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Listeria screening

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
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
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
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
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...
October 10, 2016: Infection and Immunity
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
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
Deepak B Rawool, Swapnil P Doijad, Krupali V Poharkar, Mamta Negi, Satyajit B Kale, S V S Malik, Nitin V Kurkure, Trinad Chakraborty, Sukhadeo B Barbuddhe
A novel multiplex PCR assay was developed to identify genus Listeria, and discriminate Listeria monocytogenes and its major lineages (LI, LII, LIII). This assay is a rapid and inexpensive subtyping method for screening and characterization of L. monocytogenes.
November 2016: Journal of Microbiological Methods
L Stratton, G R Caddy
Patients with Crohn's disease often require the use of immunosuppressant drugs to control disease activity. Such medication includes steroids, azathioprine, and biologic therapy. These suppress the immune response, and the patient is more susceptible to infection. We present a case of a 69-year-old gentleman with a history of Crohn's colitis who had ongoing symptoms of diarrhoea in spite of standard treatment. Biologic therapy was considered to be the next step, and screening for infection was undertaken prior to use...
2016: Case Reports in Gastrointestinal Medicine
Hongxing Liu, Xiaoming Zhou, Weipeng Liu, Xiaoke Yang, Da Xing
Genetic analysis is of great importance for the detection of pathogenic bacteria. Bacterial identification must become simpler, less expensive, and more rapid than the traditional methods. In this study, a low-cost, label-free, and wireless paper-based bipolar electrode electrochemiluminescence (pBPE-ECL) analysis system was constructed for the rapid and sensitive genetic detection of pathogenic bacteria. Wax-screen printing was used to form hydrophilic channels on filter paper, and a carbon ink-based bipolar electrode and driving electrodes were screen-printed into the channels...
October 18, 2016: Analytical Chemistry
Athena Grounta, Paschalis Harizanis, Eleftherios Mylonakis, George-John E Nychas, Efstathios Z Panagou
The use of Galleria mellonella as a model host to elucidate microbial pathogenesis and search for novel drugs and therapies has been well appreciated over the past years. However, the effect of microorganisms with functional appeal in the specific host remains scarce. The present study investigates the effect of treatment with selected lactic acid bacteria (LAB) with probiotic potential, as potential protective agents by using live or heat-killed cells at 6 and 24 h prior to infection with Listeria monocytogenes and Staphylococcus aureus or as potential therapeutic agents by using cell-free supernatants (CFS) after infection with the same pathogens...
2016: PloS One
Vi N Nguyen, Annsea Park, Anting Xu, John R Srouji, Steven E Brenner, Jack F Kirsch
The nearly 50,000 known Nudix proteins have a diverse array of functions, of which the most extensively studied is the catalyzed hydrolysis of aberrant nucleotide triphosphates. The functions of 171 Nudix proteins have been characterized to some degree, although physiological relevance of the assayed activities has not always been conclusively demonstrated. We investigated substrate specificity for eight structurally characterized Nudix proteins, whose functions were unknown. These proteins were screened for hydrolase activity against a 74-compound library of known Nudix enzyme substrates...
December 2016: Proteins
Ning Xiang, Yuan Lyu, Xiao Zhu, Arun K Bhunia, Ganesan Narsimhan
Antimicrobial peptides (AMPs) inactivate microbial cells through pore formation in cell membrane. Because of their different mode of action compared to antibiotics, AMPs can be effectively used to combat drug resistant bacteria in human health. AMPs can also be used to replace antibiotics in animal feed and immobilized on food packaging films. In this research, we developed a methodology based on mechanistic evaluation of peptide-lipid bilayer interaction to identify AMPs from soy protein. Production of AMPs from soy protein is an attractive, cost-saving alternative for commercial consideration, because soy protein is an abundant and common protein resource...
September 6, 2016: Peptides
Lili Li, Rikke Heidemann Olsen, Lei Shi, Lei Ye, Jianhua He, Hecheng Meng
A multi-drug resistant (MDR) Listeria monocytogenes isolate (serotype 1/2c) was recovered from a quick-frozen rice flour product collected from Langfang city in northern China. PCR screening identified the presence of cat, ermB and tetS genes. The plasmid profile of the strain showed the presence of an approximately 22.4-kb plasmid. Curing of this plasmid resulted in the loss of cat, ermB and tetS genes and increased susceptibility to several antibiotics, suggesting the involvement of the plasmid in multiple antibiotic resistances...
