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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Caracterização genotípica e fenotípica de cepas de Escherichia coli associadas à doença do edema em suínos / Genotypic and phenotypic characterization of E. coli associated to edema disease in swine

Gomes, Vasco Tulio de Moura 30 January 2013 (has links)
A doença do edema afeta os leitões desmamados e é causada por cepas de Escherichia coli adaptadas ao hospedeiro e produtoras da toxina Stx2e. A doença do edema é caracterizada por edema de pálpebras, ataxia, pedalagem, dificuldade locomotora, e morte súbita. No presente estudo foram avaliadas 158 cepas de E. coli positivas para presença do gene codificador da toxina Stx2e isoladas de 62 animais provenientes de 13 granjas localizadas nos Estados do Rio Grande do Sul, Santa Catarina, Mato Grosso, Paraná, São Paulo, Goiás e Minas Gerais. As cepas foram submetidas a determinação do perfil de resistência, caracterização dos genes de virulência, determinação do grupo filogenético, expressão da toxina em cultivos de célula Vero, caracterização genotípica através da eletroforese em campo pulsado (PFGE) e polimorfismo do comprimento de fragmentos amplificados com uma única enzima (SE-AFLP). Dentre as 158 cepas stx2e+ foram identificadas 83,5% (132/158) apresentando resistência a três classes de antimicrobianos ou mais. Altos níveis de resistência forma identificados contra tetraciclina, sulfonamidas e florfenicol. A frequência dos genes de virulência associados a doença do edema como a fímbria F18, por exemplo, foi baixa em relação a outros estudos. Todas as 158 cepas testadas apresentaram a expressão da toxina e efeito citotóxico em células Vero. A caracterização dos grupos filogenéticos permitiu a distribuição das cepas nos quatro grupos descritos a seguir: grupo A 27,2% (43/158), grupo B1 3,8% (6/158), grupo B2 39,2% (62/158) e grupo D 29,8% (47/158). As cepas foram caracterizadas através da PFGE e do SE-AFLP e ambas as técnicas apresentaram altos índices discriminatórios (0,98 e 0,99 respectivamente). A associação mais frequente nas duas técnicas genotípicas foi observada em relação ao animal e a granja de origem. Apesar de pertencerem a um patotipo definido (STEC) e de serem altamente especializadas em relação ao hospedeiro, o suíno, foi observada uma grande variabilidade genética e de perfis de resistência entre as cepas de E. coli estudadas. / Edema disease affects weaning piglets and is caused by a host adapted Escherichia coli and producer of Stx2e toxin. The edema disease is characterized by swollen eyelids, ataxia, recumbence, convulsions, paralysis, or sudden death. In the present study were evaluated 158 E. coli strains Stx2e toxin gene positive isolated from 62 animals, from 13 swine herds located at Rio Grande do Sul, Santa Catarina, Mato Grosso, Paraná, São Paulo, Goiás and Minas Gerais States. Strains were submitted to resistance profile determination, virulence genes detection, phylogenetic group characterization, toxin expression in Vero cell culture, genotypic characterization through pulsed field gel electrophoresis (PFGE) and single enzyme amplified fragments length polymorphism (SEAFLP). Among the 158 strains stx2e+ were identified 83.5% (132/158) resistant to more than three or more classes of antimicrobials, High levels of resistance were found against tetracycline, sulfonamide and florfenicol. The frequency of virulence genes associated to edema disease as F18 fimbriae, for example, was low in relation to other studies. All 158 tested strains presented Stx2e toxin expression and cytotoxic effect in Vero cell culture. The characterization of phylogenetic groups permitted the distribution of strains in four groups described as follow: group A 27.2% (43/158), group B1 3.8% (6/158), group B2 39.2% (62/158) and group D 29.8% (47/158). The strains were characterized through PFGE and the SE-AFLP, and both techniques presented high discriminatory index (0.98 and 0.99 respectively). The association more frequently in both techniques was observed in relation to animal and herd origin. Despite to belong to one defined pathotype (STEC) and to be highly specialized in relation to host, the swine, it was observed a high variability of genetic and resistance profile among tested E. coli.
2

