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Prokůpková, Soňa. "Logistika v Povltavských mlékárnách, a.s." Master's thesis, Vysoká škola ekonomická v Praze, 2008. http://www.nusl.cz/ntk/nusl-12039.
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The graduation theses is focused on an application of logistics in food company. Theoretical part defines terms like stocking, manipulation units, wraps, material flow etc. The application part is based on the logistics in Povltavské mlékárny, a. s. It describes different departments like purchase (and also program Milsoft), estimates of sale, finished stock room and fleet department. The second part of the application part is based on the thoughts and calculation of sufficient capacity of the finished stock room after implementation of laboratory tests for listeria.
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Resta, Andreia dos Santos. "Avaliação do efeito do extrato seco de Spirulina sp nas celulas progenitoras da medula ossea de camundongos infectados com Listeria monocytogenes." [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/313442.
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Orientador: Mary Luci de Souza QueirozDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
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Resumo: Neste trabalho foi investigado o efeito imunomodulador do extrato seco de Spirulina sp sobre o crescimento e diferenciação de precursores hematopoéticos de granulócitos-macrófagos (CFU-GM) na medula óssea e no baço de camundongos BALB/c infectados com Listeria monocytogenes. Alterações no peso do baço e na resistência dos animais à infecção também foram estudadas. Foram testadas quatro doses do extrato de Spirulina sp: 50, 150, 200 e 300 mg/kg/dia, administradas por via oral aos animais. Três protocolos de tratamento foram utilizados para avaliar os efeitos da alga sobre a resistência de camundongos infectados intraperitonealmente com uma dose letal Listeria monocytogenes (6x104 bactérias/animal). No primeiro protocolo, animais infectados foram pré-tratados por 7 dias com as diferentes doses do extrato. No segundo, doses de 150 e 200 mg/kg/dia foram administradas aos animais por 14 dias consecutivos, sendo que a suspensão de bactérias foi inoculada no 7° dia de tratamento. No terceiro protocolo, os animais foram submetidos a um pós-tratamento de 7 dias com essas mesmas doses de extrato. Para avaliação dos parâmetros hematopoéticos foi utilizado apenas o protocolo de pré-tratamento e os animais foram sacrificados 24, 48 e 72 h após inoculação intraperitoneal de uma dose subletal de Listeria monocytogenes (1x105 bactérias/animal). Animais infectados com uma dose subletal de Listeria monocytogenes apresentaram um decréscimo significativo no número de CFU-GM da medula óssea 48 e 72 h após a infecção. Esse efeito foi acompanhado por um aumento no número dessas células no baço assim como no peso deste órgão. Todas as doses de Spirulina utilizadas protegeram contra a mielossupressão provocada pela bactéria, porém um aumento estatisticamente significativo neste parâmetro foi obtido para as doses de 150 e 200 mg/kg/dia em relação ao controle e às outras doses. Estimulação da mielopoese também foi observada nos grupos de animais normais (não infectados) tratados por 7 dias com 150 e 200 mg/kg/dia de Spirulina em relação aos outros grupos. Além disso, o pré-tratamento dos animais infectados com todas as doses avaliadas inibiu o desenvolvimento da esplenomegalia e da hematopoese esplênica. Nenhuma alteração foi observada no baço dos animais apenas tratados. Empregando-se esse mesmo protocolo de pré-tratamento, as doses de 150 e 200 mg/kg/dia também aumentaram a resistência de camundongos letalmente infectados com Listeria monocytogenes, concordando com os resultados obtidos na avaliação dos parâmetros hematopoéticos. Quando o tratamento foi prolongado para 14 dias com essas mesmas doses de extrato e os animais infectados no 7o dia de tratamento, observou-se um aumento estatisticamente significativo de 35% e 30% na probabilidade de sobrevida dos animais infectados que receberam 150 e 200 mg/kg/dia da alga, respectivamente. No entanto, nenhuma alteração no tempo de sobrevida de animais infectados foi observada com o protocolo de pós-tratamento por 7 dias com 150 e 200 mg/kg/dia de extrato de Spirulina sp. Estes resultados apontam para um efeito imunoestimulante da alga quando utilizada profilaticamente e sugerem que o aumento na resistência do hospedeiro à infecção depende, em parte, do protocolo utilizado. Neste sentido, a administração do extrato seco de Spirulina sp previamente à infecção parece ser fundamental para aumentar a resistência imunológica do hospedeiro, provavelmente devido à estimulação da geração de precursores hematopoéticos de granulócitos e macrófagos, críticos para a defesa inicial do organismo contra a infecção bacteriana
Abstract: In this work, we investigated the effects of Spirulina sp extract on the growth and differentiation of bone marrow and spleen hematopoietic progenitors (CFU-GM) in normal and in Listeria monocytogenes-infected mice. Changes in spleen weight and resistance to a lethal dose of bacteria were also studied. To evaluate the hematopoietic activity, BALB/c mice were treated orally with 50, 150, 200 and 300 mg/kg doses of the extract for 7 consecutive days and, at the end of this period, they were infected intraperitoneally with a sublethal dose of the bacteria (1x103 bacteria/animal). As expected, a significant decrease in bone marrow CFU-GM numbers was observed in mice infected with L. monocytogenes at 48 and 72 h after infection. This effect was accompanied by the development of splenic hematopoiesis with splenomegaly. Pre-treatment of these animals with Spirulina sp significantly stimulated myelopoiesis, reaching normal values of bone marrow CFU-GM when 50 and 300 mg/kg of the algae were used. On the other hand, increased numbers of bone marrow CFU-GM over control values were observed when the extract was given to mice at 150 and 200 mg/kg previously to infection. Moreover, these doses also stimulated myelopoiesis in normal mice given the extract for 7 days. All of these doses of Spirulina sp completely inhibited the extramedullar hematopoiesis and the increase in spleen weight induced by the infection. This extract did not affect splenic hematopoiesis and spleen weight when administered to normal mice. Resistance to infection was studied in mice infected with a lethal dose of L. monocytogenes (6x104 bacteria/animal) and submitted to 3 protocols of treatment with Spirulina sp. These experiments show that only the doses of 150 and 200 mg/kg given for 7 days to mice previously to infection were effective to prolong survival of these animals until 12 days, compared with non-treated infected mice which died until 6 days. When 150 and 200 mg/kg of the extract were administered to mice for 14 consecutive days and the animals were infected at the 7th day of treatment, 30 and 35% of survival were observed, respectively. In contrast, post-treatment of infected mice with these doses did not affect survival, suggesting an important role for the pre-treatment with Spirulina sp in the prophylaxis of bacterial infections. Taken together, these results suggest that the stimulatory effect of Spirulina sp on myelopoiesis is critically important to improve resistance of L. monocytogenes-infected mice. Moreover, the present results support previous work in the literature suggesting the innate immune system as a major target of Spirulina-mediated immune activation
Mestrado
Mestre em Farmacologia
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HENRY, ANNE. "Les infections a listeria monocytogenes chez l'homme et leurs traitements." Strasbourg 1, 1993. http://www.theses.fr/1993STR15049.
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Castro, José Luís Draper Mineiro Romano de. "Listeria monocytogenes em alimentos prontos para consumo." Bachelor's thesis, Universidade Técnica de Lisboa. Faculdade de Medicina Veterinária, 2011. http://hdl.handle.net/10400.5/3506.
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Dissertação de Mestrado Integrado em Medicina VeterináriaNota introdutória - Bactéria matou 13 em 22 meses Um surto de Listeriose que se regista na região de Setúbal e Almada há 22 meses, desde Janeiro de 2009, já afectou, pelo menos, 24 pessoas, 13 das quais morreram. O CM apurou que uma grávida perdeu o filho na 32ª semana de gestação após comer alimentos infectados com a bactéria Listeria. As vítimas mortais foram idosos e pessoas imunodeprimidas (com o sistema imunitário debilitado) ou com doenças crónicas. Fonte das autoridades de saúde admitiu “ser muito difícil” apurar a origem da infecção provocada pela bactéria. “Não se descobriu muito, mas o que se sabe é que estaremos perante uma estirpe portuguesa da bactéria”, disse a fonte. A contaminação poderá ter ocorrido em produtos de “charcutaria e queijos cremosos, daqueles que não são normalmente produzidos em Portugal”. A mistura de alimentos contaminados com outros em frigoríficos ou microondas terá desencadeado o surto. A Direcção Geral da Saúde e a Administração Regional de Lisboa e vale do Tejo desenvolvem um estudo epidemiológico que envolve os familiares das pessoas infectadas e das vítimas mortais. O consumo de alimentos contaminados provoca febres, diarreias e, nos casos mais graves, meningites, que podem ser fatais. In Correio da Manhã, 9 de Outubro de 2010. - Esta notícia publicada em Outubro de 2010 suscitou algumas questões para as quais se procurou encontrar algumas respostas com este trabalho. O objectivo deste trabalho é fornecer elementos para a melhor compreensão do fenómeno e com isso contribuir para que estas situações sejam menos frequentes. Neste trabalho estudaremos como se comporta Listeria monocytogenes Scott A inoculada em produtos prontos a comer, ao longo do seu tempo de vida útil. Estabeleceremos curvas de crescimento e procuraremos compará-las com os modelos preditivos já existentes no mercado. Tomar-se-ão em consideração, como ponto de partida, as opiniões da EFSA sobre esta matéria. Bactéria matou 13 em 22 meses Um surto de Listeriose que se regista na região de Setúbal e Almada há 22 meses, desde Janeiro de 2009, já afectou, pelo menos, 24 pessoas, 13 das quais morreram. O CM apurou que uma grávida perdeu o filho na 32ª semana de gestação após comer alimentos infectados com a bactéria Listeria. As vítimas mortais foram idosos e pessoas imunodeprimidas (com o sistema imunitário debilitado) ou com doenças crónicas. Fonte das autoridades de saúde admitiu “ser muito difícil” apurar a origem da infecção provocada pela bactéria. “Não se descobriu muito, mas o que se sabe é que estaremos perante uma estirpe portuguesa da bactéria”, disse a fonte. A contaminação poderá ter ocorrido em produtos de “charcutaria e queijos cremosos, daqueles que não são normalmente produzidos em Portugal”. A mistura de alimentos contaminados com outros em frigoríficos ou microondas terá desencadeado o surto. A Direcção Geral da Saúde e a Administração Regional de Lisboa e vale do Tejo desenvolvem um estudo epidemiológico que envolve os familiares das pessoas infectadas e das vítimas mortais. O consumo de alimentos contaminados provoca febres, diarreias e, nos casos mais graves, meningites, que podem ser fatais. In Correio da Manhã, 9 de Outubro de 2010 2 A European Food Safety Authority (EFSA), sedeada em Parma, Itália, foi fundada e estabelecida pela Comunidade Europeia como uma entidade independente em 2002, após uma série de surtos de origem alimentar que alertaram para a possível incapacidade das autoridades reguladoras de proteger os consumidores. Também serão levados em consideração os dados disponibilizados pelo ECDC. O European Centre for Disease Prevention and Control (ECDC), é uma agência Europeia sedeada em Estocolmo (Suécia), que se estabeleceu em 2005. O objectivo da ECDC é fortificar as defesas Europeias no combate às doenças infecciosas.
