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[microbiological portrait: listeria monocytogenes]. 200818949145
[historical note: in homage to lister].joseph lister, who disputes with klebs the third place as the father of microbiology, was just about to remain without a bacteria immortalizing his ñame. thanks to seeliger, now listeria is used for identifying the genus that pirie had already named listerella in 1927. through a quick review of the history of listeria monocytogenes, we get to know the principal facts in the lives of pirie and seeliger, investigators with absolutely different characters. we also review a brief history of the life ...200818949146
relationship between sublethal injury and microbial inactivation by the combination of high hydrostatic pressure and citral or tert-butyl hydroquinone.the aim was to investigate (i) the occurrence of sublethal injury in listeria monocytogenes, escherichia coli, and saccharomyces cerevisiae after high hydrostatic pressure (hhp) treatment as a function of the treatment medium ph and composition and (ii) the relationship between the occurrence of sublethal injury and the inactivating effect of a combination of hhp and two antimicrobial compounds, tert-butyl hydroquinone (tbhq) and citral. the three microorganisms showed a high proportion of suble ...200818952869
functional impact of mutational activation on the listeria monocytogenes central virulence regulator prfa.the transcriptional activator prfa is required for the expression of virulence factors necessary for listeria monocytogenes pathogenesis. prfa is believed to become activated following l. monocytogenes entry into the cytosol of infected host cells, resulting in the induction of target genes whose products are required for bacterial intracellular growth and cell-to-cell spread. several mutations have been identified that appear to lock prfa into its highly activated cytosolic form (known as prfa* ...200818957610
development of a quantitative polymerase chain reaction method using a live bacterium as internal control for the detection of listeria monocytogenes.a novel real-time quantitative polymerase chain reaction (q-pcr) assay was developed for rapid and accurate detection of listeria monocytogenes. in this q-pcr assay, a computational dna random shuffling method was used to design an internal amplification control (iac) sequence, which was the same in length and g + c content to the hly amplicon. this iac sequence was inserted into the genome of l. monocytogenes to create a mutant strain named l. monocytogenes-iac. the lm-iac was used as an intern ...200818930623
random mutagenesis identifies novel genes involved in the secretion of antimicrobial, cell wall-lytic enzymes by lactococcus lactis.lactococcus lactis is a gram-positive bacterium that is widely used in the food industry and is therefore desirable as a candidate for the production and secretion of recombinant proteins. previously, we generated a l. lactis strain that expressed and secreted the antimicrobial cell wall-lytic enzyme lysostaphin. to identify lactococcal gene products that affect the production of lysostaphin, we isolated and characterized mutants generated by random transposon mutagenesis that had altered lysost ...200818931288
multilocus genotyping assays for single nucleotide polymorphism-based subtyping of listeria monocytogenes isolates.listeria monocytogenes is responsible for serious invasive illness associated with consumption of contaminated food and places a significant burden on public health and the agricultural economy. we recently developed a multilocus genotyping (mlgt) assay for high-throughput subtype determination of l. monocytogenes lineage i isolates based on interrogation of single nucleotide polymorphisms (snps) via multiplexed primer extension reactions. here we report the development and validation of two add ...200818931295
pathogenicity of listeria monocytogenes scott a after oral and oculonasal challenges of day-old turkey poults.listeria monocytogenes is a ubiquitous, environmental pathogen that has contaminated poultry ready-to-eat products resulting in large-scale recalls. research is needed to determine the source of product and processing plant contamination with l. monocytogenes. the purpose of this study was to compare the oral and oculonasal routes of infection on the pathogenicity of l. monocytogenes in turkey poults under different housing conditions. one-day-old turkey poults were challenged by either route wi ...200818939633
prevalence of listeria monocytogenes in poultry production in france.this study aimed to update and create a data set from laying hens and broilers regarding contamination by listeria monocytogenes. two hundred laying-hen flocks were sampled, with 88 flocks reared in cages and 112 reared on the floor. one hundred forty-five broiler flocks were sampled, with 85 conventional and 60 free-range flocks. a total of 774 and 725 samples were analyzed from laying hens and broilers, respectively. l. monocytogenes was detected in 31 of 200 flocks, yielding an estimated prev ...200818939743
elimination of listeria monocytogenes from vacuum-packed dry-cured ham by e-beam radiation.the inactivation kinetics for listeria monocytogenes scott a (cip 103575, serotype 4b) and listeria innocua (ntc 11288) after e-beam radiation were studied in vacuum-packed ready-to-eat dry-cured ham to optimize the sanitation treatment of this product. a treatment of 1.12 kgy was calculated to reach the food safety objective according to the u.s. department of agriculture criterion. no irradiation treatment is necessary to meet the european union microbiological criterion for this bacterium. no ...200818939744
inactivation kinetics of three listeria monocytogenes strains under high hydrostatic pressure.high hydrostatic pressure (hhp) inactivation of three listeria monocytogenes strains (egde, lo28, and scott a) subjected to 350 mpa at 20 degrees c in aces buffer resulted in survival curves with significant tailing for all three strains. a biphasic linear model could be fitted to the inactivation data, indicating the presence of an hhp-sensitive and an hhp-resistant fraction, which both showed inactivation according to first-order kinetics. inactivation parameters of these subpopulations of the ...200818939745
survival of listeria monocytogenes in a simulated dynamic gastrointestinal model during storage of inoculated bologna and salami slices in vacuum packages.listeria monocytogenes counts were determined during storage (82 days, 4 degrees c) in vacuum packages of inoculated bologna and salami slices and after exposure to a simulated dynamic model of the stomach and small intestine. variables controlled in the model included gastric emptying and gastrointestinal fluid secretion rates, gradual gastric acidification, and intestinal ph maintenance. l. monocytogenes populations increased on bologna and decreased on salami, reaching 8.7 and 1.4 log cfu/g, ...200818939746
