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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.
321

Mechanisms of tolerance to Melaleuca alternifolia (tea tree) oil in Pseudomonas aeruginosa

Papadopoulos, Chelsea Jade January 2009 (has links)
[Truncated abstract] Pseudomonas aeruginosa, an important opportunistic pathogen, is resistant to a wide array of functionally and structurally diverse antimicrobial agents including antibiotics, disinfectants and biocides. P. aeruginosa is more resistant than other Gram negative bacteria to tea tree oil (TTO), the essential oil steam distilled from the leaves of Melaleuca alternifolia and comprised of over 100 terpene hydrocarbon components and their oxygenated derivatives. TTO is an established topical antimicrobial agent, with antibacterial, antiviral and antifungal properties. Intrinsic antimicrobial resistance mechanisms in P. aeruginosa include the low permeability of the outer membrane and expression of multi-drug efflux pumps. A series of multi-drug efflux mutants from the resistance-nodulation-cell division family was obtained and their susceptibility to TTO and several components examined. This demonstrated that TTO and the components terpinen-4-ol, 1,8-cineole and a-terpineol were substrates of MexAB-OprM, using both pump deletion mutants and the pump inhibitor Phe-arg ß-naphthylamide dihydrochloride. In complementation studies, the addition of mexAB-oprM to deletion mutants restored susceptibility to these agents to that of the wild-type, confirming the role of MexAB-OprM in tolerance to TTO and these three components. ... An increase in susceptibility to ticarcillin and Timentin occurred in PAO1 following serial subculture in terpinen-4-ol. Susceptibility to ticarcillin has been associated with expression of the MexCD-OprJ system in P. aeruginosa. A library of transposon mutants was created to find additional mechanisms by which P. aeruginosa could tolerate TTO. The library yielded a total of 20 mutants that were more susceptible than parental strains to TTO and/or terpinen-4-ol. The insertion site of the transposon was identified in 14 mutants and, in four mutants, this was a gene related to flagellar biosynthesis. Flagella deficient mutants have previously demonstrated enhanced susceptibility to the membrane-disrupting surfactant sodium dodecyl sulfate and this echoes the increased susceptibility to TTO and terpinen-4-ol observed. Three non-sibling surA mutants were also identified. SurA is involved in the correct folding of outer membrane proteins, including porins, in Gram negative bacteria: surA mutants of Escherichia coli have phenotypes that are characteristic of a defective cell envelope, including an increased susceptibility to hydrophobic agents. The increase in susceptibility to hydrophobic TTO and terpinen-4-ol in the surA mutants is consistent with this and represents the first report linking SurA function to antimicrobial resistance in P. aeruginosa. In conclusion, several Mex efflux systems of P. aeruginosa including MexAB-OprM, MexCD-OprJ and MexEF-OprN, as well as the LPS core, outer membrane integrity and a functioning flagella biosynthetic pathway contribute to the tolerance of this organism to TTO and/or several components.
322

Caractérisation de bactéries par analyses protéomiques en spectrométrie de masse / Proteomic analysis for bacterial characterisation using mass spectrometry