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Valente, Eleutério. "Clínica de espécies pecuárias: revisão bibliográfica sobre listeriose e desenvolvimento de um caso clínico de listeriose encefálica em caprinos." Master's thesis, Universidade de Évora, 2012. http://hdl.handle.net/10174/15987.
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Revisão bibliográfica sobre listeriose e desenvolvimento de um caso clínico de listeriose encefálica em caprinos
O presente relatório visa descrever as atividades desenvolvidas durante o estágio no âmbito do Mestrado Integrado em Medicina Veterinária, assim como, a apresentação de um caso clínico de listeriose em caprinos e uma revisão bibliográfica acerca da mesma.
A primeira parte do relatório consiste numa descrição das atividades desenvolvidas na área da sanidade e profilaxia e na área da Patologia Médica.
A segunda parte do relatório corresponde à revisão bibliográfica acerca da listeriose, uma doença provocada pela Listeria monocytogenes, uma bactéria do género Listeria, Gram (+) em forma de bastonete, que normalmente surge associada ao consumo de silagem de má qualidade e que pode afetar uma vasta gama de mamíferos, incluindo ruminantes, animais monogástricos e seres humanos, provocando encefalite, septicémia e aborto.
A terceira parte comporta o desenvolvimento de um caso clínico acompanhado durante o estágio, sobre encefalites por L. monocytogenes numa exploração de caprinos de leite que afetou três animais; ABSTRACT: A review about listeriosis and a clinical case about encephalitic listeriosis in goats
This report aims to describe the training activities undertaken during the internship, as well as the presentation of a clinical case of listeriosis in goats and review about the same.
The first part of the report is a description of health activities, preventive medicine and medical pathology.
The second part of the report corresponds to the literature review about listeriosis, a disease caused by Listeria monocytogenes, a bacteria of the genus Listeria, Gram (+) rod-shaped, which normally is associated with the consumption of silage of poor quality that can affect a wide range of mammals including ruminants, monogastric and humans, causing encephalitis, abortions and septicemia.
The third part is the presentation of a clinical case during the internship, about encephalitis caused by L. monocytogenes in a dairy goat farm which affected three animals.
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Mendes, Sandra Denise Camargo. "Detecção de listeria spp em frango resfriado pelos métodos convencional em condições de aerobiose e microaerofilia." Florianópolis, SC, 2000. http://repositorio.ufsc.br/xmlui/handle/123456789/78383.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias.Made available in DSpace on 2012-10-17T13:31:36Z (GMT). No. of bitstreams: 0
A ocorrência e detecção de Listeria spp foi avaliada através de uma metodologia convencional recomendada pelo FDA, com modificações, pela introdução de (1) segunda etapa de enriquecimento em condições aerobiose e (2) do uso de microaerofilia . Um total de 48 unidades de frango inteiro resfriado de diferentes marcas comercializadas na região de Florianópolis foram analisadas durante o período de maio à julho. Encontrou-se, através do método convencional em condições de microaerofilia, 18 (37,5%) amostras positivas para Listeria spp. Através do método convencional em condições de aerobiose, 14 (29,2%) amostras foram positivas para Listeria spp. Testes posteriores de identificação empregando-se API Listeria mostraram que, das 18 amostras positivas para Listeria spp em microaerofilia, foram identificadas 13 (27,1%) como Listeria monocytogenes, 1 (2,1%) como Listeria innocua, 3 (6,2%) como Listeria seeligeri, 1 (2,1%) como Listeria welshimeri. Das 14 amostras positivas para Listeria spp isoladas em condições de aerobiose, 7 (14,6%) foram identificadas como L. monocytogenes, 6 (12,5%) como L. innocua e 1 (2,1%) como L. seeligeri. Com relação à detecção, os métodos convencional em condições de microaerofilia e aerobiose apresentaram ausência de resultados falso-positivos, demonstrando especificidade de 100% e, sensibilidade de análise, de 84% e 67%, respectivamente. Concluindo-se, assim, que existem diferenças significativas entre as médias dos métodos avaliados para o nível descritivo de 1 e 5%.
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Chikli, Isabelle. "La listériose : épidémiologie et pouvoir pathogène." Paris 5, 1991. http://www.theses.fr/1991PA05P210.
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Conceição, Francisco Manuel Aparício da. "Revisão de listeriose em ruminantes a partir de três casos clínicos." Master's thesis, Universidade de Lisboa. Faculdade de Medicina Veterinária, 2015. http://hdl.handle.net/10400.5/9753.
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Dissertação de Mestrado Integrado em Medicina VeterináriaEsta tese de Mestrado é o culminar de cinco meses e meio de estágio em Montemor-o-Novo com o Dr. Jaime Ribeiro, onde tive a oportunidade de pôr em prática os conhecimentos que aprendi durante os cinco anos de Licenciatura e Mestrado em Medicina Veterinária. Devido ao risco de zoonose de algumas doenças do foro nervoso nos ruminantes, estas têm apresentado um lugar de destaque na clínica deste animais. O papel do Médico Veterinário é saber identificar correctamente cada caso e dar-lhe o seguimento acertado com vista a diminuir a propagação destas doenças e o número de casos que se tornam fatais. Durante o estágio tive a oportunidade de acompanhar em primeira mão dois casos de listeriose na sua forma encefálica, pelo que decidi explorar esta temática. Depois de uma revisão bibliográfica sobre L. monocytogenes com ênfase na clínica de ruminantes, abordando os aspectos mais importantes que resultam da infecção dos animais pela bactéria, nomeadamente etiologia, epidemiologia, patogenicidade, sinais clínicos, diagnóstico, tratamento e prevenção, relatei os dois casos clínicos que presenciei e as medidas que foram tomadas para tratar os animais e identificar positivamente a L. monocytogenes. Faço também referência a um caso clínico relativo à espécie caprina que tive o privilégio de acompanhar e analisar. Concluí que, sendo uma doença ubiquitária e zoonótica é de extrema importância a sensibilização dos proprietários para o correcto acondicionamento e fermentação da silagem que vai ser fornecida aos animais. No entanto existem outros factores que podem promover infecções por Listeria spp., sendo por isso necessário uma constante monitorização da manada para detectar rapidamente possíveis casos e aumentar a taxa de sobrevivência dos animais.
ABSTRACT - Review of Listerosis in ruminants based on three clinical cases - This Master's thesis is the culmination of five and a half months of internship in Montemor-o-Novo with Dr. Jaime Ribeiro, where I got to put into practice the knowledge I learned over five years of studying to attain the master's degree in Veterinary Medicine. Because of the risk of zoonosis, some ruminants' neurologic diseases have shown a prominent place in the clinic of these animals. The role of the veterinarian is to correctly identify each case and give the proper follow-up in order to reduce the spread of these diseases and the number of cases that become fatal. During the internship I had the opportunity to experience firsthand two cases of nervous listeriosis, so I decided to explore this theme. After a bibliographic review of L. monocytogenes with an emphasis on the ruminant clinical cases, addressing the most important aspects resulting from infection of animals by this specific bacteria, including etiology, epidemiology, pathogenicity, clinical signs, diagnosis, treatment and prevention, I reported the two clinical cases witnessed, the measures taken to treat the animals and positively identify the bacteria. I present an outbreak in goats that I was privileged to track and analyze. Lastly I concluded that, being a ubiquitous and zoonotic disease is of paramount importance to raise the awareness of the owners for the proper packaging and fermentation of the silage that will be given to the animals. However, there are other factors that can cause listeriosis infections, so it is necessary to constant monitor the herd in order to quickly detect possible cases so increase the survival rate of the animals and reduce the public health risk.
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Engström, Linnéa, and Moa Hallqvist. "Fryst majs – ett risklivsmedel för listerios? : En mikrobiologisk undersökning på förekomsten av Listeria monocytogenes i fryst." Thesis, Örebro universitet, Restaurang- och hotellhögskolan, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-84909.
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Kayal, Samer. "Physiopathologie de la listeriose neuro-meningee : role de la listeriolysine o dans l'activation endotheliale." Paris 5, 1999. http://www.theses.fr/1999PA05N133.
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Ramos, Lívia Píccolo. "Listeria monocytogenes em linguiças do tipo frescal vendidos a varejo no município de Salvador-BA e eficácia do bacteriófago P100 no controle da contaminação pelo patógeno." Faculdade de Farmácia, 2009. http://repositorio.ufba.br/ri/handle/ri/27002.