rechargeable antimicrobial surface modification of polyethylene.polyethylene films were surface modified, to incorporate amine and amide functionalities, and subsequently were evaluated for their ability to recharge the antimicrobial n-halamine structures after contact with sodium hypochlorite, a common food-approved sanitizer. surfaces were tested for chlorine retention and release, as well as antimicrobial activity against microorganisms relevant to food quality and food safety, including escherichia coli k-12, pseudomonas fluorescens, bacillus cereus, and ...200818939750
transmission electron microscopy study of listeria monocytogenes treated with nisin in combination with either grape seed or green tea extract.the objective of this study was to use transmission electron microscopy to investigate the morphological changes that occurred in listeria monocytogenes cells treated with grape seed extract (gse), green tea extract (gte), nisin, and combinations of nisin with either gse or gte. the test solutions were prepared with (i) 1% gse, 1% gte, 6,400 iu of nisin, and the combination of these dilutions with nisin or with (ii) the pure major phenolic constituents of gse (0.02% epicatechin plus 0.02% catech ...200818939761
comparison of four commercial dna extraction kits for pcr detection of listeria monocytogenes, salmonella, escherichia coli o157:h7, and staphylococcus aureus in fresh, minimally processed vegetables.four commercial dna extraction methods, prepman ultra (applied biosystems), instagene matrix (biorad), dneasy tissue kit (qiagen), and ultraclean (mobio), were tested for pcr detection of listeria monocytogenes, escherichia coli o157: h7, salmonella, and staphylococcus aureus in fresh, minimally processed vegetables. for comparative purposes, sensitivity assays with specific pcrs were carried out after dna extraction with the four methods in green pepper, broccoli, and onion artificially inocula ...200818939762
ox40 costimulatory signals potentiate the memory commitment of effector cd8+ t cells.a t cell costimulatory molecule, ox40, contributes to t cell expansion, survival, and cytokine production. although several roles for ox40 in cd8(+) t cell responses to tumors and viral infection have been shown, the precise function of these signals in the generation of memory cd8(+) t cells remains to be elucidated. to address this, we examined the generation and maintenance of memory cd8(+) t cells during infection with listeria monocytogenes in the presence and absence of ox40 signaling. we ...200818941188
exploring regulatory mechanisms of cd8+ t cell contraction.a small fraction of the cd8 t cell effector population that responds to an infection progresses through the contraction phase to the memory stage. the factors regulating the extent of contraction are poorly understood. competition for limited resources has been widely postulated to be the cause of cell death during the contraction phase, but our data show that competition does not affect contraction kinetics. we go on to demonstrate that all effector cells present at the peak of the response hav ...200818946035
antimicrobial activity of endemic crataegus tanacetifolia (lam.) pers and observation of the inhibition effect on bacterial cells.up to now an increasing number of antibiotic-resistant bacteria have been reported and thus new natural therapeutic agents are needed in order to eradicate these pathogens. through the discovery of plants such as crataegus tanacetifolia (lam.) pers that have antimicrobial activity, it will be possible to discover new natural drugs serving as chemotherapeutic agents for the treatment of nosocomial pathogens and take these antibiotic-resistant bacteria under control. the objective of the present s ...200818946875
cytoplasmic delivery of antigens, by bacillus subtilis enhances th1 responses.endospores of the gram-positive bacterium, bacillus subtilis, have been used successfully for delivery of antigens where the immunogen is expressed on the spore surface. in this work the spore has been engineered to deliver antigens to the cytoplasm of macrophages by expressing listeriolysin o (llo) or a derivative, llo(l461t), that is stable at neutral ph, from the b. subtilis vegetative cell. following phagocytosis spores were shown to germinate in the phagosome enabling secretion of llo/llo(l ...200818809450
effects of irradiation on survival and growth of listeria monocytogenes and natural microflora in vacuum-packaged turkey hams and breast rolls.the effect of electron beam irradiation on the survival and growth of listeria monocytogenes and natural microflora in oven-roasted turkey breast rolls and turkey hams was evaluated. slices of turkey breast rolls and hams were inoculated with a 5-strain mixture of l. monocytogenes to achieve 10(6) to 10(7) cfu/cm2; vacuum-packaged; irradiated at 0 (control), 1.0, 1.5, 2.0, or 2.5 kgy; and stored at 4 degrees c for up to 28 d. numbers of naturally occurring bacteria on sliced turkey hams and brea ...200818809878
unusual infections due to listeria monocytogenes in the southern california desert.during the past 22 years, 14 patients have been hospitalized with infection due to listeria monocytogenes at the eisenhower medical center, a regional 300-bed hospital in the desert southwest of southern california. a large number of patients are retired, elderly, and have underlying and often systemic disease.200818922716
structural bioinformatics study of pnp from listeria monocytogenes.this work describes for the first time a model of purine nucleoside phosphorylase from listeria monocytogenes (lmpnp). we modeled the complexes of lmpnp with ligands in order to determine the structural basis for specificity. comparative analysis of the model of lmpnp allowed identification of structural features responsible for ligand affinities.200818855758
yersinia enterocolitica yop mutants as oral live carrier vaccines.attenuated enteropathogenic yersiniae that translocate heterologous antigens into the cytosol of antigen presenting cells via their type three secretion system (ttss) are considered promising candidates for the development of live oral vaccine carrier strains that induce cd8 t cell responses. wild type yersinia enterocolitica of serotype o:8 however efficiently suppresses the immune response of the host by translocating effector proteins called yersinia outer proteins (yops) into the cytosol of ...200818822332
frontiers in immunology research network--2008 international conference. 200818828067
effect of gamma radiation on heat shock protein expression of four foodborne pathogens.the effects of gamma radiation on three heat shock proteins (hsps) (groel, dnak and groes) synthesis in two gram-negative (escherichia coli and salmonella serotype typhimurium) and two gram-positive (staphylococcus aureus and listeria monocytogenes) bacteria were investigated.200818828787
