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Listeria screening

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https://www.readbyqxmd.com/read/28325762/a-genetic-screen-reveals-that-synthesis-of-1-4-dihydroxy-2-naphthoate-dhna-but-not-full-length-menaquinone-is-required-for-listeria-monocytogenes-cytosolic-survival
#1
Grischa Y Chen, Courtney E McDougal, Marc A D'Antonio, Jonathan L Portman, John-Demian Sauer
Through unknown mechanisms, the host cytosol restricts bacterial colonization; therefore, only professional cytosolic pathogens are adapted to colonize this host environment. Listeria monocytogenes is a Gram-positive intracellular pathogen that is highly adapted to colonize the cytosol of both phagocytic and nonphagocytic cells. To identify L. monocytogenes determinants of cytosolic survival, we designed and executed a novel screen to isolate L. monocytogenes mutants with cytosolic survival defects. Multiple mutants identified in the screen were defective for synthesis of menaquinone (MK), an essential molecule in the electron transport chain...
March 21, 2017: MBio
https://www.readbyqxmd.com/read/28319869/biofilm-inhibition-formation-of-clinical-strains-of-pseudomonas-aeruginosa-mutans-photocatalytic-activity-of-azo-dye-and-gc-ms-analysis-of-leaves-of-lagerstroemia-speciosa
#2
V Sai Saraswathi, Neethu Kamarudheen, K V Bhaskara Rao, K Santhakumar
The investigation was conducted to analyse the bioactive compounds from the leaf extracts of L. speciosa by GC-MS. The extracts were screened for antibacterial and antibiofilm activities against potential clinical strains. The bioactive compounds from the leaves of L. speciosa were extracted by soxhlet continuous extraction method and their chemical composition was analysed by Gas Chromatography-Mass Spectroscopy (GC-MS). The antibacterial activity was evaluated against clinical strain like Staphylococcus aureus, Escherichia coli, P...
March 9, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28265787/isolation-and-characterisation-of-an-enterocin-p-producing-enterococcus-lactis-strain-from-a-fresh-shrimp-penaeus-vannamei
#3
Olfa Ben Braïek, Hamdi Ghomrassi, Paola Cremonesi, Stefano Morandi, Yannick Fleury, Patrick Le Chevalier, Khaled Hani, Omrane Bel Hadj, Taoufik Ghrairi
Screening for lactic acid bacteria (LAB) from fresh shrimp samples (Penaeus vannamei) collected from retail seafood markets in the Tunisian's coast, resulted in the isolation of an Enterococcus strain termed Q1. This strain was selected for its antagonistic activity against pathogenic bacteria such as Listeria monocytogenes, Pseudomonas aeruginosa, Lactococcus garvieae and against fungi (Aspergillus niger and Fusarium equiseti). The Q1 strain was characterised using standard morphological and biochemical tests, growth assays at different temperatures, pH and salinity...
March 7, 2017: Antonie Van Leeuwenhoek
https://www.readbyqxmd.com/read/28221857/listeria-monocytogenes-isolates-carrying-virulence-attenuating-mutations-in-internalin-a-are-commonly-isolated-from-ready-to-eat-food-processing-plant-and-retail-environments
#4
A VAN Stelten, A R Roberts, C S Manuel, K K Nightingale
Listeria monocytogenes is a human foodborne pathogen that may cause an invasive disease known as listeriosis in susceptible individuals. Internalin A (InlA; encoded by inlA) is a virulence factor that facilitates crossing of host cell barriers by L. monocytogenes . At least 19 single nucleotide polymorphisms (SNPs) in inlA that result in a premature stop codon (PMSC) have been described worldwide. SNPs leading to a PMSC in inlA have been shown to be causally associated with attenuated virulence. L. monocytogenes pathogens carrying virulence-attenuating (VA) mutations in inlA have been commonly isolated from ready-to-eat (RTE) foods but rarely have been associated with human disease...
October 2016: Journal of Food Protection
https://www.readbyqxmd.com/read/28186422/seeds-of-the-wild-progenitor-of-maize-possess-bacteria-that-antagonize-foodborne-pathogens
#5
Hanan R Shehata, Mansel W Griffiths, Manish N Raizada
Endophytes are microorganisms that inhabit plant tissues without causing disease. Some endophytes help their hosts to combat pathogens. Here we explored the hypothesis that the plant-derived foods consumed by humans and other animals host endophytes that also antagonize foodborne pathogens or food-rotting agents. Our laboratory previously cultured a library of bacterial endophytes from different members of the maize/corn family (Zea) including wild relatives. Here, 190 of these endophytes were screened for their ability to antagonize four foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes, Clostridium perfringens, and Salmonella enterica Newport) and a food spoiling agent (Pseudomonas fluorescens) using dual culture assays...