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RESUMO Os surtos de Doenças Veiculadas por Alimentos (DVA) constituem alvo de preocupação para as indústrias alimentícias e para os órgãos de saúde pública. Listeria monocytogenes é conhecida como um importante patógeno causador de doenças veiculadas por alimentos, e sua importância vem aumentando desde a década de 1980. Apesar de o número de casos da doença por ano ser relativamente baixo, a infecção pode ser grave, com letalidade acima de 30%. Em pesquisas realizadas no Brasil foi identificada uma incidência de 32% em amostras de produtos cárneos com uma taxa de isolamento de 80% em linguiças do tipo frescal elaboradas com carne suína. Apesar dos recentes avanços nas tecnologias de controle de patógenos em alimentos, os consumidores têm procurado alimentos “naturais”, isto é, submetidos a tratamentos menos agressivos e isentos de conservadores químicos. Em 2007, o Departamento de Agricultura dos Estados Unidos (USDA) e a agência norte-americana Food and Drug Administration (FDA) aprovaram o uso do LISTEXTM P100, um bacteriófago específico para o controle de Listeria monocytogenes, para todos os tipos de alimentos. Bacteriófagos são vírus que infectam somente bactérias e não infectam células animais ou vegetais. Eles estão largamente distribuídos no ambiente, e o homem está exposto a eles em altas concentrações através da água e dos alimentos, sem qualquer efeito adverso à sua saúde. A importância que a carne representa na alimentação humana, associada à necessidade de se oferecer sempre um alimento inócuo e incapaz de veicular doenças ao homem, motivou o desenvolvimento desta pesquisa, que teve como objetivos verificar a ocorrência de Listeria monocytogenes em linguiças do tipo frescal vendidas a varejo em estabelecimentos comerciais da cidade de Salvador-BA e avaliar a eficácia do agente antimicrobiano, bacteriófago P100 (LISTEXTM P100), sobre células de Listeria monocytogenes inoculadas artificialmente no alimento. Foram examinadas 40 amostras de linguiças do tipo frescal de carne suína e 40 de frango, de diferentes marcas comerciais. Isolou-se Listeria spp. em 12 amostras (15%), das quais três (3,75%) foram positivas para L. monocytogenes. Entre as espécies, L. innocua foi isolada com maior frequência, em 11 amostras (13,75%); em duas amostras foram detectadas as duas espécies. As cepas de L. monocytogenes isoladas das amostras pertenciam ao sorotipo ½a. Na investigação da eficácia do uso do bacteriófago P100 no controle da contaminação do embutido pelo microrganismo, verificou-se uma redução de três ciclos logarítmicos na população inicial do microrganismo, diferença estatisticamente significativa (p<0,05). Também foi encontrada diferença significativa (p<0,05) quando se comparou o tratamento no tempo 0 (zero) e no tempo 10, com aumento da população do patógeno no alimento após 10 dias de armazenamento, o que remete a necessidade de se utilizar um fago com título mais elevado.
ABSTRACT The outbreaks of Food-borne Diseases are a reason of concern for the food industries and public health organs. Listeria monocytogenes is known as an important pathogen causing diseases transmitted by food and its importance has been growing since the 1980s. Although the number of disease cases per year is relatively low, the infection can be serious, with lethality rate at 30%. Research works conducted in Brazil reported an incidence of 32% in meat product samples with an isolation rate of 80% in Brazilian fresh sausage (“linguiça do tipo frescal”) made with pork meat. Despite the recent technological advancements in pathogen control in foods, consumers have sought natural foods, i.e., foods submitted to less aggressive treatments without chemical preservatives. In 2007, the Department of Agriculture of the United States (USDA) and the North America Agency Food and Drug Administration (FDA) approved the use of LISTEXTM P100, a bacteriophage specific for the control of Listeria monocytogenes, for all types of food. Bacteriophages are viruses that infect only bacteria and do not infect animal or plant cells. They are widely distributed in the environment and humans are exposed to them at high concentrations through water and foods, without any adverse effect to health. The role played by meat in human nutrition, associated to the need of offering an innocuous food, incapable of transmitting diseases to humans, has led to the development of this research, whose objectives were to verify the incidence of Listeria monocytogenes in Brazilian fresh sausages sold in commercial establishments in the city of Salvador-BA and to evaluate the efficacy of the antimicrobial agent bacteriophage P100 (LISTEXTM P100) in the cells of Listeria monocytogenes artificially inoculated in the food. Forty samples of type pork Brazilian fresh sausages and 40 samples of chicken, of different commercial brands were taken. Listeria spp was isolated in 12 samples (15%) of which three (3.75%) were positive for L. monocytogenes. Among the species, L. innocua was isolated with greater frequency in 11 samples (13.75%); the two species were detected in two samples. The strains of L. monocytogenes isolated from the samples belonged to the serotype ½a. When investigating the efficacy in the use of the bacteriophage P100 in controlling Brazilian fresh sausage contamination by the microorganism, the results showed a reduction of three logarithmic cycles in the initial population of the microorganism, a statistically significant difference (p<0.05). A significant difference (p<0.05) was also found when 0 (zero) time treatment was compared with time 10 treatment, showing increase in the pathogen’s population in the food after 10 days of storage and the need to use a phage with a higher titer.
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MERIC, MARIE-PIERRE. "Listeria monocytogenes." Toulouse 3, 1991. http://www.theses.fr/1991TOU32006.
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Degenhardt, Roberto. "Sobrevivência de Listeria monocytogenes em salame tipo italiano de baixa acidez, produzido sob condições brasileiras de fabricação." Florianópolis, SC, 2006. http://repositorio.ufsc.br/xmlui/handle/123456789/89063.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias. Programa de Pós-graduação em Ciência dos AlimentosMade available in DSpace on 2012-10-22T16:22:03Z (GMT). No. of bitstreams: 1 244637.pdf: 359506 bytes, checksum: 4ba72fe72924c26efac7bb1b9dac9e33 (MD5)
O baixo risco dos salames em provocarem a listeriose é atribuído aos obstáculos criados durante processo de fabricação e presentes no produto final. O pH e atividade água baixos, alta concentração de sal e a presença de bactérias ácido-lácticas e seus metabólitos secundários compõe barreiras que impedem o desenvolvimento de Listeria monocytogenes. Neste trabalho avaliou-se o comportamento das curvas de sobrevivência deste patógeno durante o processo de fabricação de salames tipo Italiano pouco ácidos (pH final de 5,2) em três formulações: inoculada com Lactobacillus plantarum, com adição de 2% lactato de sódio e uma formulação sem agentes inibidores intencionais. Cada formulação foi contaminada artificialmente com L. monocytogenes e paralelamente acompanhada por uma testemunha de igual composição. O tamanho das populações de L.monocytogenes foi avaliado semanalmente através de contagem pela técnica de tubos múltiplos (NMP), durante o período de fabricação de quatro semanas. Os salames naturalmente contaminados apresentaram discreto aumento da população de L. monocytogenes no inicio do processo, seguidas por redução até o final da maturação e os salames artificialmente contaminados tiveram redução considerável da contagem de L.monocytogenes, principalmente na formulação com adição de L. plantarum, seguido pela formulação com lactato de sódio e por último a formulação padrão, entretanto não se verificou diferença significativa entre os tratamentos. The low risk of salamis in provoking listeriosis is attributed to the obstacles created during production process and presents in the final product. The pH and low water activity, high concentration of salt and the presence of lactic acid bacteria and their secondary metabolites compose barriers that prevent the development of Listeria monocytogenes. In this work the behavior of the survival curves of this pathogen was evaluated during the production process in salamis Italian type slightly acid (final pH of 5,2) in three formulations: inoculated Lactobacillus plantarum, with addition of 2% sodium lactate and a formulation without intentional inhibitors agents. Each formulation was contaminated artificially with L. monocytogenes and parallel accompanied by a witness sample of equal composition. The size of the populations of L.monocytogenes was weekly evaluated through counting by the technique of multiple tubes (NMP), during the period of production of four weeks. The naturally contaminated sausage had presented discreet increase of the population of L. monocytogenes in the beginning of the process, followed by reduction until the end of the maturation and the salamis artificially contaminated had considerable reduction of the counting of L.monocytogenes, mainly in the formulation with addition of L. plantarum, followed by the formulation with sodium lactate and last the standard formulation, however significant difference was not verified among the treatments.
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MOURA, Fernanda Maria Lino de. "Formação de biofilme e perfil de resistência a antimicrobianos e sanitizantes de Listeria monocytogenes isoladas de leite de tanques de expansão." Universidade Federal Rural de Pernambuco, 2018. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/7290.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Among foods related to foodborne diseases are dairy products, since the quality of milk produced in several regions of Brazil is still unsatisfactory, leaving it subject to microorganisms that affect milk production and consumer health. Listeria monocytogenes is considered a serious problem in food safety and due to the importance of milk production in the country and the obtaining of safe food, the objective to evaluate the biofilm formation and antimicrobial resistance profile and sanitizers of Listeria monocytogenes isolated from milk from expansion tanks. The analyzes were carried out at the Meat and Milk Inspection Laboratory (LICAL) of UFRPE. After isolation and identification from morpho-tinctorial and biochemical characteristics, L. monocytogenes colonies were submitted to eight antimicrobials: penicillin G (10U), ampicillin (10μg), cephalothin (30μg), chloramphenicol (30μg), ciprofloxacin 5μg), erythromycin (15μg), clindamycin (2μg) and tetracycline (30μg) by the disc diffusion method. Then, the biofilm formation test was performed using a 96-well microdilution plate and the biofilm forming isolates were tested with 2.5% chlorine sanitizers and 2% chlorhexidine. Listeria monocytogenes were detected in 20% of the samples (6/30). It was observed that 83.3% (5/6) and 16.6% (1/6) of the isolates presented resistance and intermediate resistance to clindamycin, respectively, and 16.6% (1/6) resistance to chloramphenicol and erythromycin. 66.6% (4/6) of the isolates were able to form biofilm. It was detected a more effective action of chlorine in relation to the ability to interfere in the free cells, because in 50% (2/4) it completely inhibited the adhesion and in 50% (2/4) its action allowed a poor adherence. Chlorhexidine allowed moderate adherence in 100% of the isolates. In relation to the consolidated biofilm, chlorine was 75% (3/4) more effective in reducing adherence to chlorhexidine. This work was pioneer in the isolation of Listeria monocytogenes in milk from the individual expansion tanks existing in the municipalities of Alagoas State. The occurrence of Listeria monocytogenes in the samples evaluated represents a risk to public health. The biofilm formation and the resistance presented by these strains to sanitizing products predispose to the persistence of this microorganism in the milk production chain. Thus, it is necessary to monitor this microorganism and mastitis in the herd. In addition, the correct pre and post-dipping, the sanitation of the equipment and the tank, the regular evaluation of the efficiency of the sanitizers used and the collection of the milk by the truck refrigerated in the appropriate time have relevance in the guarantee of milk quality, being essential for the provision of safe food to the population. The occurrence of antimicrobial resistant strains may compromise the treatment of human listeriosis. It is evidenced the need to carry out antimicrobial tests and adhesion periodically to monitor the profile of resistance and biofilm formation by this microorganism, in order to promote the control of Listeria monocytogenes in the herd and to prevent contamination of milk by pathogenic microorganisms.
