Publications

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survival mechanism of escherichia coli o157:h7 against combined treatment with acetic acid and sodium chloride.the combination of salt and acid is commonly used in the production of many foods, including pickles and fermented foods. however, in our previous studies, the addition of salt significantly reduced the inhibitory effect of acetic acid on escherichia coli o157:h7 in laboratory media and pickled cucumbers. therefore, this study was conducted to determine the mechanism by which salt confers resistance against acetic acid in e. coli o157:h7. the addition of high concentrations (up to 9% or 15% [w/v ...201626742620
effect of sanitizer combined with steam heating on the inactivation of foodborne pathogens in a biofilm on stainless steel.the combined effect of chemical sanitizers including sodium hypochlorite, hydrogen peroxide, iodophor, and benzalkonium chloride with steam heating on the inactivation of biofilms formed by escherichia coli o157:h7, salmonella typhimurium, and listeria monocytogenes on stainless steel was investigated. six day old biofilms, comprised of a mixture of three strains each of three foodborne pathogens, were produced on stainless steel coupons at 25 °c and treated with each sanitizer alone (for 5, 15, ...201626742615
expression of listeria monocytogenes key virulence genes during growth in liquid medium, on rocket and melon at 4, 10 and 30 °c.the aim of the present study was to assess the expression of key virulence genes, during growth of a listeria monocytogenes isolate in liquid medium, on melon and rocket at different temperatures and time. for that purpose, bhi broth, rocket and melon were inoculated at 7.0-7.5 log cfu ml(-1) or g(-1)and stored at 4, 10 and 30 °c. sampling took place upon inoculation and after 0.5, 6 and 24 h of incubation. the rna was stabilized and the expression of hly, plca, plcb, sigb, inla, inlb, inlc, inl ...201626742611
tracking foodborne pathogenic bacteria in raw and ready-to-eat food illegally sold at the eastern eu border.food illegally brought into the european union, mainly in the personal luggage of travelers, represents a potential threat to consumers' health. the aim of this study was to investigate the presence of five pathogens in food brought into the european union by moldavian citizens as personal goods and illegally sold in romania in the vicinity of the border. the occurrence of staphylococcus aureus and listeria monocytogenes was 7.5% and 8%, while campylobacter spp., escherichia coli o157:h7, and sa ...201626741503
short communication: inhibitory activities of the lantibiotic nisin combined with phenolic compounds against staphylococcus aureus and listeria monocytogenes in cow milk.we aimed to investigate the antibacterial activities of carvacrol, thymol, eugenol, cinnamaldehyde, and lantibiotic nisin against standard bacterial strains of the milk pathogens staphylococcus aureus atcc 25923 and listeria monocytogenes atcc 15313 in cow milk. the minimum inhibitory concentrations (mic) of these substances were recorded. the synergistic effects were also assessed in culture medium (time kill curve) and in a food model (cow milk) during the storage period (4 °c for 6 d) after i ...201626774728
effectiveness of superheated steam for inactivation of escherichia coli o157:h7, salmonella typhimurium, salmonella enteritidis phage type 30, and listeria monocytogenes on almonds and pistachios.this study was undertaken to evaluate the effectiveness of superheated steam (shs) on the inactivation of escherichia coli o157:h7, salmonella typhimurium, salmonella enteritidis phage type (pt) 30 and listeria monocytogenes on almonds and in-shell pistachios and to determine the effect of superheated steam heating on quality by measuring color and texture changes. almonds and in-shell pistachios inoculated with four foodborne pathogens were treated with saturated steam (ss) at 100 °c and shs at ...201626773253
too much of a good thing: regulated depletion of c-di-amp in the bacterial cytoplasm.bacteria that synthesize c-di-amp also encode several mechanisms for controlling c-di-amp levels within the cytoplasm. one major class of phosphodiesterases comprises gdpp and dhhp homologs, which degrade c-di-amp into the linear molecule 5'-papa or amp by the dhh-dhha1 domain. the other major class comprises pgph homologs, which degrade c-di-amp by the hd domain. both gdpp and pgph harbor sensory domains, likely to regulate c-di-amp hydrolysis activity in response to signal input. as another po ...201626773214
impact of pathogen population heterogeneity and stress-resistant variants on food safety.this review elucidates the state-of-the-art knowledge about pathogen population heterogeneity and describes the genotypic and phenotypic analyses of persister subpopulations and stress-resistant variants. the molecular mechanisms underlying the generation of persister phenotypes and genetic variants are identified. zooming in on listeria monocytogenes, a comparative whole-genome sequence analysis of wild types and variants that enabled the identification of mutations in variants obtained after a ...201626772414
reductions in neonatal listeriosis: "collateral benefit" of group b streptococcal prophylaxis?we tested the hypothesis that declines in listeria monocytogenes in infants are related to declines in rates of early-onset group b streptococcus (gbs) infections associated with widespread prophylaxis using agents with listeria activity.201626772166
splenic leukocytes traffic to the thyroid and produce a novel tshβ isoform during acute listeria monocytogenes infection in mice.the thyroid stimulating hormone beta-subunit (tshβ) with tshα form a glycoprotein hormone that is produced by the anterior pituitary in the hypothalamus-pituitary-thyroid (hpt) axis. although tshβ has been known for many years to be made by cells of the immune system, the role of immune system tsh has remained unclear. recent studies demonstrated that cells of the immune system produce a novel splice variant isoform of tshβ (tshβv), but little if any native tshβ. here, we show that within three ...201626771831
genome sequence of listeria monocytogenes strain f6540 (sequence type 360) collected from food samples in ontario, canada.comparative genomic analysis between pathogenic and nonpathogenic listeria monocytogenes strains provides a good model for studying the virulence of this organism. here, we report the genome sequence of the nonpathogenic l. monocytogenes strain f6540 (sequence type 360) identified specifically in food samples in ontario, canada, in 2010.201626769922
[cabozantinib inhibits listeria monocytogenes infection in mice].to test the effect of the c-met inhibitor cabozantinib in inhibiting infections by listeria monocytogenes (lm) in mice.201626806739
effect of phytosanitary irradiation and methyl bromide fumigation on the physical, sensory, and microbiological quality of blueberries and sweet cherries.the objective of this study was to determine whether irradiation could serve as a suitable phytosanitary treatment alternative to methyl bromide (mb) fumigation for blueberries and sweet cherry and also to determine the effect of phytosanitary irradiation treatment on survival of salmonella spp. and listeria monocytogenes on these fruit. 'bluecrop' blueberries (vaccinium corymbosum) and 'sweetheart' cherries (prunus avium) were irradiated at 0.4 kgy or fumigated with methyl bromide and evaluated ...201626805024