Cecchini, Tiphaine 02 June 2016 (has links)
Grâce à la spectrométrie de masse de type MALDI-TOF, l'identification des bactéries est maintenant possible en quelques minutes. Mais le taux de mortalité des patients augmente lorsqu'une antibiothérapie inappropriée est utilisée et les instruments MALDI-TOF ne sont pas capables d'analyser rapidement et exhaustivement la résistance bactérienne. Actuellement, 6 à 24 heures sont nécessaires pour déterminer le phénotype de résistance. En couplant une chromatographie liquide et un spectromètre de masse à ionisation électrospray (LC-MS/MS), nous avons identifié les marqueurs de résistance en 1 à 2 heures. En 30 min, nous avons pu détecter les mécanismes de résistance aux β-lactamines, aux glycopeptides, à la méthicilline et aux fluoroquinolones, à l'aide de méthodes de type "Suivi de Réactions Sélectionnées", ou "Selected Reaction Monitoring" (SRM). Au cours de la même analyse multiplexée, des dizaines de protéines peuvent être détectées de façon hautement spécifique et sensible. Comme l'illustre l'étude de la résistance multifactorielle chez Acinetobacter baumannii, cette approche permet en outre une analyse quantitative d'un grand intérêt pour certains mécanismes de résistance. Cependant, malgré ces perspectives attrayantes, la LC-MS/MS reste, aujourd'hui, loin d'une possible implantation en routine dans les laboratoires de microbiologie. Les instruments sont trop coûteux et la technologie trop complexe pour un usage pour du diagnostic in vitro. La spectrométrie de masse pourrait déjà avantageusement compléter les technologies actuelles de biologie moléculaire. Aujourd'hui, le séquençage de nouvelle génération est la méthode de référence pour la caractérisation moléculaire des bactéries. Mais, comme démontré dans ce travail, l'annotation des gènes est perfectible. Pour quelques dizaines d'euros et quelques heures d'analyse, les peptides identifies par spectrométrie de masse facilitent l'assemblage des séquences (« scaffolds ») et la détection des gènes. De surcroît, la spectrométrie de masse permet une quantification précise des protéines. Elle apporte ainsi une nouvelle dimension analytique et une vision moléculaire plus proche du phénotype. En conclusion, la spectrométrie de masse LC-MS/MS peut être une technologie complémentaire attractive, voir une future alternative, à la biologie moléculaire pour la caractérisation des bactéries / Thanks to MALDI-TOF mass spectrometry, identification of isolated bacteria is now possible within a few minutes. But doctors also need to rapidly know the phenotype of resistance of the bacteria. Indeed, the patient mortality rate increases when the antibiotherapy is not appropriate. However, MALDI-TOF instruments are not able to analyze antibacterial resistance rapidly and comprehensively.Today, 6 to 24 hours are nedded for antibiotic susceptibility testing. When combining a liquid chromatography and a mass spectrometer with electrospray ionization (LC-MSMS), the detection of resistance biomarkers was possible within 1 to 2 hours. Using a Selected Reaction Monitoring (SRM) method, resistance mechanisms to beta-lactams, methicillin, glycopeptides and fluoroquinolones were detected in strains within 30 minutes. Tens of resistance determinants can be analyzed in a single multiplexed assay, with high specificity and sensitivity. Illustrated by the study of multifactorial resistance in Acinetobacter baumannii, the technology allows furthermore a quantitative analysis, which is of great value for some resistance mechanisms. Similarly, we identified virulent strains of enterohemorrhagic Escherichia coli by targeting toxins and serotype biomakers in the same assay. Mass spectrometry offered deeper bacterial characterization than conventional serotyping using polyclonal antibodies. However, despite all these favorable prospects, LC-MS/MS remains today far from reaching a routine use in microbiological hospital laboratories. Instruments are too expensive and the technology is too cumbersome for a daily in vitro diagnostic use. Waiting for a more suitable use, mass spectrometry could yet advantageously complement current molecular technologies. Today, the gold standard to study bacteria at molecular level is next generation sequencing. However, as demonstrated during this work, gene annotation remains imperfect. For tens of euros and few hours of analysis, peptides identified by mass spectrometry analysis of a bacteria might improve scaffold assembly and gene detection. Moreover, mass spectrometry gives an accurate protein quantitation and brings a new analytical dimension, potentially closer to the phenotype than molecular techniques. In conclusion, LC-MS/MS mass spectrometry could be an attractive complementary, or alternative technology in a near future, to conventional molecular biology techniques for deep characterization of bacteria
323

Évaluation de l'acquisition de la résistance à la colistine chez Escherichia coli O149 chez le porc

Thériault, William 04 1900 (has links)
No description available.
324

Prevalência e características de Salmonella spp em carne bovina brasileira para exportação: contribuição para uma avaliação de risco / Prevalence and characteristics of Salmonella spp in bovine meat for export: contribution for a risk assessment

