhibitory effect of these sa ...200212051475
isolation and characterisation of a 13.8-kda bacteriolytic enzyme from house dust mite extracts: homology with prokaryotic proteins suggests that the enzyme could be bacterially derived.bacteriolytic activity was detected in extracts of whole mite and spent growth medium (sgm) from the clinically important dermatophagoides pteronyssinus and dermatophagoides farinae mites and was most abundant in whole mite extract. gram-positive organisms micrococcus lysodeikticus, bacillus megaterium and listeria monocytogenes were preferentially lysed and the lytic activity was enhanced by thiols, destroyed by mite proteases, inhibited by hgcl2 and high concentrations of nacl but was resistan ...200212052562
reduction of iron by extracellular iron reductases: implications for microbial iron acquisition.the extracellular enzymatic reduction of iron by microorganisms has not been appropriately considered. in this study the reduction and release of iron from ferrioxamine were examined using extracellular microbial iron reductases and compared to iron mobilization by chemical reductants, and to chelation by edta and desferrioxamine. a flavin semiquinone was formed during the enzymatic reduction of ferrioxamine, which was consistent with the 1 e(-) reduction of iron by an enzyme. the rates for the ...200212054438
biochemical characterisation and genetic analysis of aureocin a53, a new, atypical bacteriocin from staphylococcus aureus.aureocin a53 is produced by staphylococcus aureus a53. it is encoded on a 10.4 kb plasmid, prj9, and is active against listeria monocytogenes. aureocin a53 is a highly cationic 51-residue peptide containing ten lysine and five tryptophan residues. aureocin a53 was purified to homogeneity by hydrophobic-interaction, cation-exchange, and reverse-phase chromatography. maldi-tof mass spectrometry yielded a molecular mass of 6012.5 da, which was 28 da higher than predicted from the structural gene se ...200212054867
organ-specific cd4+ t cell response during listeria monocytogenes infection.the immune response against the intracellular bacterium listeria monocytogenes involves both cd4(+) and cd8(+) t cells. we used the mhc class ii-presented peptide listeriolysin(189-201) to characterize the organ-specific cd4(+) t cell response during infection. systemic listeriosis resulted in a strong peptide-specific cd4(+) t cell response with frequencies of 1/100 and 1/30 cd4(+) splenocytes at the peak of primary and secondary response, respectively. this response was not restricted to lymph ...200212055256
assessment of the pathogenic potential of two listeria monocytogenes human faecal carriage isolates.two human faeces carriage isolates of listeria monocytogenes (h1 and h2) were compared to reference strains (scotta and lo28) with regard to their lethality in 14-day-old chick embryos, their haemolytic and phospholipase (phosphatidylcholine-phospholipase c and phosphatidylinositol-phospholipase c) activities and their invasiveness towards caco-2 cells. experimental infection of chick embryos allowed discrimination of the strains into those exhibiting high virulence (scotta and h2), those exhibi ...200212055305
programmed contraction of cd8(+) t cells after infection.the extent of infection and rate of pathogen clearance are thought to determine both the magnitude of antigen-specific cd8(+) t cell expansion and the ensuing contraction to a stable number of memory cells. we show that cd8(+) t cell expansion after listeria monocytogenes infection was primarily dependent on the initial infection dose or amount of antigen displayed, and was also influenced by the rate of pathogen clearance. however, the onset and kinetics of cd8(+) t cell contraction after l. mo ...200212055624
prevalence and risk factors for contamination with listeria monocytogenes of imported and exported meat and fish products in switzerland, 1992-2000.a total of 2053 import and 164 export samples from 425 production plants were examined over a 9-year period (1992-2000) for the presence of listeria monocytogenes (l. monocytogenes) in switzerland. overall, 282 samples (12.2%) and 85 plants (20.5%) harbored the pathogen. the highest isolation risk was for marinated fish (38%); the lowest was in cured- and dried-meat products. unconditional fixed-effect logistic regression was used to identify the main hazards associated with the presence of l. m ...200212062517
the changing epidemiology of bacterial meningitis and invasive non-meningitic bacterial disease in scotland during the period 1983-99.we reviewed population-based laboratory reports of invasive meningococcal, pneumococcal, haemophilus influenzae, group b streptococcus (gbs) and listeria monocytogenes isolates in order to examine the changing epidemiology of meningitis and invasive non-meningitic disease (inmd) caused by these 5 pathogens in the 2 periods before (1983-91) and after (1992-99) routine use of h. influenzae type b conjugate vaccine (hib) in scotland. neissieria meningitidis was the most common cause of meningitis, ...200212064693
safety and shedding of an attenuated strain of listeria monocytogenes with a deletion of acta/plcb in adult volunteers: a dose escalation study of oral inoculation.listeria monocytogenes is an intracellular bacterial pathogen which causes bacteremia and has a tropism for the central nervous system and a propensity to cause maternofetal infection. l. monocytogenes has been shown to be an effective prophylactic and a therapeutic vaccine vector for viral and tumor antigens in animal models. l. monocytogenes mutants lacking the acta protein, which is essential for intracellular movement, are attenuated but retain immunogenicity in mice. given the pathogenic po ...200212065500
sigma b contributes to prfa-mediated virulence in listeria monocytogenes.transcription of the listeria monocytogenes positive regulatory factor a protein (prfa) is initiated from either of two promoters immediately upstream of prfa (prfap(1) and prfap(2)) or from the upstream plca promoter. we demonstrate that prfap(2) is a functional sigma(b)-dependent promoter and that a sigb deletion mutation affects the virulence phenotype of l. monocytogenes. thus, the alternative sigma factor sigma(b) contributes to virulence in l. monocytogenes.200212065541
ifngamma and tnfalpha account for a pro-clonogenic activity secreted by activated murine peritoneal macrophages.in the present study, we found that murine peritoneal macrophages elicited by bcg or listeria monocytogenes release into the media an activity capable of stimulating the lung colonization as well as the expression of mhc class i antigens in b16 melanoma cells. a similar activity has previously been found in media conditioned by corynebacterium parvum-elicited macrophages. analysis by gel filtration chromatography of media conditioned by corynebacterium parvum-, bcg- or listeria monocytogenes-eli ...200212067206
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