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listeria monocytogenes septicemia in an immunocompromised dog.an 11-year-old, male castrated, boston terrier was presented to the north carolina state university college of veterinary medicine small animal emergency service with a 2-day history of progressive ataxia, left-sided head tilt, and anorexia. the dog had previously been diagnosed with chronic lymphoid leukemia and suspected immune-mediated destruction of his bone marrow precursor cells, possibly due to therapy with immunosuppressive dosages of prednisone and azathioprine. during the physical exam ...201627218230
purification of plasmodium sporozoites enhances parasite-specific cd8+ t cell responses.malaria infection caused by plasmodium parasites continues to cause enormous morbidity and mortality in areas where it is endemic, and there is no licensed vaccine capable of inducing sterile protection. hyperimmunization with attenuated whole sporozoites can induce sterile protective immune responses targeting preerythrocytic antigens. most animal models of hyperimmunization rely on sporozoites dissected from mosquito salivary glands and injected without further purification. in balb/c mice, re ...201627217420
inactivation of listeria monocytogenes, salmonella spp. and escherichia coli o157:h7 on cantaloupes by octenidine dihydrochloride.the efficacy of a new generation disinfectant, octenidine dihydrochloride (oh), as wash and coating treatments for reducing listeria monocytogenes (lm), salmonella spp. (sal), and escherichia coli o157:h7 (ec) on cantaloupe was investigated. cantaloupe rind plugs inoculated separately with the three bacterial species (∼8 log cfu/cm(2)) were washed for 1, 3, 5 min at 25 °c in water, or chlorine (200 ppm), ethanol (1%), oh (0.01, 0.05, 0.1%) and surviving populations were measured after treatment. ...201627217367
minimal inhibitory concentrations of undissociated lactic, acetic, citric and propionic acid for listeria monocytogenes under conditions relevant to cheese.minimal inhibitory concentrations (mics) of undissociated lactic acid were determined for six different listeria monocytogenes strains at 30 °c and in a ph range of 4.2-5.8. small increments in ph and acid concentrations were used to accurately establish the growth/no growth limits of l. monocytogenes for these acids. the mics of undissociated lactic acid in the ph range of 5.2-5.8 were generally higher than at ph 4.6 for the different l. monocytogenes strains. the average mic of undissociated l ...201627217360
validation of a predictive model coupling gas transfer and microbial growth in fresh food packed under modified atmosphere.predicting microbial safety of fresh products in modified atmosphere packaging implies to take into account the dynamic of o2, co2 and n2 exchanges in the system and its effect on microbial growth. in this paper a mechanistic model coupling gas transfer and predictive microbiology was validated using dedicated challenge-tests performed on poultry meat, fresh salmon and processed cheese, inoculated with either listeria monocytogenes or pseudomonas fluorescens and packed in commercially used packa ...201627217358
rna- and protein-mediated control of listeria monocytogenes virulence gene expression.the model opportunistic pathogen listeria monocytogenes has been the object of extensive research, aiming at understanding its ability to colonize diverse environmental niches and animal hosts. bacterial transcriptomes in various conditions reflect this efficient adaptability. we review here our current knowledge of the mechanisms allowing l. monocytogenes to respond to environmental changes and trigger pathogenicity, with a special focus on rna-mediated control of gene expression. we highlight ...201627217337
memory cd8(+) t cells require increased concentrations of acetate induced by stress for optimal function.how systemic metabolic alterations during acute infections impact immune cell function remains poorly understood. we found that acetate accumulates in the serum within hours of systemic bacterial infections and that these increased acetate concentrations are required for optimal memory cd8(+) t cell function in vitro and in vivo. mechanistically, upon uptake by memory cd8(+) t cells, stress levels of acetate expanded the cellular acetyl-coenzyme a pool via atp citrate lyase and promoted acetylat ...201627212436
shedding light on betl*: ppl2-lux mediated real-time analysis of betl* expression in listeria monocytogenes.we propose a mechanism of action for the betl* mutation which is based on dna topology. removing a single thymine residue from the betl σ(a) promoter's -10 and -35 spacer results in a 'twist'-mediated activation of transcription which accounts for the osmotolerance phenotype observed for strains expressing betl*.201627212260
detection, identification, and typing of listeria species from baled silages fed to dairy cows.anaerobiosis, critical for successful ensilage, constitutes a challenge in baled silages. the loss of complete anaerobiosis causes aerobic deterioration and silages undergo dry matter and nutrient losses, pathogen growth, and mycotoxin production. silage may represent an ideal substrate for listeria monocytogenes, a pathogen of primary concern in several cheeses. the aim of this research was to investigate the occurrence of listeria in baled silage fed to cows producing milk for a protected desi ...201627209131
loss of sigb in listeria monocytogenes strains egd-e and 10403s confers hyperresistance to hydrogen peroxide in stationary phase under aerobic conditions.sigb is the main stress gene regulator in listeria monocytogenes affecting the expression of more than 150 genes and thus contributing to multiple-stress resistance. despite its clear role in most stresses, its role in oxidative stress is uncertain, as results accompanying the loss of sigb range from hyperresistance to hypersensitivity. previously, these differences have been attributed to strain variation. in this study, we show conclusively that unlike for all other stresses, loss of sigb resu ...201627208116
potential impact of the resistance to quaternary ammonium disinfectants on the persistence of listeria monocytogenes in food processing environments.the persistence of certain strains of listeria monocytogenes, even after the food processing environment has been cleaned and disinfected, suggests that this may be related to phenomena that reduce the concentration of the disinfectants to subinhibitory levels. this includes (i) the existence of environmental niches or reservoirs that are difficult for disinfectants to reach, (ii) microorganisms that form biofilms and create microenvironments in which adequate concentrations of disinfectants can ...201627199964
temperature significantly affects the plaquing and adsorption efficiencies of listeria phages.listeria-infecting phages are currently being used to control and detect the important foodborne pathogen listeria monocytogenes; however, the influence of environmental conditions on the interactions between l. monocytogenes and its phages has not been explored in depth. here, we examined the infective potential of four listeria phages (two each from the p70-like and p100-like phages of listeria) against five strains of l. monocytogenes (representing serotypes 1/2a, 1/2b, 4a, and 4b) grown unde ...201627199957