Angela Palamin Azevedo 24 November 2009 (has links)
O Brasil consolidou-se como o principal produtor e exportador mundial de carne bovina. Estudos microbiológicos, geralmente realizados com amostras de carne coletadas no comércio e não na cadeia produtiva de carne, resultam numa insuficiência de dados a respeito das características fenotípicas e genotípicas das bactérias patogênicas de relevância nos produtos destinados à exportação. Objetivando determinar a prevalência e características de Salmonella spp em carne bovina para exportação, realizou-se a coleta de amostras de superfícies de 200 bovinos adultos, provenientes de 12 fazendas, abatidos em Frigorífico Exportador em São Paulo, Brasil, no ano de 2008. Foram coletadas amostras do couro do animal, logo após a realização da sangria (Co), da carcaça do mesmo animal, após a esfola (Ca I) e da carcaça do mesmo animal, após o toalete e antes da refrigeração (Ca II). O isolamento e a identificação de Salmonella spp foram realizados de acordo com o método - ISO 6579:2002, com algumas modificações. O patógeno foi detectado em 14 amostras de couro (7,0%), 5 de carcaça I (2,5%) e 4 de carcaça II (2,0%). Verificou-se a prevalência do sorovar S. Give (52,0%), seguido de S. Abaetetuba (16,0%), S. Typhimurium (8,0%), S. Agona (4,0%) e S. Dublin (4,0%), e quatro cepas (16,0%) não tipáveis. A tipagem molecular, feita por PFGE, mostrou que as salmonelas expressaram 12 perfis genéticos distintos, sendo 10 formados por apenas uma cepa, cada. As demais cepas (15) pertenceram a dois perfis genéticos apenas, que apresentaram 91,7% de similaridade. De acordo com o teste de infecção de células Caco-2, a maioria das cepas (92,0%) apresentou Eficiência de Invasão inferior a 1,0%, indicando baixo potencial de virulência. Quanto ao perfil de resistência a antibióticos, 68,0% das cepas analisadas foram multiresistentes, apresentando 12 perfis diferentes. Animais diferentes, provenientes de uma mesma fazenda, apresentaram salmonelas de um mesmo sorovar e com o mesmo perfil genético e de resistência a drogas, comprovando a ocorrência de contaminação cruzada durante o processamento da carne bovina. A multiresistência das salmonelas isoladas e a possibilidade de disseminação desses patógenos denotam a necessidade de se adotar medidas de higiene adequadas e maior prudência no emprego de antimicrobianos, na dieta alimentar e na terapêutica veterinária. / Brazil is an important bovine meat producer and exporter. Microbiological surveys are generally run with meat samples collected at retail level and not with meat for export, explaining the lack of data on the phenotypic and genotypic characteristics of pathogens of relevance in exported food products. This study aimed to evaluate the prevalence and characteristics of Salmonella spp in bovine meat destined for export, through surface sampling of hides and carcasses of 200 animals, from 12 farms, slaughtered in 2008 in an export slaughterhouse located in São Paulo, Brazil. Sampling was done from the hides right after bleeding (Co) and from carcasses of the same animal after removal of the hide (Ca I) and after cleaning but before chilling (Ca II). Isolation and identification of Salmonella spp were done according to ISO 6579:2002, with some modifications. The pathogen was detected in 14 samples of hides (7,0%), 5 of carcasses Ca I (2,5%) and 4 of carcasses Ca II (2,0%). The most prevalent serovars were S. Give (52,0%), followed by S. Abaetetuba (16,0%), S. Typhimurium (8,0%), S. Agona (4,0%) and S. Dublin (4,0%). Four isolates (16,0%) were not typable. Molecular typing using PFGE indicated that the isolates presented 12 molecular profiles, ten of them containing one single isolate. Fifteen isolates belonged to only two distinct profiles, with 91.7% similarity. Invasion Efficiency tests, run with Caco-2 cells, indicated that most isolates (92,0%) presented low virulence potential. 68,0% of the isolates were multiresistant to antimicrobial drugs, presenting 12 different resistance profiles. Different animals, coming from the same rearing farm, harbored salmonellae belonging to same serovar and presenting the same genetic and antimicrobial resistance profiles, indicating cross contamination in the slaughterhouse during production of meat. The occurrence of salmonellae that can disseminate in the slaughterhouse and the multiresistance presented by the strains strengthen the need for adoption of proper hygiene control measures and care in the use of antibiotics in human and veterinary therapeutics.
325

