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contribution of listeria monocytogenes reca to acid and bile survival and invasion of human intestinal caco-2 cells.the food-borne pathogen listeria monocytogenes is able to colonize the human gastro-intestinal tract and subsequently cross the intestinal barrier. thus, for l. monocytogenes to become virulent, it must survive the low ph of the stomach, high bile concentrations in the small intestine, and invade the epithelial cells. in this study, we show that reca, which is an important factor in dna repair and the activator of the sos response, contributes to the resistance against acid and bile and to the a ...201121273119
combined effect of ultrasound and organic acids to reduce escherichia coli o157:h7, salmonella typhimurium, and listeria monocytogenes on organic fresh lettuce.this study was performed to compare the effectiveness of individual treatments (ultrasound and organic acids) and their combination on reducing foodborne pathogens on organic fresh lettuce. lettuce leaves were inoculated with a cocktail of three strains each of escherichia coli o157:h7, salmonella typhimurium, and listeria monocytogenes and treated with ultrasound (40 khz) alone, organic acids (0.3, 0.5, 0.7, 1.0, and 2.0%--malic acid, lactic acid, and citric acid) alone and combined with ultras ...201121276633
review--persistence of listeria monocytogenes in food industry equipment and premises.to understand why listeria monocytogenes may persist in food industry equipment and premises, notably at low temperature, scientific studies have so far focused on adhesion potential, biofilm forming ability, resistance to desiccation, acid and heat, tolerance to increased sublethal concentration of disinfectants or resistance to lethal concentrations. evidence from studies in processing plants shows that the factors associated with the presence of l. monocytogenes are those that favor growth. i ...201121276634
the intracellular srna transcriptome of listeria monocytogenes during growth in macrophages.small non-coding rnas (srnas) are widespread effectors of post-transcriptional gene regulation in bacteria. currently extensive information exists on the srnas of listeria monocytogenes expressed during growth in extracellular environments. we used deep sequencing of cdnas obtained from fractioned rna (<500 nt) isolated from extracellularly growing bacteria and from l. monocytogenes infected macrophages to catalog the srna repertoire during intracellular bacterial growth. here, we report on the ...201121278422
etiology of invasive bacterial infections in immunocompetent children in korea (1996-2005): a retrospective multicenter study.the purpose of this study was to identify the major etiological agents responsible for invasive bacterial infections in immunocompetent korean children. we retrospectively surveyed invasive bacterial infections in immunocompetent children caused by eight major pediatric bacteria, namely streptococcus pneumoniae, haemophilus influenzae, neisseria meningitidis, staphylococcus aureus, streptococcus agalactiae, streptococcus pyogenes, listeria monocytogenes, and salmonella species that were diagnose ...201121286006
ifn-a-producing pdca-1+ siglec-h- b cells mediate innate immune defense by activating nk cells.b cells have multiple functions in adaptive immunity, including antibody production, antigen presentation and regulation of t-cell responses. recent evidences indicate that b cells have more subsets than previously thought and may have non-classical functions, such as involvement in innate immunity and immune regulation; however, how b cells respond to microbial infection and elicit innate defense remain unclear. in this study, we identified a new subset of pdca-1(+) siglec-h(-) cd19(+) b cells ...201121287550
antibacterial abietane-type diterpenoid, taxodone from metasequoia glyptostroboides miki ex hu.in an attempt to isolate bioactive constituents, ethyl acetate cone extract of metasequoia glyptostroboides was subjected to a column chromatographic analysis that resulted in isolation of an abietane-type diterpenoid, taxodone. its structure was elucidated by spectroscopic means. further, taxodone showed potential antibacterial effect as diameters of zones of inhibition against foodborne pathogenic bacteria, such as listeria monocytogenes atcc 19166, salmonella typhimurium kctc 2515, s. enterit ...201021289435
escherichia coli producing cnf1 toxin hijacks tollip to trigger rac1-dependent cell invasion.rho gtpases, which are master regulators of both the actin cytoskeleton and membrane trafficking, are often hijacked by pathogens to enable their invasion of host cells. here we report that the cytotoxic necrotizing factor-1 (cnf1) toxin of uropathogenic escherichia coli (upec) promotes rac1-dependent entry of bacteria into host cells. our screen for proteins involved in rac1-dependent upec entry identifies the toll-interacting protein (tollip) as a new interacting protein of rac1 and its ubiqui ...201121291504
effect of acid tolerance response (atr) on attachment of listeria monocytogenes scott a to stainless steel under extended exposure to acid or/and salt stress and resistance of sessile cells to subsequent strong acid challenge.the aim of this study was to investigate the potential effect of adaptive stationary phase acid tolerance response (atr) of listeria monocytogenes scott a cells on their attachment to stainless steel (ss) under low ph or/and high salt conditions and on the subsequent resistance of sessile cells to strong acid challenge. nonadapted or acid-adapted stationary-phase l. monocytogenes cells were used to inoculate (ca. 10⁸ cfu/ml) brain heart (bh) broth (ph 7.4, 0.5% w/v nacl) in test tubes containing ...201121295367
significant shift in median guinea pig infectious dose shown by an outbreak-associated listeria monocytogenes epidemic clone strain and a strain carrying a premature stop codon mutation in inla.listeria monocytogenes contains (i) epidemic clone (ec) strains, which have been linked to the majority of listeriosis outbreaks worldwide and are overrepresented among sporadic cases in the united states, and (ii) strains commonly isolated from ready-to-eat foods that carry a mutation leading to a premature stop codon (pmsc) in inla, which encodes the key virulence factor internalin a (inla). internalin a binds certain isoforms of the cellular receptor e-cadherin to facilitate crossing the inte ...201121296943
gene expression profiling of a pressure-tolerant listeria monocytogenes scott a ctsr deletion mutant.listeria monocytogenes is a food-borne pathogen of significant threat to public health. high hydrostatic pressure (hhp) treatment can be used to control listeria monocytogenes in food. the ctsr (class three stress gene repressor) protein negatively regulates the expression of class iii heat shock genes. a spontaneous pressure-tolerant ctsr mutant 2-1 that was able to survive under hhp treatment has been identified previously. so far, there is only limited information about the mechanisms of surv ...201121298319