community-acquired bacterial meningitis in adults with cancer or a history of cancer.to study the incidence, clinical presentation, causative bacteria, and outcome of community-acquired bacterial meningitis in adults with cancer.201626802096
draft genome sequence of a 94-year-old listeria monocytogenes isolate, slcc208.we report here the draft genome sequence of listeria monocytogenes strain slcc208 from seeliger's historical special listeria culture collection, initially cultured from a human case in france in 1921. this is, to our knowledge, the oldest l. monocytogenes isolate available and may be useful for comparative genomic studies of l. monocytogenes.201626798096
phenolic compounds, antioxidant, and antibacterial properties of pomace extracts from four virginia-grown grape varieties.grape pomace is a potential source of natural antioxidant and antimicrobial agents. phenolic compounds, antioxidant, and antibacterial properties of pomace extracts from four virginia-grown grape varieties were investigated. white grape pomaces had higher (p < 0.05) solvent extraction yield than red varieties. concentrations of total phenolic (tpc), total flavonoid (tfc), total anthocyanin (tac), tannins, condensed tannins (ct), as well as antioxidant capacities (dpph• and abts•+free radical sca ...201626788319
the incidence and distribution of listeria monocytogenes in ready-to-eat vegetables in south-western nigeria.the study investigated the incidence of listeria monocytogenes in ready-to-eat (rte) vegetables: (cucumber, cucumis sativas; cabbage, brassica olerecea; carrot, daucus carota; tomato, solanum lycopersicum; lettuce, lactuca sativa) in six states in south-western nigeria. a total of 555 composite samples were collected from 30 traditional markets within the states and only 244 l. monocytogenes species were isolated by standard methods. the incidence of l. monocytogenes was low and not statisticall ...201626788311
efficacy of activated alginate-based nanocomposite films to control listeria monocytogenes and spoilage flora in rainbow trout slice.essential oils of clove, coriander, caraway, marjoram, cinnamon, and cumin were tested for their antilisterial activity by application of agar diffusion assay (experiment 1). marjoram essential oil (meo) showed the highest inhibitory effect, followed by clove and cinnamon. subsequently, these essential oils were incorporated to alginate/clay nanocomposite films and antilisterial effectiveness of the films was studied in a model solid food system during 12 days at 10 °c (experiment 2). the result ...201626787971
impact of different cell penetrating peptides on the efficacy of antisense therapeutics for targeting intracellular pathogens.there is a pressing need for novel and innovative therapeutic strategies to address infections caused by intracellular pathogens. peptide nucleic acids (pnas) present a novel method to target intracellular pathogens due to their unique mechanism of action and their ability to be conjugated to cell penetrating peptides (cpp) to overcome challenging delivery barriers. in this study, we targeted the rna polymerase α subunit (rpoa) using a pna that was covalently conjugated to five different cpps. c ...201626860980
identification of proteins derived from listeria monocytogenes inducing human dendritic cell maturation.dendritic cells (dcs) are potent antigen-presenting cells (apcs) that can promote antitumor immunity when pulsed with tumor antigens and then matured by stimulatory agents. despite apparent progress in dc-based cancer immunotherapy, some discrepancies were reported in generating potent dcs. listeria monocytogenes as an intracellular microorganism is able to effectively activate dcs through engaging pattern-recognition receptors (prrs). this study aimed to find the most potent components derived ...201626886282
antibacterial activity of aquatic gliding bacteria.the study aimed to screen and isolate strains of freshwater aquatic gliding bacteria, and to investigate their antibacterial activity against seven common pathogenic bacteria. submerged specimens were collected and isolated for aquatic gliding bacteria using four different isolation media (dw, ma, sap2, and vy/2). gliding bacteria identification was performed by 16s rrna gene sequencing and phylogenetic analysis. crude extracts were obtained by methanol extraction. antibacterial activity against ...201626885469
[clinical characteristics of 35 non-pregnant patients with listeria monocytogenes sepsis].to better understand the clinical characteristics and predisposing factors in non-pregnant patients with listeria monocytogenes (listeria) sepsis.201626875580
production of bacteriocin by virgibacillus salexigens isolated from "terasi": a traditionally fermented shrimp paste in indonesia.a natural antibacterial-substance-producing gram-positive bacterium was isolated from terasi shrimp paste, a popular fermented product in indonesia. this strain, a spore-forming and strictly aerobic bacterium, was identified as virgibacillus salexigens by 16s rrna gene sequence analysis. the antibacterial substance purified from the precipitated product in the culture supernatant of the strain using ammonium sulfate showed a broad inhibition spectrum against gram-positive bacteria, including a t ...201626873558
structural and biochemical insights into the peptidoglycan hydrolase domain of flgj from salmonella typhimurium.flgj is a glycoside hydrolase (gh) enzyme belonging to the carbohydrate active enzyme (cazy) family gh73. it facilitates passage of the bacterial flagellum through the peptidoglycan (pg) layer by cleaving the β-1,4 glycosidic bond between n-acetylglucosamine and n-acetylmuramic acid sugars that comprise the glycan strands of pg. here we describe the crystal structure of the gh domain of flgj from bacterial pathogen salmonella typhimurium (stflgj). interestingly, the active site of stflgj was blo ...201626871950
listeria monocytogenes wall teichoic acid decoration in virulence and cell-to-cell spread.wall teichoic acid (wta) comprises a class of glycopolymers covalently attached to the peptidoglycan of gram positive bacteria. in listeria monocytogenes, mutations that prevent addition of certain wta decorating sugars are attenuating. however, the steps required for decoration and the pathogenic process interrupted are not well described. we systematically examined the requirement for wta galactosylation in a mouse oral-virulent strain by first creating mutations in four genes whose products c ...201626871418
control of relative air humidity as a potential means to improve hygiene on surfaces: a preliminary approach with listeria monocytogenes.relative air humidity fluctuations could potentially affect the development and persistence of pathogenic microorganisms in their environments. this study aimed to characterize the impact of relative air humidity (rh) variations on the survival of listeria monocytogenes, a bacterium persisting on food processing plant surfaces. to assess conditions leading to the lowest survival rate, four strains of l. monocytogenes (egde, ccl500, ccl128, and lo28) were exposed to different rh conditions (75%, ...201626840373