Disseminação de Salmonella Enteritidis isoladas em uma cadeia produtiva industrial avícola: determinação do perfil de resistência a antimicrobianos e caracterização genotípica / Salmonella Enteritidis in a commercial chicken production chain: phenotypic and genotypic characterization

Cristiano Andrigheto 23 May 2006 (has links)
Salmonella é um dos principais agentes de enfermidades transmitidas por alimentos em diversos países, sendo a carne de frango um dos principais veículos envolvidos em surtos. O Brasil vem se destacando como um dos maiores exportadores mundiais deste alimento. O ambiente de criação das aves é apontado como um importante foco de infecção das aves e o ambiente industrial de abate e processamento é importante na disseminação deste ·microrganismo. Na busca pela produção de alimentos seguros do ponto de vista microbiológico, uma das ferramentas utilizadas é a subtipagem de microrganismos isolados ao longo da cadeia de produção, que permite determinar rotas de contaminação do produto final. Os objetivos deste trabalho são: o estudo da disseminação dos subtipos de Salmonella Enteritidis nas várias etapas de uma cadeia de produção industrial de carne de frango, empregando-se diversos métodos de subtipagem e a determinação da resistência a antimicrobianos destas cepas. 108 isolados de Salmonella Enteritidis dos fagotipos PT1, PT4 e PT7a foram obtidos nos anos de 2002 e 2003, a partir de amostras ambientais e de frango relativas a sete sub-regiões de uma cadeia produtiva industrial avícola. Os perfis de resistência destes isolados foram determinados frente a antimicrobianos de uso humano e veterinário e eles foram submetidos a subtipagem por PFGE, RAPO, ribotipagem e PCR-ribotipagem. Foram detectados 21 perfis de resistência diferentes, com 6,5% das cepas sensíveis a todas as drogas, 33,3% resistentes a um ou dois antimicrobianos e 83,3% apresentando resistência intermediária a até quatro deles. Os níveis relativamente elevados de resistência são preocupantes e a diminuição da pressão seletiva deve ser um objetivo para os produtores de aves. De modo geral, a subtipagem permitiu separar as cepas em 13 genótipos, com elevada similaridade entre si. Porém, a maior parte das cepas (69,4%) pertenceu a apenas três deles, que foram encontrados ao longo de toda a cadeia produtiva. A ribotipagem foi o método que apresentou o melhor poder discriminatório (D = 0,701), porém nem todas as cepas foram tipáveis por este método. Não foram encontradas correlações entre os perfis de resistência a antimicrobianos e fagotipos, nem entre genótipos e fagotipos. Porém, dois genótipos proximamente correlacionados e predominantemente encontrados em uma sub-região reuniram apenas cepas com resistência intermediária ou resistentes exclusivamente à furazolidona. A similaridade elevada entre os genótipos evidencia a origem clonal das cepas. / Salmonella is one of the most important foodborne disease agents all over the world, and chicken is recognized as an important vehicle of the infection. Chicken production in Brazil has increased in the last couple of years and the country is now ranked 2nd as producer/exporter of this commodity. For this reason there is an increased concern over the safety of these goods. This study deals with the dissemination, antimicrobial resistance, and genetic characterization of S. Enteritidis strains isolated from an industrial chicken production chain. 108 isolates, phagetypes PT1, PT4 and PT7a, were obtained at different steps of the commercial production from farm to frozen cuts, and the broilers were from different producers supplying the same processing plant. Tests for susceptibility to 12 human and veterinary antimicrobial agents were performed. The strains were also typed by PFGE, RAPO, ribotyping, and PCR-ribotyping. 6.5% of the strains were susceptible to the 12 drugs tested and 33.3% were resistant to 1 or 2 of them. Intermediate resistance to up to 4 agents was observed in 83.3% of the isolates. Combining all the typing methods allowed the division of the strains in 13 genotypes with elevated degree of similarity. However, 69.4% of the strains belonged to 3 main phagetypes spread along the production chain. There was no correlation between phagetypes and genotypes, or phagetypes and resistance profiles. However, most strains from one sub-region were from 2 genotypes and showed intermediate resistance to, or were resistant to furazolidone. The high degree of similarity amongst the genotypes indicates the clonal origin of the strains. The relatively high resistance to antimicrobial agents is a cause of concern and trying to diminish the selective pressure has to be a goal for broiler producers.
326