purification, crystallization and preliminary x-ray crystallographic analysis of lmo0540 from listeria monocytogenes.penicillin-binding proteins catalyze the biosynthesis of the peptidoglycan chains of the bacterial cell wall, which protects cells from osmotic pressure. although lmo0540 has been identified as a putative penicillin-binding protein that contributes to the virulence of listeria monocytogenes, the biochemical role of lmo0540 remains unclear. to provide insights into its biochemical function, lmo0540 was overexpressed, purified and crystallized by the sitting-drop vapour-diffusion method. diffracti ...201121301102
neonatal listeriosis: a case report from sub-himalayas. 201121304207
antioxidant and antimicrobial activities of essential oils obtained from oregano (origanum vulgare ssp. hirtum) by using different extraction methods.in this study, antioxidant and antimicrobial activities of essential oils obtained from oregano (origanum vulgare ssp. hirtum) were determined by using solvent-free microwave extraction (sfme), supercritical fluid extraction, and conventional hydrodistillation (ch) methods. the inhibitory effects on the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical of essential oils obtained from oregano by using sfme and ch were similar. however, essential oil extracted by ch showed greater (2. ...201121314366
fate and efficacy of lacticin 3147-producing lactococcus lactis in the mammalian gastrointestinal tract.gastrointestinal survival of the bacteriocin-producing strain, lactococcus lactis dpc6520, was evaluated systematically in vitro and in vivo with a view to using this strain to deliver biologically active lacticin 3147, a broad-spectrum bacteriocin, to the gut. the activity of the lacticin 3147 producer was also evaluated against two clinically relevant pathogens: clostridium difficile and listeria monocytogenes. when suspended in an appropriate matrix, the lactococcal strain is capable of survi ...201121314706
inhibitory spectra and modes of antimicrobial action of gallotannins from mango kernels (mangifera indica l.).this study investigated the antimicrobial activities and modes of action of penta-, hexa-, hepta-, octa-, nona-, and deca-o-galloylglucose (gallotannins) isolated from mango kernels. the mics and minimum bactericidal concentrations (mbcs) against food-borne bacteria and fungi were determined using a critical dilution assay. gram-positive bacteria were generally more susceptible to gallotannins than were gram-negative bacteria. the mics of gallotannins against bacillus subtilis, bacillus cereus, ...201121317249
proof of concept for recombinant cellular controls in quantitative molecular pathogen detection.in this study, we present the concept of internal sample process controls (ispcs) to monitor the efficiency of an analytical chain using sample preparation and quantitative pcr (qpcr). a recombinant listeria monocytogenes ?prfa (targeted deletion) strain containing a competitive artificial single-copy genomic target was applied to naturally contaminated samples to demonstrate its analytical suitability as an ispc.201121317266
pregnancy reduces the genetic resistance of c57bl/6 mice to listeria monocytogenes infection by intragastric inoculation.in this study, we compared genetically resistant c57bl/6 and susceptible a/j mice for their resistance to listeria monocytogenes infection during pregnancy. intragastric infection with modest numbers of bacterial cells (10(5) cfu) caused reproducible fetal infection and abortion in both mouse strains. bioluminescence imaging demonstrated dissemination of l. monocytogenes cells from maternal to fetal organs within 3 days of intragastric infection. although non-pregnant c57bl/6 mice were significa ...201121320586
listeria monocytogenes transiently alters mitochondrial dynamics during infection.mitochondria are essential and highly dynamic organelles, constantly undergoing fusion and fission. we analyzed mitochondrial dynamics during infection with the human bacterial pathogen listeria monocytogenes and show that this infection profoundly alters mitochondrial dynamics by causing transient mitochondrial network fragmentation. mitochondrial fragmentation is specific to pathogenic listeria monocytogenes, and it is not observed with the nonpathogenic listeria innocua species or several oth ...201121321208
compatible solutes: a listerial passe-partout?recently we reported a role for compatible solute uptake in mediating bile tolerance and increased gastrointestinal persistence in the foodborne pathogen listeria monocytogenes.1 herein, we review the evolution in our understanding of how these low molecular weight molecules contribute to growth and survival of the pathogen both inside and outside the body, and how this stress survival mechanism may ultimately be used to target and kill the pathogen.201021326913
development of a novel oral vaccine against mycobacterium avium paratuberculosis and johne disease: a patho-biotechnological approach.mycobacterium avium subsp. paratuberculosis (map) is the etiological agent of johne disease, a granulomatous enteritis of cattle and other domesticated and wild ruminant species. johne disease is prevalent worldwide and has a significant impact on the global agricultural economy. current vaccines against johne are insufficient in stemming its spread, and associated side-effects prevent their widespread use in control programs. effective and safe vaccine strategies are needed. the main purpose of ...201021326921
live, attenuated strains of listeria and salmonella as vaccine vectors in cancer treatment.live, attenuated strains of many bacteria that synthesize and secrete foreign antigens are being developed as vaccines for a number of infectious diseases and cancer. bacterial-based vaccines provide a number of advantages over other antigen delivery strategies including low cost of production, the absence of animal products, genetic stability and safety. in addition, bacterial vaccines delivering a tumor-associated antigen (taa) stimulate innate immunity and also activate both arms of the adapt ...201021327055
the use of listeria monocytogenes as a dna delivery vector for cancer gene therapy.listeria monocytogenes is an intracellular pathogen that lyses the phagosomal vacuole of infected cells, proliferates in the host cell cytoplasm and can actively enter adjacent cells. the pathogen is therefore well suited to exploitation as a vector for the delivery of dna to target cells as the lifecycle favors cellular targeting with vector amplification and the potential for cell-to-cell spread. we have recently demonstrated dna transfer by l. monocytogenes in growing tumors in murine models. ...201021327062
efficacy of a lactococcus lactis δpyrg vaccine delivery platform expressing chromosomally integrated hly from listeria monocytogenes.listeria monocytogenes is a significant food-borne pathogen and the causative agent of listeriosis, a disease which manifests as meningitis in immunocompromised adults or infection of the fetus and miscarriage in pregnant women. we have previously used lactococcus lactis, a gras (generally regarded as safe) organism, as a vaccine vector against listeriosis by engineering plasmid-mediated expression of the immunodominant antigen from l. monocytogenes, listeriolysin o (llo). however, the environme ...201021327128
