Tesi: "Escherichia coli infections Pathogenesis"

1

Paton, Adrienne Webster. "Molecular characterization of variant shiga-like toxin genes of Escherichia coli /". Title page, contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09php3118.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

2

Srimanote, Potjanee. "Analysis of putative virulence factors of a locus of enterocyte effacement-negative shiga-toxigenic Escherichia coli O113:H21 strain". Title page, contents and abstract only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09php863.pdf.

Testo completo

Abstract (sommario):

"February 2003." Addendum and corrigenda inserted at back Includes bibliographical references (leaves 249-272) Aims to identify and characterise potential virulence-associated factors from the locus of enterocyte effacement-negative shiga-toxigenic Escherichia coli O113:H21 strain 98NK2 which was responsible for an outbreak of haemolytic uremic syndrome. Particular attention was focused on putative virulence genes encoded on the megaplasmid of this strain.

Gli stili APA, Harvard, Vancouver, ISO e altri

3

Rodrigues, Ângela Maria Gonçalves. "Patogénese das infeções entéricas por escherichia coli". Master's thesis, [s.n.], 2014. http://hdl.handle.net/10284/4840.

Testo completo

Abstract (sommario):

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas
As estirpes de E. coli podem ser agrupadas em estirpes comensais, patogénios extraintestinais e patogénios intestinais. É um relevante patogénio intestinal que causa infeções entéricas com grandes taxas de morbilidade e mortalidade em todo o mundo. O desenvolvimento da infeção depende da dose infeciosa ingerida pelo indivíduo, da sua susceptibilidade à doença, da interação entre o patogénio e os enterócitos e virulência do patogénio. E. coli induz diarreia através de diversos mecanismos, entre os quais a produção de adesinas, produção de toxinas, indução de alterações celulares nas células do hospedeiro e invasão da mucosa intestinal. As estirpes diarreiogénicas foram agrupadas em seis principais categorias, baseadas nos seus factores de virulência e mecanismos através dos quais provocam doença: E. coli enteropatogénicas (EPEC), enterohemorrágicas (EHEC), E. coli enterotoxicogénicas (ETEC), E. coli enteroagregativas (EAEC), E. coli enteroinvasivas (EIEC) e E. coli de adesão difusa (DAEC). As EPEC são caracterizadas pela formação de lesões histopatológicas nos enterócitos com posterior secreção de proteínas que causam alterações celulares. As EHEC têm um mecanismo semelhante, além disso, produzem toxinas Shiga, responsáveis por casos severos como diarreia sanguinolenta, colite hemorrágica (HC), síndrome hemolítico-urémico (HUS) e púrpura trombocitopénica trombótica (TTP). Quanto a estirpes de ETEC, podem produzir e libertar duas toxinas diferentes: LT e ST, que causam o desequilíbrio da homeostase intestinal por aumento do AMPc e GMPc, respetivamente. EAEC formam um biofilme e libertam toxinas como EAST1 e Pet que estimulam a secreção de fluídos e eletrólitos. EIEC são capazes de invadir enterócitos e replicarem-se. Em relação às DAEC, a infeção é caracterizada pelo crescimento de projeções em forma de “dedo” da superfície dos enterócitos. Para reduzir as taxas de morbilidade e de mortalidade, ter acesso a informação sobre as infeções entéricas causadas por E. coli e aplicar a prevenção primária são essenciais. Escherichia coli (E. coli) strains can be grouped as commensal strains, extraintestinal pathogens and intestinal pathogens. It is a relevant intestinal pathogen which causes enteric infections with high morbidity and mortality rates around the world. The development of the infection depends on the infectious dose ingested by an individual, his susceptibility to the disease, enterocytes and pathogens interaction and pathogen’s virulence. E. coli induces diarrhea through several mechanisms, among them are production of adhesins, production of toxins, induction of cellular alterations in host cells and invasion of intestinal mucosa. Diarrheagenic strains were grouped into six main categories, based on their virulence factors and mechanisms by which they provoke disease: enteropathogenic E. coli (EPEC), enterohemorrhagic E. coli (EHEC), enterotoxigenic E. coli (ETEC), enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC) and diffusely adherent E. coli (DAEC). EPEC are characterized by the formation of histopathological lesions in the enterocytes with posterior secretion of proteins that cause cellular alterations. EHEC have a similar mechanism, besides, they produce Shiga toxins, responsible for severe cases as bloody diarrhea, hemorrhagic colitis (HC), hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). As for ETEC strains, they can produce and release two different toxins: LT and ST, which cause intestinal homeostatic disequilibrium by increasing AMPc and GMPc levels, respectively. EAEC form a biofilm and release toxins as EAST1 and Pet that stimulate fluid and electrolyte secretion. EIEC are capable of invading enterocytes and replicate. Regarding to DAEC strains, the infection is characterized by the growth of finger-like projections of the enterocytes’ surface that wrap around the bacteria. To reduce morbidity and mortality rates, having access to information about enteric infections caused by E. coli and applying primary prevention are essential.

Gli stili APA, Harvard, Vancouver, ISO e altri

4

Hostetter, Shannon Jones. "Role of Shiga toxin dissemination and inflammation in the pathogenesis of Shiga toxin-producing Escherichia coli infection". [Ames, Iowa : Iowa State University], 2009.

Cerca il testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

5

Walz, Paul S. "Influence of pathogenic bacterial determinants on genome stability of exposed intestinal cells and of distal liver and spleen cells". Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Biology, c2011, 2011. http://hdl.handle.net/10133/3405.

Testo completo

Abstract (sommario):

Most bacterial infections can be correlated to contamination of consumables such as food and water. Upon contamination, boil water advisories have been ordered to ensure water is safe to consume, despite the evidence that heat-killed bacteria can induce genomic instability of exposed (intestine) and distal cells (liver and spleen). We hypothesize that exposure to components of heat-killed Escherichia coli O157:H7 will induce genomic instability within animal cells directly and indirectly exposed to these determinants. Mice were exposed to various components of dead bacteria such as DNA, RNA, protein or LPS as well as to whole heat-killed bacteria via drinking water. Here, we report that exposure to whole heat-killed bacteria and LPS resulted in significant alterations in the steady state RNA levels and in the levels of proteins involved in proliferation, DNA repair and DNA methylation. Exposure to whole heat-killed bacteria and their LPS components also leads to increased levels of DNA damage.
xiv, 132 leaves : ill. (chiefly col.) ; 29 cm

Gli stili APA, Harvard, Vancouver, ISO e altri

6

Lekmeechai, Sujinna. "The role of EspO1 in Escherichia coli pathogenesis". Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/58146.

Testo completo

Abstract (sommario):

Enterohaemorrhagic E. coli (EHEC) has been the causative agent of diarrhoeal outbreaks for decades. EHEC virulence relies on a type 3 secretion system (T3SS), which directly translocates T3SS effectors into the host cell cytoplasm. Once translocated, T3SS effectors alter various host cell functions, including manipulating the cell death response, in order to facilitate bacterial colonisation. EHEC is equipped with at least 40 effector proteins; however, not all identified effectors are fully characterised. This study set out to investigate the role of EspO during EHEC infection. EHEC O157:H7 strain EDL933 carries 2 EspO homologs: EspO1 and EspO2. EspO homologs are also found in several enteric pathogens including Shigella flexneri (OspE1 and OspE2), Salmonella enterica serovar Typhi and Typhimurium (SopD), Citrobacter rodentium (EspO), and some enteropathogenic E. coli (EPEC) clinical isolates (EspO). It has previously been established that the EspO effector family interacts with integrin linked kinase (ILK) via a conserved tryptophan residue: W68 for OspE1 and W77 for EspO1. EspO1 and EspO2 co-operatively inhibit cell detachment by blocking focal adhesion disassembly, via their interactions with ILK and EspM2, respectively. In a previous study, HAX-1 was identified as the novel interaction partner of EspO1 by a yeast 2 hybrid (Y2H) screen. HAX-1 is an ubiquitiously expressed anti-apoptotic protein that localises to mitochondria. In this study, the EspO1-HAX-1 interaction was confirmed by direct Y2H. Functionally, EspO1 and OspE1 were shown to protect HeLa cells from staurosporine-induced apoptosis during transfection and EspO1 was able to inhibit cell death during in vitro infection. Additionally it was established that the EspO1 and OspE1 anti-apoptotic activity is HAX-1 dependent, but ILK independent. To summarise, this study reported that EspO1 displays anti-apoptotic activity in a HAX-1 dependent manner. Therefore, EspO1 serves 2 main functions: inhibition of apoptosis through HAX-1 and blocking of cell detachment through ILK.

Gli stili APA, Harvard, Vancouver, ISO e altri

7

Burke, Denis Anthony. "Ulcerative colitis and Escherichia coli". Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309075.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

8

Wu, Gilbert Kar Po. "Signal transduction responses to enteropathogenic Escherichia coli and Shiga toxin-producing Escherichia coli infections". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0007/MQ46054.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

9

Solecki, Olivia. "Explaining the urban and rural differences of Escherichia coli 0157 human infection in Grampian". Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=25203.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

10

Kimmitt, Patrick Thomas. "Expression of Shiga toxin genes in Escherichia coli". Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299614.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

11

Henriques, Sofia Correia Rosa de Barros. "Escherichia coli : host interactions in the pathogenesis of canine pyometra". Doctoral thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2016. http://hdl.handle.net/10400.5/12273.

