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Listeria spp., y L. monocytogenes EN LECHE CRUDA DE CABRA
Albarracín C,Yolanda; Poutou P,Raúl; Carrascal C,Ana;
Revista MVZ Córdoba , 2008,
Abstract: objective. to test non-pasteurized goat’s milk from the village of ‘la garita’, northern santander, for listeria monocytogenes. material and methods. 90 samples of non-pasteurized goat&’s milk were obtained over a 4 month period; ph and temperature of each sample were measured. the invima technique was used to isolate l. monocytogenes; the species was confirmed by pcr. results. the study showed that eight goat milk providers of the zone neither had refrigeration nor pasteurized the milk. the prevalence of l. monocytogenes was 3%; 15% of the samples had other species of listeria. the milk obtained from this zone contained the pathogen that may cause listeriosis in children less than 5 years of age, pregnant women, adults and immunologically compromised patients. conclusions. this study shows the occurrence of this pathogen in goat&’s milk and identified areas of risk for those people who drink goat&’s milk.
Listeria spp., y L. monocytogenes EN LECHE CRUDA DE CABRA
Yolanda Albarracín C,Raúl Poutou P,Ana Carrascal C
Revista MVZ Córdoba , 2008,
Abstract: Objective. To test non-pasteurized goat’s milk from the village of ‘la Garita’, Northern Santander, for Listeria monocytogenes. Material and methods. 90 samples of non-pasteurized goat’s milk were obtained over a 4 month period; pH and temperature of each sample were measured. The INVIMA technique was used to isolate L. monocytogenes; the species was confirmed by PCR. Results. The study showed that eight goat milk providers of the zone neither had refrigeration nor pasteurized the milk. The prevalence of L. monocytogenes was 3%; 15% of the samples had other species of Listeria. The milk obtained from this zone contained the pathogen that may cause listeriosis in children less than 5 years of age, pregnant women, adults and immunologically compromised patients. Conclusions. This study shows the occurrence of this pathogen in goat’s milk and identified areas of risk for those people who drink goat’s milk.
Improved sensitivity and reproducibility of the PCR method for detection of Listeria spp. and L. monocytogenes in milk
Lakicevic Brankica,Stjepanovic Aleksandra,Tolinacki Maja,Golic Nata?a
Acta Veterinaria , 2011, DOI: 10.2298/avb1103239l
Abstract: Listeria monocytogenes is a facultative intracellular Grampositive bacterium, ubiquitous in nature and capable of causing listeriosis in humans and animals. Conventional microbiological techniques and modern molecular approaches are currently used for the isolation and detection of L. monocytogenes in food samples. The aim of this study was to improve the sensitivity and reproducibility of PCR for the detection of Listeria spp. in milk. For that purpose milk samples were artificially inoculated with serial dilutions of L. monocytogenes 4b ATCC 19115 and L. innocua ATCC 33090. The results obtained on artificially contaminated milk samples indicated that incubation time and target genes have an influence on the sensitivity of PCR detection. The best results were obtained after 24 h of preenrichment, with primers complementary to the hlyA gene, when it was possible to detect 1 CFU/mL of Listeria spp.
Protective Role of Heme Oxygenase-1 in Listeria monocytogenes-Induced Abortion  [PDF]
Masato Tachibana, Masanori Hashino, Takashi Nishida, Takashi Shimizu, Masahisa Watarai
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0025046
Abstract: It is well-known fact that various pathogens, including bacteria, virus, and protozoa, induce abortion in humans and animals. However the mechanisms of infectious abortion are little known. In this study, we demonstrated that Listeria monocytogenes infection in trophoblast giant cells decreased heme oxygenase (HO)-1 and B-cell lymphoma-extra large (Bcl-XL) expression, and that their overexpression inhibited cell death induced by the infection. Furthermore, HO-1 and Bcl-XL expression levels were also decreased by L. monocytogenes in pregnant mice. Treatment with cobalt protoporphyrin, which is known to induce HO-1, inhibited infectious abortion. Taken together, our study indicates that L. monocytogenes infection decreases HO-1 and Bcl-XL expression and induces cell death in placenta, leading to infectious abortion.