modeling and predicting the simultaneous growth of listeria monocytogenes and natural flora in minced tuna.the growth kinetics of listeria monocytogenes and natural flora (nf) in minced tuna from 2 to 30 °c were examined, and a simultaneous growth model was developed. the inhibiting effect of the nf on the growth of l. monocytogenes was examined by inoculating different levels of nf isolated from the minced tuna. the kinetic data were fitted to the baranyi model and estimated the growth parameters such as specific growth rate (µ(max)), maximum population density (n(max)), and lag time. the temperatur ...201121333135
package systems and storage times serve as postlethality controls for listeria monocytogenes on whole-muscle beef jerky and pork and beef smoked sausage sticks.to validate how packaging and storage reduces listeria monocytogenes on whole-muscle beef jerky and smoked pork and beef sausage sticks, four packaging systems (heat sealed [hs] without vacuum, heat sealed with oxygen scavenger, nitrogen flushed with oxygen scavenger [nfos], and vacuum) and four ambient temperature storage times were evaluated. commercially available whole-muscle beef jerky and smoked pork and beef sausage sticks were inoculated with a five-strain l. monocytogenes cocktail, pack ...201121333136
nisin treatment to enhance the efficacy of gamma radiation against listeria monocytogenes on meat.treatment of meat with gamma radiation for inactivation of foodborne pathogens might cause undesirable quality changes in the product. the objective of the present study was to use nisin for enhancing the lethality of gamma radiation against listeria monocytogenes, so that moderate doses of radiation can effectively eliminate the pathogen on meat. cubes of raw meat (10 g each) were inoculated with l. monocytogenes (10(7)cfu/g) and treated with nisin (10(3) iu/g), gamma radiation (0.25 to 1.5 kgy ...201121333137
time course of fetal tissue invasion by listeria monocytogenes following an oral inoculation in pregnant guinea pigs.pregnant women are 20 times more likely to develop listeriosis than are members of the general population, and infection can result in abortion, stillbirth, or neonatal illness. the objective of this study was to orally challenge pregnant guinea pigs with listeria monocytogenes to assess maternal and fetal tissue invasion at postinoculation days 2, 6, 9, and 21. the time course of invasion was followed by fluorescence microscopy and a traditional culture method. guinea pigs were treated on gesta ...201121333144
desiccation of adhering and biofilm listeria monocytogenes on stainless steel: survival and transfer to salmon products.the foodborne bacterial pathogen, listeria monocytogenes, commonly contaminates foods during processing, where the microorganisms are potentially subjected to low relative humidity (rh) conditions for extended periods of time. the objective of this study was to examine survival during desiccation (43% rh and 15 °c) of biofilm l. monocytogenes n53-1 cells on stainless steel coupons and to assess subsequent transfer to salmon products. formation of static biofilm (2 days at 100% rh and 15 °c) prio ...201121334756
a promoter probe plasmid based on green fluorescent protein : a strategy for studying meningococcal gene expression.many bacterial genes are regulated in an environment-responsive fashion, and from the perspective of a pathogen, the host represents just another environment. many genes that contribute to virulence are differentially expressed in response to host environments that they encounter during colonization and invasion (1). recognition of this has led to the development of selection or reporter systems that utilize the increased activity of promoters during growth in vivo to identify genes that are sel ...200121337172
carbohydrate nanoparticle-mediated colloidal assembly for prolonged efficacy of bacteriocin against food pathogen.the goal of this study was to demonstrate the ability of carbohydrate nanoparticle-stabilized emulsion to prolong the efficacy of bacteriocin against food pathogens. an amphiphilic, negatively charged carbohydrate nanoparticle, phytoglycogen octenyl succinate (pg-os), was used to form oil-in-water emulsion for delivering bacteriocin nisin against the food pathogen listeria monocytogenes. dynamic light scattering test showed that in emulsion all pg-os nanoparticles were adsorbed at the surface of ...201121337333
attenuated listeria monocytogenes vaccine vectors expressing influenza a nucleoprotein: preclinical evaluation and oral inoculation of volunteers.listeria monocytogenes vectors have shown promise for delivery of viral and tumor antigens in animals. we used two mutant vector strains deleted for acta/plcb (bmb72) and acta/inlb (bmb54), and engineered both strains to secrete a heterologous nucleoprotein antigen from the influenza a virus. strains were evaluated in vitro and in mice. twenty-two healthy volunteers received single oral doses of either strain in a physiological study of safety, shedding, and immunogenicity. volunteers were obser ...201121338384
a role for proline synthesis and transport in listeria monocytogenes barotolerance.to assess the contribution of proline biosynthesis to listerial barotolerance.201121338448
production of antilisterial bacteriocins by staphylococci isolated from bovine milk.a collection of 111 staphylococcal isolates recovered from healthy cows in 41 dairy herds in brazil was surveyed for the production of bacteriocins. the group included 94 coagulase-positive and 17 coagulase-negative strains of staphylococci. all cultures were grown in tryptic soy broth for 18h at 37°c, and cell-free supernatants were tested for antimicrobial activity against several target organisms by using the agar diffusion method. filtrates of 57 staphylococci showed strong activity against ...201121338785
isolation and characterization of listeria monocytogenes and other listeria species in foods of animal origin in addis ababa, ethiopia.listeriosis is a disease of humans and animals, in which it is one of the important emerging bacterial zoonotic diseases worldwide. among the different species of the genus listeria, listeria monocytogenes (l. monocytogenes) is known to cause listeriosis in humans and animals with low incidence but high case fatality rate. information on the occurrence and distribution of l. monocytogenes and other listeria species is very limited both in the veterinary and public health sectors in ethiopia. the ...201021338956
effectiveness of chitosan against mature biofilms formed by food related bacteria.chitosan has proven antimicrobial properties against planktonic cell growth. little is known, however, about its effects on already established biofilms. oriented for application in food industry disinfection, the effectiveness of both medium molecular weight (mmw) chitosan and its enzymatically hydrolyzed product was tested against mature biofilms of four pathogenic strains, listeria monocytogenes, bacillus cereus, staphylococcus aureus and salmonella enterica, and a food spoilage species, pseu ...201121340015