influence of probiotics, included in peanut butter, on the fate of selected salmonella and listeria strains under simulated gastrointestinal conditions.this study observed the behaviour of probiotics and selected bacterial pathogens co-inoculated into peanut butter during gastrointestinal simulation.201626836043
listeria monocytogenes endovascular graft infection.although best managed by surgical resection, we present a case of listeria monocytogenes endovascular graft infection alternatively treated with graft retention and antibiotic induction followed by a lifelong suppressive course. the epidemiological, pathological, and clinical features of this unique entity are reviewed.201626835477
listeria monocytogenes σh contributes to expression of competence genes and intracellular growth.the alternative sigma factor σ(h)has two functions in gram-positive bacteria: it regulates sporulation and the development of genetic competence. listeria monocytogenes is a nonsporulating species in which competence has not yet been detected. nevertheless, the main competence regulators and a series of orthologous genes that form the competence machinery are present in its genome; some of the competence genes play a role in optimal phagosomal escape. in this study, strains overexpressing σ(h) a ...201626833412
inhibition of sortase a by chalcone prevents listeria monocytogenes infection.the critical role of sortase a in gram-positive bacterial pathogenicity makes this protein a good potential target for antimicrobial therapy. in this study, we report for the first time the crystal structure of listeria monocytogenes sortase a and identify the active sites that mediate its transpeptidase activity. we also used a sortase a (srta) enzyme activity inhibition assay, simulation, and isothermal titration calorimetry analysis to discover that chalcone, an agent with little anti-l. mono ...201626826492
listeria meningoencephalitis and anti-gq1b antibody syndrome.we report the first case of listeria monocytogenes meningoencephalitis associated with anti-gq1b antibody syndrome in an immunocompetent adult. a prompt diagnosis, made thanks to the multidisciplinary contribution, allowed a combined therapeutic approach leading to final favourable outcome, despite several intercurrent complications.201626825308
fresh produce-associated listeriosis outbreaks, sources of concern, teachable moments, and insights.foodborne transmission of listeria monocytogenes was first demonstrated through the investigation of the 1981 maritime provinces outbreak involving coleslaw. in the following two decades, most listeriosis outbreaks involved foods of animal origin, e.g., deli meats, hot dogs, and soft cheeses. l. monocytogenes serotype 4b, especially epidemic clones i, ii, and ia, were frequently implicated in these outbreaks. however, since 2008 several outbreaks have been linked to diverse types of fresh produc ...201626818997
antimicrobial activity of individual and combined essential oils against foodborne pathogenic bacteria.the antimicrobial activities of essential oils from mexican oregano (lippia berlandieri schauer), mustard (brassica nigra), and thyme (thymus vulgaris) were evaluated alone and in binary combinations against listeria monocytogenes, staphylococcus aureus, or salmonella enteritidis. chemical compositions of the essential oils were analyzed by gas chromatography-mass spectrometry. the mics of the evaluated essential oils ranged from 0.05 to 0.50% (vol/vol). mustard essential oil was the most effect ...201626818994
modeling the impact of ingoing sodium nitrite, sodium ascorbate, and residual nitrite concentrations on growth parameters of listeria monocytogenes in cooked, cured pork sausage.sodium nitrite has been identified as a key antimicrobial ingredient to control pathogens in ready-to-eat (rte) meat and poultry products, including listeria monocytogenes. this study was designed to more clearly elucidate the relationship between chemical factors (ingoing nitrite, ascorbate, and residual nitrite) and l. monocytogenes growth in rte meats. treatments of cooked, cured pork sausage (65% moisture, 1.8% salt, ph 6.6, and water activity 0.98) were based on response surface methodology ...201626818978
prosthetic knee joint infection due to listeria monocytogenes bacteremia in a diabetic female. 201626813571
antimicrobial eugenol nanoemulsion prepared by gum arabic and lecithin and evaluation of drying technologies.the purpose of present work was to develop eugenol oil nanoemulsions using gum arabic and lecithin as food grade natural emulsifiers, and study their antimicrobial activity. in addition, our study also evaluated different drying techniques (spray drying and freeze drying) on the morphology and redispersibility of nanoemulsion powders. the optimal fabrication method, physicochemical and structural characterization, stability, and antimicrobial activity were investigated. results showed that nanoe ...201626902894
towards lag phase of microbial populations at growth-limiting conditions: the role of the variability in the growth limits of individual cells.the water activity (aw) growth limits of unheated and heat stressed listeria monocytogenes individual cells were studied. the aw limits varied from 0.940 to 0.997 and 0.951 to 0.997 for unheated and heat stressed cells, respectively. due to the above variability a decrease in aw results in the presence of a non-growing fraction in the population leading to an additional pseudo-lag in population growth. in this case the total apparent lag of the population is the sum of the physiological lag of t ...201626900994
genes involved in listeria monocytogenes biofilm formation at a simulated food processing plant temperature of 15 °c.listeria monocytogenes is a pathogenic foodborne bacterium whose persistence in food processing environments is in part attributed to its biofilm formation. most biofilm studies have been carried out at 30-37 °c rather than at temperatures found in the food processing plants (i.e., 10-20 °c). the objective of the present study was to mine for novel genes that contribute to l. monocytogenes biofilm formation at 15 °c using the random insertional mutagenesis approach. a library of 11,024 l. monocy ...201626900648
genotypic and antimicrobial characterization of pathogenic bacteria at different stages of cattle slaughtering in southern brazil.meat can be contaminated in different stages of the slaughtering process and the identification of these stages is the starting point to implement adequate control measures. the objectives of this study were to assess the presence of pathogenic microorganisms in cattle carcasses, to identify the most important contamination points of the slaughtering process, and to evaluate the possible risk factors related to them in a cattle slaughterhouse. to this aim, 108 cattle carcasses were sampled at th ...201626896744