high sensitivity of intestinal cd8+ t cells to nucleotides indicates p2x7 as a regulator for intestinal t cell responses.the purinoreceptor p2x7 is expressed on subsets of t cells and mediates responses of these cells to extracellular nucleotides such as atp or nad(+). we identified p2x7 as a molecule highly up-regulated on conventional cd8alphabeta(+) and unconventional cd8alphaalpha(+) t cells of the intestinal epithelium of mice. in contrast, cd8(+) t cells derived from spleen, mesenteric lymph nodes, and liver expressed only marginal levels of p2x7. however, p2x7 was highly up-regulated on cd8(+) t cells from ...200818768840
cross-tolerization between nod1 and nod2 signaling results in reduced refractoriness to bacterial infection in nod2-deficient macrophages.nod2 is an intracellular innate immune receptor that plays a role in host defense and susceptibility to inflammatory disease. we show in this study that macrophages rendered refractory to tlr4 and nod2 signaling by exposure to lps and muramyl dipeptide (mdp) exhibit impaired tnf-alpha and il-6 production in response to pathogenic listeria monocytogenes and yersinia pseudotuberculosis as well as commensal bacteria including escherichia coli and bacteroides fragilis. surprisingly, nod2 deficiency ...200818768892
induction of autophagy via innate bacterial recognition.macroautophagy (referred to hereafter as autophagy) functions not only in self-digestion, but also in the killing and degradation of infectious pathogens in in vitro-cultured cells. based on genetic manipulations of both the host, drosophila and pathogen, listeria monocytogenes, we recently reported that l. monocytogenes-induced autophagy is dependent on the recognition of the pathogen by the drosophila pattern recognition protein, pgrp-le. autophagy and pgrp-le are crucial for inhibition of the ...200818769162
xiap regulates cytosol-specific innate immunity to listeria infection.the inhibitor of apoptosis protein (iap) family has been implicated in immune regulation, but the mechanisms by which iap proteins contribute to immunity are incompletely understood. we show here that x-linked iap (xiap) is required for innate immune control of listeria monocytogenes infection. mice deficient in xiap had a higher bacterial burden 48 h after infection than wild-type littermates, and exhibited substantially decreased survival. xiap enhanced nf-kappab activation upon l. monocytogen ...200818769721
cancer immunotherapy targeting the high molecular weight melanoma-associated antigen protein results in a broad antitumor response and reduction of pericytes in the tumor vasculature.the high molecular weight melanoma-associated antigen (hmw-maa), also known as melanoma chondroitin sulfate proteoglycan, has been used as a target for the immunotherapy of melanoma. this antigen is expressed on the cell surface and has a restricted distribution in normal tissues. besides its expression in a broad range of transformed cells, this antigen is also found in pericytes, which are important for tumor angiogenesis. we generated a recombinant listeria monocytogenes (lm-llo-hmw-maa-c) th ...200818829565
endoplasmic reticulum stress regulator xbp-1 contributes to effector cd8+ t cell differentiation during acute infection.the transcription factor x-box-binding protein-1 (xbp-1) plays an essential role in activating the unfolded protein response in the endoplasmic reticulum (er). transcribed xbp-1 mrna is converted to its active form by unconventional cytoplasmic splicing mediated by inositol-requiring enzyme-1 (ire-1) upon er stress. we report activation of the ire-1/xbp-1 pathway in effector cd8(+) t cells during the response to acute infection. transcription of unspliced xbp-1 mrna is up-regulated by il-2 signa ...200818832700
[bacteriological evaluation of goat milk and cheese distributed in the metropolitan area of san josé, costa rica].in the last years, there has been an increase in the production, industrialization and consumption of goat's milk and derivate products, including cheese, worldwide. nevertheless, in costa rica there is no study of these products, reason why the objective of this work was to determine the microbiological characteristics of goat's milk and fresh cheese distributed in the metropolitan area of san josé, costa rica, in order to evaluate its impact in the economical field and as a potential risk for ...200818833996
a novel dna microarray for rapid diagnosis of enteropathogenic bacteria in stool specimens of patients with diarrhea.a microarray technique for the detection and identification of enteropathogenic bacteria at the species and subspecies levels was developed in this study, and the target bacteria included pathogenic escherichia coli, vibrio cholerae, vibrio parahaemolyticus, salmonella enterica, campylobacter jejuni, shigellae, yersinia enterocolitica, and listeria monocytogenes. the virulence gene of each pathogen was chosen as the amplification target, labeled with a fluorescence dye by multiplex polymerase ch ...200818834908
pulsed-field gel electrophoresis (pfge) analysis of listeria monocytogenes isolates from different sources and geographical origins and representative of the twelve serovars.multiplex-pcr (mpcr) serogrouping and pulsed-field gel electrophoresis (pfge) subtyping analysis are currently used by several public and private laboratories for the characterization of listeria monocytogenes. in this study a set of 80 l. monocytogenes isolates belonging to the twelve serovars was used to investigate (i) the typeability of the rare serovars, (ii) the ability of pfge analysis with apai and asci to differentiate serovars within mpcr serogroups and (iii) the association of molecul ...200818835121
a putative abc transporter is involved in negative regulation of biofilm formation by listeria monocytogenes.listeria monocytogenes may persist for long periods in food processing environments. in some instances, this may be due to aggregation or biofilm formation. to investigate the mechanism controlling biofilm formation in the food-borne pathogen l. monocytogenes, we characterized lm-49, a mutant with enhanced ability of biofilm formation generated via transposon tn917 mutagenesis of l. monocytogenes 4b g. in this mutant, a tn917 insertion has disrupted the coding region of the gene encoding a putat ...200818836003
comparative analysis of extracellular and intracellular proteomes of listeria monocytogenes strains reveals a correlation between protein expression and serovar.listeria monocytogenes, the etiologic agent of listeriosis, remains a serious public health concern, with its frequent occurrence in food environments coupled with a high mortality rate. among the 13 serovars, human listeriosis is mostly associated with the serovar 4b, 1/2b, and 1/2a strains. to investigate the diversity of l. monocytogenes, the intracellular and extracellular proteins of 12 strains were analyzed by two-dimensional gel electrophoresis. these strains had different origins, belong ...200818836007