[salmonella sp and listeria monocytogenes in fully cooked ham commercialized in supermarkets of fortaleza (ce, brazil): risk factor for public health].the objective of this work was to evaluate the occurrence of salmonella sp. and listeria spp. in fully cooked ham without fat cover, stored under refrigeration, commercialized in supermarkets of fortaleza (ce, brazil). forty samples of cooked ham, proceeding from eight trademarks, collected in 26 establishments, were analyzed according to the apha and hbp for salmonella sp. and listeria spp. detection, respectively. thirty percent of the samples were contaminated with salmonella sp. and 42.50%, ...201121340341
a single substitution in 5'-untranslated region of plcb is involved in enhanced broad-range phospholipase c activity in listeria monocytogenes strain h4.to examine whether the in vitro phospholipase activity in listeria monocytogenes strain h4 was due to two nucleotide mutations (c to t at position -26 and a to g at position +1) in plcb or resulted from regulatory activation, two mutants h4-plcb-m1 (single mutation at position -26) and h4-plcb-m2 (substitution at both positions) were constructed by site-directed mutagenesis. it was found that the two mutants had significantly lower transcription of plcb than their parent strain h4 and did not sh ...201121343163
interplay between depressive-like behavior and the immune system in an animal model of prenatal dexamethasone administration.glucocorticoids, namely dexamethasone, are prescribed during late gestation in pregnancies at risk of originating premature newborns, to promote fetal lung maturation. however, adverse early life events have been reported to induce long-lasting changes in the immune and central nervous systems. the accumulating evidence on bidirectional interactions between both systems in psychiatric disorders like depression, prompted us to further investigate the long-term impact of prenatal dexamethasone adm ...201121344016
exposure to environmental microorganisms and childhood asthma.children who grow up in environments that afford them a wide range of microbial exposures, such as traditional farms, are protected from childhood asthma and atopy. in previous studies, markers of microbial exposure have been inversely related to these conditions.201121345099
matrix metalloproteinase expression in sheep with listerial meningoencephalitis.matrix metalloproteinases (mmps) have been implicated in the pathogenesis of several central nervous system (cns) diseases. in this study, we investigated the presence of listeria monocytogenes antigens and detected the expression of mmp-9 and mmp-7 in the brains of 22 sheep with clinical signs and histopathological findings characteristic of listerial meningoencephalitis. archived sections from the brainstem, cerebrum, and cerebellum were stained for immunohistochemistry. l. monocytogenes antig ...201121345473
detection of listeria monocytogenes in pork and beef using the vidas® lmo2 automated enzyme linked immunoassay method.listeria (l.) monocytogenes, a foodborne pathogen, is known to be a possible contaminant of foods during production and processing. samples (n=985) of raw meat and by-products obtained from beef and pork were first screened by the vidas system for the presence of listeria spp., followed by testing for the presence of l. monocytogenes. positive l. monocytogenes results were confirmed by plating on selective agars: 14% of the samples were positive for listeria and 4% tested positive for l. monocyt ...201121345601
fold and function of the inlb b-repeat.host cell invasion by the facultative intracellular pathogen listeria monocytogenes requires the invasion protein inlb in many cell types. inlb consists of an n-terminal internalin domain that binds the host cell receptor tyrosine kinase met and c-terminal gw domains that bind to glycosaminoglycans (gags). met binding and activation is required for host cell invasion, while the interaction between gw domains and gags enhances this effect. soluble inlb elicits the same cellular phenotypes as the ...201121345802
il-22 production is regulated by il-23 during listeria monocytogenes infection but is not required for bacterial clearance or tissue protection.listeria monocytogenes (lm) is a gram-positive bacterium that is a common contaminant of processed meats and dairy products. in humans, ingestion of lm can result in intracellular infection of the spleen and liver, which can ultimately lead to septicemia, meningitis, and spontaneous abortion. interleukin (il)-23 is a cytokine that regulates innate and adaptive immune responses by inducing the production of il-17a, il-17f, and il-22. we have recently demonstrated that the il-23/il-17 axis is requ ...201121347242
cell biology and immunology of listeria monocytogenes infections: novel insights.listeria monocytogenes is an intracellular bacterium responsible for a disease characterized by several clinical features, such as septicemia, brain infection, abortion, and perinatal infection. these clinical features are attributed to its amazing capacity to cross several barriers in susceptible hosts. intracellular infection is a consequence of the bacterium's capacity to enter a wide variety of mammalian cells, to not only survive but also replicate therein, and to its faculty to spread from ...201121349093
utility of gel-free, label-free shotgun proteomics approaches to investigate microorganisms.this review will examine the current situation with label-free, quantitative, shotgun-oriented proteomics technology and discuss the advantages and limitations associated with its capability in capturing and quantifying large portions of proteomes of microorganisms. such an approach allows (1) comparisons between physiological or genetic states of organisms at the protein level, (2) 'painting' of proteomic data onto genome data-based metabolic maps, (3) enhancement of the utility of genomic data ...201121350852
serious bacterial infections in hospitalized febrile infants aged 90 days or younger: the traditional combination of ampicillin and gentamicin is still appropriate.a change in the bacterial epidemiology of infantile serious bacterial infection (sbi) has raised concerns regarding the appropriate empirical antibiotic therapy.201121351817
use of natural antimicrobials to improve the control of listeria monocytogenes in a cured cooked meat model system.concern about nitrite in processed meats has increased consumer demand for natural products manufactured without nitrite or nitrate. studies on commercial meat products labeled as "uncured" and "no-nitrite-or-nitrate-added" have shown less control of nitrite in these products and greater potential growth of bacterial pathogens. to improve the safety of the "naturally cured" meats, several natural ingredients were studied in a cured cooked meat model system (80:20 pork, 10% water, 2% salt, and 15 ...201121354716
growth characteristics of listeria monocytogenes as affected by a native microflora in cooked ham under refrigerated and temperature abuse conditions.this study examined the growth characteristics of listeria monocytogenes as affected by a native microflora in cooked ham at refrigerated and abuse temperatures. a five-strain mixture of l. monocytogenes and a native microflora, consisting of brochothrix spp., isolated from cooked meat were inoculated alone (monocultured) or co-inoculated (co-cultured) onto cooked ham slices. the growth characteristics, lag phase duration (lpd, h), growth rate (gr, log(10) cfu/h), and maximum population density ...201021356437