A new approach to purchasing of antibiotics for the Swedish system : A Cost-Benefit Analysis of centralized purchasing

Keshavamurthy, Nishanth, Narsipur Venkatesh, Akshay January 2020 (has links)
The fast-increasing issue of antibiotic unavailability or relatively their shortages in the healthcare system has been the point of concern for many countries. With these shortages come unnecessary costs and the need to utilize less optimal treatment thus increasing the risk of antimicrobial resistance and jeopardizing a patient’s health. This thesis is a collaboration with PLATINEA (Platform for Innovation of Existing Antibiotics), aiming to optimize the usage of antibiotics and to increase the availability of important antibiotics in Sweden. To understand the causes that affect antibiotic unavailability, a good view into the antibiotic and pharmaceutical supply chain is important, especially the purchasing systems of it. The complexities in the purchasing system can lead to interruptions in the antibiotics supply chain thus increasing the risk of antibiotic shortages. These shortages in turn increases the risk of antimicrobial resistance, therefore, the purchasing system requires the need to be analysed extensively. This study aims to explore different purchasing systems and conduct cost-benefit analysis of centralized purchasing system in efforts to help reduce shortages of antibiotics in Sweden. This study is based on the existing literature on centralized and decentralized purchasing and also the pharmaceutical supply chain. Qualitative interviews (semi-structured), multiple reports and articles steered the authors in exploring the purchasing systems and mapping the costs and benefits of centralized purchasing. Throughout the research, emphasis was kept on reducing antibiotic shortages. The findings of this study outline the various costs and benefits of a centralized purchasing system and resulted in the implementation recommendation of it over an existing decentralized purchasing system in Sweden.
327

Étude de la virulence et de la résistance aux antibiotiques des Staphylococcus aureus résistants à la méthicilline chez le porc à l'abattoir au Québec

Pelletier-Jacques, Geneviève 06 1900 (has links)
No description available.
328

Prévalence, facteurs de risque et mécanismes de dissémination des gènes de résistance aux antibiotiques, l’espèce équine et l’espèce porcine ont été étudiées en insistant particulièrement sur les antibiotiques de haute importance en médecine humaine dans chaque filière (céphalosporines de 3e génération et fluoroquinolones respectivement).