type i ifn does not promote susceptibility to foodborne listeria monocytogenes.type i ifn (ifn-α/β) is thought to enhance growth of the foodborne intracellular pathogen listeria monocytogenes by promoting mechanisms that dampen innate immunity to infection. however, the type i ifn response has been studied primarily using methods that bypass the stomach and, therefore, fail to replicate the natural course of l. monocytogenes infection. in this study, we compared i.v. and foodborne transmission of l. monocytogenes in mice lacking the common type i ifn receptor (ifnar1(-/-)) ...201626895837
systems level analyses reveal multiple regulatory activities of cody controlling metabolism, motility and virulence in listeria monocytogenes.bacteria sense and respond to many environmental cues, rewiring their regulatory network to facilitate adaptation to new conditions/niches. global transcription factors that co-regulate multiple pathways simultaneously are essential to this regulatory rewiring. cody is one such global regulator, controlling expression of both metabolic and virulence genes in gram-positive bacteria. branch chained amino acids (bcaas) serve as a ligand for cody and modulate its activity. classically, cody was cons ...201626895237
presence of a widely disseminated listeria monocytogenes serotype 4b clone in india. 201627273224
cd8(+) t cells specific to a single yersinia pseudotuberculosis epitope restrict bacterial replication in the liver but fail to provide sterilizing immunity.cd8(+) t cells use contact-dependent cytolysis of target cells to protect the host against intracellular pathogens. we have previously shown that cd8(+) t cells and perforin are required to protect against the extracellular pathogen yersinia pseudotuberculosis. here we establish an experimental system where cd8(+) t cells specific to a single model antigen are the only memory response present at time of challenge. using mice immunized with a vaccine strain of listeria monocytogenes that expresse ...201627268148
hybrid antifouling and antimicrobial coatings prepared by electroless co-deposition of fluoropolymer and cationic silica nanoparticles on stainless steel: efficacy against listeria monocytogenes.controlling formation, establishment, and proliferation of microbial biofilms on surfaces is critical for ensuring public safety. herein, we report on the synthesis of antimicrobial nanoparticles and their co-deposition along with fluorinated nanoparticles during electroless nickel plating of stainless steel. plating bath composition is optimized to ensure sufficiently low surface energy to resist fouling and microbial adhesion as well as to exert significant (>99.99% reduction) antimicrobial ac ...201627268033
comorbidities and factors associated with central nervous system infections and death in non-perinatal listeriosis: a clinical case series.listeriosis is a rare disease caused by the bacterium listeria monocytogenes and mainly affects at risk people. listeriosis can lead to sepsis, central nervous system (cns) infections and death. the objectives of this study were to describe and quantify comorbidities and neurological sequelae underlying non-perinatal listeriosis cases and to describe the factors associated with death and cns infections in non-perinatal listeriosis.201627267465
inhibitory effect of liposome-entrapped lemongrass oil on the growth of listeria monocytogenes in cheese.listeria monocytogenes infection in dairy products is of mounting public concern. to inhibit bacterial growth, we engineered stimuli-responsive liposomes containing lemongrass oil for this study. the controlled release of liposome-entrapped lemongrass oil is triggered by listerolysin o, secreted by l. monocytogenes. we investigated the antibiotic activities of lemongrass oil liposomes against l. monocytogenes in cheese. we also assessed their possible effects on the quality of the cheese. liposo ...201627265173
infective endocarditis due to listeria monocytogenes: a report of 4 patients. 201627262490
erratum for henke et al., listeria monocytogenes spreads within the brain by actin-based intra-axonal migration. 201626912561
meningoencephalitis and listeria monocytogenes, toxoplasma gondii and brucella spp. coinfection in a dolphin in italy.listeria monocytogenes, toxoplasma gondii and brucella spp. can infect a wide range of species, including humans. in cetaceans, meningoencephalitis has been associated with t. gondii and brucella spp. infection, whereas to our knowledge, l. monocytogenes infection has not previously been reported. meningoencephalitis and l. monocytogenes, t. gondii and brucella spp. were identified by means of both direct and indirect laboratory techniques in an adult female striped dolphin stenella coeruleoalba ...201626912047
nlrp3 inflammasome activation contributes to listeria monocytogenes-induced animal pregnancy failure.listeria monocytogenes (lm), a foodborne pathogen, can cause pregnancy failure in animals, especially in ruminants. recent studies have shown that lm activates inflammasomes to induce il-1β release in macrophages, however, whether the inflammasome activation regulates lm-induced pregnancy failure remains largely unknown. here we used mouse model to investigate the molecular mechanism by which lm-induced inflammsome activation contributes to lm-associated pregnancy failure201626911557
cd8(+) t cells of listeria monocytogenes-infected mice recognize both linear and spliced proteasome products.cd8(+) t cells responding to infection recognize pathogen-derived epitopes presented by mhc class-i molecules. while most of such epitopes are generated by proteasome-mediated antigen cleavage, analysis of tumor antigen processing has revealed that epitopes may also derive from proteasome-catalyzed peptide splicing (pcps). to determine whether pcps contributes to epitope processing during infection, we analyzed the fragments produced by purified proteasomes from a listeria monocytogenes polypept ...201626909514
analysis of multilocus sequence typing and virulence characterization of listeria monocytogenes isolates from chinese retail ready-to-eat food.eighty listeria monocytogenes isolates were obtained from chinese retail ready-to-eat (rte) food and were previously characterized with serotyping and antibiotic susceptibility tests. the aim of this study was to characterize the subtype and virulence potential of these l. monocytogenes isolates by multilocus sequence typing (mlst), virulence-associate genes, epidemic clones (ecs), and sequence analysis of the important virulence factor: internalin a (inla). the result of mlst revealed that thes ...201626909076
biodiversity and hypervirulence of listeria monocytogenes.the integration of large, well-sampled collections of bacterial isolates with genomics and experimental methods provides opportunities for 'top-down' discovery of the genetic basis of phenotypes of interest. in a new report, the authors apply this approach to investigate the heterogeneity in manifestations of disease caused by listeria monocytogenes and demonstrate that a previously uncharacterized cellobiose pts system is involved in central nervous system infection.201626906682