application of electron-beam irradiation combined with aging for improvement of microbiological and physicochemical quality of beef loin.the combined effects of irradiation and aging temperature on the microbial and chemical quality of beef loin were investigated. the samples were vacuum-packaged, irradiated at 0 or 2 kgy using electron-beam (eb), and stored for 10 d at different aging temperatures (2, 14, or 25℃). the microbial growth, shear values, meat color, and nucleotide-related flavor compounds of the samples were analyzed. the irradiation effect on inactivation of foodborne pathogens was also investigated. the population ...201627194930
atf3 provides protection from staphylococcus aureus and listeria monocytogenes infections. 201627190243
identification of a lipoteichoic acid glycosyltransferase enzyme reveals that gw-domain-containing proteins can be retained in the cell wall of listeria monocytogenes in the absence of lipoteichoic acid or its modifications.listeria monocytogenes is a foodborne gram-positive bacterial pathogen, and many of its virulence factors are either secreted proteins or proteins covalently or noncovalently attached to the cell wall. previous work has indicated that noncovalently attached proteins with gw (glycine-tryptophan) domains are retained in the cell wall by binding to the cell wall polymer lipoteichoic acid (lta). lta is a glycerol phosphate polymer, which is modified in l. monocytogenes with galactose and d-alanine r ...201627185829
dielectric barrier discharge atmospheric cold plasma inhibits escherichia coli o157:h7, salmonella, listeria monocytogenes, and tulane virus in romaine lettuce.the present study investigated the effects of dielectric barrier discharge atmospheric cold plasma (dacp) treatment on the inactivation of escherichia coli o157:h7, salmonella, listeria monocytogenes, and tulane virus (tv) on romaine lettuce, assessing the influences of moisture vaporization, modified atmospheric packaging (map), and post-treatment storage on the inactivation of these pathogens. romaine lettuce was inoculated with e. coli o157:h7, salmonella, l. monocytogenes (~6logcfu/g lettuce ...201627562348
notes from the field: outbreak of listeriosis associated with consumption of packaged salad - united states and canada, 2015-2016.in september 2015, pulsenet, the national molecular subtyping network for foodborne disease surveillance, identified a cluster of listeria monocytogenes (listeria) clinical isolates indistinguishable by two-enzyme pulsed-field gel electrophoresis (pfge) pattern combination and highly related by whole-genome multilocus sequence typing (wgmlst). a case was defined as isolation of listeria with the outbreak pfge pattern and highly related by wgmlst with an isolation date on or after july 5, 2015, t ...201627559935
serial magnetic resonance imaging findings of intracerebral spread of listeria utilising subcortical u-fibres and the extreme capsule.we present a case of listeria monocytogenes cerebral abscess with axonal spread via the subcortical u-fibres and extreme capsule on magnetic resonance imaging, with follow-up studies demonstrating serial reduction in oedema and enhancement pattern of the white-matter fibre tracts following antimicrobial treatment. we discuss the microbiological mechanism of bacterial mobility to account for these unique imaging features. recognition of this distinct pattern of spread of l. monocytogenes cerebral ...201627558992
modeling the behavior of listeria monocytogenes during enrichment in half fraser broth; impact of pooling and the duration of enrichment on the detection of l. monocytogenes in food.a stochastic model describing the growth of listeria monocytogenes during enrichment in half fraser was developed for the purpose of estimating the effects of modifications to the first enrichment step of the en iso 11290-1 detection method. information pertaining to the variability of growth rates, physiological state of the cell, and the behavior of individual cells contaminating the food were obtained from previously published studies. we used this model to investigate the impact of pooling e ...201627554154
influence of water activity on inactivation of escherichia coli o157:h7, salmonella typhimurium and listeria monocytogenes in peanut butter by microwave heating.this study evaluated the efficacy of a 915 mhz microwave with 3 different electric power levels to inactivate three pathogens in peanut butter with different aw. peanut butter inoculated with escherichia coli o157:h7, salmonella enterica serovar typhimurium and listeria monocytogenes (0.3, 0.4, and 0.5 aw) were treated with a 915 mhz microwave with 2, 4, and 6 kw for up to 5 min. six kw 915 mhz microwave treatment for 5 min reduced these three pathogens by 1.97 to >5.17 log cfu/g. four kw 915 mh ...201627554151
pregnane x receptor regulates pathogen-induced inflammation and host defense against an intracellular bacterial infection through toll-like receptor 4.the nuclear pregnane x receptor (pxr) plays a central role in regulating xenobiotic metabolism. we now report a novel role for pxr as a critical negative regulator of innate immunity after infection. pxr(-/-) mice exhibited remarkably elevated pro-inflammatory cytokine and chemokine production following infection with listeria monocytogenes (lm). despite the more robust innate immune response, pxr(-/-) mice were highly susceptible to lm infection. surprisingly, disruption of the toll-like recept ...201627550658
survival and growth of listeria monocytogenes on fresh-cut "athena" and "rocky ford" cantaloupes during storage at 4°c and 10°c.cantaloupes, marketed as "rocky ford," were implicated in the u.s. multistate outbreak of listeriosis in 2011, which caused multiple fatalities. listeria monocytogenes can survive on whole cantaloupes and can be transferred to the flesh of melons. the growth of l. monocytogenes on fresh-cut "athena" and "rocky ford" cantaloupe cultivars during refrigerated storage was evaluated. fresh-cut cubes (16.4 cm(3)) from field-grown cantaloupes were each inoculated with 5 log10 cfu/ml of a multi-strain m ...201627548768
morin inhibits biofilm production and reduces the virulence of listeria monocytogenes - an in vitro and in vivo approach.the current study explores the in vitro and in vivo antibiofilm efficacy of morin against a leading foodborne pathogen-listeria monocytogenes (lm). minimum inhibitory concentration (mic) of morin against lm strains was found to be 100μg/ml. the non-antibacterial effect of morin at its sub-mics (6.25, 12.5 and 25μg/ml) was determined through growth curve and xtt assay. morin at its sub-mics demonstrated a significant dose dependent inhibitory efficacy against lm biofilm formation which was also e ...201627543817
the four-component aureocin a70 as a promising agent for food biopreservation.aureocin a70 is the only four-component bacteriocin described to date. as it inhibits the growth of a wide range of gram-positive bacteria, including listeria monocytogenes strains isolated from food, its potential for improving food safety was investigated in this study. aureocin a70 (10,240au/ml) proved to be bactericidal, but not extensively lytic, against listerial strains. the antibacterial activity of aureocin a70 (16au/ml) was then tested in uht-treated skimmed milk inoculated with the fo ...201627543814