Testo completo

Abstract (sommario):

Tese de Doutoramento em Ciências Veterinárias na Especialidade de Ciências Biológicas e Biomédicas
Canine pyometra develops as a result of a complex interaction of etiological and physiopathological factors, such as the virulence and type of the bacteria and the individual host defence mechanisms. Since Escherichia coli is the most common bacterium isolated from uterus of bitches with pyometra, one main objective of this work was to characterize E. coli virulence potential, and to evaluate the role of its virulence factors (VF) and traits in the pathogenesis of canine pyometra (Chapters IV, V and VI). A second main objective was to evaluate the innate immune mechanisms within the uterus and their role in E. coli recognition (Chapters III and VI). Results indicate that: i) although no single VF genes or virulence traits were associated with E. coli pyometra isolates, these isolates were mainly from the highly virulent phylogenetic group B2, which are characterized by a high number of uropathogenic E. coli VF genes and pathogenicity-associated islands markers; ii) Toll-like receptors were involved in the activation of the inflammatory response associated with pyometra; iii) β-hemolytic E. coli infection was associated with the occurrence of metritis and with an higher uterine tissue damage; iv) α-hemolysin (HlyA) contributes to the virulence of β-hemolytic E. coli, by inducing endometrial epithelial and stromal damage and a compromised early uterine immune response. Overall, these findings provide new relevant insights into the role of the pathogen-specific modulation of host immunity, which may influence the severity of disease and its clinical outcomes. Also, HlyA is a promising target for a vaccine, with the objective to induce an immunity that can block the binding and action of this toxin.
RESUMO - Interacão hospedeiro-Escherichia coli na patogenia da piómetra na cadela - A piómetra é uma doença comum do trato genital de cadelas adultas, durante a fase de diestro. A piómetra desenvolve-se como resultado de uma complexa interação de fatores etiológicos e fisiopatológicos. Entre estes, incluem-se a influência hormonal no útero, alterações estruturais no endométrio - como a hiperplasia quística (HQE) -, o tipo de bactérias e o seu potencial de virulência, e os mecanismos de defesa do hospedeiro. O trabalho desenvolvido nesta tese baseou-se no estudo do potencial de virulência de Escherichia coli (E. coli) (Capítulos IV e V) e nos mecanismos de imunidade inata do útero (Capítulos III e VI). Tendo em conta a elevada prevalência de E. coli nos casos de piómetra (82-100% dos casos) e nas infeções do trato urinário (54 – 68%) e o facto de aquelas estirpes serem provenientes da flora fecal do animal e não de um clone específico disseminado entre animais, procedeu-se à comparação do potencial de virulência de E. coli, isolada de piómetra, de cistites e de fezes de cadela (Capítulo IV). Os resultados indicam que as estirpes de E. coli, que colonizam o útero, têm um elevado potencial de virulência, possuindo um grande número de genes que codificam para fatores de virulência (FV) e ilhas de patogenicidade (PAIs). No entanto, existem estirpes de E. coli isoladas de cistite e de origem fecal com as mesmas características, o que sugere que poderão induzir piómetra, em cadelas suscetíveis. De particular importância, foi a observação de que cerca de 50% das estirpes de E. coli isoladas de piómetra eram β- hemolíticas. A prevalência dos isolados pertencentes ao grupo filogenético B2 foi maior nos casos de piómetra (94%) do que nos casos de cistite (48%) ou do que nos de origem fecal (39%). No entanto, independentemente da origem dos isolados, o número médio de PAIs e de genes que codificam para FV foi maior nos isolados pertencentes ao grupo filogenético B2, comparativamente aos outros grupos filogenéticos. Verificou-se também que o reto poderá funcionar como um reservatório de estirpes potencialmente patogénicas dos grupos filogenéticos B2 e D. Esta observação tem especial importância pois sabe-se que as estirpes de E. coli uropatogénicas isoladas de cães e humanos são similares em relação ao seu serotipo, tipo clonal, grupo filogenético e perfil de virulência. Isto sugere que os cães podem servir como reservatórios de bactérias potencialmente virulentas que podem ser transmitidas ao homem. Na primeira semana pós-parto, E. coli é a bactéria mais frequentemente isolada do conteúdo uterino de vacas de leite que desenvolvem infeções uterinas puerperais. No entanto, a associação, entre o perfil de virulência de E. coli e o desenvolvimento de metrite puerperal ou clinica, é controverso e, em muitos dos casos, a infeção resolve-se espontaneamente. Na cadela, as piómetras por E. coli estão associadas, em 50% dos casos, à síndrome de resposta inflamatória sistémica, a qual é potencialmente letal na ausência de terapêutica adequada. Numa tentativa de relacionar o potencial de virulência de E. coli com as diferentes evoluções da metrite clinica na vaca e da piómetra na cadela, compararam-se características genómicas dos isolados de E. coli (Capítulo V). Os resultados mostram que as estirpes de E. coli isoladas de vacas com metrite clinica pertencem maioritariamente aos grupos filogenéticos B1 e A, são geneticamente distintas das estirpes de piómetra e apresentam um menor número de genes que codificam para fatores de virulência, sendo por isso consideradas estirpes de menor potencial de virulência. A resposta uterina à infeção é composta por mecanismos da imunidade inata e adaptativa. A resposta inata é desencadeada pelo reconhecimento de padrões moleculares associados aos agentes patogénicos, por recetores do tipo Toll (TLRs), induzindo uma reacção inflamatória. Os resultados apresentados no Capítulo III permitem concluir que o útero da cadela tem capacidade de reconhecer uma grande variedade de ligandos - através da activação dos TLRs - e desenvolver uma resposta inflamatória contra vários tipos de microorganismos. Verificouse, também, que a transcrição e expressão dos TLRs 2 e 4 encontram-se significativamente diminuídas no início de diestro, o que pode contribuir para a maior susceptibilidade do útero à infeção por E. coli, nesta fase. Os resultados apresentados no Capítulo VI demonstram que, nos casos de piómetra a resposta inflamatória, mediada pelos TLRs, foi caracterizada por uma reação inflamatória exuberante, demonstrada pelo influxo de células de reação inflamatória no útero e por um aumento na transcrição de genes que codificam para citocinas próinflamatórias (IL-1β, IL-6, IL-8) e anti-inflamatórias (IL-10 e TGFβ). Observação relevante foi que, nos casos de piómetra por E. coli β-hemolítica, há um aumento significativo da ...

Gli stili APA, Harvard, Vancouver, ISO e altri

12

Stevenson, Sam M. L., e University of Lethbridge Faculty of Arts and Science. "Transfer of rifampicin-resistant Escherichia coli among feedlot cattle". Thesis, Lethbridge : University of Lethbridge, Facutly of Arts and Science, 2002, 2002. http://hdl.handle.net/10133/237.

Testo completo

Abstract (sommario):

Transfer and shedding of a rifampicin-resistant strain of Escherichia coli (RREC) among cattle was studied in a research feedlot comprised of 30 pens of 11 or 12 yearling steers. On 3 separate occasions, 9,6 and 6 of the 12 steers in 3 different peripheral pens in the lot were orally inoculated with 1011 cells of an unmodified RREC isolate from bovine feces. Fecal swabs were preformed on all 360 steers in the feedlot immediately prior to and at approximately 5-week intervals thereafter. Following inoculation, fecal grab samples were collected daily from all 12 pen mates for up to 4 months. In all 3 trials, the inoculated steers each shed RREC within 24 h of inoculation. All 12 steers in each inoculated pen were positive for RREC within 48 h; all 36 steers shed RREC intermittently throughout the three sampling periods. Transfer to 4 steers in an adjacent pen was confirmed only during the first trial (3 steers shed once each on day 8, day 26 or day 40; the fourth shed on 6 occasions between days 8 and 40). Transfer to non-adjacent pens was not detected during any of the 3 trials. All recovered RREC isolates were compared to the inocula using LMX agar and fatty acid methyl ester (FAME) analysis. Additionally, select recovered isolates were subjected to carbon source utilization tests. The three inocula were further subjected to 16S rRNA sequence analysis, minimum inhibitory antibiotic concentration profiles and pulsed-field gel electrophoresis and were determined to be the same strain. It was observed with the exception of the pen floor, that the resistant strain did not move through the animal feedlot environment, as easily or pervasively as other studies suggested. The RREC did not persist in the feedlot environment beyond the 4-month trial period. Fecal contamination form the pen floor, animal-to-animal contact and the chute system may have facilitated transfer of the resistant strain between animals. Animal stress may have facilitated the pen-to-pen transfer observed during trial 1, as the inoculation was conducted within 1 week of the steers' arrival in the feedlot.
xii, 102 leaves : ill. ; 28 cm.

Gli stili APA, Harvard, Vancouver, ISO e altri

13

Fasugba, Oyebola. "Antimicrobial resistance in urinary tract infections caused by Escherichia coli". Thesis, Australian Catholic University, 2017. https://acuresearchbank.acu.edu.au/download/67ce6b272ae23ebc1ea1e8727d748f9cc7a61a59c3d5c0c98d2d1d0350c55a51/5885672/Fasugba_2017_Antimicrobial_resistance_in_urinary_tract_infections.pdf.