resistance to benzalkonium chloride, peracetic acid and nisin during formation of mature biofilms by listeria monocytogenes.increase of resistance to the application of benzalkonium chloride (bac), peracetic acid (pa) and nisin during biofilm formation at 25 °c by three strains of listeria monocytogenes (cect 911, cect 4032, cect 5873 and bac-adapted cect 5873) in different scenarios was compared. for this purpose, resistance after 4 and 11-days of biofilm formation was quantified in terms of lethal dose 90% values (ld(90)), determined according with a dose-response logistic mathematical model. microscopic analyses a ...201021356446
effects and interactions of sodium lactate, sodium diacetate, and pediocin on the thermal inactivation of starved listeria monocytogenes on bologna.the effects and interactions of temperature (56.3-60 °c), sodium lactate (sl; 0-4.8%), sodium diacetate (sda; 0-2.5%), and pediocin (0-10,000 au) on starved listeria monocytogenes (10(7) cfu/g) on bologna were investigated. bologna slices containing sl and sda in the formulation were dipped in pediocin, surface inoculated, and treated at various temperatures using combinations of parameters determined by central composite design. d-values were calculated. the observed d-values ranged from 2.8 mi ...201021356449
combination treatment of alkaline electrolyzed water and citric acid with mild heat to ensure microbial safety, shelf-life and sensory quality of shredded carrots.the objective of this study was to determine the synergistic effect of alkaline electrolyzed water and citric acid with mild heat against background and pathogenic microorganisms on carrots. shredded carrots were inoculated with approximately 6-7 log cfu/g of escherichia coli o157:h7 (932, and 933) and listeria monocytogenes (atcc 19116, and 19111) and then dip treated with alkaline electrolyzed water (alew), acidic electrolyzed water (acew), 100 ppm sodium hypochlorite (naocl), deionized water ...201021356455
staphylococcus aureus and listeria monocytogenes in norwegian raw milk cheese production.the aim of this study was to survey the presence of staphylococcus aureus and listeria monocytogenes during the cheese making process in small-scale raw milk cheese production in norway. the prevalence of s. aureus in bovine and caprine raw milk samples was 47.3% and 98.8%, respectively. an increase in contamination during the first 2-3 h resulted in a 73.6% prevalence of contamination in the bovine curd, and 23 out of 38 s. aureus-negative bovine milk samples gave rise to s. aureus-positive cur ...201021356456
comparative analysis of antimicrobial activities of valinomycin and cereulide, the bacillus cereus emetic toxin.cereulide and valinomycin are highly similar cyclic dodecadepsipeptides with potassium ionophoric properties. cereulide, produced by members of the bacillus cereus group, is known mostly as emetic toxin, and no ecological function has been assigned. a comparative analysis of the antimicrobial activity of valinomycin produced by streptomyces spp. and cereulide was performed at a ph range of ph 5.5 to ph 9.5, under anaerobic and aerobic conditions. both compounds display ph-dependent activity agai ...201121357430
isolation of highly heat-resistant listeria monocytogenes variants by use of a kinetic modeling-based sampling scheme.stable high-hydrostatic-pressure (hhp)-resistant listeria monocytogenes lo28 variants were previously isolated and characterized. these hhp variants were also more resistant to heat. in addition, nonlinear heat inactivation kinetics pointed toward the existence of heat-resistant variants, although these could not be isolated so far. in this study, we used kinetic modeling of inactivation curves of two isolated hhp variants and their wild type, and this revealed that the probability of finding re ...201121357432
antimicrobial resistance of listeria monocytogenes isolates from food and the environment in france over a 10-year period.in order to assess antimicrobial resistance in listeria monocytogenes, 202 food and environmental isolates from 1996 to 2006 were tested. only four strains displayed acquired resistance. resistance to erythromycin, tetracycline-minocycline, and trimethoprim was evidenced, and the genes erm(b), tet(m), and dfrd, already found in l. monocytogenes, were detected.201121357436
ß1 integrin is critical for the maintenance of antigen-specific cd4 t cells in the bone marrow but not long-term immunological memory.the long-term maintenance of memory cd4 t cells promotes protective immunity against future pathogen reinfection. as a site rich in survival cytokines, the bone marrow is proposed to be a critical niche for the survival of memory cd4 t cells. we demonstrate that endogenous, polyclonal ag-specific cd4 t cells rapidly enter and are recovered long-term from the bone marrow following i.v. infection with listeria monocytogenes. ß(1) integrin-deficient cd4 t cells also populate the bone marrow early f ...201121357540
potential nosocomial acquisition of epidemic listeria monocytogenes presenting as multiple brain abscesses resembling nocardiosis.listerial brain abscesses are rare, and are found mostly in patients with underlying hematological malignancies or solid-organ transplants. a case of a patient with crohn's disease and multiple brain abscesses involving the left cerebellum and right sylvian fissure is described. the gram stain and histopathology of the cerebellar abscess revealed gram-positive, beaded rods suggestive of nocardia. however, on culture, listeria monocytogenes was identified. listeria may appear gram-variable and ha ...201021358887
thioredoxin 80-activated-monocytes (tams) inhibit the replication of intracellular pathogens.thioredoxin 80 (trx80) is an 80 amino acid natural cleavage product of trx, produced primarily by monocytes. trx80 induces differentiation of human monocytes into a novel cell type, named trx80-activated-monocytes (tams).201121365006
[meningitis caused by listeria monocytogenes with high levels of adenosine deaminase]. 201121367492
structural changes of listeria monocytogenes sortase a: a key to understanding the catalytic mechanism.listeria monocytogenes is one of the most virulent foodborne pathogens. l. monocytogenes sortase a (srta) enzyme, which catalyzes the cell wall anchoring reaction of the leucine, proline, x, threonine, and glycine proteins (lpxtg, where x is any amino acid), is a target for the development of antilisteriosis drugs. in this study, the structure of the l. monocytogenes srta enzyme-substrate complex was obtained using homology modeling, molecular docking and molecular dynamics simulations. explicit ...201121374720
validation of food-grade salts of organic acids as ingredients to control listeria monocytogenes on pork scrapple during extended refrigerated storage.this study was conducted to investigate control of listeria monocytogenes on pork scrapple during storage at 4°c. in phase i, scrapple was formulated, with or without citrate-diacetate (0.64%), by a commercial processor to contain various solutions or blends of the following antimicrobials: (i) lactate-diacetate (3.0 or 4.0%), (ii) lactate-diacetate-propionate (2.0 or 2.5%), and (iii) levulinate (2.0 or 2.5%). regardless of whether citrate-diacetate was included in the formulation, without the s ...201121375875