the essential role of neutrophils during infection with the intracellular bacterial pathogen listeria monocytogenes.neutrophils have historically been characterized as first responder cells vital to host survival because of their ability to contain and eliminate bacterial and fungal pathogens. however, recent studies have shown that neutrophils participate in both protective and detrimental responses to a diverse array of inflammatory and infectious diseases. although the contribution of neutrophils to extracellular infections has been investigated for decades, their specific role during intracellular bacteri ...201627543669
cryptococcus gattii meningitis complicated by listeria monocytogenes infection. 201627532498
achillea schurii flowers: chemical, antioxidant, and antimicrobial investigations.this study aims to evaluate the phenolic profile, and antioxidant and antimicrobial activity of achillea schurii sch.-bip., an endemic species from romania that has not been investigated yet. the chromatographic profile of the phenolic components was obtained using the hplc-ms method, while the total polyphenol, flavonoid, caffeic acid derivative contents were quantified using spectrophotometric methods. the antioxidant activity was evaluated using different methods: dpph radical scavenging, hem ...201627529204
antifungal and antibacterial activities of petroselinum crispum essential oil.parsley [petroselinum crispum (mill.) fuss] is regarded as an aromatic, culinary, and medicinal plant and is used in the cosmetic, food, and pharmaceutical industries. however, few studies with conflicting results have been conducted on the antimicrobial activity of parsley essential oil. in addition, there have been no reports of essential oil obtained from parsley aerial parts, except seeds, as an alternative natural antimicrobial agent. also, microorganism resistance is still a challenge for ...201627525894
adhesion- and degranulation-promoting adapter protein promotes cd8 t cell differentiation and resident memory formation and function during an acute infection.during acute infections, naive ag-specific cd8 t cells are activated and differentiate into effector t cells, most of which undergo contraction after pathogen clearance. a small population of cd8 t cells persists as memory to protect against future infections. we investigated the role of adhesion- and degranulation-promoting adapter protein (adap) in promoting cd8 t cell responses to a systemic infection. naive ag-specific cd8 t cells lacking adap exhibited a modest expansion defect early after ...201627521337
core genome multilocus sequence typing for identification of globally distributed clonal groups and differentiation of outbreak strains of listeria monocytogenes.many listeriosis outbreaks are caused by a few globally distributed clonal groups, designated clonal complexes or epidemic clones, of listeria monocytogenes, several of which have been defined by classic multilocus sequence typing (mlst) schemes targeting 6 to 8 housekeeping or virulence genes. we have developed and evaluated core genome mlst (cgmlst) schemes and applied them to isolates from multiple clonal groups, including those associated with 39 listeriosis outbreaks. the cgmlst clusters we ...201627520821
influence of environmental factors on phage-bacteria interaction and on the efficacy and infectivity of phage p100.when using bacteriophages to control food-borne bacteria in food production plants and processed food, it is crucial to consider that environmental conditions influence their stability. these conditions can also affect the physiological state of bacteria and consequently host-virus interaction and the effectiveness of the phage ability to reduce bacteria numbers. in this study we investigated the stability, binding, and replication capability of phage p100 and its efficacy to control listeria mo ...201627516757
review of prosthetic joint infection from listeria monocytogenes.prosthetic joint infection from listeria monocytogenes is rare. we decided to shed light on this illness and review the reported cases to better understand its characteristics.201627513716
biofilm formation and disinfectant susceptibility of persistent and nonpersistent listeria monocytogenes isolates from gorgonzola cheese processing plants.the aim of this study was to investigate whether the biofilm-forming ability and/or the disinfectant susceptibility accounted for the persistence of listeria monocytogenes in gorgonzola cheese processing plants. for this purpose, a set of 16 l. monocytogenes isolates collected in the 2004-2007 period was analyzed, including 11 persistent isolates collected in different years, within the collection period, and displaying identical or highly correlated pulsotypes. the evaluation of biofilm-forming ...201627462729
the small colony variant of listeria monocytogenes is more tolerant to antibiotics and has altered survival in raw 264.7 murine macrophages.small colony variant (scv) cells of bacteria are a slow-growing phenotype that result from specific defects in the electron transport chain. they form pinpoint colonies on agar plates and have a variety of phenotypic characteristics, such as altered carbon metabolism, decreased toxin and lytic enzyme production, aminoglycoside resistance, and increased intracellular persistence. they are clinically relevant in staphylococcus aureus and pseudomonas aeruginosa, serving as a reservoir for recurrent ...201627458449
purification and characterization of a rabbit serum factor that kills listeria species and other foodborne bacterial pathogens.in an in-vitro assay, rabbit serum, but not human serum, killed listeria monocytogenes, a foodborne pathogen. the aim of our study was to purify and partially characterize this killing factor. listericidin was purified from rabbit serum by a single-step ion-exchange chromatography with deae-sephadex a-50 and its antimicrobial activity was assessed by a microdilution method. listericidin is a protein with a molecular weight of 9 kda and an isoelectric point of 8.1. it kills l. monocytogenes at 4° ...201627455064
artemisia arborescens essential oil composition, enantiomeric distribution, and antimicrobial activity from different wild populations from the mediterranean area.aerial parts of artemisia arborescens were collected from different sites of the mediterranean area (southwestern algeria and southern italy) and the chemical composition of their essential oil (eo) extracted by hydrodistillation was studied by both gas chromatography (gc) equipped with an enantioselective capillary column and gc/mass spectrometry (gc/ms). the eos obtained were tested against several listeria monocytogenes strains. using gc and gc/ms, 41 compounds were identified, accounting for ...201627447740
inactivation of salmonella enterica and listeria monocytogenes in cantaloupe puree by high hydrostatic pressure with/without added ascorbic acid.the objective of this research was to evaluate and develop a method for inactivation of salmonella enterica and listeria monocytogenes in cantaloupe puree (cp) by high hydrostatic pressure (hhp). cantaloupe being the most netted varieties of melons presents a greater risk of pathogen transmission. freshly prepared cp with or without 0.1% ascorbic acid (aa) was inoculated with a bacterial cocktail composed of a three serotype mixture of s. enterica (s. poona, s. newport h1275 and s. stanley h0558 ...201627441819
