Infecções por Listeria monocytogenes têm sido frequentemente relatadas em vários casos de surtos de infecção alimentar pelo mundo. Logo, a preocupação em tornar produtos alimentares de larga escala livres destes patógenos tem aumentado ao longo dos anos. Uma das estratégias mais eficazes são a utilização de bacteriocinas como agentes conservantes, prevenindo a multiplicação bacteriana durante os processos de fabricação, estocagem e distribuição dos produtos. A nisina é uma das bacteriocinas mais conhecidas, sendo empregada na indústria alimentícia por muitos anos. Seu mecanismo de atividade antimicrobiana principal é através da formação de um complexo, juntamente com um precursor de parede celular (lipídio II), que formam poros na membrana celular, causando o extravasamento de conteúdos celulares vitais e a perda de estabilidade eletrolítica, levando à morte celular. Entretanto, algumas evidências apontam para mecanismos alternativos, mas ainda desconhecidos, de morte celular. Uma das abordagens interessantes é por meio da análise dos processos celulares (comparado a uma condição não tratada com nisina) através de metodologias proteômicas. Os cultivos bacterianos foram tratados com concentrações subletais de nisina e os extratos proteicos foram processados em espectrometria de massas em tandem acoplado a um sistema de cromatografia líquida (LC-MS/MS). Os resultados mostraram expressão diferencial de algumas proteínas que atuam contra o estresse oxidativo, como a catalase e proteínas de armazenamento de íons ferrosos. Também verificou-se a superexpressão de uma HSP, a qual pode alterar o dobramento correto de algumas proteínas como a de divisão celular FtsZ. Por fim, a subexpressão de uma chaperona responsável pelo correto dobramento das penicillin binding proteins (PBPs) e a superexpressão de enzimas responsáveis pela síntese de lipídios precursores da membrana celular podem apontar para um sistema de divisão celular alternativo, agindo provavelmente como uma resposta à presença de membranas cobertas por complexos nisina e lipídio II. / Listeria monocytogenes infections have been frequently reported in many food poisoning outbreaks around the world. Therefore, the concern about protecting largely-scale food products from these pathogens has been rising over the years. One of the most efficient strategies is using bacteriocins as a conserving agent, preventing the growth of pathogenic bacteria during the production, storage and distribution of the product. Nisin is a well-known bacteriocin, which has been applied in the food industry for many years. Its main antimicrobial mechanism is based in forming a cell membrane pore creator complex, which coupled with a cell wall precursor (lipid II), leads to the leakage of essential cell life compounds and the loss of electrolytic stability, causing the cell death. However, recent evidences lead to an alternative, but still unknown, cell death mechanism. One interesting approach is analyzing the cell processes (compared to a non-nisin treated condition) by a proteomic approach. The L. monocytogenes cells were treated with a sublethal concentration of nisin and the protein extracts were ran through a tandem mass spectrometry attached to a liquid chromatography system (LC-MS/MS). The results showed differential expression of some agents against oxidative stress such as catalase and ferrous ions storage proteins. Furthermore, it had also presented upregulation of a HSP which can alter the correct folding of other proteins, such as the FtsZ cell division protein. Finally, the downregulation of a chaperone that is responsible of the correct folding of penicillin binding proteins (PBPs) and the superexpression of some enzymes related to the production of cell membrane lipids could point out to a different bacterial cell division system, acting probably as a response to the nisin-lipid II complexes covered cell membranes.