Caracterização genotípica e fenotípica de cepas de Escherichia coli associadas à doença do edema em suínos / Genotypic and phenotypic characterization of E. coli associated to edema disease in swine

Vasco Tulio de Moura Gomes 30 January 2013 (has links)
A doença do edema afeta os leitões desmamados e é causada por cepas de Escherichia coli adaptadas ao hospedeiro e produtoras da toxina Stx2e. A doença do edema é caracterizada por edema de pálpebras, ataxia, pedalagem, dificuldade locomotora, e morte súbita. No presente estudo foram avaliadas 158 cepas de E. coli positivas para presença do gene codificador da toxina Stx2e isoladas de 62 animais provenientes de 13 granjas localizadas nos Estados do Rio Grande do Sul, Santa Catarina, Mato Grosso, Paraná, São Paulo, Goiás e Minas Gerais. As cepas foram submetidas a determinação do perfil de resistência, caracterização dos genes de virulência, determinação do grupo filogenético, expressão da toxina em cultivos de célula Vero, caracterização genotípica através da eletroforese em campo pulsado (PFGE) e polimorfismo do comprimento de fragmentos amplificados com uma única enzima (SE-AFLP). Dentre as 158 cepas stx2e+ foram identificadas 83,5% (132/158) apresentando resistência a três classes de antimicrobianos ou mais. Altos níveis de resistência forma identificados contra tetraciclina, sulfonamidas e florfenicol. A frequência dos genes de virulência associados a doença do edema como a fímbria F18, por exemplo, foi baixa em relação a outros estudos. Todas as 158 cepas testadas apresentaram a expressão da toxina e efeito citotóxico em células Vero. A caracterização dos grupos filogenéticos permitiu a distribuição das cepas nos quatro grupos descritos a seguir: grupo A 27,2% (43/158), grupo B1 3,8% (6/158), grupo B2 39,2% (62/158) e grupo D 29,8% (47/158). As cepas foram caracterizadas através da PFGE e do SE-AFLP e ambas as técnicas apresentaram altos índices discriminatórios (0,98 e 0,99 respectivamente). A associação mais frequente nas duas técnicas genotípicas foi observada em relação ao animal e a granja de origem. Apesar de pertencerem a um patotipo definido (STEC) e de serem altamente especializadas em relação ao hospedeiro, o suíno, foi observada uma grande variabilidade genética e de perfis de resistência entre as cepas de E. coli estudadas. / Edema disease affects weaning piglets and is caused by a host adapted Escherichia coli and producer of Stx2e toxin. The edema disease is characterized by swollen eyelids, ataxia, recumbence, convulsions, paralysis, or sudden death. In the present study were evaluated 158 E. coli strains Stx2e toxin gene positive isolated from 62 animals, from 13 swine herds located at Rio Grande do Sul, Santa Catarina, Mato Grosso, Paraná, São Paulo, Goiás and Minas Gerais States. Strains were submitted to resistance profile determination, virulence genes detection, phylogenetic group characterization, toxin expression in Vero cell culture, genotypic characterization through pulsed field gel electrophoresis (PFGE) and single enzyme amplified fragments length polymorphism (SEAFLP). Among the 158 strains stx2e+ were identified 83.5% (132/158) resistant to more than three or more classes of antimicrobials, High levels of resistance were found against tetracycline, sulfonamide and florfenicol. The frequency of virulence genes associated to edema disease as F18 fimbriae, for example, was low in relation to other studies. All 158 tested strains presented Stx2e toxin expression and cytotoxic effect in Vero cell culture. The characterization of phylogenetic groups permitted the distribution of strains in four groups described as follow: group A 27.2% (43/158), group B1 3.8% (6/158), group B2 39.2% (62/158) and group D 29.8% (47/158). The strains were characterized through PFGE and the SE-AFLP, and both techniques presented high discriminatory index (0.98 and 0.99 respectively). The association more frequently in both techniques was observed in relation to animal and herd origin. Despite to belong to one defined pathotype (STEC) and to be highly specialized in relation to host, the swine, it was observed a high variability of genetic and resistance profile among tested E. coli.
3