capture and concentration of viral and bacterial foodborne pathogens using apolipoprotein h.the need for improved pathogen separation and concentration methods to reduce time-to-detection for foodborne pathogens is well recognized. apolipoprotein h (apoh) is an acute phase human plasma protein that has been previously shown to interact with viruses, lipopolysaccharides (lps) and bacterial proteins. the purpose of this study was to determine if apoh was capable of binding and efficiently capturing two representative human norovirus strains (gi.1 and gii.4), a cultivable surrogate, and f ...201627439140
listeria monocytogenes cross-contamination of cheese: risk throughout the food supply chain.listeria monocytogenes has been the most common microbial cause of cheese-related recalls in both the united states and canada in recent years. since l. monocytogenes is inactivated by pasteurization, the majority of these cases have been linked to environmental and cross-contamination of fresh-soft, soft-ripened, and semi-soft cheeses. cross-contamination of foods with l. monocytogenes is a continuous risk throughout the food supply chain and presents unique challenges for subsequent illness an ...201627435307
growth differences and competition between listeria monocytogenes strains determine their predominance on ham slices and lead to bias during selective enrichment with the iso protocol.listeria monocytogenes strains are widespread in the environment where they live well mixed, often resulting in multiple strains contaminating a single food sample. the occurrence of different strains in the same food might trigger strain competition, contributing to uneven growth of strains in food and to bias during selective procedures. we tested the growth of seven l. monocytogenes strains (c5, 6179, scotta, pl24, pl25, pl26, pl27) on ham slices and on nutrient-rich agar at 10°c, singly and ...201627434679
application of lemongrass oil-containing polylactic acid films to the packaging of pork sausages.polylactic acid (pla) is a biodegradable and renewable polymer, which represents a valuable alternative to plastic packaging films, often associated with environmental problems. in this study, we tested the suitability of pla as a biodegradable packaging film and assessed the antimicrobial activity of lemongrass oil (lo), incorporated into the pla film in different concentrations. to obtain the optimal physical properties for pla films, tensile strength, elongation at break, and water vapor perm ...201627433114
use of whole genome sequencing and patient interviews to link a case of sporadic listeriosis to consumption of prepackaged lettuce.we report on a case of listeriosis in a patient who probably consumed a prepackaged romaine lettuce-containing product recalled for listeria monocytogenes contamination. although definitive epidemiological information demonstrating exposure to the specific recalled product was lacking, the patient reported consumption of a prepackaged romaine lettuce-containing product of either the recalled brand or a different brand. a multinational investigation found that patient and food isolates from the r ...201627296429
transfer of pathogens from cantaloupe rind to preparation surfaces and edible tissue as a function of cutting method.whole and cut cantaloupes have been implicated as vehicles in foodborne illness outbreaks of norovirus, salmonellosis, and listeriosis. preparation methods that minimize pathogen transfer from external surfaces to the edible tissue are needed. two preparation methods were compared for the transfer of listeria monocytogenes, salmonella enterica serovar typhimurium lt2, murine norovirus, and tulane virus from inoculated cantaloupe rinds to edible tissue and preparation surfaces. for the first meth ...201627296423
capacity of listeria monocytogenes strains from the 2011 cantaloupe outbreak to adhere, survive, and grow on cantaloupe.the 2011 listeriosis outbreak attributed to whole cantaloupe involved several genetically distinct strains of serotypes 1/2a and 1/2b that had not been previously reported in invasive listeriosis outbreaks. here we investigated the potential of strains from the 2011 cantaloupe outbreak to adhere, survive, and grow on cantaloupe rind and flesh and in juice extracted from cantaloupe at different temperatures (4, 8, and 25°c). all strains were able to adhere and grow, with ∼10-fold increases after ...201627296422
an outbreak of human listeriosis in england between 2010 and 2012 associated with the consumption of pork pies.an outbreak of listeriosis in england affecting 14 people between 2010 and 2012 and linked to the consumption of pork pies was investigated. all 14 individuals were older than 55 years, 12 were men, and 10 reported the presence of an underlying condition. all were resident in or had visited either of two english regions and were infected with the same strain of listeria monocytogenes. in interviews with 12 patients, 9 reported eating pork pies, and individuals that consumed pork pies were signif ...201627296419
fate of listeria monocytogenes in fresh apples and caramel apples.an outbreak of listeriosis in late 2014 and early 2015 associated with caramel apples led to questions about how this product became a vector for listeria monocytogenes. this investigation aimed to determine information about the survival and growth of l. monocytogenes in both fresh apples and caramel apples, specifically examining the effects of site and level of inoculation, inoculum drying conditions, and storage temperature. at a high inoculation level (7 log cfu per apple), l. monocytogenes ...201627296414
bacterial manipulation of nk cell regulatory activity increases susceptibility to listeria monocytogenes infection.natural killer (nk) cells produce interferon (ifn)-γ and thus have been suggested to promote type i immunity during bacterial infections. yet, listeria monocytogenes (lm) and some other pathogens encode proteins that cause increased nk cell activation. here, we show that stimulation of nk cell activation increases susceptibility during lm infection despite and independent from robust nk cell production of ifnγ. the increased susceptibility correlated with il-10 production by responding nk cells. ...201627295349
whole genome sequence-based serogrouping of listeria monocytogenes isolates.whole genome sequencing (wgs) is currently becoming the method of choice for characterization of listeria monocytogenes isolates in national reference laboratories (nrls). wgs is superior with regards to accuracy, resolution and analysis speed in comparison to several other methods including serotyping, pcr, pulsed field gel electrophoresis (pfge), multilocus sequence typing (mlst), multilocus variable number tandem repeat analysis (mlva), and multivirulence-locus sequence typing (mvlst), which ...201627288594
propagation method for persistent high yield of diverse listeria phages on permissive hosts at refrigeration temperatures.the efficient production of a high concentration of bacteriophage in large volumes has been a limiting factor in the exploration of the true potential of these organisms for biotechnology, agriculture and medicine. traditional methods focus on generating small volumes of highly concentrated samples as the end product of extensive mechanical and osmotic processing. to function at an industrial scale mandates extensive investment in infrastructure and input materials not feasible for many smaller ...201627287043