Infecções por Listeria monocytogenes têm sido frequentemente relatadas em vários casos de surtos de infecção alimentar pelo mundo. Logo, a preocupação em tornar produtos alimentares de larga escala livres destes patógenos tem aumentado ao longo dos anos. Uma das estratégias mais eficazes são a utilização de bacteriocinas como agentes conservantes, prevenindo a multiplicação bacteriana durante os processos de fabricação, estocagem e distribuição dos produtos. A nisina é uma das bacteriocinas mais conhecidas, sendo empregada na indústria alimentícia por muitos anos. Seu mecanismo de atividade antimicrobiana principal é através da formação de um complexo, juntamente com um precursor de parede celular (lipídio II), que formam poros na membrana celular, causando o extravasamento de conteúdos celulares vitais e a perda de estabilidade eletrolítica, levando à morte celular. Entretanto, algumas evidências apontam para mecanismos alternativos, mas ainda desconhecidos, de morte celular. Uma das abordagens interessantes é por meio da análise dos processos celulares (comparado a uma condição não tratada com nisina) através de metodologias proteômicas. Os cultivos bacterianos foram tratados com concentrações subletais de nisina e os extratos proteicos foram processados em espectrometria de massas em tandem acoplado a um sistema de cromatografia líquida (LC-MS/MS). Os resultados mostraram expressão diferencial de algumas proteínas que atuam contra o estresse oxidativo, como a catalase e proteínas de armazenamento de íons ferrosos. Também verificou-se a superexpressão de uma HSP, a qual pode alterar o dobramento correto de algumas proteínas como a de divisão celular FtsZ. Por fim, a subexpressão de uma chaperona responsável pelo correto dobramento das penicillin binding proteins (PBPs) e a superexpressão de enzimas responsáveis pela síntese de lipídios precursores da membrana celular podem apontar para um sistema de divisão celular alternativo, agindo provavelmente como uma resposta à presença de membranas cobertas por complexos nisina e lipídio II. / Listeria monocytogenes infections have been frequently reported in many food poisoning outbreaks around the world. Therefore, the concern about protecting largely-scale food products from these pathogens has been rising over the years. One of the most efficient strategies is using bacteriocins as a conserving agent, preventing the growth of pathogenic bacteria during the production, storage and distribution of the product. Nisin is a well-known bacteriocin, which has been applied in the food industry for many years. Its main antimicrobial mechanism is based in forming a cell membrane pore creator complex, which coupled with a cell wall precursor (lipid II), leads to the leakage of essential cell life compounds and the loss of electrolytic stability, causing the cell death. However, recent evidences lead to an alternative, but still unknown, cell death mechanism. One interesting approach is analyzing the cell processes (compared to a non-nisin treated condition) by a proteomic approach. The L. monocytogenes cells were treated with a sublethal concentration of nisin and the protein extracts were ran through a tandem mass spectrometry attached to a liquid chromatography system (LC-MS/MS). The results showed differential expression of some agents against oxidative stress such as catalase and ferrous ions storage proteins. Furthermore, it had also presented upregulation of a HSP which can alter the correct folding of other proteins, such as the FtsZ cell division protein. Finally, the downregulation of a chaperone that is responsible of the correct folding of penicillin binding proteins (PBPs) and the superexpression of some enzymes related to the production of cell membrane lipids could point out to a different bacterial cell division system, acting probably as a response to the nisin-lipid II complexes covered cell membranes.

Orientador: Mary Luci de Souza Queiroz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-04T00:31:06Z (GMT). No. of bitstreams: 1 Resta_AndreiadosSantos_M.pdf: 837966 bytes, checksum: ca84712f5cd6dd4ba54f60e463697d96 (MD5) Previous issue date: 2004 / 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