Survival of Listeria monocytogenes during Frying of Chicken Burger Patties  [PDF]
Woan Chwen Wong, Chai Fung Pui, Tuan Zainazor Tuan Chilek, Ahmad Noorlis, John Yew Huat Tang, Yoshitsugu Nakaguchi, Mitsuaki Nishibuchi, Son Radu
Food and Nutrition Sciences (FNS) , 2011, DOI: 10.4236/fns.2011.25067
Abstract: This study was aimed to determine sufficient frying time to reduce the number of Listeria monocytogenes present in chicken burger patties to non-detectable level which is fit for human consumption. Commercially available chicken burger patties were artificially contaminated with L. monocytogenes at level of approximately 9 log CFU/ml. The contaminated chicken burger patties were cooked for 0, 2, 4, 5, 8, and 10 minutes to determine survival of L. monocyto-genes. Results demonstrated a linear correlation between mean log reduction of L. monocytogenes and frying time. L. monocytogenes was not detected in chicken burger patties that were cooked for 6 minutes and above. As a result from this study, it is suggested that a minimum frying time for burger patties is 6 minutes. This can be treated as a safety measure to avoid consequences of consumption of undercooked burger patties.
Antibiotic and Bacteriocin Sensitivity of Listeria monocytogenes Strains Isolated from Different Foods  [PDF]
Evrim Gunes Altuntas, Deniz Kocan, Serap Cosansu, Kamuran Ayhan, Vijay K. Juneja, Luis Materon
Food and Nutrition Sciences (FNS) , 2012, DOI: 10.4236/fns.2012.33052
Abstract: This study aimed to determine the antibiotic and bacteriocin sensitivity of Listeria monocytogenes strains isolated from animal derived foods. With disc diffusion assay, all fourteen L. monocytogenes strains were suscepti-ble to the antibiotics, including penicillin G, vancomycin, tetracycline, chloramphenicol, rifampicin, erythromycin, gentamicin and trime- thoprim. However, the percentages of fosfomycin and streptomycin resistances were 92.9% and 7.1%, respectively. Multiple resistances were not observed among the tested strains. The results of well diffusion assays showed that all strains were inhibited by the cell-free supernatant of a bacteriocin-producing strain, Pediococcus acidilactici 13, with the inhibition zones ranging from 16.00 to 24.50 mm. These results provide useful information on antibiotic resistance of L. monocytogenes strains isolated from foods, and can potentially be used to develop bacteriocin-based interventions to guard against the hazards associated with L. monocytogenes in ready-to-eat meat and poultry products.
Linkage of Bacterial Protein Synthesis and Presentation of MHC Class I-Restricted Listeria monocytogenes-Derived Antigenic Peptides  [PDF]
Silke Grauling-Halama,Simone Schenk,Andreas Bubert,Gernot Geginat
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033335
Abstract: The processing and MHC class I-restricted presentation of antigenic peptides derived from the p60 protein of the facultative intracellular bacterium Listeria monocytogenes is tightly linked to bacterial protein synthesis. We used non-linear regression analysis to fit a mathematical model of bacterial antigen processing to a published experimental data set showing the accumulation and decay of p60-derived antigenic peptides in L. monocytogenes-infected cells. Two alternative models equally describe the experimental data. The simulation accounting for a stable and a hypothetical rapidly degraded form of antigen predicts that the antigenic peptides p60 217–225 and p60 449–457 are derived from a putative instable form of p60 with an average intracellular half-life of approximately 3 minutes accounting for approximately 31% of all p60 molecules synthesized. The alternative model predicts that both antigenic peptides are processed from p60 degraded intracellularly with a half-life of 109 min and that antigen processing only occurs as long as bacterial protein synthesis is not inhibited. In order to decide between both models the intracellular accumulation of p60 in infected cells was studied experimentally and compared with model predictions. Inhibition of p60 degradation by the proteasome inhibitor epoxomicin revealed that during the first 3 h post infection approximately 30% of synthesized p60 molecules were degraded. This value is significantly lower than the approximately 50% degradation of p60 that would be expected in the presence of the predicted putative short-lived state of p60 and also fits precisely with the predictions of the alternative model, indicating that the tight connection of bacterial protein biosynthesis and antigen processing and presentation of L. monocyctogenes-derived antigenic peptides is not caused by the presence of a highly instable antigenic substrate.