Dentre os alimentos relacionados às doenças transmitidas por alimentos estão os lácteos, pois a qualidade do leite produzido em diversas regiões do Brasil ainda é insatisfatória, deixando-o sujeito a micro-organismos que afetam a produção leiteira e a saúde dos consumidores. Considera-se Listeria monocytogenes um sério problema na segurança de alimentos e diante da relevância da produção de leite no país e da obtenção de alimentos seguros, objetivou-se avaliar a formação de biofilme e o perfil de resistência a antimicrobianos e sanitizantes de Listeria monocytogenes isoladas de leite de tanques de expansão. As análises foram realizadas no Laboratório de Inspeção de Carne e Leite (LICAL) da UFRPE. Após isolamento e identificação a partir de características morfo-tintoriais e bioquímicas, colônias de L. monocytogenes foram submetidas a oito antimicrobianos, sendo estes penicilina G, ampicilina (10μg), cefalotina (30μg), cloranfenicol (30μg), ciprofloxacina (5μg), eritromicina (15μg), clindamicina (2μg) e tetraciclina (30μg), através do método de difusão em disco. Em seguida, realizou-se o teste de formação de biofilme utilizando-se placa de microdiluição de 96 poços e os isolados formadores de biofilme foram submetidos ao teste com os sanitizantes cloro a 2,5% e clorexidine a 2%. Detectou-se Listeria monocytogenes em 20% das amostras (6/30). Observou-se que 83,3% (5/6) e 16,6% (1/6) dos isolados apresentaram resistência e resistência intermediária a clindamicina, respectivamente e 16,6% (1/6) de resistência a cloranfenicol e eritromicina. 66,6% (4/6) dos isolados foram capazes de formar biofilme. Detectou-se ação mais eficaz do cloro em relação à capacidade de interferir nas células livres, pois em 50% (2/4) inibiu completamente a aderência e em 50% (2/4) a sua ação permitiu uma fraca aderência. O clorexidine permitiu aderência moderada em 100% dos isolados. Em relação ao biofilme consolidado o cloro foi 75% (3/4) mais eficaz na redução da aderência em relação ao clorexidine. Este trabalho foi pioneiro no isolamento de Listeria monocytogenes em leite proveniente de tanques de expansão individuais em municípios do estado de Alagoas. A ocorrência de Listeria monocytogenes nas amostras avaliadas representa um risco à saúde pública. A formação de biofilme e a resistência apresentada por estas cepas a produtos sanitizantes predispõem para a persistência deste micro-organismo na cadeia de produção de leite. Desta forma, faz-se necessário o monitoramento deste micro-organismo e da mastite no rebanho. Além disso, a realização de pré e pós-dipping de forma correta, a sanitização dos equipamentos e do tanque, a avaliação regular da eficiência dos sanitizantes utilizados e a coleta do leite pelo caminhão refrigerado no tempo adequado possuem relevância na garantia da qualidade do leite, sendo imprescindíveis para o fornecimento de alimentos seguros à população. A ocorrência de cepas resistentes a antimicrobianos pode comprometer o tratamento da listeriose humana. Evidencia-se a necessidade de realização de testes com antimicrobianos e de aderência periodicamente para monitoramento do perfil de resistência e da formação do biofilme por parte deste micro-organismo, com o intuito de promover o controle da Listeria monocytogenes no rebanho e de prevenir a contaminação do leite por micro-organismos patogênicos.
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Norwood, David Edmund. "Listeria monocytogenes in biofilms." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314102.
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Autard, Thierry. "Méningo-encéphalites à listeria." Montpellier 1, 1989. http://www.theses.fr/1989MON11278.
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Walsh, Desmond. "The detection, properties, and stress responses of Listeria monocytogenes and other Listeria species." Thesis, University of Ulster, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342425.
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Lopes, Micaela Mestre Pereira da Silva. "Surto de listeria monocytogenes na Região de Lisboa e Vale do Tejo : 2009-2011." Master's thesis, Escola Nacional de Saúde Pública. Universidade Nova de Lisboa, 2013. http://hdl.handle.net/10362/11540.
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RESUMO - O género Listeria contém oito espécies (L. monocytogenes, L. ivanovii, L. innocua, L. seeligeri, L. welshimeri, L. grayi, L. marthii, e a L. rocoutiae), das quais duas são patogénicas. L. monocytogenes é patogénica para humanos e animais; L. ivanovii primeiramente infecta animais e raramente causa doenças em humanos.
A Listeria monocytogenes é uma bactéria patogénica Gram-positiva facultativa intracelular, ubíqua na natureza. Nos últimos anos o número de casos de listeriose tem vindo a aumentar. Pode causar uma doença rara e grave chamada listeriose, especialmente nas mulheres grávidas, nos idosos ou em indivíduos com o sistema imunitário debilitado, de maneira esporádica ou em forma surtos.
Realizou-se um estudo observacional, descritivo com o objectivo de se fazer a descrição e a caracterização do surto de listeriose ocorrido na região de Lisboa e Vale do Tejo entre 2009-2011.
O período de maior número de casos diagnosticados de listeriose ocorreu entre o mês de Abril e Agosto de 2010. Mas a janela temporal em que ocorreu o surto estendeu-se de Março de 2009 a Janeiro de 2012.
Ocorreram 51 casos de internamento com diagnóstico de listeriose, dos quais 25 casos foram confirmados, pela técnica de PFGE, pertencer à mesma estirpe I, sorotipo 4b e pulsotipo 070 e 0101. Na maioria dos casos eram do sexo feminino, com uma média de 57,14 anos de idade e com residência na região de Lisboa e Vale do Tejo.
Em 96,08% dos doentes internados com listeriose apresentavam factores de predisposição, comorbilidade e /ou imunossupressão. A bacteriemia foi a manifestação clínica mais frequente, seguida da meningite. A letalidade da listeriose foi de 15,69%.SUMMARY - The genus Listeria contains eight species (L. monocytogenes, L. ivanovii, L. innocua, L. seeligeri, L. welshimeri, L. grayi, L. marthii, e a L. rocoutiae), where two are pathogenic. L. monocytogenes is pathogenic to humans and animals; L. ivanovii primarily affects animals and rarely causes diseases in humans. The L. monocytogenes is a Gram-positive facultatively intracellular pathogenic bacterium, ubiquitous in nature. In recent years the number of listeriosis has been increasing. It may cause a rare and serious disease called listeriose, especially in pregnant women, in the elderly or individuals with a debilitated immune system, in sporadic events or outbreaks. A observational study was conducted, described with the objective of making a description and characterization of the listeriosis outbreak that occurred in the Lisboa and Vale do Tejo region between 2009-2011. The period in which the most diagnosed cases occurred was between the month of April and August of 2010. The time frame in which the outbreak occurred extended from March of 2009 to January of 2012. There were 51 cases of internment with listeriosis diagnosis, of which 25 were confirmed, by the PFGE technique, to belong to the same strain I, serotype 4b and subtype 070 e 0101. In the majority of the cases the patients were females, with an average age of 57,14 that resided in the Lisboa and Vale do Tejo region. In 96,08% of the interned patients with listeriosis presented predisposing factors, comorbidity and/or immunosuppression. The bacteriemia was the most frequent clinical manifestation, followed by meningitis. The lethality of the listeriosis was 15,69%.
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Meadows, Bridget Archibald. "Survival of Listeria monocytogenes, Listeria innocua, and Lactic acid bacteria species in chill brine." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/9970.
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Listeria monocytogenes is the major pathogen in ready-to-eat meat products such as deli meats and frankfurters. Contamination can occur via the salt brines that are used to cool thermally processed meats. Both L. monocytogenes and lactic acid bacteria can grow and thrive under these brine conditions, and may become competitive with each other for available nutrients. The objective of this study was to determine the effect of a
three strain cocktail of lactic acid bacteria Enterococcus faecalis, Carnobacterium gallinarum, and Lactobacillus plantarum on the survival of Listeria monocytogenes and Listeria innocua in brines stored under low temperatures up to 10 days. Three brine concentrations (0%, 7.9%, and 13.2% NaCl) were inoculated with ~7.0 log10 cfu/ml of one of five cocktails (L. monocytogenes, L. innocua, lactic acid bacteria (LAB), L. monocytogenes + LAB, or L. innocua + LAB) and stored for 10 days at either 4°C or 12°C. Three replications of each brine/cocktail/temperature combination were performed. No reductions of L. monocytogenes were seen in 7.9 or 13.2% NaCl with LAB; however, reductions of L. monocytogenes were seen in the 0% NaCl with LAB (1.43 log at 4°C and 3.02 log at 12°C). Listeria innocua was significantly less resilient to environmental stresses than L. monocytogenes, both with and without LAB present (p<0.05). This research indicates these strains of lactic acid bacteria are not effective at reducing L. monocytogenes in brines at low temperatures. Furthermore, the use of L. innocua as a model for L. monocytogenes is not appropriate under these environmental conditions.Master of Science
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Mujahid, Sana. "PROTEOMIC ANALYSIS OF LISTERIA MONOCYTOGENES." MSSTATE, 2008. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11012007-174823/.
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Listeria monocytogenes is a deadly, Gram-positive foodborne pathogen that is ubiquitous in the environment. The bacterium expresses a number of virulence and stress adaptation proteins that support its pathogenic capabilities. Two-dimensional gel electrophoresis (2-DE) was used to map L. monocytogenes surface proteins, which play a central role in virulence, and to examine protein expression by L. monocytogenes grown on ready-to-eat meat, an important source of Listeria infections. A novel method for solubilization of surface proteins from L. monocytogenes for 2-DE was developed. Additionally, the unique proteome expressed by L. monocytogenes grown on a meat matrix was uncovered. The developed solubilization method will facilitate efforts to identify and routinely compare surface proteins of Listeria by 2-DE. Furthermore, the 2-DE database of proteins expressed by L. monocytogenes grown on a meat matrix will allow further understanding of the interactions of Listeria with its food environment that influence its ability to cause disease.
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Ridley, Anne McAlpine. "Epidemiological typing of Listeria monocytogenes." Thesis, Open University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361592.
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Silva, Sara Maria Cunha Oliveira. "Stress response of Listeria monocytogenes." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12617.