February 10, 2017: Foodborne Pathogens and Disease
https://www.readbyqxmd.com/read/28045020/structural-characterisation-of-the-fatty-acid-biosynthesis-enzyme-fabf-from-the-pathogen-listeria-monocytogenes
#6
Tatiana P Soares da Costa, Jeffrey D Nanson, Jade K Forwood
Development of new antimicrobial agents is required against the causative agent for listeriosis, Listeria monocytogenes, as the number of drug resistant strains continues to increase. A promising target is the β-ketoacyl-acyl carrier protein synthase FabF, which participates in the catalysis of fatty acid synthesis and elongation, and is required for the production of phospholipid membranes, lipoproteins, and lipopolysaccharides. In this study, we report the 1.35 Å crystal structure of FabF from L. monocytogenes, providing an excellent platform for the rational design of novel inhibitors...
January 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28039138/an-effective-counterselection-system-for-listeria-monocytogenes-and-its-use-to-characterize-the-monocin-genomic-region-of-strain-10403s
#7
Tal Argov, Lev Rabinovich, Nadejda Sigal, Anat A Herskovits
Construction of Listeria monocytogenes mutants by allelic exchange has been laborious and time-consuming due to lack of proficient selection markers for the final recombination event, that is, a marker conveying substance sensitivity to the bacteria bearing it, enabling the exclusion of merodiploids and selection for plasmid loss. In order to address this issue, we engineered a counterselection marker based on a mutated phenylalanyl-tRNA synthetase gene (pheS*). This mutation renders the phenylalanine-binding site of the enzyme more promiscuous and allows the binding of the toxic p-chloro-phenylalanine analog (p-Cl-phe) as a substrate...
March 15, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28002645/biologically-active-heterocyclic-hybrids-based-on-quinazolinone-benzofuran-and-imidazolium-moieties-synthesis-characterization-cytotoxic-and-antibacterial-evaluation
#8
Parvin Asadi, Ghadamali Khodarahmi, Ali Jahanian-Najafabadi, Lotfollah Saghaie, Farshid Hassanzadeh
Cytotoxic and antimicrobial agents structurally based on quinazolinone, benzofuran and imidazole pharmacophores, have been designed and synthesized. Spectral (IR, (1) H NMR) and elemental analysis data established the structures of these novel 1-[[(1-(benzofuran-2-yl)-2-(quinazolin-4(3H)-one-3-yl)]ethyl-1-yl]-3- methyl imidazol-1-ium chloride hybrid derivatives. All the synthesized compounds were evaluated for in vitro cytotoxicity and antimicrobial activities. Cytotoxic evaluation using MTT assay revealed that compounds 12c, 12g and 12i exhibited significant cytotoxicity with IC50 values 1, 1, 0...
December 21, 2016: Chemistry & Biodiversity
https://www.readbyqxmd.com/read/28002492/cell-based-screen-identifies-human-interferon-stimulated-regulators-of-listeria-monocytogenes-infection
#9
Sofya S Perelman, Michael E Abrams, Jennifer L Eitson, Didi Chen, Alyssa Jimenez, Marcel Mettlen, John W Schoggins, Neal M Alto
The type I interferon (IFN) activated transcriptional response is a critical antiviral defense mechanism, yet its role in bacterial pathogenesis remains less well characterized. Using an intracellular pathogen Listeria monocytogenes (Lm) as a model bacterial pathogen, we sought to identify the roles of individual interferon-stimulated genes (ISGs) in context of bacterial infection. Previously, IFN has been implicated in both restricting and promoting Lm growth and immune stimulatory functions in vivo. Here we adapted a gain-of-function flow cytometry based approach to screen a library of more than 350 human ISGs for inhibitors and enhancers of Lm infection...
December 2016: PLoS Pathogens
https://www.readbyqxmd.com/read/27998823/benzalkonium-tolerance-genes-and-outcome-in-listeria-monocytogenes-meningitis
#10
P H C Kremer, J A Lees, M M Koopmans, B Ferwerda, A W M Arends, M M Feller, K Schipper, M Valls Seron, A van der Ende, M C Brouwer, D van de Beek, S D Bentley
OBJECTIVES: Listeria monocytogenes is a food-borne pathogen that can cause meningitis. The listerial genotype ST6 has been linked to increasing rates of unfavourable outcome over time. We investigated listerial genetic variation and the relation with clinical outcome in meningitis. METHODS: We sequenced 96 isolates from adults with listerial meningitis included in two prospective nationwide cohort studies by whole genome sequencing, and evaluated associations between bacterial genetic variation and clinical outcome...