Listeria monocytogenes causes a serious foodborne illness (listeriosis) with a fatality rate of about 30% in susceptible individuals (1). Timely identification of foods and food processing environments carrying this deadly bacterium is crucial for implementing effective interventions but remains a practical challenge due to the complexity of test samples, low level of bacterial contamination, and the ubiquity and the genetic diversity of Listeria isolates. The purpose of this work was to identify and assess surface proteins of L. monocytogenes that can serve as diagnostic biomarkers for pathogen isolation and detection using antibody-based methods. Bioinformatics analysis of 130 putative surface proteins encoded by the genome of L. monocytogenes F2365 (serotype 4b) revealed four uncharacterized proteins with extensive amino acid sequences unique to L. monocytogenes. These proteins did not contain identifiable PrfA-controlled promoter elements. The four proteins were expressed at the transcriptional level in vitro, as demonstrated by RT-PCR, but only one of the four proteins, LMOf2365_0639, was detected on the cell surface by immunofluorescence microscopy (IFM) using rabbit polyclonal antibodies (PAbs) raised against corresponding recombinant proteins. Transcription start site mapping and promoter prediction analysis provided evidence that the LMOf2365_0639 gene was expressed under the control of a sigma B factor-dependent promoter, an alternative sigma factor involved in stress response. Non-gel based proteomics analysis of L. monocytogenes surface proteins identified 36 surface proteins in at least one of the three trials performed. IFM with PAbs raised against each of the five candidate surface proteins identified from the proteomics study revealed a strong fluorescence signal on the surface of live L. monocytogenes cells with LMOf2365_0148 specific PAbs, indicating a good level of expression of this protein. These results suggested the potential of the surface proteins LMOf2365_0639 and LMOf2365_0148 as diagnostic biomarkers for L. monocytogenes. Thirty-five and 24 monoclonal antibodies (MAbs) were developed against purified recombinant LMOf2365_0639 and LMOf2365_0148, respectively. Three MAbs against LMOf2365_0639 and five MAbs against LMOf2365_0148 were selected and evaluated for their potential in L. monocytogenes detection and isolation based on the observation that these MAbs recognized the highest number of the 53 L. monocytogenes isolates and the lowest number of the 10 other Listeria species isolates tested. None of these MAbs reacted with the four foodborne pathogens (Campylobacter jejuni, Samonella enterica serovar Typhimurium, Escherichia coli O157:H7 and Bacillus cereus) tested. All three MAbs to LMOf2365_0639 were specific for lineage I and II isolates of L. monocytogenes commonly found in clinical and food isolates respectively and recognized the N-terminal region of LMOf2365_0639. Anti-LMOf2365_0148 MAbs were reactive to lineage I and lineages III L. monocytogenes isolates commonly found in clinical and animal isolates respectively. Both LMOf2365_0639 and LMOf2365_0148 were expressed in standard enrichment culture conditions according to Health Canada’s MFHPB-30 and MFHPB-07 methods. In addition, MAbs against LMOf2365_0148 could specifically isolate live L. monocytogenes by immunomagnetic separation even in a mixture of L. monocytogenes and non-target L. innocua. The dissociation constants of the MAbs capable of capturing L. monocytogenes ranged from 2.58 x 10-8 M to 8.87 x 10-10 M. In conclusion, two novel surface proteins LMOf2365_0639 and LMOf2365_0148 were identified, were shown to be expressed in L. monocytogenes grown in standard selective enrichment cultures, and can be explored as surface biomarkers for the isolation and detection of L. monocytogenes with specific MAbs developed in this study.

Orientador: Tomomasa Yano / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-03T15:36:39Z (GMT). No. of bitstreams: 1 Marques_EneidaGoncalvesLemes_M.pdf: 6403857 bytes, checksum: aba606a1028881cdd6692f20d1eb780b (MD5) Previous issue date: 2003 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The abstract is available with the full electronic digital document / Mestrado / Microbiologia / Mestre em Genética e Biologia Molecular

Cholesterol has been shown to play important role in the pathogenesis and persistence of intracellular pathogens. Here, we modulate host cholesterol biosynthesis pathway using pharmacological agent statins, which are reversible inhibitors of HMG†CoA reductase enzyme. The aim of the study was to investigate the role of statins in inducing host protective responses against intracellular pathogens. We report reduced growth of Listeria monocytogenes (LM) and Mycobacterium tuberculosis (Mtb) in murine macrophages. We show prominent immunomodulatory activity induced by statins, mainly increased phagosomal maturation and autophagy resulting in decreased bacterial growth in macrophages. Subsequently, statin†treated mice showed decrease in bacterial loads, accompanied by reduced histopathology in the acute phase of infection during listeriosis and tuberculosis. Furthermore, we found decreased growth of Mtb in peripheral blood mononuclear cells (PBMC) and monocyte†derived macrophages (MDM) isolated from patients with familial hypercholesterolemia (FH) on statin therapy when compared to healthy subjects. Together, our results show that statins induces protection against Mtb in murine macrophages, mice and human mononuclear cells and monocyte†derived macrophages.