development and implementation of a multiplex single-nucleotide polymorphism genotyping assay for detection of virulence-attenuating mutations in the listeria monocytogenes virulence-associated gene inla.the virulence factor internalin a (inla) facilitates the uptake of listeria monocytogenes by epithelial cells that express the human isoform of e-cadherin. previous studies identified naturally occurring premature stop codon (pmsc) mutations in inla and demonstrated that these mutations are responsible for virulence attenuation. we assembled >1,700 l. monocytogenes isolates from diverse sources representing 90 ecori ribotypes. a subset of this isolate collection was selected based on ribotype fr ...200818836010
immunomagnetic separation and pcr detection of listeria monocytogenes in turkey meat and antibiotic resistance of the isolates.1. conventional cultivation and immunomagnetic separation (ims) cultivation methods were compared for the isolation specificity and sensitivity of l. monocytogenes from turkey meat samples. pcr was used to confirm the isolates. disc diffusion was performed to determine the antibiotic susceptibility profiles. a total of 180 turkey meat samples collected from markets in turkey were tested. 2. l. monocytogenes was detected in 23 samples (12.7%) by ims and conventional cultivation. it was isolated f ...200818836902
bacteriophage therapy and the mutant selection window.we use kinetic models to investigate how to design antimicrobial phage therapies to minimize emergence of resistant bacteria. we do this by modifying the "mutant selection window" hypothesis in a way that accounts for the ongoing self-replication of the phage. we show that components of combination phage therapies need to be appropriately matched if treatment is to avoid the emergence of resistant bacteria. matching of components is more easily achieved when phage dosages are high enough that on ...200818838590
birth-and-death evolution of the internalin multigene family in listeria.the birth-and-death model of multigene family evolution describes patterns of gene origination, diversification and loss within multigene families. since it was first developed in the 1990s, the model has been found to characterize a large number of eukaryotic multigene families. in this paper, we report for the first time a bacterial multigene family that undergoes birth-and-death evolution. by analyzing the evolutionary relationships among internalins, a relatively large and diverse family of ...200818840511
lineage specific recombination rates and microevolution in listeria monocytogenes.the bacterium listeria monocytogenes is a saprotroph as well as an opportunistic human foodborne pathogen, which has previously been shown to consist of at least two widespread lineages (termed lineages i and ii) and an uncommon lineage (lineage iii). while some l. monocytogenes strains show evidence for considerable diversification by homologous recombination, our understanding of the contribution of recombination to l. monocytogenes evolution is still limited. we therefore used structure and c ...200818842152
enhancing bile tolerance improves survival and persistence of bifidobacterium and lactococcus in the murine gastrointestinal tract.the majority of commensal gastrointestinal bacteria used as probiotics are highly adapted to the specialised environment of the large bowel. however, unlike pathogenic bacteria; they are often inadequately equipped to endure the physicochemical stresses of gastrointestinal (gi) delivery in the host. herein we outline a patho-biotechnology strategy to improve gastric delivery and host adaptation of a probiotic strain bifidobacterium breve ucc2003 and the generally regarded as safe (gras) organism ...200818844989
outbreak of listeria monocytogenes infections associated with pasteurized milk from a local dairy--massachusetts, 2007.on november 27, 2007, a local health officer in central massachusetts contacted the massachusetts department of public health (mdph) to report listeriosis in a man aged 87 years. pulsed-field gel electrophoresis (pfge) performed on the patient's listeria monocytogenes isolate produced a pattern indistinguishable from that of isolates from three other cases identified in residents of central massachusetts in june, october, and early november 2007. mdph, in collaboration with local public health o ...200818846031
characterization of human invasive isolates of listeria monocytogenes in sweden 1986-2007.since 1986, 68% of the listeria monocytogenes isolates from human cases of invasive listeriosis in sweden are available for retrospective studies. the aim of the present study was to characterize 601 human invasive isolates of l. monocytogenes in sweden from 1986 to 2007 by using serotyping and pulsed-field gel electrophoresis. since 1996, serovar 4b was permanently reduced to the second or third most common serovar in human cases in sweden. during the latter period, 2000-2007, only 13% belonged ...200818847381
precut prepackaged lettuce: a risk for listeriosis?the most recent outbreaks of listeriosis have been traced back to contaminated ready-to-eat (rte) poultry and meat products. however, listeria monocytogenes can be isolated from every food group, including fresh vegetables. this review is focused on one of the most popular rte vegetable products, precut prepackaged lettuce. the available literature concerning listeria contamination of vegetables is reviewed, and possible reasons why no recent outbreaks or sporadic cases of listeriosis due to con ...200818847382
the tsc-mtor signaling pathway regulates the innate inflammatory response.the innate inflammatory immune response must be tightly controlled to avoid damage to the host. here, we showed that the tuberous sclerosis complex-mammalian target of rapamycin (tsc-mtor) pathway regulated inflammatory responses after bacterial stimulation in monocytes, macrophages, and primary dendritic cells. inhibition of mtor by rapamycin promoted production of proinflammatory cytokines via the transcription factor nf-kappab but blocked the release of interleukin-10 via the transcription fa ...200818848473
dynamic regimes and bifurcations in a model of actin-based motility.propulsion by actin polymerization is widely used in cell motility. here, we investigate a model of the brush range of an actin gel close to a propelled object, describing the force generation and the dynamics of the propagation velocity. we find transitions between stable steady states and relaxation oscillations when the attachment rate of actin filaments to the obstacle is varied. the oscillations set in at small values of the attachment rate via a homoclinic bifurcation. a second transition ...200818851073
surveillance of listeriosis in navarre, spain, 1995-2005--epidemiological patterns and characterisation of clinical and food isolates.we monitored the incidence of human listeriosis in navarre, a region in north of spain between 1995 and 2005, and carried out the characterisation of listeria monocytogenes isolates obtained from clinical samples and ready-to-eat products (sliced cooked meat, smoked salmon and liver pate). the active surveillance requesting hospitals to notify all listeriosis cases (n=40) yielded higher incidence rates (average annual rate 0.65/100,000 inhabitants, range 0.18-1.18/100,000 inhabitants) than expec ...200819081001