Testo completo

Abstract (sommario):

Urinary tract infections (UTI) are one of the most common bacterial infections in hospital and community settings requiring antimicrobial treatment. Escherichia coli (E. coli), a bacterium frequently implicated in UTI, is becoming increasingly resistant to antimicrobials. Antimicrobial resistance (AMR) reduces the effectiveness of antimicrobial agents, leading to difficulty in treatment of patients, with the potential to prolong the duration of illness and increase mortality in patients. To date in Australia, there is a paucity of data comparing resistance patterns over time for hospital- and community-acquired E. coli UTI with no published data on incidence and risk of urinary E. coli resistance in Australia. Ciprofloxacin, a high priority critically important antimicrobial, is not recommended for empirical therapy of UTI yet resistance to this antimicrobial agent is increasing. There are no systematic reviews of studies investigating ciprofloxacin resistance in hospital- and community-acquired E. coli UTI. Therefore, the research program sought to address these knowledge gaps in three separate but interrelated studies. The research described in this thesis is the first of its kind in Australia.

Gli stili APA, Harvard, Vancouver, ISO e altri

14

Cremet, Lise. "Physiopathologie des infections ostéo-articulaires sur matériel à Escherichia coli". Nantes, 2015. http://archive.bu.univ-nantes.fr/pollux/show.action?id=476e2187-f5ed-4fe6-a97b-2280632ebd5f.

Testo completo

Abstract (sommario):

Les bacilles à Gram négatif sont impliqués dans 6 à 23% des infections ostéo-articulaires sur matériel (IOAM), et Escherichia coli est la première cause de ces infections. La pathogénèse des IOAMs à E. Coli reste encore mal connue. Dans le but de déterminer si les souches de E. Coli responsables d'IOAMs présentent une virulence spécifique et/ou une capacité particulière à échapper au système immunitaire, 30 souches cliniques de E. Coli isolées dans ce contexte ont été étudiées. Nos travaux soulignent le fort potentiel pathogène de la majorité des E. Coli isolés d'IOAMs, et indiquent que des souches de E. Coli uropathogènes pourraient être responsables, après diffusion hématogène, d'un grand nombre d'IOAMs à E. Coli. La plupart des E. Coli isolés d'IOAMs parviennent à échapper à l'activité bactéricide des polynucléaires neutrophiles et du système du complément, impliqués dans la réponse précoce à l'infection. Seule une faible proportion des souches semble capable de former du biofilm in vitro. Nous montrons aussi la faible adhérence et très faible internalisation des E. Coli isolés d'IOAMs, dans les cellules ostéoblastiques. Les souches les plus adhérentes induisent la même réponse cytokinique (IL-6 et TNF-α) que des souches de Staphylococcus aureus ou Pseudomonas aeruginosa, isolées dans le même contexte. Enfin, nos travaux mettent en évidence l'importante activité cytolytique des souches de E. Coli productrices d'alpha-hémolysine, vis-à-vis des polynucléaires neutrophiles et des cellules ostéoblastiques
Gram-negative bacilli are involved in 6 to 23% of orthopaedic implant infections (OII), and E. Coli is the first cause of Gram-negative OII. However, the pathogenesis of E. Coli has not been investigated in this context. To better understand if E. Coli strains from OII can be distinguished on the basis of a singular virulence and/or an ability to avoid host innate immune responses, 30 clinical strains isolated in this context were studied. Most of the 30 OII E. Coli showed a high virulence potential, and urinary tract infections and bacteremia represented a common source of implant seeding. Our results highlight the formidable subversive capacities of OII E. Coli against two major components of the innate immunity, i. E. Polymorphonuclear neutrophils and the complement system. Only a few proportion of the strains formed a strong biofilm in our experimental conditions. Furthermore, the OII E. Coli showed low adherence rates to osteoblastic cells and were poorly internalized. The most adherent strains induced IL-6 or TNF-α responses, which were equivalent to those elicited by S. Aureus or P. Aeruginosa strains recovered in the same clinical context. Finally, our study highlighted the high cytolytic potential of the alpha-hemolysin-producing E. Coli strains towards polymorphonuclear neutrophils and osteoblastic cells

Gli stili APA, Harvard, Vancouver, ISO e altri

15

Racicot, Bergeron Catherine. "Food animal reservoir for extraintestinal pathogenic «Escherichia coli» causing human infections". Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104886.

Testo completo

Abstract (sommario):

Studies of extraintestinal infections caused by genetically related strains of Escherichia coli among unrelated people have demonstrated the epidemic potential of this group of bacteria. These related extraintestinal pathogenic E. coli (ExPEC) may have a common source. Our group recently described how retail meat, particularly chicken, may be a reservoir for ExPEC causing human urinary tract infections (UTIs). By moving upstream on the farm to fork continuum, this study tests whether the reservoir for ExPEC is in food animals themselves. A total of 824 geographically and temporally matched E. coli isolates from cecal contents of slaughtered food animals (n=349) and human UTI (n=475) sources were compared. Using 6 different typing methods, an evolutionary relationship was observed between E. coli isolates from the food animal reservoir and human UTI. Moreover, chicken was the predominant animal species from where the related isolates originated. Using an evolutionary model, chicken was determined to be the most likely source of the human UTI isolates. This study confirmed that an animal reservoir, principally in chicken, may exist for ExPEC causing community-acquired UTI.
Les études portant sur les infections extra-intestinales causées par des souches d'Escherichia coli génétiquement apparentées, chez des personnes non reliées entre elles, ont démontré le potentiel épidémique de ce groupe de bactéries. Ces souches d'E. coli pathogènes extra-intestinales (ExPEC) apparentées auraient possiblement une source commune. Notre groupe a récemment décrit comment la viande de détail, plus particulièrement le poulet, pourrait être un réservoir d'ExPEC responsables d'infections urinaires (IUs) chez les humains. En se déplaçant plus en amont dans le continuum de la ferme à la fourchette, cette étude teste si le réservoir d'ExPEC se trouve dans les animaux de production eux-mêmes. Un total de 824 isolats d'E. coli de provenances géographique et temporelle communes, prélevés dans le contenu caecal d'animaux abattus (n=349) et de cas d'IU humaine (n=475) ont été comparés. Par l'utilisation de 6 différentes méthodes de typage, une relation évolutionnaire a été observée entre les isolats d'E. coli provenant du réservoir animal et d'IU humaine. De plus, le poulet était l'espèce animale prédominante parmi les isolats parentés. L'utilisation d'un modèle évolutionnaire a permis de déterminer que le poulet est la source la plus probable des isolats d'IU humaine. Cette étude a confirmé qu'un réservoir animal, principalement chez le poulet, pourrait exister pour les ExPEC qui causent des IUs acquises en communauté.

Gli stili APA, Harvard, Vancouver, ISO e altri

16

Vincent, Caroline. "Food reservoir for «Escherichia coli» causing community- acquired urinary tract infections". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95200.

Testo completo

Abstract (sommario):

Closely related strains of Escherichia coli have been shown to cause extraintestinal infections in unrelated persons. This study tests whether a food reservoir may exist for these E. coli. Isolates from three sources collected over the same time period and geographic area were compared. The sources comprised E. coli isolates from women with urinary tract infection (UTI) (n = 353); retail meat (n = 417); and restaurant/ready-to-eat foods (n = 74). E. coli were evaluated for antimicrobial susceptibility and O:H serotype and compared by using six different genotyping methods. We identified 17 clonal groups that contained E. coli isolates (n = 72) from more than one source. E. coli from retail chicken (O25:H4-ST131 and O114:H4-ST117) and honeydew melon (O2:H7-ST95) were indistinguishable from or closely related to E. coli from human UTIs. This study provides strong support for the role of food reservoirs in the dissemination of E. coli causing community-acquired UTIs.
Il a été démontré que des souches de Escherichia coli étroitement reliées causaient des infections extraintestinales chez des personnes non-reliées. Cette étude teste l'hypothèse selon laquelle il existerait un réservoir alimentaire pour ces souches d'E. coli. Des isolats provenant de trois sources différentes et récoltés durant les mêmes périodes et régions géographiques ont été comparés. Les sources incluaient des isolats d'E. coli provenant de femmes soufrant d'infection urinaire (IU) (n=353); de viande vendue au détail (n = 417); et d'aliments de restauration/prêts-à-manger (n =74). Les E. coli ont été évalués pour leur susceptibilité aux agents antimicrobiens et leur sérotype O:H, et ont été comparés par l'intermédiaire de six différentes méthodes de génotypage. Nous avons identifié 17 groupes clonaux contenant des isolats d'E. coli (n = 72) provenant de plus d'une source. Des E. coli provenant de viande de poulet (O25:H4-ST131 et O114:H4-ST117) et de melon au miel (O2:H7-ST95) étaient indistinguables ou étroitement reliés à des E. coli provenant d'IUs. Cette étude supporte fortement le rôle des réservoirs alimentaires dans la dissémination du E. coli causant des IUs acquises dans la communauté.

Gli stili APA, Harvard, Vancouver, ISO e altri

17

Bin, Thani Ali Salman. "Genomic diversity of ten Escherichia coli strains associated with bloodstream infections". Thesis, University of Leicester, 2009. http://hdl.handle.net/2381/4246.