evaluation of a serotyping scheme using a combination of an antibody-based serogrouping method and a multiplex pcr assay for identifying the major serotypes of listeria monocytogenes.to evaluate a simplified serotyping scheme, we used a combination of an antibody-based serogrouping assay that identified only type 1 and type 4 strains and a multiplex pcr-based serogrouping assay to analyze 362 l. monocytogenes isolates collected over more than 20 years. the multiplex pcr assay also incorporated a set of primers specific for l. monocytogenes hlya gene to verify the species identification of these isolates. a subset (n = 120) of these isolates were also serotyped with the denka ...201121375876
encephalitozoonosis in new zealand rabbits and potential transmission risk.encephalitozoon cuniculi is a small protozoan parasite in the phylum microspora. it has been shown to naturally infect several host species, including humans. encephalitozoonosis is routinely diagnosed in vivo by serological examination or post mortem by histopathology. in a conventional rabbit colony, two animals suddenly showed clinical signs (torticollis and asthenia of limbs). serum samples of these rabbits were seropositive for e. cuniculi after definitive diagnosis (toxoplasma gondii and l ...201121377801
diverse geno- and phenotypes of persistent listeria monocytogenes isolates from fermented meat sausage production facilities in portugal.the persistence of listeria monocytogenes in food-associated environments represents a key factor in transmission of this pathogen. to identify persistent and transient strains associated with production of fermented meat sausages in northern portugal, 1,723 l. monocytogenes isolates from raw material and finished products from 11 processors were initially characterized by random amplification of polymorphic dna (rapd), pcr-based molecular serotyping, and epidemic clone characterization, as well ...201121378045
combined effect of temperature, ph, and presence of nisin on inactivation of staphylococcus aureus and listeria monocytogenes by pulsed electric fields.the combined effect of ph (3.5-7.0), temperature (4┬░c-50┬░c), and the presence of nisin (0-200ôçë╬╝g/ml) on the inactivation caused by pulsed electric fields (pef) in two pef-resistant gram-positive microorganisms, staphylococcus aureus and listeria monocytogenes, was investigated. a response surface model using a central composite design was developed for the purpose of understanding the individual effects and interactions of these factors and to identify the most promising combinations for mi ...201121381918
the sigma b operon is a determinant of fitness for a listeria monocytogenes serotype 4b strain in soil.in nature the foodborne pathogen listeria monocytogenes lives as a saprophyte where it can contaminate preharvest produce. this environment can present many stresses such as ultraviolet light, variations in temperature and humidity, and oxidative stress from growing plant matter in the soil. the alternative sigma factor sigma b, encoded by sigb, controls the response to most stresses in l. monocytogenes. fitness in soil and on radishes sown and grown in contaminated soil was measured in a wild-t ...201121381923
effect of heat exposure on invasiveness of listeria monocytogenes strains.the effect of a 54-¦c heat exposure lasting 20 and 60 minutes on the invasiveness of 10 listeria monocytogenes strains in the exponential and stationary phases was investigated. it was shown that heat exposure significantly reduced the l. monocytogenes count. a maximal reduction of 5 log took place after 60 minutes of heating. no significant differences in survival between exponential and stationary phases were observed for most strains. twenty minutes of heat exposure resulted in a reduction of ...201121381944
structure-activity relationships of an antimicrobial peptide plantaricin s from two-peptide class iib bacteriocins.class iib bacteriocins are ribosomally synthesized antimicrobial peptides comprising two different peptides synergistically acting in equal amounts for optimal potency. in this study, we demonstrate for the first time potent (nanomolar) antimicrobial activity of a representative class iib bacteriocin, plantaricin s (pls), against four pathogenic gram-positive bacteria, including listeria monocytogenes. the structure-activity relationships for pls were studied using activity assays, circular dich ...201121388140
listeria monocytogenes and salmonella enterica enteritidis biofilms susceptibility to different disinfectants and stress-response and virulence gene expression of surviving cells.disinfection of food contact surfaces is a challenging task, aggravated by bacteria's capacity to survive and/or resist antimicrobials by means of mechanisms not yet completely understood. this work evaluated the susceptibility of listeria monocytogenes and salmonella enterica biofilms to four disinfectants, and analyzed how those chemical agents influenced stress-response and virulence genes expression by surviving cells. three strains of each bacterial species mentioned were used, and their bi ...201121388333
regulation of listeria virulence: prfa master and commander.listeria monocytogenes is the causative agent of listeriosis, a severe foodborne infection. these bacteria live as soil saprotrophs on decaying plant matter but also as intracellular parasites, using the cell cytosol as a replication niche. prfa, a regulatory protein, integrates a number of environmental cues that signal the transition between these two contrasting lifestyles, activating a set of key virulence factors during host infection. while a number of details concerning the general mode o ...201121388862
autolysin amidase of listeria monocytogenes promotes efficient colonization of mouse hepatocytes and enhances host immune response.listeria monocytogenes is an intracellularly growing pathogen which is able to infect and to spread from cells to cells. it produces several virulence factors required for invasion and intracellular niche colonization. endogenous peptidoglycan hydrolases which are important for survival of bacteria have been shown to be involved in pathogenesis. an autolysin amidase (ami)-deficient mutant of l. monocytogenes (+öami) is attenuated in virulence as evidenced by a reduction in mortality of infected ...201121388880
partial characterization of bacteriocins produced by two lactobacilus strains with probiotic properties.the probiotic characteristics of lactobacillus brevis bg18 and lb. plantarum bg33, isolated from traditional turkish tulum cheese were assessed. these two bacteriocinproducer strains exhibited good probiotic characteristics such as resistance in media containing 0.3% bile salt, pepsin (3 mg mlôü+-¦), and pancreatine (1 mg mlôü+-¦) as well as acid resistance at ph 2. they were also adhered to caco-2 epithelial cells in a manner comparable to escherichia coli lmg3083 (etec) and salmonella typhimur ...201121388923