new insights into determinants of listeria monocytogenes virulence.listeria monocytogenes is the causative agent of human listeriosis, a potentially fatal foodborne infection. clinical manifestations range from febrile gastroenteritis to more severe invasive forms including meningitis, encephalitis, abortions, and perinatal infections. this gram-positive facultative intracellular pathogen has evolved multiple strategies to face extracellular innate defense mechanisms of the host and to invade and multiply intracellularly within macrophages and nonphagocytic cel ...200819081533
identification of a new molecular target of class iia bacteriocins in listeria monocytogenes egde.it was shown recently (calvez et al. 2007) that glpq and pde genes are involved in intermediate resistance of enterococcus faecalis jh2-2 to dvnv41, a class iia bacteriocin produced by carnobacterium divergens v41. the listerial orthologs of lpq and pde genes might be lmo0052 and lmo1292 genes, respectively. here, the role of lmo0052 and lmo1292 genes in resistance of listeria monocytogenes egde to dvnv41 and mesy105 was investigated. l. monocytogenes egde was inactivated in lmo0052 and/or lmo12 ...200819085076
[characterization and prevalence of clones of listeria monocytogenes isolated from patients in 2001-2008 in the czech republic].to characterize human isolates of listeria monocytogenes by typing methods and to test them for use in epidemiological investigations.200819069026
[rapid detection method of three types of bacterial pathogens in aquatic products established by multiplex pcr].to develop a rapid multiplex pcr (m-pcr) assay for simultaneously detection of three foodborne pathogens in aquatic products.200819069666
modulation of prfa activity in listeria monocytogenes upon growth in different culture media.prfa is the major transcriptional activator of most virulence genes of listeria monocytogenes. its activity is modulated by a variety of culture conditions. here, we studied the prfa activity in the l. monocytogenes wild-type strain egd and an isogenic prfa deletion mutant (egddeltaprfa) carrying multiple copies of the wild-type prfa or the mutant prfa* gene (strains egddeltaprfapprfa and egddeltaprfapprfa*) in response to growth in brain heart infusion (bhi), luria-bertani broth (lb) or a defin ...200819047753
rapid and sensitive detection of listeria monocytogenes using a pcr-enzymelinked immunosorbent assay.a pcr-enzyme-linked immunosorbent assay (pcr-elisa) was developed for the rapid and sensitive detection of l. monocytogenes. pcr primers generating a 132-bp amplicon and a capture probe able to hybridize to the pcr amplicon were designed based on the l. monocytogenes-specific hly gene encoding listeriolysin. the detection limit of pcr-elisa for l. monocytogenes was determined to be as low as 10 cells per pcr reaction, and this level of detection was achieved within 5 h. these results indicate th ...200819047833
il-12 produced by dendritic cells augments cd8+ t cell activation through the production of the chemokines ccl1 and ccl17.il-12 family members are an important link between innate and adaptive immunity. il-12 drives th1 responses by augmenting ifn-gamma production, which is key for clearance of intracellular pathogens. il-23 promotes the development of il-17-producing cd4(+) t cells that participate in the control of extracellular pathogens and the induction of autoimmunity. however, recent studies have shown that these cytokines can modulate lymphocyte migration and cellular interactions. therefore, we sought to d ...200819050277
impact of -2 degrees c superchilling before refrigerated storage (4 and 8 degrees c) on the microbiological and sensory qualities of cold-smoked salmon.detection and enumeration of listeria monocytogenes and total spoilage bacteria in 40 batches of cold-smoked salmon (one batch = 42 products from the same day of manufacture) straight from the factory were carried out. if l. monocytogenes was detected in at least one of the nine samples analyzed on receipt at the laboratory, 9 products of the same batch were stored for 10 days at 4 degrees c, which was followed by 18 days at 8 degrees c (control), 12 products were superchilled for 14 days at -2 ...200819044261
enhanced detection of listeria spp. in farmstead cheese processing environments through dual primary enrichment, pcr, and molecular subtyping.the incidence and ecology of listeria spp. in farmstead cheese processing environments were assessed through environmental sampling conducted in nine different plants over a 10-week period. environmental samples (n = 705) were examined for the presence of listeria spp. by using three detection/isolation protocols. the use of dual enrichment methods, which allowed for the recovery of injured listeria spp. (musda), identified more listeria species-positive samples with higher sensitivity than the ...200819044268
radiation d10-values on thawed and frozen catfish and tilapia for finfish isolates of listeria monocytogenes.with the popularity of catfish and tilapia in the healthy diet, the consumption and harvesting of farm-raised finfish have increased. since 1987 the pathogenic bacterium listeria monocytogenes has been isolated from seafood, particularly farm-raised catfish in the united states. seafood isolates of l. monocytogenes are now available. in order to maintain the raw finfish product, nonthermal interventions to remove bacterial pathogens need to be evaluated using these isolates. a nonthermal interve ...200819044273
development of unique bacterial strains for use as positive controls in the food microbiology testing laboratory.nalidixic acid-resistant (nalr) mutants of salmonella enterica serovar berta and escherichia coli o157:h7 were derived from wild-type laboratory cultures to serve as distinguishable control strains for routine use in food microbiology testing programs. the prevalence of the nalr phenotype among different bacteria was verified using panels of related and unrelated strains with the ability to grow vigorously on plating media containing nalidixic acid, being restricted to the nalr mutants. the nalr ...200819044277
listeria monocytogenes infection in patients with rheumatic diseases on tnf-alpha antagonist therapy: the spanish study group experience.the prognosis of patients with rheumatic diseases has improved considerably following the use of biological therapies. however, an increase in the frequency of bacterial infections has been observed in patients receiving these therapies. in the present study we aimed to assess the frequency of listeria monocytogenes infection in a large series of patients with rheumatic diseases on treatment with tumor necrosis factor (tnf)-alpha blockers because of active disease refractory to conventional ther ...200819032819