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Mestrado em Biologia Molecular e CelularThirty-five Listeria monocytogenes isolates previously collected from food (n=20) and human patients suffering from listeriosis (n=15), with different antibiotic resistance profiles were characterized and compared based on: (i) their ability to survive through sequential conditions that parallel the digestive tract; (ii) their capacity to survive extreme pH values; (iii) the potential relationship, between antibiotic resistance and the resistance of L. monocytogenes isolates to the stress conditions investigated. The response was shown to be strain- and stress-dependent and no relation between food and clinical isolates was observed (p > 0.05). The results showed that L. monocytogenes is able to survive under extreme acid and alkaline conditions and did not survive when submitted to simulated sequential gastro-intestinal transit, i.e. the activity of bile salts after combined action of hydrochloric acid and pepsin. No correlation was observed between antibiotic resistance and response to the stress conditions applied to the isolates investigated.
Trinta e cinco isolados de Listeria monocytogenes provenientes de alimentos (n=20) e pacientes humanos com listeriose (n=15) e com diferentes perfis de resistência a antibióticos foram caracterizados e comparados com base na: (i) sua capacidade de sobrevivência à passagem pelo trato gastrointestinal simulado, (ii) sua capacidade de sobrivência a condições extremas de pH, (iii) potencial relação entre a resistência a antibióticos e a resistência às condições de stresse investigadas. A resposta às várias condições de stresse demonstrou ser estirpe- e stresse-dependente e não foi observada nenhuma relação entre isolados alimentares e clínicos (p > 0.05). Os resultados mostraram que L. monocytogenes sobrevive em condições ácidas e alcalinas extremas e não sobrevive quando submetida à passagem pelo trato gastrointestinal simulado, ou seja, à atividade dos sais biliares após ação conjunta do ácido clorídrico e pepsina. Não foi observada qualquer correlação entre a resistência a antibióticos e a resposta às condições de stresse aplicadas para os isolados estudados.
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McCluskey, Jackie. "Iron acquisition in Listeria monocytogenes." Thesis, University of Leicester, 1997. http://hdl.handle.net/2381/29756.
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This investigation was designed to study iron acquisition mechanisms of Listeria monocytogenes. Molecular biology techniques were employed. A listerial genomic library in E. coli and a library of listerial transposon mutants was constructed and screened. The assay used to screen both libraries was based on the ability of a ferrous iron chelator, ferrozine, to produce a red colour when complexed with ferrous iron. After screening approximately 10,000 clones from the genomic library and 12,000 mutants from the transposon library of mutants, 11 apparently ferric reductase-negative transposon mutants were identified. Subsequent analysis of these mutants showed them to be ferric reductase-positive. The reason for this reversal of phenotype is now known and was not investigated further. To identify genes which were involved in the growth of L. monocytogenes in low-iron environments, the library of listerial transposon mutants were screened in low-iron medium. From the 5,500 screened, two mutants were identified which showed reduced ability to grow in both low-ferric and low-ferrous iron medium. In the high-iron medium, the growth of the mutants was similar to that of the wild type. Mutant 9E was phenotypically similar to the wild type except for the inability to grow in low-iron medium. Mutant 7D had two additional differences; increased haemolytic activity and decreased motility when observed using phase microscopy. Sequencing of the flanking chromosomal DNA led to the identity of the genes which had been disrupted; flaA in mutant 7D and argiC in mutant 9E. Sequence analysis upstream from the flaA gene identified a new gene, cheV, in L. monocytogenes. The relationship of these mutations to the observed phenotypes was discussed. The ability of both mutants to grow in vivo was similar to that of the parental wild type.
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CHEN, BANG-YUAN. "SDS-PAGE AND WESTERN BLOTTING ANALYSES OF INTERNALIN A IN LISTERIA MONOCYTOGENES AND LISTERIA SPP." MSSTATE, 2006. http://sun.library.msstate.edu/ETD-db/theses/available/etd-08302006-145543/.
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Attachment strength of Listeria spp. and their InlA expression was assessed. Listeria monocytogenes 19111 exhibited the strongest attachment strength with L. monocytogenes 19115, L. grayi, L. innocua, and L. monocytogenes 7644 being the weakest. InlA expression was not detected in silver stained SDS gels but was detected in Western blotting images. Internalin A was only detected in protein extracts of L. monocytogenes 19111 and 7644 with band intensities of 50.1 and 2.5 pixels, respectively. Greater InlA expression was correlated with higher attachment strength in L. monocytogenes 19111. Listeria monocytogenes 19115 did not express InlA but it had a stronger attachment than L. monocytogenes 7644 which demonstrated InlA expression. Intensity of InlA expressed in L. monocytogenes 19111 increased when temperature increased from 10 to 40 oC, and L. monocytogenes 7644 only expressed InlA at 40 oC. It was also determined that InlA was more expressed in nutrient-rich media than in nutrient-poor media.
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Estrada, Erika M. "Investigating the Prevalence, Persistence, and Diversity of Listeria monocytogenes and Listeria species in Produce Packinghouses." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/89919.
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Listeria monocytogenes has emerged as a food safety concern for a number of produce commodities. While L. monocytogenes contamination can occur throughout the supply chain, contamination from the packinghouse environment represents a particular challenge and has been linked to recalls. This study aimed to investigate the prevalence, persistence, and diversity of Listeria monocytogenes (LM) and other Listeria species (LS) in produce packinghouses. A longitudinal study was performed in 11 packinghouses (commodities included micro-green, peach, apple, tomato, broccoli, cauliflower, and cucumber) in three US states. In each packinghouse, 34 to 46 sites representing zones 2-4 were selected and swabbed. Packinghouses were visited 4 times and samples were processed for Listeria by US Food and Drug Administration's Bacteriological Analytical Manual methods. Presumptive Listeria-positive isolates were confirmed by PCR. Species and allelic type (AT) were identified by sigB sequencing. Among the 1,584 samples tested, 3.2%, 2.7%, and 0.6% of the samples were positive for LM, LS, and both LM and LS, respectively. Five different species of Listeria were identified with L. monocytogenes being the most prevalent species. A high AT diversity (0.95 Simpson's Diversity Index) was observed amongst Listeria isolates. There were 15 instances of Listeria repeated isolation (site testing positive ≥2 times). Upon analysis of subtype data, only 3 sites tested positive for the same Listeria AT >2 times. Data showed in this longitudinal study that Listeria prevalence and persistence in packinghouses was low (e.g., <4% prevalence). Therefore, sanitation program development and implementation in packinghouses are critical to limit Listeria harborage and residence.Master of Science in Life Sciences
Listeria monocytogenes is one of the deadliest foodborne pathogens, accounting for about 20% of the deaths caused by foodborne illnesses in the US. Historically, L. monocytogenes has been a big concern for Ready-to-Eat products (ice cream, deli meats, etc.), but in the last decade, there have been several listeriosis outbreaks associated with fresh produce (e.g. cantaloupes, apples, celery, packaged salad) becoming a produce safety concern. Some of these outbreaks have been traced back to the produce farm (pre-harvest) and the operations after harvesting (post-harvest). Though there is research focusing on the prevalence of Listeria in the pre-harvest environment, there is a need for studies investigating Listeria at the post-harvest level. This research project, focused on gaining a better understanding of the prevalence, persistence, and diversity of Listeria (including L. monocytogenes) in produce packinghouses. 11 packinghouses facilities were sampled four times during the packing season. The samples were obtained from different stationary (e.g. walls, drains, floors) and moving (e.g. bins, forklifts, pallets) non-food contact surfaces and equipment during operation hours. Isolates were processed to detect and isolate Listeria species (including L. monocytogenes). Listeria isolates were confirmed and fingerprinted. Listeria prevalence in these packinghouses was low (6.4%), and it varied among packinghouses. Drains, cold storages, and wet non-food contact surfaces were the sites with the highest Listeria prevalence. There were 3 cases of Listeria repeated isolation (same Listeria detected in the same site in at least 2 of the 4 visits). The diversity of Listeria in these packinghouses was high. The information gathered through this research provides a better understanding of where and what species of Listeria can be found in a produce packinghouse iv facility. This knowledge may be used to develop and implement mitigation strategies and interventions to control and/or reduce the risk of Listeria contamination in produce packinghouses.
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Meyer, Philippe. "Apport de l'I. R. M. Dans le diagnostic des rhombencéphalites à listéria." Bordeaux 2, 1993. http://www.theses.fr/1993BOR23021.
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Steinweg, Christiane. "Genomsequenzierung von L. welshimeri und L. seeligeri, zwei apathogenen Spezies des Genus Listeria." Wettenberg VVB Laufersweiler, 2005. http://deposit.d-nb.de/cgi-bin/dokserv?idn=97618320X.
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CESAR, Alessandra Paro Rodrigues. "Listeria spp. E Listeria monocytogenes NA PRODUÇÃO DE SALSICHAS TIPO HOT DOG E HÁBITOS DE CONSUMO." Universidade Federal de Goiás, 2008. http://repositorio.bc.ufg.br/tede/handle/tde/910.