Testo completo

Abstract (sommario):

Escherichia coli are usually regarded as a harmless human colonic flora. However, pathogenic strains of E. coli have been associated with infections that could range from infected mucosal surfaces by intestinal pathogenic E. coli to the more severe cases of disseminated infections throughout the body by the extraintestinal pathogroups. The main focus of this project was to investigate the genomic contents of pathogenic bloodstream infection (BSI)-associated E. coli strains. This is because the genome contents of the E. coli BSI-associated isolates have not been well studied, with only few reports indicating that the pathogenincity of these strains could be attributed to horizontally acquired DNAs known as genomic islands (GEIs). The genomic contents of 10 clinical BSI-associated E. coli strains, isolated at the Leicester Royal Infirmary were investigated in this study. The first approach used to investigate the genomic contents of these strains was by interrogating the downstream ends of tRNA genes for their GEI contents by the sequential PCR strategy tRIP-PCR (tRNA interrogation for pathogenicity islands) followed by the SGSP-PCR (single genome specific primer-PCR). In this approach the flanking regions of the tRNA sites were used to first screen the tRNA genes for their GEIs followed by amplifying the boundaries of the identified GEIs. In the second approach termed Microarray-Assisted mobilome Prospecting (MAmP), the physical genome size of the tested strains obtained by the pulsed-field gel electrophoresis (PFGE) is compared to the sum total of the bits of the genome detected or visualized by the array. The difference between the two measurements is used to estimate the size of the novel, non-microarray-represented mobile genome (mobilome) present in the tested strains. Remarkably, despite only studying 10 E. coli strains, associated with a single disease type the tRIP-PCR method has identified at least 3 GEIs that contain novel sequences, and 46 GEIs, resembling uropathogenic E. coli CFT073-like entities. One particular strain E105 had 13 tRNA sites occupied with GEIs. On the other hand, an average novel, non-microarray-borne mobilome of (219 kb /strain) was obtained by the MAmP which, corresponds with previous studies. The strategies used in this study had proved successful in addressing and identifying mobilome-rich strains. Therefore, using such approaches in combination with whole genome sequencing progects could prioritize the strains and the genomic regions that need to be sequenced. Such prioritization would avoid sequencing of hundreds of isolates to identify their novel gene pool and would reduce the cost of genomic sequencing. Moreover, applying such approaches for the identification of new virulence genes and/or pathogenic mechanisms could lead to significant improvements in the treatment of E. coli infections.

Gli stili APA, Harvard, Vancouver, ISO e altri

18

Houdouin, Véronique. "Caractérisation des souches de Escherichia coli responsables de pathologies extra-intestinales chez l'enfant : approche moléculaire et approche clinique". Paris 5, 2007. http://www.theses.fr/2007PA05D039.

Testo completo

Abstract (sommario):

Pour mieux appréhender les mécanismes physiopathologiques impliqués dans les infections extra-intestinales à E. Coli chez l'enfant, nous avons recherché une relation entre les caractéristiques génétiques bactériennes et les facteurs pronostiques cliniques des méningites néonatales et des infections urinaires. Notre stratégie repose sur trois approches : une approche moléculaire globale et ciblée, une approche fonctionnelle associant mutagénèse et modèle de méningite expérimentale et une approche clinique. Nous avons retrouvé une relation négative entre la virulence bactérienne et la mortalité des méningites néonatales, et entre la virulence et les anomalies anatomiques lors des pyélonéphrites. La relation négative entre virulence et résistance aux quinolones n'a pas été retrouvée dans le modèle animal. Enfin nous avons mis en évidence l'émergence d'un clone O45 : K1 hautement virulent, responsable de méningites en France et la présence d'un domaine génétique semblable à l'îlot de pathogénicité PAA IIJ96 dans la souche archétype C5
To understand the pathogenesis of extra-intestinal E. Coli in meningitis and urinary tract infections in children, we used a molecular, experimental model and clinical approach. We found a negative association between virulence and lethal outcome in neonatal meningitis as between virulence and anatomical abnormalities in urinary tract infections. The link between genetic virulence and in vitro resistance to quinolones was not proved in the neonatal meningitis rat model. Among our collection of French E. Coli neonatal meningitis we identified a major highly virulent O45 : K1 clonal group. The archetypal strain C5 causing neonatal meningitis harbors a pathogenicity island similar to the PAI IIJ96

Gli stili APA, Harvard, Vancouver, ISO e altri

19

Edwards, Kelly Katherine. "Bacterial factors contributing to the pathogenesis of the hemolytic uremic syndrome". MU has:, 2002. http://wwwlib.umi.com/cr/mo/fullcit?p3060096.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

20

Karami, Nahid. "Antibiotic resistance and fitness of Escherichia coli in the infantile commensal microbiota /". Göteborg : Department of Clinical Bacteriology, Göteborg University, 2007. http://hdl.handle.net/2077/4418.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

21

MacRitchie, Laura. "Human campylobacteriosis : elucidating the exposure, disease burden, health cost and acceptability of interventions". Thesis, University of Aberdeen, 2012. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=195982.

Testo completo

Abstract (sommario):

Campylobacter is the most commonly reported bacterial cause of gastrointestinal disease in developed countries. Campylobacteriosis is an infectious disease that causes severe diarrhoea, abdominal cramps, vomiting, blood in stools and fever, along with the inability to carry out normal activities for an estimated 3-5 days. Long term sequelae associated with Campylobacter infection includes Guillain Barré syndrome, irritable bowel syndrome and reactive arthritis. The incidence of human campylobacteriosis in the Grampian region was 138.8 per 100,000 people in 2011 which was one of the highest incidence rates within Scotland. Identified areas of limited knowledge in Campylobacter research include: population exposure to risk factors, financial burden and public acceptability of interventions to reduce Campylobacter in the poultry process. This thesis utilises questionnaire methods to gather data from the Grampian population to expand our knowledge in these research areas to assist in the reduction of human campylobacteriosis.

Gli stili APA, Harvard, Vancouver, ISO e altri

22

Omolajaiye, Sunday Abraham. "Isolation and characterization of E. coli and Campylobacter spp. from diarrhoeal samples collected from selected hospitals in Amathole District Municipality, Eastern Cape, South Africa". Thesis, University of Fort Hare, 2018. http://hdl.handle.net/10353/6213.

Testo completo

Abstract (sommario):

Approximately 2-4 billion cases of infectious diarrhoea occur every year, with the highest numbers recorded in sub-Saharan Africa. It remains the most common public health issue among children in developing nations. The purpose of this research was to unfold the prevalence of diarrhoeagenic E. coli and Campylobacter pathotypes as well as elucidate their antibiogram characteristics in diarrhoeal stool samples collected in some medical facilities in Eastern Cape Province, South Africa. Two hundred stool samples were collected from both inpatients and outpatients from male and females of all age groups attending selected medical facilities in the study area. Isolation and characterization of both organisms were done using culture based and molecular methods. Antibiotic susceptibility patterns of identified isolates were determined against a panel of 12 antimicrobial agents. One hundred and twenty presumptive E. coli isolates and 42 presumptive isolates of Campylobacter spp. Were isolated. Eighty-two percent (82 percent) of the presumptive E. coli isolates were confirmed as E. coli while 46.3 percent belonged to Campylobacter spp. Pathotyping of the diarrhoeagenic E. coli isolates by Polymerase chain reaction (PCR) showed the following prevalences: DAEC 43 (32 percent), EHEC 18 (17 percent), EIEC 11 (10 percent) and EPEC 18 (17 percent). EAEC and ETEC were not detected, while for Campylobacter spp. 37 (88 percent) were C. jejuni, and C. coli was not detected. A total of 12 (32.4 percent) of the confirmed Campylobacter jejuni isolates were found to possess the fliM gene, 9 (24.3 percent) possessed the flhA gene and only 6 (16.2 percent) harboured the gene flgE2. None were positive for the flaA, flab and flhB genes.The antibiotic resistance patterns observed among the E. coli isolates were high against ampicillin (98.1 percent), chloramphenicol (94.3 percent) and tetracycline (90.6 percent). For Campylobacter spp., resistance observed were: chloramphenicol (91.6 percent), tetracycline (25.2 percent), erythromycin (49.6 percent) and gentamycin (56.4 percent). A lesser resistance against imipenem (35.9 percent) and quinolone (ciprofloxacin) (45.5 percent) were exhibited by the E.coli isolates. 10.8 percent and 20.3 percent of the Campylobacter isolates were resistant to imipenem and ciprofloxacin respectively. The presence of chloramphenicol (CatA1) and tetracycline (tetA) resistance genes were detected in 94 percent and 89 percent of E. coli isolates respectively while 98 percent of Campylobacter spp. Harboured the catA1 resistance gene. It could be deduced from this study that E. coli and Campylobacter spp. are predomiant enteric pathogens as the etiologic agents of diarrhoea in the study community, and that their antimicrobial resistance is high in the study location. The need to develop strategies to prevent infection and control resistant organisms is evident.

Gli stili APA, Harvard, Vancouver, ISO e altri

23

Chu, Pui-shan, e 朱佩珊. "Antimicrobial resistant escherichia coli and sequence type 131 in urinary tract infections". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206499.