kbma listeria monocytogenes is an effective vector for dc-mediated induction of antitumor immunity.vaccine strategies that utilize human dcs to enhance antitumor immunity have yet to realize their full potential. approaches that optimally target a spectrum of antigens to dcs are urgently needed. here we report the development of a platform for loading dcs with antigen. it is based on killed but metabolically active (kbma) recombinant listeria monocytogenes and facilitates both antigen delivery and maturation of human dcs. highly attenuated kbma l. monocytogenes were engineered to express an e ...200819033668
antimicrobial peptides effectively kill a broad spectrum of listeria monocytogenes and staphylococcus aureus strains independently of origin, sub-type, or virulence factor expression.host defense peptides (hdps), or antimicrobial peptides (amps), are important components of the innate immune system that bacterial pathogens must overcome to establish an infection and hdps have been suggested as novel antimicrobial therapeutics in treatment of infectious diseases. hence it is important to determine the natural variation in susceptibility to hdps to ensure a successful use in clinical treatment regimes.200819036162
listeria associated mural and valvular endocarditis in an alpaca.an alpaca presented for emergency evaluation of respiratory distress. physical examination revealed weakness, pyrexia, and a grade v/vi left apical holosystolic murmur. initial thoracic examination and radiographs were consistent with left sided congestive heart failure. blood cultures, echocardiographic evaluation, and necropsy findings established a diagnosis of bacterial endocarditis associated with a listeria monocytogenes infection. left ventricular endocarditis is uncommon in ruminants, an ...200819036668
influence of zinc, sodium bicarbonate, and citric acid on the antibacterial activity of ovotransferrin against escherichia coli o157:h7 and listeria monocytogenes in model systems and ham.the influence of nahco(3) and citric acid on the antibacterial activity of apo-ovotransferrin in model systems and ham was investigated. the antibacterial activity of 20 mg/ml of ovotransferrin solution with added nahco(3) (0, 25, 50, or 100 mm) or citric acid (0.25 or 0.5%) was evaluated against escherichia coli o157:h7 and listeria monocytogenes in brain heart infusion broth. the antimicrobial activity of ovotransferrin saturated with fe(2+) or zn(2+) against both pathogens was also measured. ...200819038824
molecular template for a voltage sensor in a novel k+ channel. iii. functional reconstitution of a sensorless pore module from a prokaryotic kv channel.kvlm is a prokaryotic voltage-gated k(+) (kv) channel from listeria monocytogenes. the sequence of the voltage-sensing module (transmembrane segments s1-s4) of kvlm is atypical in that it contains only three of the eight conserved charged residues known to be deterministic for voltage sensing in eukaryotic kv's. in contrast, the pore module (pm), including the s4-s5 linker and cytoplasmic tail (linker-s5-p-s6-c-terminus) of kvlm, is highly conserved. here, the full-length (fl)-kvlm and the kvlm- ...200819029373
acid stress responses in listeria monocytogenes. 200819026862
the role of sigma b (sigma b) in the stress adaptations of listeria monocytogenes: overlaps between stress adaptation and virulence. 200819026864
inactivation of escherichia coli o157:h7, salmonella typhimurium, and listeria monocytogenes on stored iceberg lettuce by aqueous chlorine dioxide treatment.inactivation of escherichia coli o157:h7, salmonella typhimurium, and listeria monocytogenes in iceberg lettuce by aqueous chlorine dioxide (clo(2)) treatment was evaluated. iceberg lettuce samples were inoculated with approximately 7 log cfu/g of e. coli o157:h7, s. typhimurium, and l. monocytogenes. iceberg lettuce samples were then treated with 0, 5, 10, or 50 ppm clo(2) solution and stored at 4 degrees c. aqueous clo(2) treatment significantly decreased the populations of pathogenic bacteria ...200819021812
image analysis based quantification of bacterial volume change with high hydrostatic pressure.scanning electron microscopy (sem) images of staphylococcus aureus 485 and escherichia coli o157:h7 933 were taken after pressure treatments at 200 to 400 mpa. software developed for this purpose was used to analyze sem images and to calculate the change in view area and volume of cells. significant increase in average cell view area and volume for s. aureus 485 was observed in response to pressure treatment at 400 mpa. cell view area for e. coli o157:h7 933 significantly increased at 325 mpa, t ...200819021813
evaluation of changes in listeria monocytogenes populations on frankfurters at different stages from manufacturing to consumption.this study evaluated the fate of inoculated listeria monocytogenes on frankfurters stored under conditions simulating those that may be encountered between manufacturing and consumption. frankfurters with or without 1.5% potassium lactate and 0.1% sodium diacetate (pl/sd) were inoculated (1.8 +/- 0.1 log cfu/cm(2)) with a 10-strain composite of l. monocytogenes, vacuum-packaged, and stored under conditions simulating predistribution storage (24 h, 4 degrees c), temperature abuse during transport ...200819021814
antilisterial activity of hops beta acids in broth with or without other antimicrobials.hops beta acids (hba) are parts of hops flowers used to preserve wort and provide flavor in beer, and are reported as having antimicrobial properties. this study evaluated the antilisterial activity of hba alone or in combination with other known antimicrobials in a culture broth medium. listeria monocytogenes (10-strain mixture) was inoculated (2.6 to 2.8 log cfu/ml) into tryptic soy broth supplemented with 0.6% yeast extract (tsbye) without (control) or with hba (0.5 to 5.0 microg/ml), potassi ...200819021815
fractional differential equations based modeling of microbial survival and growth curves: model development and experimental validation.a fractional differential equations (fdes)-based theory involving 1- and 2-term equations was developed to predict the nonlinear survival and growth curves of foodborne pathogens. it is interesting to note that the solution of 1-term fde leads to the weibull model. nonlinear regression (gauss-newton method) was performed to calculate the parameters of the 1-term and 2-term fdes. the experimental inactivation data of salmonella cocktail in ground turkey breast, ground turkey thigh, and pork shoul ...200819019113
evaluation of antibacterial activity of whey protein isolate coating incorporated with nisin, grape seed extract, malic acid, and edta on a turkey frankfurter system.the effectiveness of whey protein isolate (wpi) coatings incorporated with grape seed extract (gse), nisin (n), malic acid (ma), and ethylenediamine tetraacetic acid (edta) and their combinations to inhibit the growth of listeria monocytogenes, e. coli o157:h7, and salmonella typhimurium were evaluated in a turkey frankfurter system through surface inoculation (approximately 10(6) cfu/g) of pathogens. the inoculated frankfurters were dipped into wpi film forming solutions both with and without t ...200819019119