risk assessment of human listeriosis from semisoft cheeses made from raw sheep's milk in lazio and tuscany (italy).semisoft cheese made from raw sheep's milk is traditionally and economically important in southern europe. however, raw milk cheese is also a known vehicle of human listeriosis and contamination of sheep cheese with listeria monocytogenes has been reported. in the present study, we have developed and applied a quantitative risk assessment model, based on available evidence and challenge testing, to estimate risk of invasive listeriosis due to consumption of an artisanal sheep cheese made with ra ...201627285819
new antimicrobial peptides against foodborne pathogens: from in silico design to experimental evidence.recently there has been growing interest in the discovery of new antimicrobial agents to increase safety and shelf-life of food products. here, we developed an innovative approach by introducing the concept that mitochondrial targeting peptides (mtp) can interact and disrupt bacterial membranes, acting as antimicrobial agents. as proof-of-principle, we used a multidisciplinary strategy by combining in silico predictions, docking simulations and antimicrobial assays, to identify two peptides, mtp ...201627283665
sharing is caring: international sharing of data enhances genomic surveillance of listeria monocytogenes. 201627282712
the effect of oxygen on bile resistance in listeria monocytogenes.listeria monocytogenes is a gram-positive facultative anaerobe that is the causative agent of the disease listeriosis. the infectious ability of this bacterium is dependent upon resistance to stressors encountered within the gastrointestinal tract, including bile. previous studies have indicated bile salt hydrolase activity increases under anaerobic conditions, suggesting anaerobic conditions influence stress responses. therefore, the goal of this study was to determine if reduced oxygen availab ...201627274623
listeriosis downregulates hepatic cytochrome p450 enzymes in sublethal murine infection.listeria monocytogenes (lm) can cross the intestinal barrier in humans and then disseminates into different organs. invasion of the liver occurs even in sublethal infections, however, knowledge of affected physiological processes is scarce. this study employed a sublethal murine infection model to investigate liver responses systematically by proteomics.201627273978
lactococcus piscium: a psychrotrophic lactic acid bacterium with bioprotective or spoilage activity in food-a review.the genus lactococcus comprises 12 species, some known for decades and others more recently described. lactococcus piscium, isolated in 1990 from rainbow trout, is a psychrotrophic lactic acid bacterium, probably disregarded because most of the strains are unable to grow at 30°c. during the last 10 years, this species has been isolated from a large variety of food: meat, seafood and vegetables, mostly packed under vacuum (vp) or modified atmosphere (map) and stored at chilled temperature. recent ...201627172050
free-living species of carnivorous mammals in poland: red fox, beech marten, and raccoon as a potential reservoir of salmonella, yersinia, listeria spp. and coagulase-positive staphylococcus.the objective of the study was to examine a population of free-living carnivorous mammals most commonly found in poland (red fox, beech marten, and raccoon) for the occurrence of bacteria that are potentially pathogenic for humans and other animal species and to determine their virulence potential (the presence of selected virulence genes). from the total pool of isolates obtained (n = 328), we selected 90 belonging to species that pose the greatest potential threat to human health: salmonella s ...201627171434
a rare case of listeriosis, acute cholecystitis and multiple myeloma.listeria monocytogenes (lm) is an aerobic, motile, intracellular gram-positive bacterium. most invasive systemic infections caused by lm are commonly seen in patients at both extremes of age, during pregnancy or in immunocompromised hosts. common clinical manifestations of lm infection in immunocompromised adults are bacteremia, infections of central nervous system, such as meningitis, and self-limiting febrile gastroenteritis. focal infections of listeria are rare, especially cholecystitis, wit ...201627170703
ongoing outbreak of invasive listeriosis due to serotype 1/2a listeria monocytogenes, ancona province, italy, january 2015 to february 2016.in the first seven weeks of 2016, five serotype 1/2a listeria monocytogenes isolates were collected from patients with invasive listeriosis in ancona province in italy. these strains and six 1/2a isolates identified in 2015 in the same area were typed by eric-pcr and pfge. a clonal relationship, documented between the two sets of isolates, suggested a listeriosis outbreak in ancona that started most probably in 2015. investigation into the source of infection is still ongoing.201627168589
listeria monocytogenes in different specimens from healthy red deer and wild boars.in the past, listeria monocytogenes has been isolated from game feces and meat. however, less information is available on the occurrence of l. monocytogenes in other specimens originating from game animals. hence, the aim of this study was to get an overview of the occurrence and distribution of l. monocytogenes in game animals by characterization of isolates from different matrices. for that purpose, samples were collected from red deer (cervus elaphus), wild boars (sus scrofa), and feed during ...201627159352
endothelial cells use a formin-dependent phagocytosis-like process to internalize the bacterium listeria monocytogenes.vascular endothelial cells act as gatekeepers that protect underlying tissue from blood-borne toxins and pathogens. nevertheless, endothelial cells are able to internalize large fibrin clots and apoptotic debris from the bloodstream, although the precise mechanism of such phagocytosis-like uptake is unknown. we show that cultured primary human endothelial cells (huvec) internalize both pathogenic and non-pathogenic listeria bacteria comparably, in a phagocytosis-like process. in contrast with pr ...201627152864
the absence of a mature cell wall sacculus in stable listeria monocytogenes l-form cells is independent of peptidoglycan synthesis.l-forms are cell wall-deficient variants of otherwise walled bacteria that maintain the ability to survive and proliferate in absence of the surrounding peptidoglycan sacculus. while transient or unstable l-forms can revert to the walled state and may still rely on residual peptidoglycan synthesis for multiplication, stable l-forms cannot revert to the walled form and are believed to propagate in the complete absence of peptidoglycan. l-forms are increasingly studied as a fundamental biological ...201627149671
preliminary study on the effect of fermented cheese whey on listeria monocytogenes, escherichia coli o157:h7, and salmonella goldcoast populations inoculated onto fresh organic lettuce.cheese whey fermented by an industrial starter consortium of lactic acid bacteria was evaluated for its antibacterial capacity to control a selection of pathogenic bacteria. for their relevance on outbreak reports related to vegetable consumption, this selection included listeria monocytogenes, serotype 4b, escherichia coli o157:h7, and salmonella goldcoast. organically grown lettuce was inoculated with an inoculum level of ∼10(7) colony-forming unit (cfu)/ml and was left for about 1 h in a safe ...201627149657