listeria monocytogenes mutants defective in gallbladder replication represent safety-enhanced vaccine delivery platforms.the gram positive intracellular pathogen listeria monocytogenes represents a promising vaccine or therapeutic dna delivery vector that has been successfully administered to humans in clinical trials. however in generating listeria mutants with therapeutic potential it is important to balance safety attenuation with efficacy. here we show that l. monocytogenes mutants with a reduced capacity for murine gallbladder replication are capable of stimulating t cell responses in mice and protecting vacc ...201626905522
proteolysis triggers self-assembly and unmasks innate immune function of a human α-defensin peptide.human α-defensin 6 (hd6) is a unique peptide of the defensin family that provides innate immunity in the intestine by self-assembling to form high-order oligomers that entrap bacteria and prevent host cell invasion. here, we report critical steps in the self-assembly pathway of hd6. we demonstrate that hd6 is localized in secretory granules of small intestinal paneth cells. hd6 is stored in these granules as an 81-residue propeptide (prohd6), and is recovered from ileal lumen as a 32-residue mat ...201627076903
validation of the applied biosystems 7500 fast instrument for detection of <em>listeria monocytogenes</em> with the suretect <em>listeria monocytogenes</em> pcr assay.in 2013, the thermo scientific™ suretect™ listeria monocytogenes real-time pcr assay was certified by the aoac research institute (ri) performance tested methods (sm) program as a rapid method for the detection of l. monocytogenes from a wide range of food matrixes and surface samples. this report details the method modification studies undertaken to extend the analysis of this pcr assay to the applied biosystems™ 7500 fast pcr instrument and applied biosystems rapidfinder™ express 2.0 software ...201627075433
il-12p40/il-10 producing precd8α/clec9a+ dendritic cells are induced in neonates upon listeria monocytogenes infection.infection by listeria monocytogenes (lm) causes serious sepsis and meningitis leading to mortality in neonates. this work explored the ability of cd11c(high) lineage dcs to induce cd8+ t-cell immune protection against lm in mice before 7 days of life, a period symbolized by the absence of murine il-12p70-producing cd11c(high)cd8α+ dendritic cells (dcs). we characterized a dominant functional batf3-dependent precursor of cd11c(high) dcs that is clec9a+cd205+cd24+ but cd8α- at 3 days of life. afte ...201627074026
picoliter well array chip-based digital recombinase polymerase amplification for absolute quantification of nucleic acids.absolute, precise quantification methods expand the scope of nucleic acids research and have many practical applications. digital polymerase chain reaction (dpcr) is a powerful method for nucleic acid detection and absolute quantification. however, it requires thermal cycling and accurate temperature control, which are difficult in resource-limited conditions. accordingly, isothermal methods, such as recombinase polymerase amplification (rpa), are more attractive. we developed a picoliter well a ...201627074005
inhibition of listeria monocytogenes in fresh cheese using chitosan-grafted lactic acid packaging.a chitosan from biologically obtained chitin was successfully grafted with d,l-lactic acid (la) in aqueous media using p-toluenesulfonic acid as catalyst to obtain a non-toxic, biodegradable packaging material that was characterized using scanning electron microscopy, water vapor permeability, and relative humidity (rh) losses. additionally, the grafting in chitosan with la produced films with improved mechanical properties. this material successfully extended the shelf life of fresh cheese and ...201627070568
matrix metalloproteinase-9 plays a role in protecting zebrafish from lethal infection with listeria monocytogenes by enhancing macrophage migration.zebrafish could serve as an alternative animal model for pathogenic bacteria in multiple infectious routes. our previous study showed that immersion infection in zebrafish with listeria monocytogenes did not cause lethality but induced transient expression of several immune response genes. we used an affymetrix gene chip to examine the expression profiles of genes of zebrafish immersion-infected with l. monocytogenes. a total of 239 genes were up-regulated and 56 genes down-regulated compared wi ...201627068748
the metalloprotease mpl supports listeria monocytogenes dissemination through resolution of membrane protrusions into vacuoles.listeria monocytogenes is an intracellular pathogen that disseminates within the intestinal epithelium through acquisition of actin-based motility and formation of plasma membrane protrusions that project into adjacent cells. the resolution of membrane protrusions into vacuoles from which the pathogen escapes results in bacterial spread from cell to cell. this dissemination process relies on the mlp-acta-plcb operon, which encodes acta, a bacterial nucleation-promoting factor that mediates actin ...201627068088
role of proapoptotic bh3-only proteins in listeria monocytogenes infection.the ability of pathogens to influence host cell survival is a crucial virulence factor. listeria monocytogenes (lm) infection is known to be associated with severe apoptosis of hepatocytes and spleen cells. this impairs host defense mechanisms and thereby facilitates the spread of intracellular pathogens. the general mechanisms of apoptosis elicited by lm infection are understood, however, the roles of bh3-only proteins during primary lm infection have not been examined. to explore the roles of ...201627064265
characterization of antimicrobial resistance of listeria monocytogenes strains isolated from a pork processing plant and its respective meat markets in southern china.a total of 78 listeria monocytogenes isolates from a pork processing plant and the respective meat markets in southern china were examined. this number includes 60 isolates from pork at markets, 5 from cooked pork products at markets, 10 from pork at a processing plant, and 3 from food-contact surfaces at the processing plant. all isolates were subjected to serotyping, antimicrobial susceptibility testing, pulsed-field gel electrophoresis (pfge), and molecular basis of antibiotic resistance. fou ...201627058266
genome sequences for a cluster of human isolates of listeria monocytogenes identified in south africa in 2015.listeria monocytogenesis a gram-positive bacterium with a ubiquitous presence in the environment. there is growing concern about the increasing prevalence ofl. monocytogenesassociated with food-borne outbreaks. here we report genome sequences for a cluster of human isolates ofl. monocytogenesidentified in south africa in 2015.201627056221
listeria meningitis in an immunocompetent child: a case report.listeria monocytogenes is a facultative anerobic, gram-positive bacillus that is isolated from the soil, vegetables, and wild or domestic animals. listeria infection is usually found in the older adults, immunocompromised patients, pregnant women, and newborns, whereas it is rare in healthy infants and children. listeria monocytogenes may cause meningitis, meningoencephalitis, brain abscess, pyogenic arthritis, osteomyelitis, and liver abscess in children. the course of meningoencephalitis by li ...201627055168