Testo completo

Abstract (sommario):

Background A pandemic clone, Escherichia coli sequence type 131 (ST131), has been disseminated worldwide and represents an important cause of antimicrobial resistant infections. The spread of this resistant clone has become a great public health concern. Objectives The aims of this study were to investigate the prevalence of ST131 in Escherichia coli isolates from human urinary cultures in Hong Kong and study the antimicrobial phenotypes of ST131. Methodology This study included 340 E. coli clinical urinary isolates obtained from patients in four district hospitals between May 2013 and July 2013 in Hong Kong. Antimicrobial susceptibilities were assessed by disk diffusion method with reference to CLSI. The isolates were investigated by phylogroup-specific and ST131-specific PCR assays. ST131 strains were further assessed for subclone distribution, antimicrobial resistance and extended-spectrum β-lactamase (ESBL) type. Results A total of 18.5% (63/340) of the E. coli population was identified as ST131. ST131 isolates were significantly more likely than non-ST131 isolates to be ciprofloxacin resistant (69.8%, 44/63 versus 31.0%, 86/277; P <0.001), gentamicin resistant (38.1%, 24/63 versus 24.9%, 69/277; P=0.03) and ESBL producers (41.3%, 26/63 versus 18.8%, 52/277; P <0.001). Among the ST131 E. coli isolates, 68.3% (43/63) belonged to the H30 subclone. Most H30 isolates were ST131-O25b (97.7%, 42/43). Also, the ST131-H30 E. coli subclone was statistically associated with ciprofloxacin resistance compared with the non-H30 ST131 isolates (P <0.001). Additionally, strains which were co-resistant to ciprofloxacin, co-trimoxazole and gentamicin were overwhelmingly associated with the H30 subclone than non-H30 (23.3%, 10/43 versus 0%, 0/20; P=0.02). Conclusion This study showed that ST131 isolates were widespread among human E. coli urinary isolates in Hong Kong. The increase in antimicrobial resistance phenotypes are highlighted with ST131, especially the H30 subclone isolates. The dissemination of the ST131 resistant clonal group has aroused clinical attention and limited the choice of empirical treatment.
published_or_final_version
Medical Sciences
Master
Master of Medical Sciences

Gli stili APA, Harvard, Vancouver, ISO e altri

24

McPeake, Stuart John William. "Investigation into primary septicaemic infections caused by Escherichia coli strains in chickens". Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437481.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

25

Synge, Barti Arnold. "Epidemiological studies of verocytotoxin-producing Escherichia coli infections in animals in Scotland". Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/30813.

Testo completo

Abstract (sommario):

This thesis is a summation of studies carried out between 1991 and 2004 and attempts to place the work in context with other knowledge to establish the role of animals as a source of human infection with verocytotoxin-producing Escherichia coli (VTEC). VTEC O157 was first isolated from cattle in Scotland in 1992. In a preliminary prevalence study using basic techniques to examine faeces sample routinely submitted to the Scottish Agricultural College (SAC) Veterinary Centres, 0.25% samples from cattle were positive for VTEC O157. The organism was more commonly isolated from calves less than two months of age. A very large prevalence study was commissioned following the Central Scotland outbreak. Using what has now become the nationally adopted technique (immunomagnetic separation following enrichment of 1g faeces in buffered peptone water with no antibiotics), prevalence levels were established with 95% confidence limits as follows. 7.9% (6.5, 9.6) animals sampled (12-30 months of age) were shedding VTEC O157. 22.8% (19.6, 26.3) of farms had at least one animal shedding in the group sampled. There was a significant drop in the proportion of farms where shedding was detected between the three years of the study 1998, 1999 and 2000. When farms were repeatedly visited twelve times, the organism was detected on 87.5% farms. Because of the lack of sensitivity of the test and the uneven distribution of the organism in faeces, these are underestimates of the true prevalence. In a cohort study in beef finishing cattle and a longitudinal study in beef cows risk factors for shedding VTEC O157 were determined from questionnaires followed by univariate and multivariate analysis. Increased levels of shedding were associated with animals being housed rather than grazing. Farms with animals at pasture have lower prevalence if the water is from a natural source. The presence of wild geese was also seen as a risk factor. Farms that spread slurry on grazing land were more likely to have shedding animals. Larger farms were more likely to be positive. There were no significant regional differences in shedding within Scotland. A pilot prevalence study in sheep determined a Group Level Prevalence of 8% with 95% confidence of 2% to 19% and an Animal Level Prevalence of 1%). Enumeration of VTEC O157 organisms gave counts ranging from <5x10²g^-1 to >10⁴g^-1. A similar study in deer in Scotland suggested that the prevalence was low. Finally it is postulated that the regional variation in the rate of infection per unit population in Scotland and the difference between Scotland and England relate to the relative cattle and human populations in the areas being considered.

Gli stili APA, Harvard, Vancouver, ISO e altri

26

Canhizares, Thaisy Milanelli [UNESP]. "O papel da Escherichia coli na retocolite ulcerativa". Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/151404.

Testo completo

Abstract (sommario):

Submitted by THAISY MILANELLI CANHIZARES null (thaisymilanelli@yahoo.com.br) on 2017-08-24T01:15:33Z No. of bitstreams: 1 DEFESA final.pdf: 700718 bytes, checksum: 9c3cbfade3105f6f93da40a95c86b3c6 (MD5)
Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-08-25T14:14:51Z (GMT) No. of bitstreams: 1 canhizares_tm_me_bot.pdf: 700718 bytes, checksum: 9c3cbfade3105f6f93da40a95c86b3c6 (MD5)
Made available in DSpace on 2017-08-25T14:14:51Z (GMT). No. of bitstreams: 1 canhizares_tm_me_bot.pdf: 700718 bytes, checksum: 9c3cbfade3105f6f93da40a95c86b3c6 (MD5) Previous issue date: 2017-08-04
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Retocolite Ulcerativa (RU) é um tipo de patologia que acomete o cólon intestinal, se apresentando na forma de lesões superficiais de gravidade variável. Não possui causa definida, mas sabe-se que é influenciada por fatores genéticos e ambientais, na qual, esse último, inclui um desequilíbrio na composição de espécies da microbiota intestinal. Escherichia coli (E. coli), uma das bactérias que se encontra aumentada nesses pacientes, tem sido foco de estudos de caracterização, com o objetivo de esclarecer sua participação na etiologia ou complicação dos sintomas da doença. Esse trabalho adotou essa abordagem para a caracterização de uma coleção de E. coli isoladas de portadores de RU atendidos no Hospital das Clínicas da Universidade Estadual Paulista Júlio de Mesquita Filho (HC/UNESP) de Botucatu, com base em sua capacidade de produção de biofilme, sorotipagem e filotipagem. Juntamente a esses testes, foi realizada uma revisão bibliográfica sobre a possível relação da E. coli com a RU. O objeto de estudo dos testes foi uma coleção de E. coli composta por 68 isolados bacterianos de 34 portadores de RU e 44 de 22 indivíduos controle (CO). A tipagem bacteriana teve como foco genes que identificam os sorogrupos O25 e O83 e determinação de filogrupos da coleção de referência de E. coli (EcoR – A, B1, B2 e D). Os resultados obtidos foram: 1) predomínio de E. coli dos filogrupos B2 e A nos grupos CO (54,5% x 26,5%, p=0,01) e de portadores de RU (32,4% x 9,1%, p=0,04) respectivamente, 2) no grupo portador de RU, 8,8% e 11,8% dos indivíduos apresentaram os sorogrupos O25 e O83, respectivamente e, entre os CO, a prevalência de ambos os sorogrupos foi de 4,5% e, 3) isolados produtores de biofilme forte (Fo), moderado (Mo) e fraco (Fra) foram encontrados em 45,5%, 22,7% e 27,3% dos CO, respectivamente. Em portadores de RU, a prevalência foi de 32,4%, 8,8% e 14,7%, respectivamente. A divergência nos dados de filotipagem em relação à literatura denota o caráter de extensa variabilidade observada nas populações naturais de E. coli e que dificulta sua vinculação com a causa da RU. A ausência de diferença na prevalência de isolados produtores de biofilme entre os grupos sugere que tal propriedade não pode ser vinculada a um eventual potencial de E. coli em provocar ou complicar os sintomas da RU. A análise bibliográfica mostrou resultados divergentes sobre a relação da E. coli na RU, possivelmente devido às variações no método de colheita, características teciduais e método de quantificação das culturas, sendo necessário mais pesquisas sobre o tema para sua maior clareza.
Ulcerative colitis (UC) is a type of pathology that affects the intestinal colon, presenting as superficial lesions of different severity. It has no defined cause, but it is known to be influenced by genetic and environmental factors, which includes an imbalance in the composition of species of the intestinal microbiota. Escherichia coli (E. coli), one of the bacteria that is increased in these patients, has been the focus of characterization studies, to clarify its participation in the etiology or complication of the disease’s symptoms. Following a line of research already consolidated in our laboratory, this work adopted this approach for the characterization of a collection of E. coli isolated from UC patients treated at the HC / UNESP of Botucatu, based on its biofilm production capacity, serotyping and filotyping. Also, a literature review was performed on the possible relationship between E. coli and UC. The study’s object of these tests was a collection of E. coli composed of 68 bacterial isolates from 34 UC carriers and 44 from 22 control individuals (CO). Bacterial typing focused on genes that identify the O25 and O83 serogroups and determination of phylogroups from the E. coli reference collection (EcoR - A, B1, B2 and D). The results obtained were: 1) Predominance of E. coli of the phylogenetic groups B2 and A in the CO groups (54.5% x 26.5%, p = 0.01) and in the UC group (32.4% x 9, 1, p = 0.04), respectively. 2) In the UC group, 8.8% and 11.8% of the individuals had serogroups O25 and O83, respectively, and among CO, the prevalence of both serogroups was 4,5% and, 3) Isolated producers of strong (St), moderate (Mo) and weak (We) biofilms were found in 45,5%, 22,7% e 27,3% of the CO, respectively. In UC patients, the prevalence was 32.4%, 8.8% and 14.7%, respectively. The divergence in the data of phylotyping in relation to the literature denotes the character of extensive variability observed in the natural populations of E. coli and that makes it difficult to be linked to the cause of the UC. The absence of a difference in the prevalence of biofilm isolates among the groups suggests that such property can’t be linked to an eventual potential of E. coli to cause or complicate UC symptoms. The literature analysis showed divergent results on the relationship of E. coli and UC, possibly due to variations in the collection method, tissue characteristics and quantification method of the cultures, being necessary more researches on the subject for its greater clarity.