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Previous issue date: 2008-12-12Listeria monocytogenes is a gram-positive bacterium, anaerobic facultative, that grows under refrigerator temperature and it can cause listeriosis in human and animals. It is widely distributed in the environment and it has been isolated from food of animal and vegetal origin that was associated to outbreaks of high lethality in many coutries. Thus, this bacterium represents an important pathogen to the public health. Ready-to-eat products, like cooked stuffed food, within them, frankfurters are associated to human listeriosis in many countries. Taking into consideration the importance of the subject and the need of data about it, the occurrence of Listeria spp. and L. monocytogenes in industrial plants, in meat raw materials, in slurry and frankfurters was investigated. Theses samples were harvest in this two production plants with FIS; in one of them GMP, HACCP and SOP were implemented. The results of the microbiological analysis were submitted to the program @Risk to obtain the danger analysis; the mean values results showed that 7 to 9% of the frankfurters in the market may have L. monocytogenes. After serological typification, performed by Oswaldo Cruz Institute, 88 strains of L. monocytogenes were obtained from 106 samples; among them, 76 were harvest in the industrial plants that participate in the experiment, during a day shift production and 30 were harvest in the market. In serological typification, 95% of these strains were classified as serotypes 4b, 1/2a and 1/2b. Impressions about the behavior of the population that consumes frankfurters in the matters of storage proceedings and the pattern of consumption were obtained by the application of 500 questionnaires at random. The results of these questionnaires showed that the presence of the pathogenic serotypes of L. monocytogenes in meat raw materials, as well in frankfurters commercialized by heaps, and purchased like this by about 75% of the consumers interviewed, may represent a danger to the susceptible population, especially when considering the fact of 40% of the consumers said that they eat the frankfurters directly from the package, without cooking them. Besides the consumption practices, as unknown risk factors of the presence of L. monocytogenes found in frankfurters consumed in the country, we also have lack of epidemiological data, absence of patterns as well the deficient information given to the consumer associated to the incipient relation between federal regulatory agencies and the people
Listeria monocytogenes é uma bactéria Gram-positiva, anaeróbia facultativa, que se multiplica sob temperatura de refrigeração e pode causar listeriose em humanos e outros animais. Amplamente distribuída no ambiente, tem sido isolada de alimentos de origem animal e vegetal associados a surtos de elevada letalidade em diversos países, representando, portanto um patógeno importante para a saúde pública. Produtos prontos para consumo, como embutidos cozidos, entre os quais as salsichas, estão associadas à listeriose humana em alguns países. Considerando a relevância do tema e a necessidade de dados, analisou-se a ocorrência de Listeria spp. e L. monocytogenes no ambiente industrial, nas matérias-primas cárneas, emulsões e em salsichas produzidas nesses dois estabelecimentos com SIF, sendo que em um deles as ferramentas de autocontrole estavam implantadas. Os resultados das análises microbiológicas submetidos a análise de perigos, utilizando o programa @Risk, apresenta valores médios de que 7 a 9% das salsichas destinadas ao consumo possam conter L. monocytogenes. Na sorotipificação, realizada no Instituto Oswaldo Cruz, obteve-se 88 isolados de L. monocytogenes a partir de 106 amostras, sendo 76 colhidas durante um turno de produção diurno nas indústrias que participaram do experimento e 30 no varejo, sendo 95% dos sorotipos patogênicos 4b, 1/2a e 1/2b. Noções acerca do comportamento da população consumidora de salsichas quanto aos procedimentos de estocagem e as formas de consumo praticadas foram obtidas por meio da aplicação de 500 questionários de forma aleatória, demonstrando que a presença de sorotipos patogênicos de L. monocytogenes nas matérias-primas cárneas, bem como em salsichas comercializadas a granel, adquiridas nessa apresentação por cerca de 75% dos entrevistados, oferece riscos à população susceptível, especialmente relacionando-se aos fatos de que cerca de 40% dos consumidores admitem consumir salsichas diretamente da embalagem, sem antes submetê-las ao calor. Além das práticas de consumo, como fatores do risco desconhecido da presença de L. monocytogenes em salsichas consumidas no país, ressalta-se a escassez de dados epidemiológicos, a ausência de padrãos, bem como a falta de informação ao consumidor, associada a relação incipiente entre órgãos regulamentadores e cidadãos
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Reinhard, Robert Gordon. "Application of Bacteriophage in Food Manufacturing Facilities for the Control of Listeria monocytogenes and Listeria sp." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/96726.
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The purpose of this research was to determine if bacteriophage (phage) could be used to treat and reduce the incidence of Listeria in food manufacturing facilities, and thereby reduce the risk of food products being cross-contaminated with Listeria monocytogenes. Listeria incidence in food manufacturing ready-to-eat environments was surveyed at 31 ready-to-eat (RTE) food plants. A total 4,829 samples were collected from all locations. Nine (29%) facilities had zero samples positive for Listeria spp., whereas 22 (71%) had one or more samples positive. The total incidence of Listeria spp. in all RTE food plants was 4.5%.
The effectiveness of phage against Listeria was determined when applied to stainless steel, polyurethane thermoplastic, and epoxy. Each material was inoculated with a cocktail containing L. monocytogenes and L. innocua (4 to 5-log10 CFU/cm2) and treated with two different concentrations of phage (2x10^7 and 1x10^8 PFU/cm2). Treated samples were held at 4 or 20°C for 1 and 3h. After treatment with phage, Listeria reductions ranged from 1.27–3.33 log10 CFU/cm2 on stainless steel, 1.17–2.76 log10 CFU/cm2 on polyurethane thermoplastic, and 1.19–1.76 log10 CFU/cm2 on epoxy. Listeria reduction occurred on all materials tested, under all conditions. Higher phage concentration, longer time, and higher environmental temperatures led to significantly (P<0.05) greater reduction of Listeria on stainless-steel and polyurethane thermoplastic.
The effectiveness of a phage against Listeria spp. was evaluated in two food manufacturing facilities, operating at either 4°C or 20°C. First, a moderate application of a 2x10^7 PFU/mL phage was applied once per day over three days and samples were collected and analyzed for Listeria at 0, 24, 48 and 72 h. This phage treatment led to a decrease in the incidence of Listeria by 67%. A second application method was studied with phage being applied in the food manufacturing environment in an intensified manner (3 times in 18 hours) at a higher concentration of phage (1x10^8 pfu/mL). This intensified application led to a 32% overall reduction in the incidence of Listeria in the production environment. Applications of Listeria specific phage can be an additional intervention strategy for controlling pathogenic Listeria organisms in food production facilities.Doctor of Philosophy
Listeriosis is a serious illness caused by the bacterium Listeria monocytogenes. Annually in the United States it is estimated that 95.7% of all listeriosis illnesses are caused by the consumption of contaminated food, and it is generally recognized that L. monocytogenes is caused by cross contamination of ready-to-eat foods from an environmental source. The purpose of this research was to determine if food manufacturing facilities could use bacteriophage (phage) to treat and reduce the incidence of Listeria in food manufacturing plant, and thereby reduce the risk of food products being cross-contaminated with L. monocytogenes. The incident rate of Listeria was surveyed by collecting 4,829 samples from 31 ready-to-eat (RTE) food plants across the United States. Nine (29%) facilities had zero samples positive for Listeria spp., whereas 22 (71%) plants had one or more samples positive. The total incidence of Listeria spp. in all RTE food plant samples was 4.5%. Second, research was completed to determine if phage at different levels reduced Listeria on three common food manufacturing plant materials (stainless steel, polyurethane belting and epoxy flooring). After Listeria was attached to each material (4 to 5-log10 CFU/cm2), they were treated with two different levels of phage (2x10^7 and 1x10^8 PFU/cm2) at two temperatures (4 or 20°C) for 1 and 3 hours. After treatment with phage, Listeria reduction of 93.2 to 99.9% occurred on all materials tested, under all conditions. Finally, two different methods of applying phage (moderate and intensified) in a food manufacturing plant was studied. The moderate application was a single treatment with lower concentration of phage (2x10^7 PFU/mL) once per day for three days, while the intensified treatment was the application of high phage concentrations (1x10^8 pfu/mL) three different times, all in a single day. Both application methods reduced the incidence of Listeria in the food manufacturing plant. The total reduction across all trials was 67% using the moderate application method and 32% using the intensified application of phage.
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Villegas, Chiroque Miguel. "Caracterización molecular de cepas clínicas de Listeria monocytogenes aisladas en el Hospital Madre Niño San Bartolomé de Lima durante el periodo 2001-2005." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2010. https://hdl.handle.net/20.500.12672/971.
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El presente estudio se realizó con la finalidad de caracterizar cepas clínicas de Listeria monocytogenes aisladas en el Hospital San Bartolomé de Lima- Perú durante los años 2001 a 2005. Durante el periodo del estudio, se identificaron 18 casos de listeriosis perinatal, de los cuales fueron aisladas 20 cepas de L. monocytogenes. Las cepas fueron caracterizadas mediante pruebas convencionales y técnicas de biología molecular. Las 20 cepas en estudio fueron identificadas mediante las características fenotípicas conocidas de L. monocytogenes, tales como presencia de β-hemólisis incompleta, reacción de Christhie, Atkins y Munch-Peterson positiva con S. aureus y negativa con R. equi, así como la utilización de carbohidratos como D-glucosa y L-ramnosa, pero no de D-xilosa ni D-manitol. Todas las cepas fueron confirmadas mediante la reacción en cadena de la polimerasa y tipificadas por la técnica del ADN polimórfico amplificado al azar (RAPD). Con los cebadores OMP-01 y PJ108 se obtuvieron 6 RAPD tipos, distribuidas así: ocho cepas del tipo A-I, tres de cada uno de los tipos A-II, A-III y B-II, dos del tipo B-I y una del tipo A-IV. Se concluye que, en los 18 casos de listeriosis se obtuvieron 20 cepas de L. monocytogenes con seis genotipos diferentes, siendo el RAPD tipo A-I el más frecuente (8/20, 40%) entre las cepas estudiadas.--- This study was conducted in order to characterize strains of Listeria monocytogenes isolates from the San Bartolome´s Hospital in Lima-Peru during the years from 2001 to 2005. During the study period, we identified 18 cases of perinatal listeriosis, which were isolated 20 strains of L. monocytogenes. The strains were characterized by conventional tests and molecular biology techniques. The 20 strains studied were identified by known phenotypic characteristics of L. monocytogenes, such as the presence of incomplete β-hemolysis, positive CAMP reaction with S. aureus and negative CAMP reaction with R. equi, and the use of carbohydrates as D-glucose and L-rhamnose but not from D-xylose or D-mannitol. The strains of L. monocytogenes were confirmed by polymerase chain reaction and typed by random amplified polymorphic DNA (RAPD) technique. With the primers OMP-01 and PJ108 were obtained six RAPD types, distributed as follows: eight strains of type AI, three of each type A-II, A-III and B-II, two type B-I and one strain of type A-IV. We conclude that, in 18 cases of listeriosis were obtained 20 strains of L. monocytogenes with six different genotypes, RAPD type A-I being the most frequent (8/20, 40%) among the studied strains.
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Pompili, Sara. "Sopravvivenza di Listeria nel tratto gastrointestinale." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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La tesi è focalizzata su una revisione critica della letteratura scientifica relativa allo studio dei meccanismi di sopravvivenza e adattamento di Listeria monocytogenes, in particolare nel tratto gastrointestinale umano. É stata presa in considerazione Listeria, responsabile della listeriosi nell’uomo se assunta per via alimentare. Il patogeno oltre ad essere in grado di sopravvivere all’interno degli alimenti durante la conservazione, è in grado di adattarsi e sopravvivere anche alle condizioni ambientali ostili che incontra dopo l’ingestione grazie a delle modificazioni che mette in atto in seguito a segnali di stress esterni. All’interno del tratto gastrointestinale, Listeria si trova ad affrontare una serie di condizioni a lui sfavorevoli, ad ognuna delle quali però è in grado di rispondere grazie a dei fattori di trascrizione che codificano per geni specifici che attivano i cosiddetti fattori di virulenza. I geni che codificano per adesione, invasività e virulenza gli permettono di aderire, entrare e colonizzare le cellule dell’ospite. Nell’elaborato viene presa in considerazione la risposta immunitaria innata dell’ospite, che se immunocompetente è in grado di rallentare l’invasione tramite l’azione antimicrobica dei fluidi gastrici e della microflora intestinale. La dieta può influenzare la resistenza dell’ospite al patogeno, in particolare sono alcuni tipi di grassi alimentari che diminuiscono la facilità di adesione alle membrane intestinali, i carboidrati non digeribili con azione probiotica e le batteriocine soprattutto prodotte da Lattobacilli che vanno ad agire da antimicrobici contro le cellule del patogeno.