hygiene and safety in the meat processing environment from butcher shops: microbiological contamination and listeria monocytogenes.the quality and safety of meat products can be estimated by assessing their contamination by hygiene indicator microorganisms and some foodborne pathogens, with listeria monocytogenes as a major concern. to identify the main sources of microbiological contamination in the processing environment of three butcher shops, surface samples were obtained from the hands of employees, tables, knives, inside butcher displays, grinders, and meat tenderizers (24 samples per point). all samples were subjecte ...201627052868
viability of listeria monocytogenes on boneless, water-added hams, commercially prepared with and without food-grade chemicals, during extended storage at 4 and/or -2.2°c.viability of listeria monocytogenes was monitored during refrigerated (4°c) and/or frozen (i.e., deep chilling at -2.2°c) storage on casing-cooked hams that were commercially prepared with and without potassium lactate and sodium diacetate (1.6%), buffered vinegar (2.2%), buffered vinegar and potassium lactate (1.7%), or a blend of potassium lactate, potassium acetate, and sodium diacetate (1.7%). a portion of these hams were subsequently surface treated with lauric arginate ester (lae; 44 ppm). ...201627052866
effectiveness of broad-spectrum chemical produce sanitizers against foodborne pathogens as in vitro planktonic cells and on the surface of whole cantaloupes and watermelons.over the past few years, foodborne disease outbreaks linked to enteric pathogens present on cantaloupe and watermelon surfaces have raised concerns in the melon industry. this research evaluated the effectiveness of commercially available produce sanitizers against selected foodborne pathogens, both in cell suspensions and on the outer rind surface of melons. the sanitizers (65 and 200 ppm of chlorine, 5 and 35% hydrogen peroxide, 5 and 50 ppm of liquid chlorine dioxide, various hydrogen peroxid ...201627052854
efficacy of uv-c irradiation for inactivation of food-borne pathogens on sliced cheese packaged with different types and thicknesses of plastic films.in this study, the efficacy of using uv-c light to inactivate sliced cheese inoculated with escherichia coli o157:h7, salmonella typhimurium, and listeria monocytogenes and, packaged with 0.07 mm films of polyethylene terephthalate (pet), polyvinylchloride (pvc), polypropylene (pp), and polyethylene (pe) was investigated. the results show that compared with pet and pvc, pp and pe films showed significantly reduced levels of the three pathogens compared to inoculated but non-treated controls. the ...201627052716
microbial and sensorial models for head-on and gutted (hog) atlantic salmon (salmo salar) stored from 0 to 15 °c.predictive models offer efficient means to manage the quality and safety of highly perishable seafood. salmon is an increasingly popular seafood, and relies on well managed domestic and international supply chains to minimize growth of spoilage and pathogenic bacteria. while the literature describes predictive models for smoked and modified atmosphere packaged salmon, there are no reported models for spoilage bacteria and listeria monocytogenes on head-on and gutted (hog) aerobically-stored atla ...201627052713
metagenomic analysis of a mexican ripened cheese reveals a unique complex microbiota.cotija cheese is a mexican handcrafted product made from raw cow milk whose ripening process occurs spontaneously and, presumably, it is influenced by environmental conditions. its sensory characteristics and safety are probably the result of the balance between microbial populations and their metabolic capacity. in this work, we studied the dominance and richness of the bacteria in the cotija cheese microbiome, as well as their metabolic potential by high-throughput sequencing. by the analysis ...201627052710
persistent and non-persistent strains of listeria monocytogenes: a focus on growth kinetics under different temperature, salt, and ph conditions and their sensitivity to sanitizers.this study aimed to investigate the effect of different conditions, including temperature (37 °c, 22 °c, and 4 °c), nacl concentrations (2.5%, 4%, and 8%), and acidity (ph = 5), on the growth response of persistent and non-persistent isolates of listeria monocytogenes. the resistance to two common sanitizers (benzalkonium chloride and hydrogen peroxide) was also investigated. a selected group of 41 persistent and non-persistent l. monocytogenes isolates recovered from three cheese processing pla ...201627052708
inhibition of listeria monocytogenes on cooked cured chicken breasts by acidified coating containing allyl isothiocyanate or deodorized oriental mustard extract.ready-to-eat meats are considered foods at high risk to cause life-threatening listeria monocytogenes infections. this study screened 5 l. monocytogenes strains for their ability to hydrolyze sinigrin (a glucosinolate in oriental mustard), which formed allyl isothiocyanate (aitc) and reduced l. monocytogenes viability on inoculated vacuum-packed, cooked, cured roast chicken slices at 4 °c. tests involved incorporation of 25-50 μl/g aitc directly or 100-250 mg/g oriental mustard extract in 0.5% ( ...201627052706
h3k4me3 demethylase kdm5a is required for nk cell activation by associating with p50 to suppress socs1.the h3k4me3 demethylase kdm5a regulates gene transcription and is implicated in carcinogenesis. however, the role of kdm5a in innate immune response remains poorly understood. here, we demonstrate that kdm5a deficiency impairs activation of natural killer (nk) cells, with decreased ifn-γ production. accordingly, kdm5a(-/-) mice are highly susceptible to listeria monocytogenes (lm) infection. during nk cell activation, loss of kdm5a profoundly impairs phosphorylation and nuclear localization of s ...201627050510
optimizing application parameters for lactic acid and sodium metasilicate against pathogens on fresh beef, pork and deli meats.lactic acid (la) and sodium metasilicate (sm) have been approved for use as antimicrobials on meat. the objectives were to determine optimum concentrations, temperatures and hot-water dips of la and sm for reduction of escherichia coli o157:h7, non-o157 shiga-toxin producing e. coli (stec), salmonella spp., and listeria monocytogenes on beef, pork and deli meats. la was applied at 1, 2, 3, and 4% and sm was applied at 2, 3, 4, and 5%. sm4 and la4 were the lowest concentrations most effective aga ...201627050408
nanoemulsions of thymol and eugenol co-emulsified by lauric arginate and lecithin.lauric arginate (lae) is a cationic surfactant with excellent antimicrobial activities. to incorporate essential oil components (eocs) in aqueous systems, properties of eoc nanoemulsions prepared with a lae and lecithin mixture were studied. the lae-lecithin mixture resulted in stable translucent nanoemulsions of thymol and eugenol with spherical droplets smaller than 100nm, contrasting with the turbid emulsions prepared with individual emulsifiers. zeta-potential data suggested the formation of ...201627041312