Gli stili APA, Harvard, Vancouver, ISO e altri

27

Canhizares, Thaisy Milanelli. "O papel da Escherichia coli na retocolite ulcerativa". Botucatu, 2017. http://hdl.handle.net/11449/151404.

Testo completo

Abstract (sommario):

Orientador: Josias Rodrigues
Resumo: Retocolite Ulcerativa (RU) é um tipo de patologia que acomete o cólon intestinal, se apresentando na forma de lesões superficiais de gravidade variável. Não possui causa definida, mas sabe-se que é influenciada por fatores genéticos e ambientais, na qual, esse último, inclui um desequilíbrio na composição de espécies da microbiota intestinal. Escherichia coli (E. coli), uma das bactérias que se encontra aumentada nesses pacientes, tem sido foco de estudos de caracterização, com o objetivo de esclarecer sua participação na etiologia ou complicação dos sintomas da doença. Esse trabalho adotou essa abordagem para a caracterização de uma coleção de E. coli isoladas de portadores de RU atendidos no Hospital das Clínicas da Universidade Estadual Paulista Júlio de Mesquita Filho (HC/UNESP) de Botucatu, com base em sua capacidade de produção de biofilme, sorotipagem e filotipagem. Juntamente a esses testes, foi realizada uma revisão bibliográfica sobre a possível relação da E. coli com a RU. O objeto de estudo dos testes foi uma coleção de E. coli composta por 68 isolados bacterianos de 34 portadores de RU e 44 de 22 indivíduos controle (CO). A tipagem bacteriana teve como foco genes que identificam os sorogrupos O25 e O83 e determinação de filogrupos da coleção de referência de E. coli (EcoR – A, B1, B2 e D). Os resultados obtidos foram: 1) predomínio de E. coli dos filogrupos B2 e A nos grupos CO (54,5% x 26,5%, p=0,01) e de portadores de RU (32,4% x 9,1%, p=0,04) respectivamente, ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Ulcerative colitis (UC) is a type of pathology that affects the intestinal colon, presenting as superficial lesions of different severity. It has no defined cause, but it is known to be influenced by genetic and environmental factors, which includes an imbalance in the composition of species of the intestinal microbiota. Escherichia coli (E. coli), one of the bacteria that is increased in these patients, has been the focus of characterization studies, to clarify its participation in the etiology or complication of the disease’s symptoms. Following a line of research already consolidated in our laboratory, this work adopted this approach for the characterization of a collection of E. coli isolated from UC patients treated at the HC / UNESP of Botucatu, based on its biofilm production capacity, serotyping and filotyping. Also, a literature review was performed on the possible relationship between E. coli and UC. The study’s object of these tests was a collection of E. coli composed of 68 bacterial isolates from 34 UC carriers and 44 from 22 control individuals (CO). Bacterial typing focused on genes that identify the O25 and O83 serogroups and determination of phylogroups from the E. coli reference collection (EcoR - A, B1, B2 and D). The results obtained were: 1) Predominance of E. coli of the phylogenetic groups B2 and A in the CO groups (54.5% x 26.5%, p = 0.01) and in the UC group (32.4% x 9, 1, p = 0.04), respectively. 2) In the UC group, 8.8% and 11.8% of the individuals ... (Complete abstract click electronic access below)
Mestre

Gli stili APA, Harvard, Vancouver, ISO e altri

28

Choi, Suk Ho. "Binding mechanism of K88ab pili produced by enterotoxigenic Escherichia coli". Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/74764.

Testo completo

Abstract (sommario):

Binding of K88ab pili by brush border membrane and mucus from pig small intestine was characterized by inhibition assay and Western blot. In Western blot, K88ab pili were bound by two major brush border membrane polypeptides with molecular weight of 61,500 and 57,000 in addition to numerous minor polypeptides and a major mucus polypeptide with molecular weight of 27,500. The results from Western blot assays with periodate oxidized and carbamylated brush border membrane and inhibition assay with brush border membrane glycopeptide suggest that amino groups (rather than carbohydrate) present on the protein moiety are a part of the recognition site for K88ab pili of receptor polypeptides in brush border membrane. Differences were obtained in the binding patterns of K88ab pili when brush border membranes were prepared from small intestines obtained from 2-, 21-, and 42-day-old piglets as well as adult hogs. Binding of K88ab pili by mucus polypeptides was greater when prepared from small intestines obtained from 2-day-old piglets than from piglets of other ages and adult hogs. In inhibition assay, most fractions from sow milk and colostrum inhibited binding of K88ab pili. After gel filtration of colostral whey, fractions which contained IgG, IgA, and IgM produced the strongest inhibition of K88ab binding. Among fractions prepared from cow milk, casein and skim milk significantly inhibited binding of K88ab pili. In Western blot, α_s1-casein, immunoglobulin chains, and MFGM polypeptides in sow milk and colostrum were shown to be able to bind K88ab pili. Additionally, α_s1-casein was the major protein in bovine milk responsible for binding K88ab pili. In dot blot assay, IgG as well as brush border membrane could strongly bind K88ab pili. However, bovine α_s1-casein showed only weak binding of K88ab pili. Binding of K88ab pili to these proteins and brush border membrane was inhibited by carbamylation and by addition of 100 mM D-galactosamine. The results suggest that the K88ab-binding proteins in milk and colostrum compete to bind K88ab pili with the receptors in the brush border membrane and that mechanisms involved in binding of K88ab pili by these proteins is similar to that by brush border membrane.
Ph. D.

Gli stili APA, Harvard, Vancouver, ISO e altri

29

Chen, Ming. "Renal cell death in urinary tract infections : role of E. coli toxins /". Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-166-0/.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

30

Dahan, Stéphanie. "Effets et mécanismes de protection de saccharomyces boulardii vis-à-vis des infections intestinales causées par escherichia coli entéropathogène et escherichia coli entérohémorragiques". Aix-Marseille 3, 2002. http://www.theses.fr/2002AIX30059.

Testo completo

Abstract (sommario):