The pathogenicity of food-borne intracellular bacterium Listeria monocytogenes is greatly associated with its abilities to invade non-phagocytic cells, counteract the host innate immune system, resist bactericidal antibiotic-mediated killing, and breaking the physical barriers. In the last 30 years of research on L. monocytogenes, several virulence factors, such as Listeriolysin O (LLO), InlA, InlB, ActA, PI-PLC, and PC-PLC have already been characterized as important players that help this bacterium to achieve the key stage of infection. There are approximately 3,000 open reading frames in Listeria’s genome; however, only few virulence factors are functionally characterized. Thus, it is important to identify new virulence factors and understand how new virulence factors in Listeria help this opportunistic pathogen to counteract the host innate immune system, resist antibiotic-mediated killing, colonize vital organs, and finally successfully develop life-threatening listeriosis. In this study, inrame deletion mutagenesis was used to generate the deletion mutants of novel listerial virulence factors and a series of biochemical, in vitro and in vivo experiments were conducted to characterize the roles of these virulence factors during the infection process. In the first part of this study, an AlkD-like protein (Adlp, LmoF2365_0220) was identified and the protein is associated with oxidant tolerance and aminoglycoside antibiotic resistance. In the second part of this study, a new internalin-like protein (LmoH7858_0369) was shown to be involved in invasion of Hep-G2 cells and organ colonization in mice. The third part of this study showed that listeriolysin O (LLO) mediates cytotoxicity on brain endothelial cells, suggesting that LLO may contribute to the invasion of the central nervous system by L. monocytogenes. In summary, we identified and characterized two novel virulence factors, Adlp and LmoH7858_0369 that contributed to bacterial infection and revealed a new invasion mechanism of CNS cells that is mediated by LLO. Results from these studies provide a better understanding on the pathogenicity of L. monocytogenes and can be used as therapeutical targets or vaccine candidates

La surveillance de la listériose en France s’est construite par étapes depuis les années 1980 sur deux piliers, la microbiologie et l’épidémiologie. Grâce à la création du Centre National de Référence des Listeria et à la mise au point de techniques de typage performantes, l’Institut Pasteur assure une surveillance microbiologique depuis 1987. Une surveillance épidémiologique initiée entre 1984 et 1992 par le Laboratoire National de la Santé, a été développée par le Réseau National de Santé Publique de 1993 à 1999, puis amplifiée par l’Institut de Veille Sanitaire à partir de 2000. Le premier objectif de cette thèse est de décrire les différentes phases de la construction de cette surveillance afin d’analyser leurs contributions respectives au cours de ces 30 dernières années. Cette construction s’est faite en 4 phases : 1. L’étape fondatrice de 1982 à 1992 a été la reconnaissance et la prise en compte du rôle des aliments dans la transmission de la maladie et dans la survenue d’épidémies. 2. La deuxième phase de 1993 à 2000 a été l’édification d’un système de surveillance opérationnel pour détecter et investiguer les épidémies en France. 3. La troisième phase de 2000 à 2005 a permis de consolider le système de surveillance et de le perfectionner en ajoutant un volet complémentaire avec des prélèvements alimentaires.4. Depuis 2005, nous sommes dans la quatrième phase avec comme objectif l’optimisation du système. Cette optimisation repose sur l’adaptation des outils de surveillance et d’alerte aux connaissances. Ainsi, après avoir montré que la durée d’incubation de la maladie varie selon la forme clinique de la maladie, nous avons proposé d’intégrer cette variation pour déterminer la période d’évaluation des expositions alimentaires à risque. L’analyse des performances du système a permis à deux reprises de proposer de nouveaux seuils de signalement plus spécifiques afin d’optimiser cette surveillance tout en réduisant son coût. Le deuxième objectif de cette thèse est de montrer la contribution des données de surveillance à une politique de santé publique. Un premier travail a consisté à mettre en perspective les variations temporelles d’incidence observées avec les différentes sources de données disponibles afin d’en analyser les déterminants. La phase de décroissance de 1987 à 1997 a été concomitante des mesures de contrôles prises par l’industrie agro-alimentaire et de la réduction de la contamination des aliments. La phase d’augmentation en 2006-2007 semble multifactorielle. L’augmentation de la prescription de traitements de réduction de l’acidité gastrique par des inhibiteurs de la pompe à protons pourrait être l’un des déterminants majeurs de cette augmentation.Dans une deuxième analyse, nous avons hiérarchisé les groupes à risque de listériose sur la base de l’estimation du taux d’incidence de listériose et de sa mortalité dans ces groupes. Cela a permis d’identifier les groupes les plus vulnérables : hémopathies, certains cancers (digestifs, cérébral et pulmonaire), maladie de Horton, cirrhose hépatique, les dialysés rénaux, les greffés, et les femmes enceintes. Une analyse épidémiologique des listérioses materno-néonatales (MN) a montré une association entre les régions avec une incidence plus faible de listérioses materno-néonatales et les régions où la séroprévalence toxoplasmique des femmes enceintes est la plus faible, ce qui suggère un effet positif des recommandations contre la toxoplasmose pour la prévention de la listériose MN. / Listeriosis surveillance was built up stage by stage in France since the 1980s on a twofold basis: microbiology and epidemiology. Thanks to the creation of the Listeria National Reference Centre (Centre National de Référence des Listeria), the Pasteur Institute has been doing microbiological surveillance since 1987. Epidemiological surveillance was initiated by the National Health Laboratory, then conducted by the National Health Network and further developed by the National Institute of Health Surveillance. This thesis aims first of all to describe the different stages in the setting up of this surveillance system in order to analyze their respective inputs during these last thirty years. The four stages are:1. From 1982 to 1992: awareness and recognition of the role of food in the transmission of listeriosis and as the source of outbreaks. 