evidence of metabolically active but non-culturable listeria monocytogenes in long-term growth at 10 °c.cultures of listeria monocytogenes at low temperatures (10 °c) in a broth model revealed long-term survival at about 0.04% cell density in relation to the log phase. in contrast, direct viable counts and pma real-time pcr data suggested that 50% and 1% of the population retain membrane integrity, respectively. to elucidate the observed difference, the metabolic activity of the bacterial population was investigated by multiparametric flow cytometry, including the assessment of membrane integrity, ...201627040843
evaluation of a cross contamination model describing transfer of salmonella spp. and listeria monocytogenes during grinding of pork and beef.in a previous study, a model was developed to describe the transfer and survival of salmonella during grinding of pork (møller, c.o.a., nauta, m.j., christensen, b.b., dalgaard, p., hansen, t.b., 2012. modelling transfer of salmonella typhimurium dt104 during simulation of grinding of pork. journal of applied microbiology 112 (1), 90-98). the robustness of this model is now evaluated by studying its performance for predicting the transfer and survival of salmonella spp. and listeria monocytogene ...201627035678
genome sequences of five nonvirulent listeria monocytogenes serovar 4 strains.we present the complete genome sequences of five nonpathogeniclisteria monocytogenesserovar 4 strains: wslc 1018 (4e), 1019 (4c), 1020 (4a), 1033 (4d), and 1047 (4d). these sequences may help to uncover genes involved in the synthesis of the serovar antigens-phenotypic determinants of virulence deemed clinically relevant.201627034489
mechanistic studies of the agmatine deiminase from listeria monocytogenes.listeria monocytogenes is a gram-positive food-borne pathogen that is capable of living within extreme environments (i.e. low temperatures and ph). this ability to survive in such conditions may arise, at least in part, from agmatine catabolism via the agmatine deiminase system (agds). this catabolic pathway utilizes an agmatine deiminase (agd) to hydrolyse agmatine into n-carbamoylputrescine (ncp), with concomitant release of ammonia, which increases the ph, thus mitigating the ill effects of t ...201627034081
the regulatory roles of ncrna rli60 in adaptability of listeria monocytogenes to environmental stress and biofilm formation.listeria monocytogenes is a facultative anaerobic gram-positive bacterium. it is well adapted to external environments and able to infect both humans and animals. to understand the impacts of ncrna rli60 on the adaptability of l. monocytogenes to environmental stresses and biofilm formation, a rli60 deletion strain of l. monocytogenes (lm-δrli60) was constructed using splicing by overlap extension pcr (soe-pcr) and homologous recombination and then compared it with wild-type strain l. monocytoge ...201627032404
retail deli slicer cleaning frequency--six selected sites, united states, 2012.listeria monocytogenes (listeria) causes the third highest number of foodborne illness deaths (an estimated 255) in the united states annually, after nontyphoidal salmonella species and toxoplasma gondii (1). deli meats are a major source of listeriosis illnesses, and meats sliced and packaged at retail delis are the major source of listeriosis illnesses attributed to deli meat (4). mechanical slicers pose cross-contamination risks in delis and are an important source of listeria cross-contamina ...201627031689
whole-genome sequencing used to investigate a nationwide outbreak of listeriosis caused by ready-to-eat delicatessen meat, denmark, 2014.listeriosis is a serious foodborne infection. outbreaks of listeriosis occur rarely, but have often proved difficult to solve. in june 2014, we detected and investigated a listeriosis outbreak in denmark using patient interviews and whole-genome sequencing (wgs).201627025820
comparing listeriosis risks in at-risk populations using a user-friendly quantitative microbial risk assessment tool and epidemiological data.although infection by the pathogenic bacterium listeria monocytogenes is relatively rare, consequences can be severe, with a high case-fatality rate in vulnerable populations. a quantitative, probabilistic risk assessment tool was developed to compare estimates of the number of invasive listeriosis cases in vulnerable canadian subpopulations given consumption of contaminated ready-to-eat delicatessen meats and hot dogs, under various user-defined scenarios. the model incorporates variability and ...201627019157
overexpression of angiotensin-converting enzyme in myelomonocytic cells enhances the immune response.angiotensin-converting enzyme (ace) converts angiotensin i to the vasoconstrictor angiotensin ii and thereby plays an important role in blood pressure control. however, ace is relatively non-specific in its substrate specificity and cleaves many other peptides. recent analysis of mice overexpressing ace in monocytes, macrophages, and other myelomonocytic cells shows that these animals have a marked increase in resistance to experimental melanoma and to infection by listeria monocytogenes or meth ...201627018193
acidified nitrite inhibits proliferation of listeria monocytogenes - transcriptional analysis of a preservation method.sodium nitrite (nano2) is added as a preservative during raw meat processing such as raw sausage production to inhibit growth of pathogenic bacteria. in the present study it was shown in challenge assays that the addition of sodium nitrite indeed inhibited growth and survival of listeria monocytogenes in short-ripened spreadable raw sausages. furthermore, in vitro growth analyses were performed, which took into account combinations of various parameters of the raw sausage ripening process like t ...201627017279
antimicrobial properties of microemulsions formulated with essential oils, soybean oil, and tween 80.it was previously found that blending soybean oil with cinnamon bark oil (cbo), eugenol or thyme oil, tween 80, and equal masses of water and propylene glycol could be used to prepare microemulsions. in the present study, the objective was to determine the antimicrobial activity of the microemulsions in tryptic soy broth (tsb) and 2% reduced fat milk. in tsb, the minimum inhibitory concentration (mic) of cbo solubilized in microemulsions was up to 625 ppm against cocktails of listeria monocytoge ...201627016636
silver as antibacterial toward listeria monocytogenes.listeria monocytogenes is a serious foodborne pathogen that can contaminate food during processing and can grow during food shelf-life. new types of safe and effective food contact materials embedding antimicrobial agents, like silver, can play an important role in the food industry. the present work aimed at evaluating the in vitro growth kinetics of different strains of l. monocytogenes in the presence of silver, both in its ionic and nano form. the antimicrobial effect was determined by assay ...201627014230
acidic electrolyzed water as a novel transmitting medium for high hydrostatic pressure reduction of bacterial loads on shelled fresh shrimp.acidic electrolyzed water (aew), a novel non-thermal sterilization technology, is widely used in the food industry. in this study, we firstly investigated the effect of aew as a new pressure transmitting medium for high hydrostatic pressure (aew-hhp) processing on microorganisms inactivation on shelled fresh shrimp. the optimal conditions of aew-hhp for vibrio parahaemolyticus inactivation on sterile shelled fresh shrimp were obtained using response surface methodology: nacl concentration to ele ...201627014228