SACCHAROMYCES BOULARDII (S. B. ) EST UNE LEVURE ADMINISTREE POUR SES PROPRIETES ANTI-DIARRHEIQUES. LES DIARRHEES A ESCHERICHIA COLI ENTEROPATHOGENES (EPEC) SONT FREQUENTES CHEZ LES ENFANTS DES PAYS EN VOIE DE DEVELOPPEMENT. L'INFECTION PAR EPEC PROVOQUE LA DESTRUCTION DE LA MUQUEUSE INTESTINALE ET UNE REPONSE INFLAMMATOIRE CONDUISANT A UNE DIARRHEE AQUEUSE PERSISTANTE POUVANT ENTRAINER LA MORT. LES ESCHERICHIA COLI ENTEROHEMORRAGIQUES (EHEC) SONT DEVENUES EN QUELQUES ANNEES UNE MENACE POUR LES PAYS DEVELOPPES. ELLES FAVORISENT LA SURVENUE SURTOUT CHEZ LES ENFANTS ET LES SUJETS AGES DE COLITES HEMORRAGIQUES SE COMPLIQUANT PARFOIS DU SYNDROME HEMOLYTIQUE UREMIQUE (SHU). NOUS AVONS ETUDIE LES MECANISMES INFECTIEUX DES EPEC ET EHEC PAR L'UTILISATION DE LA LIGNEE EPITHELIALE INTESTINALE, T84, DERIVEE D'UN ADENOCARCINOME COLIQUE HUMAIN, ET ETUDIE LES MECANISMES DE PROTECTION DE S. B. VIS-A-VIS DE CES INFECTIONS. EPEC ACTIVE ERK1/2, P38, ET JNK DANS LES CELLULES T84. LA MODIFICATION DES RESISTANCES TRANSEPITHELIALES (RTE) ET LA FORMATION DES LESIONS D'ATTACHEMENT/EFFACEMENT SONT INDEPENDANTES DE ERK1/2 ET P38, MAIS CES CASCADES SONT IMPLIQUEES DANS LA REPONSE PRO-INFLAMMATOIRE. LA PRESENCE DE LA LEVURE LORS DES INFECTIONS PAR EPEC MAINTIENT L'INTEGRITE DE LA BARRIERE EPITHELIALE. DE PLUS, L'APOPTOSE MEDIEE PAR EPEC EST RETARDEE PAR LA LEVURE. L'ACTIVATION DE ERK1/2 EST DIMINUEE EN PRESENCE DE LA LEVURE. LA MODULATION DE CETTE VOIE INTERVIENT DANS LA DIMINUTION DE L'INTERNALISATION DES BACTERIES DANS LES CELLULES HOTES. DE PLUS, S. B. PRESERVE L'INTEGRITE DE LA BARRIERE EPITHELIALE LORS DES INFECTIONS PAR EHEC EN DIMINUANT LA PHOSPHORYLATION DE LA MLC QUI EST ENGAGEE DANS LE CONTROLE DE LA PERMEABILITE DE L'EPITHELIUM. NOUS AVONS MONTRE QUE EHEC INDUIT IN VITRO UNE REPONSE PRO-INFLAMMATOIRE PAR LA SECRETION DE L'IL-8 EN ACTIVANT LES MAPK, AP-1, ET NF-kB. S. B. A UN EFFET PREVENTIF A L'EGARD DES CELLULES T84 INFECTEES PAR EHEC EN DIMINUANT LA PRODUCTION D'IL-8, VIA L'INHIBITION DE LA VOIE DES MAPK, ET DU FACTEUR DE TRANSCRIPTION NF-kB. L'ENSEMBLE DE CES RESULTATS PERMET D'AFFIRMER QUE SACCHAROMYCES BOULARDII EXERCE UNE ACTIVITE ANTI-INFLAMMATOIRE VIS-A-VIS DES CELLULES T84 INFECTEES PAR EPEC ET EHEC EN MAINTENANT L'INTEGRITE DE LA BARRIERE EPITHELIALE, ET EN REDUISANT LA REPONSE PRO-INFLAMMATOIRE LIEE AUX INFECTIONS
SACCHAROMYCES BOULARDII (S. B. ) IS A NONPATHOGENIC YEAST USED IN INFECTIOUS DIARRHEA TREATMENT. ENTEROPATHOGENIC ESCHERICHIA COLI (EPEC) INFECTION OF T84 CELLS INDUCES A DECREASE IN TRANSEPITHELIAL RESISTANCE (TER), ALTERS THE FORMATION OF ATTACHING AND EFFACING (A/E) LESIONS, AND REDUCES CYTOKINE PRODUCTION. ENTEROHAEMORRHAGIC ESCHERICHIA COLI (EHEC) INFECTION IS ASSOCIATED WITH HEMORRHAGIC COLITIS AND THE HEMOLYTIC-UREMIC SYNDROME (HUS). IN VIVO, ELEVATED PLASMA LEVELS OF THE PROINFLAMMATORY CYTOKINE INTERLEUKIN-8 (IL-8) IN EHEC-INFECTED CHILDREN ARE CORRELATED WITH A HIGH RISK OF DEVELOPING HUS. WE STUDIED THE EPEC AND EHEC INFECTIOUS MECHANISMS ON EPITHELIAL INTESTINAL CELL LINE, T84, AND THE ASSOCIATED S. B. PROTECTIVE MECHANISMS. EPEC INDUCES ERK1/2, P38, AND JNK ACTIVATION IN INFECTED T84. THE TER MODIFICATIONS AND A/E LESIONS DO NOT DEPEND ON ERK1/2 AND P38, BUT THESE SIGNAL TRANSDUCTIONS TRIGGER THE PROINFLAMMATORY RESPONSE. S. B. ABROGATES THE EPEC-INDUCED ALTERATIONS ON BARRIER FUNCTION, DELAYS THE EPEC-INDUCED APOPTOSIS. ERK1/2 ACTIVATION IS MODULATED BY S. B. , AND THIS MODULATION IMPLICATES THE DECREASE OF EPEC INTERNALIZATION. S. B. DECREASES MLC PHOSPHORYLATION IN EHEC-INFECTED T84 CELLS WHICH IN TURN REGULATES THE EPITHELIUM PERMEABILITY. WE HAVE SHOWN THAT EHEC INDUCES IN VITRO A PROINFLAMMATORY RESPONSE BY IL-8 SECRETION IN INFECTED T84 CELLS BY ACTIVATION OF MAPK, AP-1, AND NF-kB PATHWAYS. S. B. EXERTS A PREVENTIVE EFFECT ON EHEC INFECTION BY DECREASING IL-8 PRODUCTION VIA MODULATION OF MAPK AND NF-kB ACTIVATION. THESE FINDINGS DEMONSTRATE THAT SACCHAROMYCES BOULARDII EXERTS AN ANTI-INFLAMMATORY ACTIVITY AGAINST EPEC AND EHEC INFECTIONS : I) S. B. MAINTAINS THE BARRIER FUNCTION OF EPITHELIAL CELLS, AND II) S. B. REDUCES THE INFECTIOUS PROINFLAMMATORY RESPONSES

Gli stili APA, Harvard, Vancouver, ISO e altri

31

Takahashi, Akira. "Molecular epidemiological studies of Escherichia coli isolates obtained from lower urinary tract infections". Kyoto University, 2010. http://hdl.handle.net/2433/120579.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

32

Alhashash, F. A. "Populations of Escherichia coli in clinical samples of urinary tract infections and bacteraemia". Thesis, Nottingham Trent University, 2015. http://irep.ntu.ac.uk/id/eprint/27939/.

Testo completo

Abstract (sommario):

Extraintestinal pathogenic E. coli (ExPEC) strains are the main etiologic agent of urinary tract infections (UTIs). ExPEC strains are also reported to be the most common cause of bacteraemia in the world, which often originate from UTI. The population structure of UTI E. coli strains is well described in the literature with increased prevalence of multidrug resistance driven by extended spectrum β lactamases (ESBLs). ESBL carriage and multidrug resistance of bacteraemia E. coli is on the increase yet little information is available about their population structure. With the aim to define the bacteraemia population structure, E. coli isolated from urine samples and blood cultures were collected from the Nottingham University Hospital NHS trust over a five month period. Isolates were tested for antimicrobial resistance, ESBL and virulence associated gene (VAG) carriage, and were typed by MLST. Significantly higher ESBL driven multidrug resistant strains were observed in the bacteraemia E. coli compared to the UTI isolates with no significant difference in the carriage of VAGs. Our data shows a reduction in population diversity within the bacteraemia isolates compared to the concomitant urine sample population resulting in a small number of dominant sequence types (STs) (ST131, ST73, ST95) which is associated with ESBL conferred multi drug resistance and not specific virulence genes. This suggests that the increased prevalence of ESBL carriage in ExPEC isolates is leading to a selective advantage in a small number of dominant lineages causing bacteraemia in patients. Comparative genome analysis of selected isolates belonging to the dominant ST (ST73) from bacteraemia and UTI was performed to investigate the presence of bacteraemia specific loci that may explain the loss of diversity in bacteraemia. No genomic regions were identified specific for the bacteraemia ST73 isolates other than ESBL carriage. Plasmid profiling of the ESBL positive isolates of this ST73 group from bacteraemia and UTI identified diverse types of plasmids spread between the strains. No specific genomic loci were identified specific for ESBL positive ST73 isolates from bacteraemia and UTI. This concludes that random acquisition of ESBL plasmids by any ST73 E. coli may select for its progression to bacteraemia which is serious and debilitating. Our study provided a comprehensive snapshot of the E.coli population structure from contemporaneous clinical cases of UTI and bacteraemia. The large increase in multi-drug resistance in bacteraemia ExPEC populations compared to co-circulating UTI populations is of clinical concern and represents a challenge in control and treatment of serious extra-intestinal E. coli infections. This provides an important clinical insight into how common E. coli STs could adapt to become dominant bacteraemia agents.

Gli stili APA, Harvard, Vancouver, ISO e altri

33

Nicklasson, Matilda. "Studies on the expression and regulation of enterotoxins and colonization factors in enterotoxigenic Escherichia coli (ETEC) /". Göteborg : Institute of Biomedicine, Dept. of Microbiology and immunology, Göteborg University, 2008. http://hdl.handle.net/2077/9610.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

34

Levert, Maxime. "Compréhension de la diversité génotypique et phénotypique générée chez Escherichia coli lors des infections extraintestinales". Paris 5, 2010. http://www.theses.fr/2010PA05S002.

Testo completo

Abstract (sommario):

Ce travail a consisté à obsever et étudier les mécanismes responsable de la diversification génotypique et phénotypiques des clones d'E. Coli lors des infections extraintestinales. Plusieurs polymorphismes phénotypiques s'expliquent par des niveaux différents de la protéine RpoS dans les isolats. L'étude fine des isolats d'un patient n'a pas permis de détecter de mutations dans le gène RpoS mais le séquençage de quatre de ces souches a permis de découvrir au moins six mutations ponctuelles, une délétion et une insertion d'élément IS;. La moitié présentant un lien direct avec l'expression de certaines protéines differentiellement exprimées. En utilisant un modèle murin d'infection extraintestinale, nous avons observé que ces 8 isolats se partagent en 4 groupes de virulence significativement distincts. Les résultats montrent qu'il est possible que de multiples génotypes et phénotypes bactériens soient générés à partir d'une population clonale dans les infections extraintestinales à E. Coli|
This work consisted to observe and study the mechanisms responsible for the genotypic and phenotypic diversification of clones E. Coli in extraintestinal infections. Several phenotypic polymorphisms are explained by different levels of RpoS protein in the isolates. The detailed study of isolates from one patient failed to detect mutations in the gene RpoS but four of these strains revealed at least six point mutations, a deletion and an insertion of IS element; half of the mutations are linked with the expression of certain proteins differentially expressed. Using a mouse model of extraintestinal infection, we observed that these 8 isolates were divided into 4 groups of significantly different virulence. The results show that it is possible that multiple bacterial genotypes and phenotypes are generated from a clonal population in extraintestinal infections E. Coli

Gli stili APA, Harvard, Vancouver, ISO e altri

35

Miranda, Regina L. "The role of glycolytic substrates in the initiation and maintenance phases of colonization of the mouse large intestine by Escherichia coli MG1655 and Escherichia coli EDL933 /". View online ; access limited to URI, 2004. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3147802.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

36

Farra, Anna. "Antibiotic resistance and antibiotic consumption in Sweden with focus on Escherichia coli and Pseudomonas aeruginosa /". Stockholm, 2007. http://diss.kib.ki.se/2007/978-91-7357-201-9/.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

37

Bernier-Febreau, Christine. "Identification et caractérisation de facteurs de pathogénicité produits par les Escherichia coli entéroagrégatifs". Paris 7, 2003. http://www.theses.fr/2003PA077012.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

38

Tahoun, Amin M. Abd El Hady. "Role of Type III secretory effectors EspF and SopB in enteric pathogenesis of Escherichia coli and Salmonella enterica serovar Typhimurium". Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5899.