two listeria outbreaks caused by smoked fish consumption-using whole-genome sequencing for outbreak investigations.listeria monocytogenes may contaminate and persist in food production facilities and cause repeated, seemingly sporadic, illnesses over extended periods of time. we report on the investigation of two such concurrent outbreaks. we compared patient isolates and available isolates from foods and food production facilities by use of whole-genome sequencing and subsequent multilocus sequence type and single nucleotide polymorphism analysis. outbreak cases shared outbreak strains, defined as listeria ...201627145209
bacteriocin from epidemic listeria strains alters the host intestinal microbiota to favor infection.listeria monocytogenes is responsible for gastroenteritis in healthy individuals and for a severe invasive disease in immunocompromised patients. among the three identified l. monocytogenes evolutionary lineages, lineage i strains are overrepresented in epidemic listeriosis outbreaks, but the mechanisms underlying the higher virulence potential of strains of this lineage remain elusive. here, we demonstrate that listeriolysin s (lls), a virulence factor only present in a subset of lineage i stra ...201627140611
anti-infective activity of 2-cyano-3-acrylamide inhibitors with improved drug-like properties against two intracellular pathogens.due to the rise of antibiotic resistance and the small number of effective antiviral drugs, new approaches for treating infectious diseases are urgently needed. identifying targets for host-based therapies represents an emerging strategy for drug discovery. the ubiquitin-proteasome system is a central mode of signaling in the eukaryotic cell and may be a promising target for therapies that bolster the host's ability to control infection. deubiquitinase (dub) enzymes are key regulators of the hos ...201627139470
blue-light inhibition of listeria monocytogenes growth is mediated by reactive oxygen species and is influenced by σb and the blue-light sensor lmo0799.listeria monocytogenes senses blue light via the flavin mononucleotide-containing sensory protein lmo0799, leading to activation of the general stress response sigma factor sigb (σ(b)). in this study, we investigated the physiological response of this foodborne pathogen to blue light. we show that blue light (460 to 470 nm) doses of 1.5 to 2 mw cm(-2) cause inhibition of growth on agar-based and liquid culture media. the inhibitory effects are dependent on cell density, with reduced effects evid ...201627129969
characteristics and distribution of listeria spp., including listeria species newly described since 2009.the genus listeria is currently comprised of 17 species, including 9 listeria species newly described since 2009. genomic and phenotypic data clearly define a distinct group of six species (listeria sensu strictu) that share common phenotypic characteristics (e.g., ability to grow at low temperature, flagellar motility); this group includes the pathogen listeria monocytogenes. the other 11 species (listeria sensu lato) represent three distinct monophyletic groups, which may warrant recognition a ...201627129530
[increased apoptosis and down-regulation of rhoa in hepg2 cells infected by listeria monocytogenes].to explore the apoptosis of hepg2 cells infected by listeria monocytogenes egd strain (lm-egd) as well as rho family small gtpases rhoa expression.201627126939
interrupting cd28 costimulation before antigen rechallenge affects cd8(+) t-cell expansion and effector functions during secondary response in mice.the role of cd28-mediated costimulation in secondary cd8(+) t-cell responses remains controversial. here, we have used two tools - blocking mouse anti-mouse cd28-specific antibodies and inducible cd28-deleting mice - to obtain definitive answers in mice infected with ovalbumin-secreting listeria monocytogenes. we report that both blockade and global deletion of cd28 reveal its requirement for full clonal expansion and effector functions such as degranulation and ifn-γ production during the secon ...201627122236
term-seq reveals abundant ribo-regulation of antibiotics resistance in bacteria.riboswitches and attenuators are cis-regulatory rna elements, most of which control bacterial gene expression via metabolite-mediated, premature transcription termination. we developed an unbiased experimental approach for genome-wide discovery of such ribo-regulators in bacteria. we also devised an experimental platform that quantitatively measures the in vivo activity of all such regulators in parallel and enables rapid screening for ribo-regulators that respond to metabolites of choice. using ...201627120414
restraining reactive oxygen species in listeria monocytogenes promotes the apoptosis of glial cells.listeria monocytogenes is a facultative anaerobic foodborne pathogen that can traverse the blood-brain barrier and cause brain infection. l. monocytogenes infection induces host cell apoptosis in several cell types. in this study, we investigated the apoptosis of human glioma cell line u251 invaded by l. monocytogenes and evaluated the function of bacterial reactive oxygen species (ros) during infection.201627120397
the continuous challenge of characterizing the foodborne pathogen listeria monocytogenes.listeria monocytogenes is an important foodborne pathogen commonly isolated from food processing environments and food products. this organism can multiply at refrigeration temperatures, form biofilms on different materials and under various conditions, resist a range of environmental stresses, and contaminate food products by cross-contamination. l. monocytogenes is recognized as the causative agent of listeriosis, a serious disease that affects mainly individuals from high-risk groups, such as ...201627120361
the microbiological quality of pasteurized milk sold by automatic vending machines.the microbiological quality of pasteurized milk samples (n = 39) collected during 13 weekly intervals from three automatic vending machines (avm) in greece was investigated. microbiological counts (total aerobic (tac), total psychrotrophic (tpc), enterobacteriaceae (ec), and psychrotrophic aerobic bacterial spore counts (pabsc)) were obtained at the time of sampling and at the end of shelf-life (3 days) after storage of the samples at 4 or 8°c. tac were found to be below the 10(7 ) cfu ml(-1) li ...201627116619
fully automated and colorimetric foodborne pathogen detection on an integrated centrifugal microfluidic device.this work describes fully automated and colorimetric foodborne pathogen detection on an integrated centrifugal microfluidic device, which is called a lab-on-a-disc. all the processes for molecular diagnostics including dna extraction and purification, dna amplification and amplicon detection were integrated on a single disc. silica microbeads incorporated in the disc enabled extraction and purification of bacterial genomic dna from bacteria-contaminated milk samples. we targeted four kinds of fo ...201627112702
click-em for imaging metabolically tagged nonprotein biomolecules.em has long been the main technique for imaging cell structures with nanometer resolution but has lagged behind light microscopy in the crucial ability to make specific molecules stand out. here we introduce click-em, a labeling technique for correlative light microscopy and em imaging of nonprotein biomolecules. in this approach, metabolic labeling substrates containing bioorthogonal functional groups are provided to cells for incorporation into biopolymers by endogenous biosynthetic machinery. ...201627110681