antibacterial activity of ozone-depolymerized crawfish chitosan.antimicrobial activities of chitosan samples with different molecular weights (1333, 432, 201, 131, and 104 kda) prepared by ozone treatment were examined against 2 gram-positive bacteria (listeria monocytogenes and staphylococcus aureus) and 2 gram-negative bacteria (escherichia coli and pseudomonas fluorescen) to investigate the effect of chitosan's molecular weight and concentration on the inhibition of bacterial growth. antimicrobial activity of chitosan varied depending on the molecular wei ...200819019121
the pta-acka pathway controlling acetyl phosphate levels and the phosphorylation state of the degu orphan response regulator both play a role in regulating listeria monocytogenes motility and chemotaxis.degu is considered to be an orphan response regulator in listeria monocytogenes since the gene encoding the cognate histidine kinase degs is absent from the genome. we have previously shown that degu is involved in motility, chemotaxis and biofilm formation and contributes to l. monocytogenes virulence. here, we have investigated the role of degu phosphorylation in listeria and shown that degs of bacillus subtilis can phosphorylate degu of l. monocytogenes in vitro. we introduced the b. subtilis ...200819019159
microbial quality control of raw ground beef and fresh sausage in casablanca (morocco).in this study, samples of raw ground beef (n = 150) and fresh sausage (n = 100) were collected randomly from butcheries, supermarkets, and fast-food shops, in casablanca, morocco. two types of meat product samples were considered, one with spices (n = 115) and other without spices (n = 135). all the samples were analyzed for the presence of the following bacteria: escherichia coli, staphylococcus, clostridium perfringens, salmonella, and listeria monocytogenes. e. coli strains were further typed ...200819004395
single pre-exposure to a high dose of zymosan enhances lung defense mechanisms and accelerates the pulmonary clearance of a bacterial pathogen in rats.the present study examines the effects of pre-exposure to zymosan (a 1 --> 3-beta-glucan from baker yeast) on lung defense against bacterial infection. rats received a single dose of zymosan a (0.6, 1.2, or 2.5 mg/kg body weight [bw]) or vehicle control (saline) via intratracheal instillation 3 days prior to intratracheal inoculation with 5 x 10(5) listeria monocytogenes. left lungs were homogenized and cultured to assess bacterial clearance, and bronchoalveolar lavage was performed on the right ...200819005921
coordinating innate immune cells to optimize microbial killing.the mechanisms underlying innate immune cell trafficking and activation during infection remain incompletely defined. in this issue of immunity, kang et al. (2008) begin to reveal the cytokine and chemokine cascades that coordinate cellular responses induced by microbial pathogens.200819006691
regulation of hierarchical clustering and activation of innate immune cells by dendritic cells.an early granulomatous response, characterized by collections of white blood cells at foci surrounding pathogens, occurs after infection by many intracellular organisms, including listeria, but how these clusters become organized and for what purpose remain poorly understood. here, we showed that dendritic cell (dc) activation by listeria nucleated rapid clustering of innate cells, including granulocytes, natural killer (nk) cells, and monocytes, to sites of bacteria propagation where interleuki ...200819006696
[nosocomial infection caused by listeria monocytogenes in a patient with a lung transplant]. 200819007574
short-term genome evolution of listeria monocytogenes in a non-controlled environment.while increasing data on bacterial evolution in controlled environments are available, our understanding of bacterial genome evolution in natural environments is limited. we thus performed full genome analyses on four listeria monocytogenes, including human and food isolates from both a 1988 case of sporadic listeriosis and a 2000 listeriosis outbreak, which had been linked to contaminated food from a single processing facility. all four isolates had been shown to have identical subtypes, sugges ...200819014550
cell biology: a listeria escape trick. 200818972010
inhibition of listeria monocytogenes by oregano, cranberry and sodium lactate combination in broth and cooked ground beef systems and likely mode of action through proline metabolism.listeria monocytogenes is a food safety challenge in various food systems including fresh and frozen meat and poultry. natural antimicrobials from plant sources in combination with salts of organic acids have the potential to control l. monocytogenes. in this research the efficiency of water soluble phenolic extracts of oregano and cranberry in combination with sodium lactate was evaluated for control of l .monocytogenes. in both broth and cooked meat studies, the results indicated that the comb ...200818973962
listeriosis. 200818977860
digest this! a role for autophagy in controlling pathogens.autophagy provides a mechanism for cells to conserve nutrients, but was recently associated with immunity to intracellular pathogens. here, zhao et al. (2008) present direct in vivo evidence that autophagy is linked to macrophage control of toxoplasma gondii and listeria monocytogenes and highlights that this process intersects with cytokine-mediated antimicrobial responses.200818996340
autophagosome-independent essential function for the autophagy protein atg5 in cellular immunity to intracellular pathogens.the physiologic importance of autophagy proteins for control of mammalian bacterial and parasitic infection in vivo is unknown. using mice with granulocyte- and macrophage-specific deletion of the essential autophagy protein atg5, we show that atg5 is required for in vivo resistance to the intracellular pathogens listeria monocytogenes and toxoplasma gondii. in primary macrophages, atg5 was required for interferongamma (ifn-gamma)/lps-induced damage to the t. gondii parasitophorous vacuole membr ...200818996346
attachment of listeria monocytogenes, escherichia coli o157:h7 and pseudomonas aeruginosa on food soiled plastic surfaces.this study investigated the ability of three different pathogens, escherichia coli o157:h7, listeria monocytogenes and pseudomonas aeruginosa, to attach food soiled (salad dressing, cooking oil, milk and yogurt) polyvinyl chloride (pvc) plastic. the pre-soiled pvc coupons were incubated with 10(8) cfu/cm2 of each bacterium in 50% tryptic soy broth for 6 h to allow attachment. it was found that the effect of food products was not significant while the effect of bacterial strain was highly signifi ...200719086561
chromium in stainless steel welding fume suppresses lung defense responses against bacterial infection in rats.pulmonary infections have been reported to be increased in welders. previous animal studies have indicated that manual metal arc, stainless steel welding fume (mma-ss) increased susceptibility to lung infections. mma-ss is composed of a complex of metals (e.g., iron, chromium, nickel). the objective was to determine which metal component of mma-ss welding fume alters lung defense responses. at day 0, rats were intratracheally instilled one time with saline or mma-ss at a concentration of 2 mg/ra ...200718958720