December 18, 2016: Clinical Microbiology and Infection
https://www.readbyqxmd.com/read/27990138/purification-of-antilisterial-peptide-subtilosin-a-from-novel-bacillus-tequilensis-fr9-and-demonstrate-their-pathogen-invasion-protection-ability-using-human-carcinoma-cell-line
#11
Rizwana Parveen Rani, Marimuthu Anandharaj, Subramani Hema, Ramasamy Deepika, Abraham David Ravindran
This study focuses on isolation, screening, and characterization of novel probiotics from gastrointestinal tract of free-range chicken (Gallus gallus domesticus). Fifty seven colonies were isolated and three isolates (FR4, FR9, and FR12) were selected and identified as Lactobacillus gasseri FR4, Bacillus tequilensis FR9, and L. animalis FR12 by 16S rRNA sequencing. Three strains were able to survive in stimulated acidic and bile conditions and inhibit the growth of pathogens. Especially, FR9 exhibited maximum inhibition against Listeria monocytogenes and none of them exhibited hemolytic activity...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27986731/novel-cadmium-resistance-determinant-in-listeria-monocytogenes
#12
Cameron Parsons, Sangmi Lee, Victor Jayeola, Sophia Kathariou
Listeria monocytogenes is a foodborne pathogen that can cause severe disease (listeriosis) in susceptible individuals. It is ubiquitous in the environment and often exhibits resistance to heavy metals. One of the determinants that enables Listeria to tolerate exposure to cadmium is the cadAC efflux system, with CadA being a P-type ATPase. Three different cadA genes (designated cadA1 to cadA3) were previously characterized in L. monocytogenes A novel putative cadmium resistance gene (cadA4) was recently identified through whole-genome sequencing, but experimental confirmation for its involvement in cadmium resistance is lacking...
March 1, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/27980380/prevalence-and-antibiotic-susceptibility-profiles-of-listeria-monocytogenes-contamination-of-chicken-flocks-and-meat-in-oyo-state-south-western-nigeria-public-health-implications
#13
REVIEW
O O Ishola, J I Mosugu, H K Adesokan
INTRODUCTION: Food contamination with Listeria monocytogenes is on the increase posing threats to public health with growing trends in food products recalls due to suspected Listeria contamination. METHODS: We conducted a cross-sectional study to determine the prevalence and antibiotic susceptibility profiles of Listeria monocytogenes (Lm) among 71 randomly selected poultry farms in Oyo State, Nigeria. A total of 450 samples comprising cloacal swabs (426) and randomly selected dressed chicken meat (24) were cultured for Lm isolation using BrillianceTM Selective Listeria Agar with antibiotics and microbial load count with Nutrient Agar...
September 2016: Journal of Preventive Medicine and Hygiene
https://www.readbyqxmd.com/read/27800434/detection-of-food-hazards-in-foods-comparison-of-real-time-polymerase-chain-reaction-and-cultural-methods
#14
Paolo Bonilauri, Lia Bardasi, Roberto Leonelli, Mattia Ramini, Andrea Luppi, Federica Giacometti, Giuseppe Merialdi
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, could be used...
January 18, 2016: Italian Journal of Food Safety
https://www.readbyqxmd.com/read/27800430/in-vitro-evaluation-of-bacteriocin-like-inhibitory-substances-produced-by-lactic-acid-bacteria-isolated-during-traditional-sicilian-cheese-making
#15
Giusi Macaluso, Gerlando Fiorenza, Raimondo Gaglio, Isabella Mancuso, Maria Luisa Scatassa
Bacteriocins are antimicrobial proteins produced by bacteria that inhibit the growth of other bacteria with a bactericidal or bacteriostatic mode of action. Many lactic acid bacteria (LAB) produce a high diversity of different bacteriocins. Bacteriocinogenic LAB are generally recognised as safe (GRAS) and useful to control the frequent development of pathogens and spoilage microorganisms. For this reason they are commonly used as starter cultures in food fermentations. In this study, the authors describe the results of a screening on 699 LAB isolated from wooden vat surfaces, raw milk and traditional Sicilian cheeses, for the production of bacteriocin-like inhibitory substances, by comparing two alternative methods...