Inflammasome-Mediated Inhibition of Listeria monocytogenes-Stimulated Immunity Is Independent of Myelomonocytic Function  [PDF]
Cassandra R. Williams, Michael L. Dustin, John-Demian Sauer
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0083191
Abstract: Activation of the Nlrc4 inflammasome results in the secretion of IL-1β and IL-18 through caspase-1 and induction of pyroptosis. L. monocytogenes engineered to activate Nlrc4 by expression of Legionella pneumophilia flagellin (L. monocytogenes L.p.FlaA) are less immunogenic for CD8+ T cell responses than wt L. monocytogenes. It is also known that IL-1β orchestrates recruitment of myelomonocytic cells (MMC), which have been shown to interfere with T cell-dendritic cells (DC) interactions in splenic white pulp (WP), limiting T cell priming and protective immunity. We have further analyzed the role of MMCs in the immunogenicity of L. monocytogenes L.p.FlaA. We confirmed that MMCs infiltrate the WP between 24–48 hours in response to wt L. monocytogenes infection and that depletion of MMCs enhances CD8+ T cell priming and protective memory. L. monocytogenes L.p.FlaA elicited accelerated recruitment of MMCs into the WP. While MMCs contribute to control of L. monocytogenes L.p.FlaA, MMC depletion did not increase immunogenicity of L.p.FlaA expressing strains. There was a significant decrease in L. monocytogenes L.p.FlaA in CD8α+ DCs independent of MMCs. These findings suggest that limiting inflammasome activation is important for bacterial accumulation in CD8α+ DCs, which are known to be critical for T cell response to L. monocytogenes.
Contribution of Sigma B to environmental stress tolerance in Listeria monocytogenes-A review
Sigma B在单核细胞增生李斯特菌耐受环境压力胁迫中的作用

Qiang Zhang,Yingying Feng,Qingchun Zhou,Qin Luo,Xiaoli Zhang,Longjuan Qin,
张强
,冯莹颖,周青春,罗勤,张晓莉,秦龙娟

微生物学报 , 2009,
Abstract: Abstract: The alternative sigma factor Sigma B plays important roles in both virulence and stress tolerance in Listeria monocytogenes. It is now clear that there is a strong link between the virulence potential of Listeria monocytogenes and its ability to tolerate stress. Several studies have identified genes that play important roles in stress tolerance and virulence. For example, genes involved in osmotic stress tolerance, acid and alkaline tolerance, oxidative stress tolerance, extreme temperature tolerance, and bile salt tolerance have all been implicated in the virulence of L. monocytogenes. We reviewed the role of Sigma B in several environmental stress conditions to understand the physical character of this microorganism, to discuss the best preservation conditions of food, and to prevent bacterial infection.
Loop-Mediated Isothermal Amplification (LAMP) for the Detection of Listeria monocytogenes and Major Pathogenic Serotypes  [PDF]
Ana Paula Rocha da Costa, Mariana de Lira Nunes, Carina Lucena Mendes-Marques, Alzira Maria Paiva de Almeida, Nilma Cintra Leal
American Journal of Analytical Chemistry (AJAC) , 2014, DOI: 10.4236/ajac.2014.516112
Abstract: Rapid identification and characterization of Listeria monocytogenes are required for the food industry, epidemiological studies, and disease prevention and control. However, typing procedures are labor-intensive and time-consuming, and they require technical expertise, a panel of sera and reference culture strains or sophisticated and expensive equipment. To improve upon traditional diagnostic methods for L. monocytogenes we developed and evaluated an efficient procedure for the specific identification of L. monocytogenes and the major pathogenic serotypes of the species based on loop-mediated isothermal amplification (LAMP). Four individual reactions were designed using primers targeting any L. monocytogenes serotypes (LAMP-AS) and the 1/2a (LAMP-1/2a), 1/2b (LAMP-1/2b), and 4b (LAMP-4b) serotypes. The procedure distinguished L. monocytogenes from closely genetically related species and the targeted serotypes. Cross-reactivity with a few rare serotypes isolated from food or clinical samples did not impair the usefulness of the procedure. Thus, our approach constitutes a fast, easy and low-cost alternative for L. monocytogenes diagnosis and serotyping and may be useful for surveillance and epidemiological investigation programs.
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