occurrence of campylobacter, salmonella, yersinia enterocolitica and listeria monocytogenes in some retail food products in novi sad.the official reporting system in the province of vojvodina (pv) indicates that cases of human salmonellosis were partly covered by complete epidemiological investigation including laboratory analysis of the suspected food. intestinal campylobacteriosis and yersiniosis and four cases of septicemias caused by listeria monocytogenes were not fully epidemiologically investigated. actual country legislation on food safety does not include provisions for a routine control of the above mentioned pathog ...200718251233
[molecular characteristics of inlb protein of listeria monocytogenes wild strain and it's expression and purification].internalin b of listeria monocytogenes ta wild strain was amplified by pcr method and sequenced, then subcloned into prokaryotic vector pet28a for expression. the complete length of inlb gene was 1893 bp, encoding 630 amino acids. the front 35 amino acids consisted of signal peptide. there were one cap domain with alpha-helix region, 6 leucine-rich repeat motifs, one immunoglobulin (ig)-like domain, one b repeat sequence, 3 direct repeat gw domains and 5 n-glycosylation sites. the amino acid of ...200718271273
rage: exacting a toll on the host in response to polymicrobial sepsis and listeria monocytogenes.the receptor for advanced glycation endproducts (rage) has complex roles in the immune/inflammatory response. rage is expressed on monocytes/macrophages, t and b lymphocytes, and dendritic cells. previous studies illustrated that homozygous rage-/- mice subjected to overwhelming bacterial sepsis displayed normal clearance of pathogenic bacteria and significantly increased survival. in this issue of critical care, lutterloh and colleagues confirm these findings and provide evidence that blocking ...200718190725
screening of the enterocin genes and antimicrobial activity against pathogenic bacteria in enterococcus strains obtained from different origins.antimicrobial activities of 139 enterococcus isolates (48 e. faecium and 91 e. faecalis) obtained from canine feces, boiler meat samples, swine feces, wild waterfowl feces, and human feces were examined against respective bacteria, including streptococcus pyogenes, staphylococcus aureus, bacillus subtilis, listeria monocytogenes, salmonella enteritidis, and escherichia coli. bacteriocin (bac) production assay revealed that the antimicrobial activity against at least one of 6 indicator strains (b ...200718176018
[synthesis and antimicrobial activity of some new (sulfon-amidophenyl)-amide derivatives of n-(m-nitrobenzoyl)-d,l-methionine].in order to obtain new compounds with potential antimicrobial activity some new (sulfon-amidophenyl)-amide derivatives of n-(m-nitrobenzoil)-d,l-methionine have been synthesized. the compounds have been obtained by decyclization reaction of 2-(m-nitrophenyl)-4-(beta-p-methylthioethyl)- delta2-5-oxazolinone with various sulfonamides. the chemical structure of the new sulfonamides was confirmed by elemental analysis data and ir and 1nmr spectral measurements. the compounds were also investigated f ...200718293716
[listeria monocytogenes infection during pregnancy--modern aspects].during a ten years period (1997-2006) at the delivery ward of maychin dom university hospital were admitted 31,430 parturients. among all of them we indentified and evaluated only 4 pregnant patients with listeria monocytogenes infection. during the first 8 years of the investigated period there was no even single case of the infection, whilst during the last 2 years the frequency of the listeria infection among all birth deliveries was 0,068%. all of our four cases were admitted with clinical s ...200718646305
linezolid activity against disseminated listeria monocytogenes meningitis and central nervous system abscesses: focus on early drug myelotoxicity.a very infrequent report of listeria monocytogenes meningitis and multiple subtentorial abscesses (cerebellar, bulbar, and pontine in location), occurred in an immunocompetent man, and is described and discussed on the ground of the most recent literature evidences regarding the frequency, presentation, and outcome of this disease. the possibility to resort to combination linezolid therapy in patients who appear to be not responsive to first-line treatment of cerebral abscess of definite origin, ...200718690960
listeria inlb takes a different route to met.inlb, a surface protein of the human bacterial pathogen listeria monocytogenes, interacts with the receptor tyrosine kinase met on host cells to enable bacterial invasion. in this issue, niemann et al. (2007) provide the first structural evidence that inlb does not compete for the same interaction site on met as the natural ligand hgf.200717662936
structure of the human receptor tyrosine kinase met in complex with the listeria invasion protein inlb.the tyrosine kinase met, the product of the c-met proto-oncogene and the receptor for hepatocyte growth factor/scatter factor (hgf/sf), mediates signals critical for cell survival and migration. the human pathogen listeria monocytogenes exploits met signaling for invasion of host cells via its surface protein inlb. we present the crystal structure of the complex between a large fragment of the human met ectodomain and the met-binding domain of inlb. the concave face of the inlb leucine-rich repe ...200717662939
[pleural effusion due to listeria monocytogenes in a woman with cirrhosis of the liver]. 200717663897
t-cell-independent humoral immunity is sufficient for protection against fatal intracellular ehrlichia infection.although humoral immunity has been shown to contribute to host defense during intracellular bacterial infections, its role has generally been ancillary. instead, cd4 t cells are often considered to play the dominant role in protective immunity via their production of type i cytokines. our studies of highly pathogenic ehrlichia bacteria isolated from ixodes ovatus (ioe) reveal, however, that this paradigm is not always correct. immunity to ioe infection can be induced by infection with a closely ...200717664264
the lmo1078 gene encoding a putative udp-glucose pyrophosphorylase is involved in growth of listeria monocytogenes at low temperature.the gram-positive bacterium listeria monocytogenes is a food-borne pathogen with the ability to grow at low temperature. given the importance of refrigeration as a means of food preservation, the psychrotolerant nature of this microorganism poses a significant public health hazard. in order to better understand the mechanisms underlying cold adaptation of l. monocytogenes, a library of tn917-lac insertional mutants was screened. a cold-sensitive mutant, named cs1, was isolated and found to be al ...200717666069
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