2. From 1993 to 2000: building a reliable surveillance system in order to detect and investigate outbreaks in France. 3. From 2000 to 2005: strengthening and perfecting the surveillance system by taking additional measures, such as food sampling.4. Since 2005, we have reached the fourth stage, designed to optimize the surveillance system. This optimization involves adapting surveillance and early warning tools to new knowledge and information. For instance, having established that listeriosis incubation periods vary according to the clinical form of the illness, we suggested the integration of the variation of exposure period factor when interviewing patients with the food questionnaire. On two separate occasions, analysis of the surveillance system performance results made it possible to modify the criteria for early warning so as to optimize surveillance by increasing its specificity whilst reducing costs.The second aim of this thesis is to illustrate how surveillance data can contribute to public health policies. A first study analyzed temporal trends, using all available data in order to give some explanation as to major trends. The first trend was a reduction of incidence from 1987 to 1997 that was concomitant with control measures by the food industry and a drop in food contamination. The increased trend observed in 2006-2007 appears to be due to several factors. The increased rate of sales of proton pump inhibitors medication could be the major factor in this increase. In a second study, we ranked groups at risk of acquiring listeriosis based on the incidence of listeriosis and its lethality in each group. This enabled us to identify the most vulnerable groups : hematological malignancy, some cancers (digestive, lung, and brain cancer), dialysis, cirrhosis, organ transplantation and pregnancy. Epidemiological analysis of listeriosis cases associated with pregnancy indicated an association between regions with low rate listeriosis associated with pregnancy and regions where toxoplasmosis prevalence of pregnant women is low. This suggests that recommendations for avoiding toxoplasmosis have a positive effect on preventing listeriosis during pregnancy.

Listeria monocytogenes é o microrganismo patogênico de maior relevância em carnes processadas prontas para consumo. A presença frequente de L. monocytogenes no ambiente pode levar a uma contaminação dos produtos após o processamento industrial e como esses produtos não passam por tratamento bactericida antes de serem consumidos, a saúde do consumidor pode estar em risco. Para inibir a multiplicação de L. monocytogenes nos produtos cárneos durante o armazenamento em refrigeração após o processamento, os fabricantes podem utilizar diversos aditivos antimicrobianos na formulação destes produtos. Este estudo objetivou avaliar a atividade antimicrobiana de aditivos tradicionalmente empregados em produtos cárneos processados, e de quatro novos blends preparados à base de nisina (Nisaplin®) contra cepas de L. monocytogenes, fazendo-se a avaliação in vitro e in situ, em mortadelas experimentalmente contaminadas, formuladas com os compostos estudados, armazenadas à vácuo e em refrigeração (8 °C) por 70 dias. Os compostos extrato de alecrim, diacetato de sódio e Nisaplin®, quando testados in vitro, apresentaram maior eficiência na inibição das cepas de L. monocytogenes que lactato de sódio e vinagre tamponado. Quando testados in vitro, os produtos comerciais BioVia® CL600 e NovaGARD® LM100 e os quatro blends utilizados no preparo das mortadelas foram igualmente efetivos na inibição de L. monocytogenes. De acordo com os resultados dos testes in situ, o melhor controle de L. monocytogenes em mortadelas durante 70 dias a 8 °C ocorreu nos produtos preparados com o blend contendo extrato de alecrim, diacetato de sódio, vinagre tamponado e Nisaplin®. O blend contendo extrato de alecrim, lactato de sódio e Nisaplin®, foi o menos efetivo entre os blends testados. / Listeria monocytogenes is the most important microbial pathogen in ready-to-eat processed meat products. The frequent presence of L. monocytogenes in the environment can lead to product contamination after industrial processing and since these products do not have a bactericidal step before consumed, consumer health may be at risk. To inhibit the multiplication of L. monocytogenes in processed meat products during refrigerated storage, manufacturers may use various antimicrobial additives in the formulation of these products. This study aimed to evaluate the in vitro and in situ activity of additives traditionally used in processed meat products and four new blends based on nisin (Nisaplin®) against L. monocytogenes, in experimentally contaminated bolognas, formulated with the studied compounds and stored under vacuum and refrigerated (8 °C) for 70 days. Rosemary extract, sodium diacetate and Nisaplin®, when tested in vitro, were more effective than sodium lactate and buffered vinegar for the inhibition of the L. monocytogenesstrains. When tested in vitro, the commercial products BioVia® CL600 and NovaGARD® LM100 and the four blends used in bologna preparation were equally effective in inhibiting L. monocytogenes. According to the results of the in situ tests, the best control of L. monocytogenes in bolognas for 70 days at 8 °C occurred in the products prepared with the blend containing rosemary extract, sodium diacetate, buffered vinegar and Nisaplin®. The blend containing rosemary extract, sodium lactate and Nisaplin®, was the least effective among the tested blends.