Etude des facteurs de risque et de pathogénicité et de l’évolution spatio-temporelle de la maladie de l’œdème chez le sanglier (Sus scrofa) en Ardèche / Study of risk and pathogenicity factors and spatio-temporal evolution of oedema disease in wild boar (Sus scrofa) in Ardeche

Petit, Geoffrey 03 October 2019 (has links)
La maladie de l’œdème est une maladie connue depuis de nombreuses années chez le porc. Les premiers cas recensés dans une population de suidés sauvages sont apparus en 2013 en Ardèche. Un nouveau foyer de cette maladie est ensuite apparu en 2016 dans les Pyrénées-Orientales à la frontière entre la France et l’Espagne. Comprendre les facteurs permettant son apparition ainsi que sa transmission est nécessaire afin d’anticiper de futures mortalités dues à cette maladie. Dans cette thèse, une analyse épidémiologique de cette maladie chez le sanglier a été réalisée. Des clusters de mortalités sont alors apparus et ont permis de mettre en évidence une possible source de contamination unique et récurrente dans le temps. La mise en place d’une nouvelle méthode pour étudier la détectabilité des cadavres de sanglier a souligné la difficulté de retrouver des cadavres de sanglier en forêt. La dernière analyse épidémiologique à partir d’un modèle de type « Spatial point pattern » a mis en avant de possibles facteurs de risque d’apparition et de transmission qui ont ensuite été analysés plus précisément. L’analyse des données issus des tableaux de chasse en Ardèche a été réalisée afin de détecter des variations de la densité et du ratio J/A des populations de sanglier suggérant un stress alimentaire chez le sanglier, un prodrome ou une conséquence de la maladie. Aucun stress alimentaire ne fut détecté lors de cette analyse. Des hypothèses ont pu être émises pour expliquer certaines variations observées : i) la conséquence directe de la maladie, ii) un phénomène environnemental particulier et iii) un évènement pathogénique. La piste de l’événement pathogénique a été approfondie avec la découverte du SDRP (syndrome dysgénésique et respiratoire du porc). Les interactions porcs-sangliers, nombreuses en Ardèche, ont été déterminées comme potentiellement responsables du passage de la bactérie entre le compartiment domestique et sauvage. Une étude génétique a également été effectuée pour investiguer le gène alpha-1-fucosyltransferase associé à la sensibilité du porc à la maladie. Tous les sangliers analysés étaient sensibles à la maladie. D’autres analyses complémentaires sont nécessaires afin de comprendre au mieux cette maladie ainsi que les différents facteurs de risque pour l’apparition mais également la transmission. / Edema disease has been a known disease in pigs for many years. The first cases recorded in a population of wild suids appeared in 2013 in Ardèche. A new outbreak of this disease then emerged in 2016 in the Pyrénées-Orientales on the border between France and Spain. Understanding the factors that enable its onset and transmission is necessary to anticipate future mortality from this disease. In this thesis, an epidemiological analysis of this disease in wild boar was carried out. Clusters of mortalities then emerged, highlighting a possible single and recurrent source of contamination over time. The introduction of a new method to study the detectability of wild boar corpses highlighted the difficulty of finding wild boar corpses in the forest. The latest epidemiological analysis using a Spatial point pattern model highlighted possible risk factors for onset and transmission, which were then analysed more precisely. Analysis of data from hunting tables in the Ardèche was carried out in order to detect variations in the density and J/A ratio of wild boar populations suggesting food stress in the wild boar, a prodrome or consequence of the disease. No dietary stress was detected during this analysis. Assumptions could be made to explain some observed variations: i) the direct consequence of the disease, ii) a particular environmental phenomenon and iii) a pathogenic event. The trail of the pathogenic event was deepened with the discovery of the PRRS (Pork Respiratory and Dygesic Syndrome). The pig-boar interactions, numerous in the Ardeche, were determined as potentially responsible for the passage of the bacteria between the domestic and wild compartment. A genetic study was also conducted to investigate the alpha-1-fucosyltransferase gene associated with the susceptibility of pigs to the disease. All the wild boars tested were susceptible to the disease.Further further analysis is needed in order to better understand this disease as well as the different risk factors for both onset and transmission.

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