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Waak, Elisabet. "Listeria monocytogenes : farm and dairy studies /." Uppsala : Dept. of Food Hygiene, Swedish Univ. of Agricultural Sciences ([Institutionen för livsmedelshygien], Sveriges lantbruksuniv.), 2002. http://epsilon.slu.se/avh/2002/91-576-6376-9.pdf.
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Wang, Qingqi. "Regulation of motility in Listeria monocytogenes." Thesis, University of Nottingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490996.
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Listeria monocytogenes is a saprophytic food borne microorganism which is pathogenic to humans and animals. The pathogenicity and physiological features of L. monocytogenes have been studied for many years. Some characteristics of this microorganism have been described, such as its low temperature growth and adaptation, the expression of its flagellin gene, and the regulation of its virulence genes. Previous studies imply a possible reversed relationship that may exist between the regulation of the listerial flagellin gene, flaA and its virulence regulator gene, prfA.
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Barnard, Faye Marie. "Cold shock proteins of Listeria monocytogenes." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285457.
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Vogel, Markus. "Beitrag zur Epizootologie von Listeria monocytogenes /." [S.l : s.n.], 1987. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Perni, Stefano. "Listeria innocua : growth and biofilm formation." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/33600.
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The contamination of food processing equipment by pathogenic bacteria is a serious threat to food safety and public health. Much attention has recently been focussed on Listeriae because of their ability to both grow over a wide temperature range and to adhere to a wide range of materials. However, whilst many previous studies have studied attachment under static or low Reynolds number (Re) flow, no published work exists on the effects of flow conditions at industrially relevant Re on the phenomenon of attachment. This is examined here using non-pathogenic Listeria innocua—frequently claimed to be a surrogate for the pathogen L. monocytogenes—in relation to stainless steel. This material was chosen because it is widely used in the food industry.
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Camargo, Anderson Carlos. "Uncovering the Listeria monocytogenes virulence traits." Universidade Federal de Viçosa, 2017. http://www.locus.ufv.br/handle/123456789/17751.
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Listeria monocytogenes é uma bactéria Gram-positiva comumente encontrada no ambiente de processamento de alimentos, produtos in natura e processados. Esse patógeno é reconhecido como o agente causador da listeriose, uma doença grave que afeta principalmente indivíduos de grupos de risco. O presente estudo teve como objetivo caracterizar isolados de L. monocytogenes recuperados no Brasil a partir de fontes clínicas, ambiente de processamento de produtos cárneos, e de carne bovina. Os perfis de susceptibilidade aos antibióticos, genes de virulência, diversidade de sorotipos, capacidade de invadir, replicar e se disseminar em células hospedeiras, bem como a morte celular e a produção de IFN induzidas por isolados de L. monocytogenes foram caracterizados. Todos os isolados apresentaram sensibilidade aos antimicrobianos utilizados para o tratamento da listeriose, no entanto a maioria apresentou resistência ou resistência intermediária à clindamicina e à oxacilina. A sorotipagem molecular produziu resultados contraditórios para sete isolados do sorotipo 1/2a, que foram positivos para o gene lmo1118 e exibiram o perfil IIc (sorotipos 1/2c ou 3c). Além disso, quinze isolados do sorotipo 4b amplificaram o gene lmo0737, e foram classificados como atipico IVb-v1. O potencial de invadir células Caco-2 foi significativamente afetado pela presença de codons de parada prematuros (PMSCs) no gene inlA do sorotipo 1/2c (p < 0,005). As cepas variaram amplamente em seus tempos de duplicação intracelular em celulas Caco- 2, e não houve relação clara entre sorotipo ou fonte. Foram observadas diferenças significativas entre os sorotipos com relação a disseminação em células Caco-2; isolados do sorotipo 1/2a apresentaram defeito na disseminação celular, enquanto isolados do sorotipo 1/2b apresentaram maior habilidade de disseminação celular (p <0,0001). Além disso, identificamos três isolados de sorotipo 4b que se disseminaram em uma área aproximadamente duas vezes maior que a cepa de referência 10403S. Não foram observadas tendências quanto aos tempos duplicação intracelular em iBMDM, comparando fontes de isolamento e sorotipos. Os resultados indicam que a replicação intracelular é determinada pelas características genotípicas de cada isolado. A morte celular induzida por alguns isolados após a infecção de iBMDM foi dependente da enzima Caspase 1, indicando que eles induzem morte celular por piroptose. Alguns isolados também induziram alta produção de INF pela linhagem celular iBMDM. Usando macrófagos primários, foi revelado que a produção de INF foi sempre STING dependente, em alguns casos totalmente cGAS independente, parcialmente cGAS dependente, ou mesmo cGAS dependente. Este trabalho caracterizou o perfil patogênico de isolados de L. monocytogenes, permitindo uma melhor compreensão dos mecanismos de infectividade desse patógeno, e levando a uma análise mais profunda dos genomas e outras abordagens experimentais para revelar os mecanismos associados aos fenótipos de virulência mais extremos.
Listeria monocytogenes is a Gram-positive bacterium commonly isolated from food processing environment, raw and processed foods. It is recognized as the causative agent of listeriosis, a serious disease that affects mainly individuals from risk groups. The present study aimed to characterize L. monocytogenes isolates recovered in Brazil from clinical sources, meat processing environmental and beef. Antibiotic resistance profiles, virulence genes, serotype diversity, ability to invade, replicate and spread in host cells, as well as cell death and IFN production induced by L. monocytogenes isolates were characterized. All isolates presented sensitivity to antimicrobials used for listeriosis treatment while most of them presented resistance or intermediate resistance to clindamycin and oxacillin. Molecular serogrouping produced contradictory results for seven isolated from serotype 1/2a, which were positive for the gene lmo1118 and exhibited the profile IIc (serotypes 1/2c or 3c). In addition, fifteen isolates from serotype 4b amplified the gene lmo0737, being classified as atypical IVb-v1. The potential to invade Caco-2 cells was significantly affected by the presence of premature stop codons (PMSCs) in inlA gene of isolates from serotype 1/2c (p < 0.005). The isolates varied widely in their intracellular doubling times, and there was no clear relationship between serotype or source. There were significant differences between serotypes for cell-to-cell spread in Caco-2 cells, isolates from serotype 1/2a were generally impaired in their spreading ability while most os isolates from serotype 1/2b exhibited increased spreading ability (p < 0.0001). In addition, we identified three isolates from serotype 4b that spread nearly twice as much as the reference strain 10403S. No trends were observed regarding intracellular doubling times in iBMDM by comparing sources and serotypes; based on these results, intracellular growth seems to be determined by genetic characteristics of each strain. The cell death induced by some isolates after infection of iBMDM was Caspase 1 dependent, indicating that they induce pyroptosis. Some of these isolates also induced high INF production by iBMDM. Using primary macrophages, it was revealed that INF production was always STING dependent, and in some cases it is fully cGAS independent, partially cGAS dependent, or even mostly cGAS dependent. We have characterized L. monocytogenes isolates that could provide novel insight into infectivity of this pathogen that may not be revealed by studying common laboratory strains, demanding further analysis of their genomes and other experimental approaches to reveal the mechanisms associated with the most extreme phenotypes exhibited.
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Carrière, Christian. "Polymorphisme de l'adn de listeria monocytogenes." Montpellier 1, 1990. http://www.theses.fr/1990MON11275.
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NOIREAUX, VINCENT. "Etude d'un systeme biomimetique de listeria." Paris 11, 2000. http://www.theses.fr/2000PA112201.
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L'actine est la proteine la plus abondante des cellules eucaryotes. Cette molecule s'assemble en filaments semi-flexibles qui constituent une partie du cytosquelette. Ces filaments qui polymerisent et depolymerisent rapidement permettent a la cellule de se deplacer et de changer de forme. Un systeme modele pour etudier la motilite cellulaire est la bacterie listeria monocytogenes qui utilise la polymerisation de l'actine pour se deplacer a des vitesses d'environ 0. 1 m/s dans des cellules mammiferes. L'assemblage de l'actine, qui prend la forme d'une comete, est initie par la proteine bacterienne acta ancree a la membrane du parasite. Nous avons mis au point un autre systeme modele ou des particules sont recouvertes de la proteine acta. Avec ce nouveau modele, nous avons etudie quelques proprietes physiques et biochimiques du cytosquelette d'actine. Nous avons effectue des experiences avec un variant de la proteine acta. Nous avons couple cette proteine sur des particules spheriques que nous avons melangees dans des extraits cellulaires. Nous avons observe la formation d'un gel d'actine dont l'epaisseur depend de la taille des billes. Nous proposons par un modele quantitatif que le gel d'actine exerce une contrainte sur la surface des particules. Ce modele peut expliquer l'origine de la force de propulsion de listeria. Nous donnons les resultats obtenus avec deux autres proteines capables de polymeriser l'actine. La proteine gst-pro qui recrute vasp et la proteine gst-wa qui active le complexe arp2/3 et pour laquelle nous avons observe la formation de cometes sur des billes de petites tailles. Nous avons aussi etudie la dynamique de croissance des reseaux d'actine induits par ces differents nucleateurs par video microscopie. Au cours de ce travail nous avons mis au point un systeme pour etudier les proteines du cytosquelette. Il nous a permis de montrer que le complexe gst-pro/vasp est une nouvelle voie de polymerisation de l'actine independante de la voie arp2/3.
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Lemaître, Jean-Paul. "Caracterisation phenotypique des especes de listeria." Dijon, 1994. http://www.theses.fr/1994DIJOPE02.
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Vávrová, Helena. "Marketingová strategie značky Listerine Smart Rinse." Master's thesis, Vysoká škola ekonomická v Praze, 2010. http://www.nusl.cz/ntk/nusl-75056.