affinity purification of specific anti-listeria monocytogenes egg yolk antibodies (igy) using amino-activated cells as receptors.it is difficult to isolate the specific egg yolk antibody (igy) from large amounts of accompanied nonspecific ones with the usually exploited techniques. in this article, using immunogen bacteria as receptors, an affinity chromatography was developed for separation of specific igy. listeria monocytogens cells were amino activated with divinyl sulfone to increase the binding efficiency between cells and sepharose 4b. after the modification, the separation efficiency of corresponding columns was e ...201121391050
microbiology. listeria unwinds host dna. 201121393530
systematic review: neonatal meningitis in the developing world.meningitis is more common in the neonatal period than any other time in life and is an important cause of morbidity and mortality globally. despite the majority of the burden occurring in the developing world, the majority of the existing literature originates from wealthy countries. mortality from neonatal meningitis in developing countries is estimated to be 40-58%, against 10% in developed countries. important differences exist in the spectrum of pathogens isolated from cerebrospinal fluid cu ...201121395927
vasoactive intestinal peptide receptor 1 is downregulated during expansion of antigen-specific cd8 t cells following primary and secondary listeria monocytogenes infections.as regulation of cd8 t cell homeostasis is incompletely understood, we investigated the expression profile of the vasoactive intestinal peptide (vip) receptors, vpac1 and vpac2, on cd8 t cells throughout an in vivo immune response. herein, we show that adoptively transferred cd8 t cells responding to a listeria monocytogenes infection significantly downregulated, functionally active vpac1 protein expression during primary and secondary expansion. vpac1 mrna expression was restored during contrac ...201121396722
the relevance of aortic endograft prosthetic infection.vascular prosthetic graft infection is a severe complication after open aortic aneurysm repair. reports of infected endografts are scarce. general treatment consensus with infected graft material is that it should be removed completely. the objective of this study was to describe the incidence of endograft infection after endovascular repair of abdominal (evar) and thoracic aortic aneurysm (tevar) and to report treatment options and their outcome.201121397443
assessment of the antibacterial activity of a triclosan-containing cutting board.several studies have shown that consumers may not clean cutting boards properly between preparation of raw and cooked meat. cutting boards may therefore act as sources for contamination of cooked meat or other ready-to-eat foods with pathogenic and spoilage bacteria. the aim of the work was to investigate if cutting boards containing the antimicrobial compound triclosan can reduce the viability of bacteria, thus acting as a hygiene barrier. survival and growth of food pathogens and spoilage bact ...201121402423
priming of protective anti-listeria monocytogenes memory cd8+ t cells requires a functional seca2 secretion system.the seca2 auxiliary secretion system of gram-positive bacteria promotes the export of virulence proteins essential for colonization of the host in the case of both mycobacterium tuberculosis and listeria monocytogenes, two intracellular bacteria causing diseases in humans. we and others have demonstrated that this secretion system is also linked to the onset of long-term cd8(+) t cell-mediated protective immunity in mice. in the case of l. monocytogenes, expression of seca2 inside the cytosol of ...201121402759
serine/threonine protein kinase prka of the human pathogen listeria monocytogenes: biochemical characterization and identification of interacting partners through proteomic approaches.listeria monocytogenes is the causative agent of listeriosis, a very serious food-borne human disease. the analysis of the proteins coded by the l. monocytogenes genome reveals the presence of two eukaryotic-type ser/thr-kinases (lmo1820 and lmo0618) and a ser/thr-phosphatase (lmo1821). protein phosphorylation regulates enzyme activities and protein interactions participating in physiological and pathophysiological processes in bacterial diseases. however in the case of l. monocytogenes there is ...201121406257
invasive extravillous trophoblasts restrict intracellular growth and spread of listeria monocytogenes.listeria monocytogenes is a facultative intracellular bacterial pathogen that can infect the placenta, a chimeric organ made of maternal and fetal cells. extravillous trophoblasts (evt) are specialized fetal cells that invade the uterine implantation site, where they come into direct contact with maternal cells. we have shown previously that evt are the preferred site of initial placental infection. in this report, we infected primary human evt with l. monocytogenes. evt eliminated ~80% of intra ...201121408203
novel approach to the microbial decontamination of strawberries: chlorophyllin-based photosensitization.this study is focused on the possibility to control microbial contamination of strawberries by chlorophyllin (na-chl)-based photosensitization. moreover, photosensitization-induced effects on key quality attributes of treated strawberries was evaluated.201121410603
high hydrostatic pressure and biopreservation of dry-cured ham to meet the food safety objectives for listeria monocytogenes.this work aimed to evaluate the effect of nisin application (biopreservation) combined with high hydrostatic pressure processing (hhp) on the behavior of listeria monocytogenes ctc1034 intentionally inoculated (at ca. 10(7)cells/g) onto the surface of ready-to-eat (rte) sliced dry-cured ham. two types of dry-cured ham, which had different water activities and fat contents were studied (a(w) of 0.92 and 14.25% fat and a(w) of 0.88 and 33.26% fat). three batches were prepared for each type of prod ...201121411167
efficacy of bacteriocin-containing cell-free culture supernatants from lactic acid bacteria to control listeria monocytogenes in food.consumer demands have led to an increased interest in the use of natural antimicrobials for food protection. with the objective of developing novel products for enhancing the microbial safety of food, we have tested cell-free culture supernatants (cfs's) of eight antagonistic bacterial strains for their efficacy to inhibit listeria monocytogenes in different food matrices. the antagonistic strains represented different members of the order lactobacillales as well as one isolate of staphylococcus ...201121411169
gads regulates the expansion phase of cd8+ t cell-mediated immunity.the gads adaptor protein is critical for tcr-mediated ca(2+) mobilization. we investigated the effect of gads deficiency on the proliferation of cd8(+) t cells following peptide stimulation and in the context of infection with an intracellular pathogen. we stimulated cd8(+) t cells from gads(+/+) ot-i and gads(-/-) ot-i mice with cognate ag (siinfekl) or altered peptide ligand. in vitro experiments revealed that gads was required for optimal proliferation of cd8(+) t cells. this defect was most ...201121411729