listeria monocytogenes infection differentially affects expression of ligands for nk cells and nk cell responses, depending on the cell type infected.the pivotal role of nk cells in viral infection is extensively studied, whereas the role of nk cells in bacterial infection has been poorly investigated. here, we have examined how listeria monocytogenes (lm) affects expression of ligands for nk cell receptors and subsequent nk cell responses, depending on the type of cell infected. lm infected rat cell lines derived from different tissues were coincubated with splenic nk cells, and nk cell proliferation and ifn-γ production were measured. in ad ...201627106671
listeriolysin o membrane damaging activity involves arc formation and lineaction -- implication for listeria monocytogenes escape from phagocytic vacuole.listeriolysin-o (llo) plays a crucial role during infection by listeria monocytogenes. it enables escape of bacteria from phagocytic vacuole, which is the basis for its spread to other cells and tissues. it is not clear how llo acts at phagosomal membranes to allow bacterial escape. the mechanism of action of llo remains poorly understood, probably due to unavailability of suitable experimental tools that could monitor llo membrane disruptive activity in real time. here, we used high-speed atomi ...201627104344
rifampin phosphotransferase is an unusual antibiotic resistance kinase.rifampin (rif) phosphotransferase (rph) confers antibiotic resistance by conversion of rif and atp, to inactive phospho-rif, amp and pi. here we present the crystal structure of rph from listeria monocytogenes (rph-lm), which reveals that the enzyme is comprised of three domains: two substrate-binding domains (atp-grasp and rif-binding domains); and a smaller phosphate-carrying his swivel domain. using solution small-angle x-ray scattering and mutagenesis, we reveal a mechanism where the swivel ...201627103605
in vivo efficacy of trans-cinnamaldehyde, carvacrol, and thymol in attenuating listeria monocytogenes infection in a galleria mellonella model.listeria monocytogenes is a major foodborne pathogen that causes life-threatening illnesses in humans. with emergence of antibiotic resistance in l. monocytogenes, there is considerable interest in testing the efficacy of alternative therapies for controlling listeriosis in humans. this study investigated the efficacy of three phytochemicals, namely trans-cinnamaldehyde (tc), carvacrol (cr), and thymol (ty) in reducing l. monocytogenes virulence in the recently established invertebrate model, ga ...201627094514
previous homologous and heterologous stress exposure induces tolerance development to pulsed light in listeria monocytogenes.as one of the emerging non-thermal technologies, pulsed light (pl) facilitates rapid, mild and residue-free microbial surface decontamination of food and food contact materials. while notable progress has been made in the characterization of the inactivation potential of pl, experimental data available on the tolerance development to the same (homologous) stress or to different (heterologous) stresses commonly applied in food manufacturing (e.g., acid, heat, salt) is rather controversial. the fi ...201627092137
implementation of nationwide real-time whole-genome sequencing to enhance listeriosis outbreak detection and investigation.listeria monocytogenes (lm) causes severe foodborne illness (listeriosis). previous molecular subtyping methods, such as pulsed-field gel electrophoresis (pfge), were critical in detecting outbreaks that led to food safety improvements and declining incidence, but pfge provides limited genetic resolution. a multiagency collaboration began performing real-time, whole-genome sequencing (wgs) on all us lm isolates from patients, food, and the environment in september 2013, posting sequencing data i ...201627090985
agricultural by-products with bioactive effects: a multivariate approach to evaluate microbial and physicochemical changes in a fresh pork sausage enriched with phenolic compounds from olive vegetation water.the use of phenolic compounds derived from agricultural by-products could be considered as an eco-friendly strategy for food preservation. in this study a purified phenol extract from olive vegetation water (peovw) was explored as a potential bioactive ingredient for meat products using italian fresh sausage as food model. the research was developed in two steps: first, an in vitro delineation of the extract antimicrobial activities was performed, then, the peovw was tested in the food model to ...201627088870
how many parameters does it take to describe disease tolerance?the study of infectious disease has been aided by model organisms, which have helped to elucidate molecular mechanisms and contributed to the development of new treatments; however, the lack of a conceptual framework for unifying findings across models, combined with host variability, has impeded progress and translation. here, we fill this gap with a simple graphical and mathematical framework to study disease tolerance, the dose response curve relating health to microbe load; this approach hel ...201627088212
a molluscan calreticulin ortholog from haliotis discus discus: molecular characterization and transcriptional evidence for its role in host immunity.calreticulin (calr), a ca(2+) binding chaperone of the endoplasmic reticulum (er) and mainly involved in ca(2+) storage and signaling. in this study, we report the molecular characterization and immune responses of calr homolog from disk abalone (abcalr). the full length abcalr cdna (1837 bp) had an orf of 1224 bp. according to the multiple alignments analysis, n- and p-domains were highly conserved in all the selected members of calrs. in contrast, the c-domain which terminated with the charact ...201627086846
how nacl and water content determine water activity during ripening of gouda cheese, and the predicted effect on inhibition of listeria monocytogenes.this study describes the diffusion of nacl and water in gouda cheese during brining and ripening. furthermore, we established water activity as a function of the nacl-in-moisture content in gouda cheese during ripening. we determined nacl content, water content, and water activity in block-type gouda cheeses that were brined for 3.8d and foil-ripened for a period of 26 wk, and in wheel-type gouda cheeses that were brined for 0.33, 2.1, or 8.9d and subsequently nature-ripened for a period of 26 w ...201627085417
listeria monocytogenes remodels the cell surface in the blood-stage.after crossing the intestinal barrier, the bacterial pathogen listeria monocytogenes disseminates via the blood to the liver, spleen, brain and placenta. transcriptomic studies have shown that l. monocytogenes changes expression of many genes during this blood-stage. however, no comparable data at the protein level are known. as main interactors with the environment, we focused in surface proteins produced by l. monocytogenes in an ex vivo bovine blood model. bacteria exposed to blood alter sele ...201627085096
simultaneous detection of waddlia chondrophila and listeria monocytogenes in aborted ruminant samples by real-time quantitative pcr. 201627083520
determination of virulence and antibiotic resistance pattern of biofilm producing listeria species isolated from retail raw milk.one of the foodborne pathogens is listeria monocytogenes, which causes serious invasive illness in elderly and immunocompromised patients, pregnant women, newborns and infants ranking second after salmonellosis because of its high case fatality rate. listerial cow mastitis marked by abnormal milk, increased cell counts and reduced production has not been reported. therefore, apparently healthy cows can be reservoirs of l. monocytogenes. a number of 203 udder milk samples from apparently healthy ...201627821054