characterization of antimicrobial activity against listeria and cytotoxicity of native melittin and its mutant variants.antimicrobial peptides (amps) are relatively short peptides that have the ability to penetrate the cell membrane, form pores leading to cell death. this study compares both antimicrobial activity and cytotoxicity of native melittin and its two mutants, namely, melittin i17k (gigavlkvlttglpalkswikrkrqq) with a higher charge and lower hydrophobicity and mutant g1i (iigavlkvlttglpaliswikrkrqq) of higher hydrophobicity. the antimicrobial activity against different strains of listeria was investigate ...201627011349
a structural comparison of listeria monocytogenes protein chaperones prsa1 and prsa2 reveals molecular features required for virulence.listeria monocytogenes is a gram-positive environmental bacterium that lives within soil but transitions into a pathogen upon contact with a mammalian host. the transition of l. monocytogenes from soil dweller to cytosolic pathogen is dependent upon secreted virulence factors that mediate cell invasion and intracellular growth. prsa1 and prsa2 are secreted bacterial lipoprotein chaperones that contribute to the folding of proteins translocated across the bacterial membrane; prsa2 is required for ...201627007641
prevalence and contamination levels of listeria monocytogenes in ready-to-eat foods in tokyo, japan.we surveyed prevalence and contamination levels of listeria monocytogenes in ready-to-eat foods between 2000 and 2012 in tokyo. l. monocytogenes was isolated from 52 (1.7%) out of 2,980 samples. comparing the prevalence in the study period, 2.2% were positive in the former period (2000-2005) and 1.2% in the latter (2006-2012). using the most probable number (mpn) technique, 32 samples were contaminated with fewer than 0.3 l. monocytogenes/g, 10 samples with 0.3-1.0/g and 4 samples with more than ...201627000951
immunotherapy with a her2-targeting listeria induces her2-specific immunity and demonstrates potential therapeutic effects in a phase i trial in canine osteosarcoma.recombinant listeria vaccines induce tumor-specific t-cell responses that eliminate established tumors and prevent metastatic disease in murine cancer models. we used dogs with her2/neu(+) appendicular osteosarcoma, a well-recognized spontaneous model for pediatric osteosarcoma, to determine whether a highly attenuated, recombinant listeria monocytogenes expressing a chimeric human her2/neu fusion protein (adxs31-164) could safely induce her2/neu-specific immunity and prevent metastatic disease.201626994144
virulence gene-associated mutant bacterial colonies generate differentiating two-dimensional laser scatter fingerprints.in this study, we investigated whether a laser scatterometer designated bardot (bacterial rapid detection using optical scattering technology) could be used to directly screen colonies of listeria monocytogenes, a model pathogen, with mutations in several known virulence genes, including the genes encoding listeria adhesion protein (lap; lap mutant), internalin a (δinla strain), and an accessory secretory protein (δseca2 strain). here we show that the scatter patterns of lap mutant, δinla, and δ ...201626994085
occurrence and antimicrobial resistance patterns of listeria monocytogenes isolated from vegetables.although the consumption of fresh and minimally processed vegetables is considered healthy, outbreaks related to the contamination of these products are frequently reported. among the food-borne pathogens that contaminate vegetables is listeria monocytogenes, a ubiquitous organism that exhibits the ability to survive and multiply at refrigerated temperatures. this study aimed to evaluate the occurrence of l. monocytogenes in vegetables as well as the antimicrobial resistance of isolates. the res ...201626991279
opposing role of tumor necrosis factor receptor 1 signaling in t cell-mediated hepatitis and bacterial infection in mice.death receptor (dr) ligands such as tumor necrosis factor (tnf) have been identified as fundamental mediators of liver damage both in mouse models and in humans. while the essential site of function of dr signaling is conceivably the hepatocyte, a systematic analysis is missing. using mice with conditional gene ablation, we analyzed the tissue-specific function of dr signaling in t cell-dependent (concanavalin a) and independent (lipopolysaccharide/galactosamine) hepatitis and in models of bacte ...201626991125
attenuating listeria monocytogenes virulence by targeting the regulatory protein prfa.the transcriptional activator prfa, a member of the crp/fnr family, controls the expression of some key virulence factors necessary for infection by the human bacterial pathogen listeria monocytogenes. phenotypic screening identified ring-fused 2-pyridone molecules that at low micromolar concentrations attenuate l. monocytogenes cellular uptake by reducing the expression of virulence genes. these inhibitors bind the transcriptional regulator prfa and decrease its affinity for the consensus dna-b ...201626991105
a hot water extract of aralia cordata activates bone marrow-derived macrophages via a myeloid differentiation protein 88-dependent pathway and protects mice from bacterial infection.in traditional asian medicine, aralia cordata (ac) is a known as a pain reliever and anti-inflammatory drug. although several of its biological activities have been reported, the immunomodulatory effects of a hot water extract of ac (hac) have not yet been described. the aim of this study was to investigate whether hac modulates the activation of macrophages, which play important roles in innate immune responses against microbial pathogens, and if so, to determine the molecular mechanisms by whi ...201626989992
molecular typing and epidemiology of human listeriosis cases, denmark, 2002-2012.denmark has a high incidence of invasive listeriosis (0.9 cases/100,000 population in 2012). we analyzed patient data, clinical outcome, and trends in pulsed-field gel electrophoresis (pfge) and multilocus sequence typing (mlst) of listeria monocytogenes strains isolated in denmark during 2002-2012. we performed 2-enzyme pfge and serotyping on 559 isolates and mlst on 92 isolates and identified some correlation between molecular type and clinical outcome and patient characteristics. we found 178 ...201626982714
trends in us hospital stays for listeriosis in infants.although listeriosis is rare in infants, it is common for young infants with suspected serious bacterial infection to be treated empirically with agents selected, in part, for their activity against listeria monocytogenes. our objectives were to describe the recent epidemiology of hospital discharges for listeriosis among infants in the united states and to precisely estimate the incidence of listeriosis according to infant age and meningitis status.201626980754
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