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The aim of the diploma thesis is to analyse marketing strategy of Listerine Smart Rinse and recommend possible improvements into the future. Theoretical part is divided into three chapters. The first chapter deals with the essence of marketing and definition of marketing process. The second chapter covers brand policy and the importance of brand in marketing. The third chapter offers basic theoretical approaches for the formulation of product, pricing, promotional and distribution strategy which are applied in the practical part. The theoretical part is followed by analysis of Listerine Smart Rinse strategy in terms of 4Ps -- product, price, promotional and distribution policy. Based on the findings there are recommendations offered in the last chapter to improve marketing strategy for the future.
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Portman, Jonathan Lewis. "Virulence Factor Regulation in Listeria monocytogenes." Thesis, University of California, Berkeley, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10620349.
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Listeria monocytogenes is a Gram-positive intracellular pathogen that is readily amenable to genetic manipulation and for which there are excellent in vitro and in vivo virulence models. These attributes have allowed a thorough examination of the molecular underpinnings of L. monocytogenes pathogenesis, however, there are still a number of major unresolved questions that remain to be answered. For example, it has been known for many years that L. monocytogenes rapidly changes its transcriptional profile upon access to the host cytosol, however the host cues and bacterial components that are involved in driving this change have remained continually unanswered. One large piece of evidence came when the long-sought co-factor for the primary virulence regulator, PrfA, was discovered to be the antioxidant tripeptide, glutathione. Glutathione was demonstrated to play a crucial role in the activation of PrfA in vivo— a finding that has since led to two important discoveries that are described herein. First, the activation of PrfA in vitro requires both exogenous glutathione and a metabolic licensing step that can be recapitulated by a chemically defined synthetic media. Second, glutathione also functions as a post-translational regulator of the pore-forming virulence factor, Listeriolysin O (LLO), by reversibly binding via an S-glutathionylation reaction and preventing membrane association of the LLO monomers. These discoveries elucidate numerous regulatory roles for glutathione during infection and describe how L. monocytogenes is able to sense and respond to critical host compartments to mount a successful infection.
Upon entry to the host cell cytosol, the facultative intracellular pathogen Listeria monocytogenes coordinates the expression of numerous essential virulence factors by allosteric binding of glutathione (GSH) to the Crp-Fnr family transcriptional regulator, PrfA. Here we report that robust virulence gene expression can be recapitulated by growing bacteria in a synthetic medium (iLSM) containing GSH or other chemical reducing agents. Bacteria grown under these conditions were 45-fold more virulent in an acute murine infection model and conferred greater immunity to a subsequent lethal challenge compared to bacteria grown in conventional media. During cultivation in vitro , PrfA activation was completely dependent on intracellular levels of GSH, as a glutathione synthase mutant (ΔgshF) was activated by exogenous GSH but not reducing agents. PrfA activation was repressed in iLSM supplemented with oligopeptides, but suppression was relieved by stimulation of the stringent response. These data suggest that cytosolic L. monocytogenes interpret a combination of metabolic and redox cues as a signal to initiate robust virulence gene expression in vivo.
Cholesterol-dependent cytolysins (CDCs) represent a family of homologous pore-forming proteins secreted by many Gram-positive bacterial pathogens. CDCs mediate membrane binding partly through a conserved C-terminal undecapeptide, which contains a single cysteine residue. While mutational changes to other residues in the undecapeptide typically have severe effects, mutating the cysteine residue to alanine has minor effects on overall protein function. Thus, the function of this highly conserved reactive cysteine residue remains largely unknown. We report here that the CDC Listeriolysin O (LLO), secreted by the facultative intracellular pathogen Listeria monocytogenes, was post-translationally modified by a S-glutathionylation at this conserved cysteine residue, and that either endogenously synthesized or exogenously added glutathione was sufficient to form this modification. When recapitulated with purified protein in vitro, this modification completely ablated the activity of LLO, and this inhibitory effect was fully reversible by treatment with reducing agents. A cysteine-to-alanine mutation in LLO rendered the protein completely resistant to inactivation by S-glutathionylation and retained full hemolytic activity. A mutant strain of L. monocytogenes expressing the cysteine-to-alanine variant of LLO was able to infect and replicate within bone marrow-derived macrophages indistinguishably from wild-type in vitro, yet was attenuated 4-6 fold in a competitive murine infection model in vivo. This study suggests that S-glutathionylation may represent a mechanism by which CDC family proteins are post-translationally modified and regulated, and help explain an evolutionary pressure behind the highly conserved undecapeptide cysteine.
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Pereira, Sónia Maria Leite. "Efeito da temperatura e pH na inativação de Listeria por alta pressão." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/13360.
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Mestrado em MicrobiologiaO estudo dos efeitos da pressão começou a despertar interesse na área das ciências biológicas a partir do final do século XIX. Desde então, o uso de alta pressão nas biociências tem sido alvo de crescente interesse e originado inovações notáveis em processos laboratoriais e industriais. O setor alimentar é atualmente um dos campos de maior potencial para a aplicação da tecnologia de alta pressão, pela possibilidade de inativar microrganismos e aumentar a segurança e estabilidade dos alimentos, sem alterar as suas propriedades organoléticas e nutricionais. A necessidade de adequar o protocolo de processamento às características dos organismos alvo tem levado à combinação da pressão com outros fatores físico-químicos que maximizam a eficiência de inativação. O objetivo do presente estudo foi avaliar a influência da temperatura e do pH do meio na suscetibilidade de Listeria, à inativação por alta pressão, no sentido de criar conhecimento que permita a implementação de protocolos de processamento combinado. Para tal, culturas em fase estacionária foram submetidas a 300 MPa durante 5 minutos. Nos ensaios com variação de temperatura a pressurização foi conduzida a 4, 10 e 20 C. Para o estudo do efeito do pH foram realizados ensaios em ambiente ácido (pH = 4), neutro (pH = 7) e alcalino (pH = 10). Para quantificação da inativação, fizeram-se diluições em série e procedeu-se à sementeira por incorporação das suspensões de células, antes e depois da pressurização, para determinação do teor de células viáveis (UFC mL-1). Pressurizações a baixas temperaturas (4 e 10 C) revelaram ser mais eficientes do que quando efetuadas à temperatura ambiente (20 C) e as células mostraram maior suscetibilidade à inativação, por alta pressão, em meio neutro e ácido do que em meio alcalino. Os resultados permitem concluir que a eficiência de inativação depende não só do valor de pressão aplicado, mas também de outros parâmetros físico-químicos relacionados com o ambiente extracellular durante a pressurização, e evidenciam a necessidade da rigorosa adequação do protocolo de inativação às caracerísticas físico químicas da matriz, no sentido de obter a maior eficiência de inativação dos microrganismos alvo.
The study of the biological effects of high pressure began to gain interest in the late nineteenth century. Since then, the use of high pressure in biosciences increased and originated notable innovations in laboratory and industrial processes. Currently, the food sector represents a field of great potential for the application of high pressure technology, due the possibility to inactivate microorganisms and increase food safety and stability while preserving organoleptic and nutritional properties. The need to adapt processing protocols to target microorganisms has led to the combination of pressure with other physical and chemical factors, in order to maximize inactivation efficiency. The purpose of this study was the evaluation of the effects of temperature and pH of the medium on the susceptibility of Listeria to high pressure inactivation, in order to establish that the scientific basis for the design of combined processing protocols. To this end, stationary phase cultures were subjected to 300 MPa, for 5 minutes. Pressurization was conducted at 4, 10 and 20 C and the pH of the medium was manipulated to represent acid (pH 4), neutral (pH = 7) and alkaline (pH = 10) conditions. For determination of viable cells (CFU mL-1), serial dilutions of the cell suspensions were made and pour-plated in solid medium before and after pressurization. Low temperature pressurization (4, 10 C) was more efficient that the process conducted at room temperature (20 C) and cell susceptibility to high pressure was enhanced in neutral and acidic environment, comparatively with alkaline medium. The results confirm that the efficiency of the high pressure inactivation of Listeria depends not only the pressure applied, but also on other physical and chemical parameters related to the extracellular environment during pressurization, such as temperature and pH. As a consequence, a careful design of the processing protocol may significantly improve the efficiency of inactivation of target microorganisms.
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Otto, Rachel. "Listeria survival after isoelectric solubilization and precipitation of fish protein with organic acids." Morgantown, W. Va. : [West Virginia University Libraries], 2010. http://hdl.handle.net/10450/11044.
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Kannius, Sara, and Jonas Karlsson. "Listeria monocytogenes : Mikrobiologisk analys av tre riskprodukter." Thesis, Örebro universitet, Restaurang- och hotellhögskolan - Grythytte akademi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-11874.
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Inledning: Det är få personer som insjuknar av den livsmedelsburna bakterien Listeria monocytogenes, men dödligheten beräknas vara 20-30 %. L. monocytogenes förekommer i ätfärdiga livsmedel som konsumeras utan någon upphettning. I EU ligger Sverige näst högst på listan med antalet insjuknade.SyfteSyftet var att undersöka förekomsten av L. monocytogenes i gravad respektive kallrökt lax samt smörgåspålägg. Metod och material: Denna uppsats har skrivits utefter laborationer och databassökningar där vetenskapliga artiklar hämtats samt internetsökningar.Resultat Resultatet visade att i två av 15 risklivsmedel påvisades L. monocytogenes. Båda dessa risklivsmedel var gravad lax.Slutsats Slutsatsen av denna studie blev att vakuumförpackad gravad lax är ett risklivsmedel. Nyckelord: Gravad lax, kallrökt lax, listerios och smörgåspålägg
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Baumgärtner, Maja. "Membranproteomanalyse des fakultativ intrazellulären Erregers Listeria monocytogenes." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972338551.
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Unnerstad, Helle. "Listeria monocytogenes : strain diversity demonstrated by genotyping /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-5919-2.pdf.
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Ooi, Poh Im Amy. "Structural studies of internalins from Listeria monocytogenes." Thesis, Queen Mary, University of London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406428.
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Neamatallah, Abdullatiff A. N. "Studies on Listeria monocytogenes recovered from fish." Thesis, Heriot-Watt University, 2005. http://hdl.handle.net/10399/223.
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Taylor, James Gareth William. "Isolation and characterisation of Listeria monocytogenes bacteriophages." Thesis, University of Warwick, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425993.
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