Listeria monocytogenes é o microrganismo patogênico de maior relevância em carnes processadas prontas para consumo. A presença frequente de L. monocytogenes no ambiente pode levar a uma contaminação dos produtos após o processamento industrial e como esses produtos não passam por tratamento bactericida antes de serem consumidos, a saúde do consumidor pode estar em risco. Para inibir a multiplicação de L. monocytogenes nos produtos cárneos durante o armazenamento em refrigeração após o processamento, os fabricantes podem utilizar diversos aditivos antimicrobianos na formulação destes produtos. Este estudo objetivou avaliar a atividade antimicrobiana de aditivos tradicionalmente empregados em produtos cárneos processados, e de quatro novos blends preparados à base de nisina (Nisaplin®) contra cepas de L. monocytogenes, fazendo-se a avaliação in vitro e in situ, em mortadelas experimentalmente contaminadas, formuladas com os compostos estudados, armazenadas à vácuo e em refrigeração (8 °C) por 70 dias. Os compostos extrato de alecrim, diacetato de sódio e Nisaplin®, quando testados in vitro, apresentaram maior eficiência na inibição das cepas de L. monocytogenes que lactato de sódio e vinagre tamponado. Quando testados in vitro, os produtos comerciais BioVia® CL600 e NovaGARD® LM100 e os quatro blends utilizados no preparo das mortadelas foram igualmente efetivos na inibição de L. monocytogenes. De acordo com os resultados dos testes in situ, o melhor controle de L. monocytogenes em mortadelas durante 70 dias a 8 °C ocorreu nos produtos preparados com o blend contendo extrato de alecrim, diacetato de sódio, vinagre tamponado e Nisaplin®. O blend contendo extrato de alecrim, lactato de sódio e Nisaplin®, foi o menos efetivo entre os blends testados. / Listeria monocytogenes is the most important microbial pathogen in ready-to-eat processed meat products. The frequent presence of L. monocytogenes in the environment can lead to product contamination after industrial processing and since these products do not have a bactericidal step before consumed, consumer health may be at risk. To inhibit the multiplication of L. monocytogenes in processed meat products during refrigerated storage, manufacturers may use various antimicrobial additives in the formulation of these products. This study aimed to evaluate the in vitro and in situ activity of additives traditionally used in processed meat products and four new blends based on nisin (Nisaplin®) against L. monocytogenes, in experimentally contaminated bolognas, formulated with the studied compounds and stored under vacuum and refrigerated (8 °C) for 70 days. Rosemary extract, sodium diacetate and Nisaplin®, when tested in vitro, were more effective than sodium lactate and buffered vinegar for the inhibition of the L. monocytogenesstrains. When tested in vitro, the commercial products BioVia® CL600 and NovaGARD® LM100 and the four blends used in bologna preparation were equally effective in inhibiting L. monocytogenes. According to the results of the in situ tests, the best control of L. monocytogenes in bolognas for 70 days at 8 °C occurred in the products prepared with the blend containing rosemary extract, sodium diacetate, buffered vinegar and Nisaplin®. The blend containing rosemary extract, sodium lactate and Nisaplin®, was the least effective among the tested blends.