de Lagarde, Maud 09 1900 (has links)
La résistance aux antibiotiques a pris une ampleur considérable du fait de l’utilisation des antibiotiques dans de nombreux domaines. Pour respecter l’approche « OneHealth », il est essentiel d’avoir une image spécifique de chaque situation, afin d’orienter les recommandations et de limiter la dissémination des gènes, des plasmides et des clones. Nos objectifs étaient adaptés à nos populations d’étude (chevaux et porcs) afin d’ajuster les résultats aux besoins des filières. Dans la filière équine, nous avons quantifié les résistances phénotypiques et identifié les gènes de β-lactamases à spectre étendu (BLSE/AmpC) présents dans le microbiome des chevaux sains, et nous avons identifié les facteurs de risque associés à leur portage en France et au Québec. En France, nous avons également caractérisé les mécanismes de dissémination des gènes de BLSE/AmpC. Nous avons mis en évidence qu’en France et au Québec, les E. coli commensaux provenant de fèces de chevaux sains étaient majoritairement non susceptibles à l’ampicilline, l’amoxicilline/acide clavulanique et la streptomycine et que des E. coli multirésistants et porteurs de gènes codant pour des BLSE/AmpC étaient détectés dans respectivement environ 45% et 8% des chevaux. Le blaCTX-M-1 était majoritairement détecté bien qu’en France d’autres BLSE aient été identifiés (blaCTX-M-2 et blaCTX-M-14) ainsi que le gène AmpC blaCMY-2. L’administration d’un traitement médical, le nombre de personnes s’occupant des chevaux, le type d’activité et le fait de participer à un évènement équestre dans les trois derniers mois ont été identifiés comme des facteurs de risque du portage des E. coli multirésistants ou producteurs de gènes BLSE/AmpC, soit en France soit au Québec. En France, le plasmide IncHI1-ST9 était majoritairement associé aux gènes blaCTX-M-1/2 et à l’opéron fos. Pour la filière porcine, nos objectifs étaient de colliger les données de la base de données du laboratoire EcL entre 2008 et 2016, d’évaluer la présence d’un agrégat spatio-temporel pour les isolats ETEC:F4 non susceptibles à l’enrofloxacine et de caractériser ces isolats et les éléments génétiques mobiles qu’ils transportent. En effet, l’enrofloxacine est un antibiotique de haute importance en santé humaine, et doit donc faire l’objet d’une surveillance accrue. Nous avons trouvé que plus de 90% des isolats d’E. coli entérotoxinogènes détectés chez des cas de porcs malades soumis au laboratoire EcL de 2008 à 2016 au Québec, étaient multirésistants. Le virotype LT:STb:F4 prédominait jusqu’en 2014, puis a été dépassé par le virotype LT:STb:STa:F4. Un agrégat spatio-temporel d’isolats LT:STb:STa:F4 non susceptibles à l’enrofloxacine a été détecté entre 04/2015 et 09/2016 au centre de la Montérégie. Nous avons démontré la présence d’un clone ETEC:F4 non susceptible à l’enrofloxacine, à haut risque, qui se dissémine en Amérique du Nord depuis 2013. Les isolats appartenant à ce clone sont ST100, O149:H10. Ils sont multirésistants, et associés à une pathogénicité et une virulence augmentée par rapport aux isolats détectés avant 2000. Ils portent le réplicon IncFII. Les résistances et leur mécanisme de dissémination sont différents selon l’espèce animale. Ces divergences sont fonction de l’usage des antibiotiques, et des échanges possibles avec les différents protagonistes en contact avec les animaux. / Antimicrobial resistance has become an essential issue in the last decades because of the extensive use of antimicrobials in numerous sectors. In order to follow the OneHealth approach, it is critical to have a precise picture of each situation, to adjust recommendations and prevent resistance gene dissemination as well as plasmid and clone spread. Our objectives were adapted to the animal populations under study. Therefore, our results were compatible with each sector. In the equine sector, we quantified phenotypic resistance and identified β-lactamase (ESBL/AmpC) genes present in the intestinal microbiome of healthy horses and we identified risk factors associated with their carriage both in France and in Quebec. Then, in France we characterized ESBL/AmpC gene spread mechanisms. We demonstrated that commensal E. coli originating from the feces of healthy horses were mostly non-susceptible to ampicillin, amoxicillin/clavulanic acid and streptomycin. The presence of multidrug resistant E. coli and of E. coli carrying ESBL/AmpC genes was found in around 45% and 8% of horses respectively. The most frequently detected gene was blaCTX-M-1, although blaCTX-M-2 and blaCTX-M-14 were also identified in France. The AmpC gene blaCMY-2 was identified in both localities. Medical treatment, staff number, activity, and participation in an equestrian event within the last three months were identified as risk factors for MDR or ESBL/AmpC E. coli. In France, commensal E. coli from healthy horses most commonly possessed the IncHI1-ST9 plasmid. This plasmid carries blaCTX-M-1/2 genes and the fos operon. For the swine sector in Quebec, our objectives were to gather data provided by the Animal pathogenic and zoonotic E. coli (APZEC) database between 2008 and 2017, to assess the presence of a spatio-temporal cluster for enrofloxacin non-susceptible ETEC:F4 and to characterize these isolates and the mobile genetic elements they carry. Enrofloxacin is an antibiotic classified as highly important in human medicine and as such needs to come under higher scrutiny. For this sector, we demonstrated that more than 90% of enterotoxigenic E. coli (ETEC) isolates from diseased swine submitted to the EcL between 2008 and 2016, were multidrug resistant. The main virotype in 2014 was LT:STb:F4. It was subsequently replaced by the LT:STb:STa:F4 virotype. A spatio-temporal cluster of LT:STb:STa:F4 isolates non-susceptible to enrofloxacin was detected between 04/2015 and 09/2016 in the centre of the Monteregie region. These isolates constituted an ETEC:F4 high risk enrofloxacin non-susceptible clone, which has been spreading in North America since 2013. Isolates belonging to this clone are ST100, O149H10, phylogroup A, and fimH gene negative. These isolates are multidrug resistant and associated with a higher pathogenicity and virulence than isolates detected before 2000. They all carry the incFII replicon. Resistance and mechanisms of dissemination are different according to the animal species being studied. This is likely due to different patterns of antimicrobial use in each industry and possible interactions with different protagonists in contact with the animals. It is essential to understand the situation for each animal species in order to adapt recommendations for efficiently limiting the spread of resistance genes, plasmids and clones.
329