neonatal bacterial meningitis: 444 cases in 7 years.neonatal bacterial meningitis remains a severe infectious disease with mortality rates varying between 10% and 15%. the clinical and bacteriologic features of neonatal meningitis collected from january 2001 to december 2007 in a french national survey are presented here.201121416693
antibacterial activity of the enniatin b, produced by fusarium tricinctum in liquid culture, and cytotoxic effects on caco-2 cells.the enniatins (ens) are bioactive compounds of hexadepsipeptidic structure produced by several strains of fusarium sp. the en b was purified from extracts of fusarium tricinctum growth on liquid culture of potato dextrose broth (pdb), using a semipreparative liquid chromatography (lc) followed by an analytical lc. the purity and the structure of the isolated compound were confirmed by the determination of the extinction coefficient and with electrospray ionization-mass spectrometry (esi-ms) stud ...201121417626
nisin and class iia bacteriocin resistance among listeria and other foodborne pathogens and spoilage bacteria.food safety has been an important issue globally due to increasing foodborne diseases and change in food habits. to inactivate foodborne pathogens, various novel technologies such as biopreservation systems have been studied. bacteriocins are ribosomally synthesized peptides or proteins with antimicrobial activity produced by different groups of bacteria, but the bacteriocins produced by many lactic acid bacteria offer potential applications in food preservation. the use of bacteriocins in the f ...201121417775
use of carnobacterium maltaromaticum cultures and hydroalcoholic extract of lippia sidoides cham. against listeria monocytogenes in fish model systems.minimally processed refrigerated ready-to-eat fishes may offer health risk of severe infection to susceptible individuals due to contamination by the psychrotolerant bacterium l. monocytogenes. in this work, inhibition of l. monocytogenes by a plant extract and lactic acid bacteria (lab) was studied in model fish systems kept at 5 °c for 35 days. for that, fillets of tropical fish "surubim" (pseudoplatystoma sp.) and hydroalcoholic extract of the plant lippia sidoides cham. ("alecrim pimenta") w ...201121419508
[listeria monocytogenes pyonephrosis on an ectopic kidney]. 201121420265
artificial leucine rich repeats as new scaffolds for protein design.the leucine rich repeat (lrr) motif that participates in many biomolecular recognition events in cells was suggested as a general scaffold for producing artificial receptors. we describe here the design and first total chemical synthesis of small lrr proteins, and their structural analysis. when evaluating the tertiary structure as a function of different number of repeating units (1-3), we were able to find that the 3-repeats sequence, containing 90 amino acids, folds into the expected structur ...201121420858
mechanisms of resistance to bacteriocins targeting the mannose phosphotransferase system.the membrane proteins iic and iid of the mannose phosphotransferase system (man-pts) together form a membrane-located complex that serves as a receptor for several different bacteriocins, including the pediocin-like class iia bacteriocins and the class iic bacteriocin lactococcin a. bacterial strains sensitive to class iia bacteriocins readily give rise to resistant mutants upon bacteriocin exposure. in the present study, we have therefore investigated lactococcin a-resistant mutants of lactococ ...201121421780
pascale cossart: the ins and outs of listeria. interview by caitlin sedwick. 201121422225
cancer immunotherapy using recombinant listeria monocytogenes: transition from bench to clinic.cancer immunotherapy has developed into a field of intense study as aspects of the immune system involved in the eradication of cancer have become delineated. listeria monocytogenes is a gram-positive, facultative intracellular bacterium which infects antigen presenting cells (apc), and is being used as a cancer vaccine to deliver tumor antigens directly to the apc. this results in the generation of a strong immune response towards the tumor associated antigen and direct targeting of the tumor b ...201121422819
an eight-year report on the implementation of haccp in a university canteen: impact on the microbiological quality of meals.an investigation aimed at assessing the microbiological quality of meals consumed at a university canteen after implementation of the haccp system and personnel training was carried out. cooked and warm-served products (74 samples), cooked and cold-served products (92 samples) and cold gastronomy products (63 samples) sampled from 2000 to 2007 underwent microbiological analyses. all the samples were tested for: samonella spp., listeria monocytogenes, total mesophilic aerobes, coliforms, escheric ...201121424969
secondary cd8+ t-cell responses are controlled by systemic inflammation.repeated infections and experimental prime-boost regimens frequently result in the generation of secondary (2°) cd8(+) t-cell responses. in contrast to primary (1°) cd8(+) t cells, the parameters that influence the abundance and phenotype of 2° effector and memory cd8(+) t-cell populations are largely unknown. here, we analyze the impact of different booster infections, ag curtailment, and systemic inflammation on the quality and quantity of secondary cd8(+) t-cell responses. we show that simila ...201121425157
essential oil from leaves of lantana canescens and l. lopez-palacii grown in colombia.the chemical composition of the volatile compounds from the leaves of lantana canescens kunth (verbenaceae) and l. lopez-palacii moldenke grown in colombia were analyzed by gc and gc/ms. one hundred and thirty-nine volatile compounds were identified in l. canescens, of which the major ones were beta-caryophyllene (13.5%), germacrene d (10.3%) and 1-octen-3-ol (8.4%). in the oil obtained from l. lopez-palacii, eighty-three compounds were identified, of which the most prominent were 1-octen-3-ol ( ...201121425686
[biofilm formation capacity of listeria monocytogens strains isolated from soft cheese from costa rica].listeria monocytogenes is a bacteria associated with the production of severe infectious disease in human being, but also with the formation of biofilms in different surfaces related to the food production environment. biofilm represents a serious problem in food industry, since it is a constant and important contamination source and also, bacteria present in it have an increased resistance towards physical and chemical agents of common use. the capacity of biofilm formation of l. monocytogenes ...201021427885
[microbiological evaluation of ready-to-eat foods manufactured by small costa rican industries].ready-to-eat (rte) foods are processed foodstuffs which have gained popularity in recent times because they can be ingested without further thermic treatments. in this work, the microbiological quality and safety of 90 samples of rte foods manufactured by small costa rican industries was determined to evaluate whether they represent a public health risk. twenty-six samples of pickled vegetables, 18 dips, 18 salads, and 12 sweet treats were studied. each sample was analyzed with regard to its ph, ...201021427886
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