structure to function of an α-glucan metabolic pathway that promotes listeria monocytogenes pathogenesis.here we employ a 'systems structural biology' approach to functionally characterize an unconventional α-glucan metabolic pathway from the food-borne pathogen listeria monocytogenes (lm). crystal structure determination coupled with basic biochemical and biophysical assays allowed for the identification of anabolic, transport, catabolic and regulatory portions of the cycloalternan pathway. these findings provide numerous insights into cycloalternan pathway function and reveal the mechanism of rep ...201627819654
the impact of a cold chain break on the survival of salmonella enterica and listeria monocytogenes on minimally processed 'conference' pears during their shelf life.in recent years, improved detection methods and increased fresh-cut processing of produce have led to an increased number of outbreaks associated with fresh fruits and vegetables. during fruit and vegetable processing, natural protective barriers are removed and tissues are cut, causing nutrient rich exudates and providing attachment sites for microbes. consequently, fresh-cut produce is more susceptible to microbial proliferation than whole produce.201627813092
prevalence, and virulence determination of listeria monocytogenes strains isolated from clinical and non-clinical samples by multiplex polymerase chain reaction.this study aimed to determine the prevalence, and virulence factors of listeria monocytogenes isolated from various samples by multiplex polymerase chain reaction (mpcr).201627812659
effectiveness of washing procedures in reducing salmonella enterica and listeria monocytogenes on a raw leafy green vegetable (eruca vesicaria).vegetables are an important source of nutrients, but they can host a large microbial population, particularly bacteria. foodborne pathogens can contaminate raw vegetables at any stage of their production process with a potential for human infection. appropriate washing can mitigate the risk of foodborne illness consequent to vegetable consumption by reducing pathogen levels, but few data are available to assess the efficacy of different practices. in the present work, six different washing metho ...201627812356
resistance to biocides in listeria monocytogenes collected in meat-processing environments.the emergence of microorganisms exerting resistance to biocides is a challenge to meat-processing environments. bacteria can be intrinsically resistant to biocides but resistance can also be acquired by adaptation to their sub-lethal concentrations. moreover, the presence of biocide resistance determinants, which is closely linked to antibiotic resistance determinants, could lead to co-selection during disinfection practices along the food chain, and select cross-resistant foodborne pathogens. t ...201627807430
inhibition effect of tea tree oil on listeria monocytogenes growth and exotoxin proteins listeriolysin o and p60 secretion.listeria monocytogenes (l. monocytogenes) is a gram-positive bacterium that causes infections in humans. in this study, the effects of tea tree oil (tto) at subinhibitory concentrations on l. monocytogenes growth and two important exotoxin proteins secreted by l. monocytogenes were researched. treatment with half of minimal inhibitory concentration of tto demonstrated very little or no reduction in numbers of viable atcc 19115 cells. listeriolysin o (llo) and p60, were investigated. a listerioly ...201627591558
listeria spp. and listeria monocytogenes contamination in ready-to-eat sandwiches collected from vending machines.ready-to-eat (rte) food is characterised by a long shelf-life at refrigerated temperature and can be consumed as such, without any treatment. the aim of the work was to evaluate the presence of listeria spp. and listeria monocytogenes in rtes collected from refrigerated vending machines placed in hospital environment and accessible to the hospitalised patients. in 4 different sampling, 55 rtes were collected from vending machines of six hospitals located in different areas of sardinia region. al ...201627800439
detection of food hazards in foods: comparison of real time polymerase chain reaction and cultural methods.foodstuffs should not contain microorganisms or their toxins or metabolites in quantities suggesting an unacceptable risk for human health. the detection of food hazards in foods is performed by several tests that produce results dependent on the analytical method used: an analytical reference method, defined as standard, is associated with each microbiological criterion laid down in regulation 2073/2005/ec, but, analytical methods other than the reference ones, in particular more rapid methods, ...201627800434
antimicrobial activity of chitosan films with essential oils against listeria monocytogenes on cabbage.the highest incidence of listeriosis, due to consumption of ready-to-eat foods and fresh, shredded, minimally processed vegetables, occurs among pregnant women and the elderly. in order to reduce the prevalence of listeriosis among consumers, better protective measures are recommended. chitosan films, with or without added essential oils, represent a modern, safe method of preserving the quality of such vegetables and significantly reducing the incidence of listeria monocytogenes in these foods.201627800143
adaptive response of listeria monocytogenes to heat, salinity and low ph, after habituation on cherry tomatoes and lettuce leaves.pathogens found on fresh produce may encounter low temperatures, high acidity and limited nutrient availability. the aim of this study was to evaluate the effect of habituation of listeria monocytogenes on cherry tomatoes or lettuce leaves on its subsequent response to inhibitory levels of acid, osmotic and heat stress. habituation was performed by inoculating lettuce coupons, whole cherry tomatoes or tryptic soy broth (tsb) with a three-strains composite of l. monocytogenes, which were further ...201627798688
menin plays a critical role in the regulation of the antigen-specific cd8+ t cell response upon listeria infection.menin, a tumor suppressor protein, is encoded by the men1 gene in humans. certain germinal mutations of men1 induce an autosomal-dominant syndrome that is characterized by concurrent parathyroid adenomas and several other tumor types. although menin is also expressed in hematopoietic lineages, its role in cd8(+) t cells remains unclear. we generated menin(flox/flox) cd4-cre (menin-ko) mice by crossing menin(flox/flox) mice with cd4-cre transgenic (tg) mice to determine the role of menin in cd8(+ ...201627798149
met-activating residues in the b-repeat of the listeria monocytogenes invasion protein inlb.the facultative intracellular pathogen listeria monocytogenes causes listeriosis, a rare but life-threatening disease. host cell entry begins with activation of the human receptor tyrosine kinase met through the bacterial invasion protein inlb, which contains an internalin domain, a b-repeat, and three gw domains. the internalin domain is known to bind met, but no interaction partner is known for the b-repeat. adding the b-repeat to the internalin domain potentiates met activation and is require ...201627789707
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