Identification of broad host range phage that antagonize multidrug resistant Pseudomonas aeruginosa and their therapeutic potential to restore antibiotic susceptibility among these pathogens

Lake, Alexandra E. 12 August 2020 (has links)
No description available.
330

Moléculas con capacidad de inhibición de la enzima Glucosa 1-fosfato timidil transferasa (RMLA) de Klebsiella penumoniae resistente a antibiótico

Capuñay Torres, Harold January 2024 (has links)
Introducción: La resistencia antimicrobiana es un problema alarmante en la salud pública mundial. A mediados del 2017, la Organización Mundial de la Salud (OMS) reportó una lista de las bacterias para la búsqueda de nuevos antibióticos, incluyendo sobre todo enterobacterias. En el Perú, hubo reporte de casos de Klebsiella pneumoniae resistente a antibióticos en diferentes regiones del país. Por lo tanto, existe una necesidad de encontrar nuevos sitios diana de acción farmacológica para enfrentar esta problemática sanitaria. Objetivo: Identificar las moléculas orgánicas con capacidad de inhibición de la enzima Glucosa 1-fosfato Timidilil Transferasa (RmlA) de K. pneumoniae resistente a antibióticos utilizando la técnica de acoplamiento molecular. Materiales y métodos: Se realizó un estudio in-silico, mediante programas para acoplamiento molecular por ordenador local. La semejanza de fármacos con el sustrato natural de la enzima fue dada con programas de similaridad de ligandos, se obtuvieron datos teóricos de las interacciones entre los fármacos seleccionados con el sitio activo de la enzima. Finalmente se analizó cada ligando en función de sus energías libres. Resultados: Se analizó computacionalmente 14100 unidades farmacológicas con posible interacción con la enzima RmlA de K. pneumoniae resistente a antibióticos, según las energías libres de interacción los valores enteros están entre 96 a 103 (kcal/mol), frente al valor de acoplamiento del sustrato-enzima de -222.357 (kcal/mol). Conclusiones: Se encontraron posibles fármacos inhibidores de la enzima RmlA de K. pneumonia, es necesario continuar con la valoración y estudio de estos fármacos en estudios laboratoriales para mejorar la propuesta de inhibición enzimática basada en este trabajo de investigación computacional. / Introduction: Antimicrobial resistance is an alarming problem in global public health. In mid-2017, the World Health Organization (WHO) reported a list of bacteria for the search for new antibiotics, including especially Enterobacteriaceae. In Peru, there were reports of cases of antibiotic-resistant Klebsiella pneumoniae in different regions of the country. Therefore, there is a need to find new target sites for pharmacological action to address this health problem. Objective: Identify organic molecules with the capacity to inhibit the enzyme Glucose 1-phosphate Thymidylyl Transferase (RmlA) of antibioticresistant K. pneumoniae using the molecular docking technique. Materials and methods: An in-silico study was carried out, using programa for molecular docking by local computer. The similarity of drugs with the natural substrate of the enzyme was given with ligand similarity programs, theoretical data were obtained on the interactions between the selected drugs with the active site of the enzyme. Finally, each ligand was analyzed based on its free energies. Results: 14100 pharmacological units with possible interaction with the RmlA enzyme of antibiotic-resistant K. pneumoniae were computationally analyzed. According to the interaction free energies, the integer values are between 96 to 103 (kcal/mol), compared to the coupling value of the substrate. enzyme of -222,357 (kcal/mol). Conclusions: Possible drugs that inhibit the RmlA enzyme of K. pneumonia were found; it is necessary to continue with the evaluation and study of these drugs in laboratory studies to improve the proposal for enzyme inhibition based on this computational research work.

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