January 18, 2016: Italian Journal of Food Safety
https://www.readbyqxmd.com/read/27790215/the-scavenger-receptor-ssc5d-physically-interacts-with-bacteria-through-the-srcr-containing-n-terminal-domain
#16
Catarina Bessa Pereira, Markéta Bocková, Rita F Santos, Ana Mafalda Santos, Mafalda Martins de Araújo, Liliana Oliveira, Jiří Homola, Alexandre M Carmo
The scavenger receptor cysteine-rich (SRCR) family comprises a group of membrane-attached or secreted proteins that contain one or more modules/domains structurally similar to the membrane distal domain of type I macrophage scavenger receptor. Although no all-inclusive biological function has been ascribed to the SRCR family, some of these receptors have been shown to recognize pathogen-associated molecular patterns (PAMP) of bacteria, fungi, or other microbes. SSc5D is a recently described soluble SRCR receptor produced by monocytes/macrophages and T lymphocytes, consisting of an N-terminal portion, which contains five SRCR modules, and a large C-terminal mucin-like domain...
2016: Frontiers in Immunology
https://www.readbyqxmd.com/read/27774088/fermented-alore%C3%A3-a-table-olives-as-a-source-of-potential-probiotic-lactobacillus-pentosus-strains
#17
Beatriz Pérez Montoro, Nabil Benomar, Leyre Lavilla Lerma, Sonia Castillo Gutiérrez, Antonio Gálvez, Hikmate Abriouel
A collection of 31 Lactobacillus pentosus strains isolated from naturally fermented Aloreña green table olives were screened in depth in the present study for their probiotic potential. Several strains could be considered promising probiotic candidates since they showed good growth capacity and survival under simulated gastro-intestinal conditions (acidic pH of 1.5, up to 4% of bile salts and 5 mM of nitrate), good ability to auto-aggregate which may facilitate their adhesion to host cells as multiple aggregates and the subsequent displacement of pathogens...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27736782/inlp-a-new-virulence-factor-with-strong-placental-tropism
#18
Cristina Faralla, Gabrielle A Rizzuto, David E Lowe, Byoungkwan Kim, Cara Cooke, Lawrence R Shiow, Anna I Bakardjiev
Intrauterine infection is a major detriment for maternal-child health and occurs despite local mechanisms that protect the maternal-fetal interface from a wide variety of pathogens. The bacterial pathogen Listeria monocytogenes causes spontaneous abortion, stillbirth, and preterm labor in humans and serves as a model for placental pathogenesis. Given the unique immunological environment of the maternal-fetal interface, we hypothesized that virulence determinants with placental tropism are required for infection of this tissue...
December 2016: Infection and Immunity
https://www.readbyqxmd.com/read/27716469/characterization-of-nonpathogenic-listeria-species-isolated-from-food-and-food-processing-environment
#19
Dorota Korsak, Magdalena Szuplewska
A total of 127 Listeria isolates from food and food processing environments, including 75 L. innocua, 49 L. welshimeri, 2 L. seeligeri and 1L. grayi were tested for susceptibility to eight antimicrobials, benzalkonium chloride (BC), cadmium and arsenic. The isolates were also screened for the presence of extrachromosomal genetic elements - plasmids, and their restriction pattern types were determined. All strains were susceptible to ampicillin, ciprofloxacin, erythromycin, gentamicin, rifampicin, trimethoprim and vancomycin...
December 5, 2016: International Journal of Food Microbiology
https://www.readbyqxmd.com/read/27688001/evaluation-of-bacteriocinogenic-activity-safety-traits-and-biotechnological-potential-of-fecal-lactic-acid-bacteria-lab-isolated-from-griffon-vultures-gyps-fulvus-subsp-fulvus
#20
Sara Arbulu, Juan J Jiménez, Loreto Gútiez, Cristina Campanero, Rosa Del Campo, Luis M Cintas, Carmen Herranz, Pablo E Hernández
BACKGROUND: Lactic acid bacteria (LAB) are part of the gut microbiota and produce ribosomally synthesized antimicrobial peptides or bacteriocins with interest as natural food preservatives and therapeutic agents. Bacteriocin-producing LAB are also attractive as probiotics. Griffon vultures (Gyps fulvus subspecies fulvus) are scavenger birds that feed almost exclusively on carrion without suffering apparent ill effects. Therefore, griffon vultures might be considered a reservoir of bacteriocin-producing lactic acid bacteria (LAB) with potential biotechnological applications...
September 29, 2016: BMC Microbiology
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