December 5, 2016: International Journal of Food Microbiology
Qi Chen, Dan Wang, Gaozhe Cai, Yonghua Xiong, Yuntao Li, Maohua Wang, Huiling Huo, Jianhan Lin
Early screening of pathogenic bacteria is a key to prevent and control of foodborne diseases. In this study, we developed a fast and sensitive bacteria detection method integrating electrochemical impedance analysis, urease catalysis with microfluidics and using Listeria as model. The Listeria cells, the anti-Listeria monoclonal antibodies modified magnetic nanoparticles (MNPs), and the anti-Listeria polyclonal antibodies and urease modified gold nanoparticles (AuNPs) were incubated in a fluidic separation chip with active mixing to form the MNP-Listeria-AuNP-urease sandwich complexes...
December 15, 2016: Biosensors & Bioelectronics
Thomas D Curtis, Lone Gram, Gitte M Knudsen
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 or prolonged infections...
2016: Frontiers in Microbiology
Hanen Ghodhbane, Valentina Alessandria, Mejdi Snoussi, Chedly Abdelly, Jean Marc Sabatier, Luca Cocolin, Imed Regaya
A total of 94 lactic acid bacteria (LAB) were isolated from Tunisian artisanal (Ricotta cheese's whey) and industrial (bactofugate) milk waste, identified and then screened for their antimicrobial activity against some bacteria implicated on nosocomial infections. Bacterial genera and species identification was perfomed using molecular tools. The antimicrobial activity was tested against 7 strains of Gram-negative bacteria and 4 strains of Gram-positive bacteria as well as 6 yeasts. The Crude extract was found to have a narrow antimicrobial spectrum on Gram-positive bacteria mainly Listeria monocytogenes...
July 19, 2016: Infectious Disorders Drug Targets
Michelle L Reniere, Aaron T Whiteley, Daniel A Portnoy
Listeria monocytogenes is an environmental saprophyte and facultative intracellular bacterial pathogen with a well-defined life-cycle that involves escape from a phagosome, rapid cytosolic growth, and ActA-dependent cell-to-cell spread, all of which are dependent on the master transcriptional regulator PrfA. The environmental cues that lead to temporal and spatial control of L. monocytogenes virulence gene expression are poorly understood. In this study, we took advantage of the robust up-regulation of ActA that occurs intracellularly and expressed Cre recombinase from the actA promoter and 5' untranslated region in a strain in which loxP sites flanked essential genes, so that activation of actA led to bacterial death...
July 2016: PLoS Pathogens
Oscar F Hernández-Saldaña, Mauricio Valencia-Posadas, Norma M de la Fuente-Salcido, Dennis K Bideshi, José E Barboza-Corona
Currently, there are few reports on the isolation of microorganisms from goat milk and goat cheese that have antibacterial activity. In particular, there are no reports on the isolation of microorganisms with antibacterial activity from these products in central Mexico. Our objective was to isolate bacteria, from goat products, that synthesized antimicrobial peptides with activity against a variety of clinically significant bacteria. We isolated and identified Lactobacillus rhamnosus, L. plantarum, L. pentosus, L...
September 2016: Indian Journal of Microbiology
Mariana Pérez-Ibarreche, Patricia Castellano, Alexandre Leclercq, Graciela Vignolo
The effect of the bacteriocin-producing Lactobacillus sakei CRL1862 and its bacteriocin in the control of Listeria biofilm formation on industrial surfaces at 10°C was investigated. A screening among different Listeria species was performed allowing selecting L. monocytogenes FBUNT for its use as a biofilm producer on stainless steel (SS) and polytetrafluoroe-thylene (PTFE) surfaces. Three conditions were simulated to evaluate the ability of the bacteriocinogenic strain to displace, exclude and compete pathogen biofilm formation...
June 2016: FEMS Microbiology Letters
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