Testo completo

Abstract (sommario):

The EspF protein is translocated into host cells by the type III secretion system of enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC). EspF sequences differ between EPEC and EHEC serotypes in terms of the number of SH3-binding polyproline rich repeats and specific residues in these regions as well as residues in the amino domain involved in cellular localization. In this study we have compared the capacity of different espF alleles to inhibit: (i) bacterial phagocytosis by macrophages; (ii) translocation through an M-cell co-culture system; (iii) uptake by and translocation through cultured bovine epithelial cells. The espFO157 allele was significantly less effective at inhibiting phagocytosis and also had reduced capacity to inhibit E. coli translocation through a human-derived in vitro M-cell co-culture system in comparison to espFO127 and espFO26. In contrast, espFO157 was the most effective allele at restricting bacterial uptake into and translocation through primary epithelial cells cultured from the bovine terminal rectum, the predominant colonisation site of EHEC O157 in cattle and a site containing M-like cells. As functional differences could not be simply assigned to variation in established interactions of EspF with Sorting Nexin 9 and N-WASP, yeast-2-hybrid screening was used to identify additional host proteins that may interact with EspF. The anaphase promoting complex inhibitor, Mad2L2, was identified from this screen. Mad2L2 was then demonstrated to interact with EspF variants from EHEC O157:H7, O26:H11 and EPEC O127:H6 by Lumier assays. While Mad2L2 has been shown to be targeted by the non homologous Shigella effector protein IpaB to limit epithelial cell turnover, we presume that EspF interactions with this protein may indicate a similar function to promote EPEC and EHEC colonization. The final section of work addressed whether bacterial interactions can actually induce M-cell differentiation on follicle-associated epithelium. The work focused on bovine rectal primary cell cultures interacting with Salmonella enterica serovar Typhimurium. The type III secreted protein, SopB, was required for Salmonella to: III (i) activate parts of epithelial to mesenchymal transition (EMT) pathway; (ii) transform a subset of epithelial cells to a cell type that phenotypically and functionally resembles specialized antigen sampling M cells; (iii) induce RANKL and downstream RelB dependent NFkB signaling. The work suggests that Salmonella may induce this cellular transformation to promote its invasion and colonization of intestinal mucosa.

Gli stili APA, Harvard, Vancouver, ISO e altri

39

Valério, Nádia Castanho. "Potential effects between bacteriophages and antibiotics to inactivate Escherichia coli". Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/22360.

Testo completo

Abstract (sommario):

Mestrado em Microbiologia
Escherichia coli is part of the normal flora of the gastrointestinal tract of humans and various mammals. This opportunistic microorganism is capable of cause several infections, such as urinary tract infections (UTI). E. coli is resistant to a large number of antibiotics, becoming harder the control of infections caused by this bacterium. Phage therapy may be a useful tool to control infections caused by antibiotic resistant strains. However, the major concern of the phage therapy is also the emergence of phage resistant bacteria. In this study, was evaluated the combination of two different therapies, chemotherapy and phage therapy, to evaluate the possibility of synergic effects between them. It was used the phage ECA2 (a phage previously isolated by the research group) and various antibiotics (ampicillin, kanamycin, piperacillin, tetracycline, chloramphenicol and ciprofloxacin) with different mechanisms of action. The E. coli strain used in this study is sensitive to the antibiotics ciprofloxacin, tetracycline and chloramphenicol and resistant to the antibiotics ampicillin, kanamycin and piperacillin The phage ECA2 caused a reduction in E. coli concentration of ≈ 4.5 log after 2 hours of treatment in phosphate buffered saline (PBS). The results obtained with the mixtures of the phage with ampicillin, kanamycin and piperacillin did not cause significantly differences when compared with the results obtained just with the phage. As the bacterium E. coli showed resistance to those antibiotics, the bacterial inactivation was just due the action of the phage. Otherwise, the results obtained using the mixtures of ECA2 with tetracycline and chloramphenicol were worse than the results obtained just with the phage. The conjugation of the phage with ciprofloxacin resulted in a bacterial inactivation of about 8.3 log, compared to the ≈4.5 log of bacterial inactivation obtained with the phage alone. In addition, the conjugation of the phage ECA2 with ciprofloxacin resulted in a decrease of the bacterial resistances obtained the phage and the antibiotic individually. The efficacy of phage therapy in urine was also evaluated, with the phage and the mix of phage and ciprofloxacin. The inactivation of E. coli in urine samples was similar to that obtained in PBS. It was observed a decrease of 4.3 log after 4 hours of treatment. Furthermore, a cocktail with two phages, the phage ECA2 and another E. coli specific phage, previously isolated by the research group, the phage phT4A, was also tested. The E. coli inactivation was 3.5 log after 4 hours. The results indicate that phage and antibiotic combinations could result in synergistic effect in the inactivation of bacteria, but only when the bacterium is sensitive to the antibiotic. Also, the combination of antibiotics with phages contributes to managing resistance levels, controlling the antibiotic resistance and phage-resistant mutants. The phages limit the emergence of antibiotic resistant variants in combined treatments independently of antibiotic type, but the antibiotics limit the resistance of phage-mutants only when bacteria are sensitive to the antibiotic. However, overall, in the presence of antibiotics the resistance of phage-mutants was the same or less than when phages were tested alone. The high bacterial inactivation efficiency with phages combined with a higher bacterial inactivation in the presence of antibiotic and the long periods of phage survival in urine samples, paves the way for depth studies to control urinary tract infection and to overcome the development of resistances by E. coli, the bacterium most frequently isolated in UTI at the community level and at hospital settings
Escherichia coli é uma bactéria oportunista que pode ser encontrada como parte da flora normal do trato gastrointestinal humano e de alguns mamíferos. Este microrganismo é capaz de provocar diversas infeções, sendo responsável pela maioria das infeções do trato urinário (ITU). E. coli é resistente a uma grande variedade de antibióticos, tornando difícil o tratamento de infeções por ela causadas. Deste modo, a terapia fágica pode ser uma ferramenta útil no tratamento de infeções causadas por estirpes de E. coli resistentes aos antibióticos. Contudo, também a terapia fágica também leva ao desenvolvimento de bactérias mutantes resistentes aos fagos. Por esta razão, neste trabalho, foi avaliada a combinação de duas terapias, quimioterapia e terapia fágica, de modo a avaliar possíveis efeitos sinérgicos e atenuar o desenvolvimento de resistências aos fagos e antibióticos. Foi usado o fago ECA2, isolado num estudo prévio, e vários antibioticos (ampicilina, canamicina, piperacilina, ciprofloxacina tetraciclina e cloranfenicol) com diferentes mecanismos de ação. A estirpe de E. coli usada é sensível aos antibióticos ciprofloxacina, tetraciclina e cloranfenicol e resistente aos antibióticos ampicilina, canamicina e piperacilina. O fago ECA2 inativou eficientemente a bactéria E. coli, causando uma redução de ≈4,5 log na concentração da bactéria após 2 horas de tratamento em phosphate buffered saline (PBS). A inativação bacteriana com a mistura de fago e antibióticos ampicilina, canamicina e piperacilina foram similares aos resultados obtidos apenas com o fago. Como a estirpe bacteriana apresentava resistência a estes antibióticos, a inativação bacteriana resultante foi devida apenas à ação do fago. As misturas do fago ECA2 com cloranfenicol e com tetraciclina mostraram ser menos eficazes na inativação da bactéria do que o fago sozinho. A conjugação do fago com a ciprofloxacina resultou numa inativação bacteriana de cerca de 8,3 log, em detrimento dos ≈ 4,5 log de inativação bacteriana obtidos com apenas o fago. Além disso, a conjugação do fago ECA2 com a ciprofloxacina resultam numa diminuição das resistências bacterianas obtidas em relação ao fago e ao antibiótico individualmente. A terapia fágica também foi avaliada em urina com vista a avaliar o uso desta terapia no controlo de infeções urinárias. A inativação de E. coli na urina foi semelhante à obtida nos ensaios em PBS, tanto para o fago como para a conjugação do fago ECA2 com a ciprofloxacina. Foi ainda testado na urina um cocktail com dois fagos, o fago ECA2 e com outro fago específico para esta bactéria, o fagophT4A (previamente isolado pelo grupo de trabalho). Observou-se numa redução bacteriana de 3,5 log. Os resultados indicam que a combinação fagos e antibióticos pode resultar num efeito sinérgico na inativação de bactérias, mas apenas quando a bactéria é sensível ao antibiótico. Além disso, a combinação de antibióticos com fagos contribui para a gestão dos níveis de resistência, controlando a resistência aos antibióticos e os mutantes resistentes ao fago. Os fagos limitam o desenvolvimento de variantes resistentes a antibióticos em tratamentos combinados independentemente do tipo de antibiótico, mas os antibióticos limitam a resistência de mutantes aos fagos apenas quando as bactérias são sensíveis ao antibiótico. Contudo, em geral, na presença de antibióticos, a resistência dos mutantes aos fagos foi a mesma ou menor do que quando os fagos foram testados isoladamente. A elevada eficiência de inativação bacteriana por fagos combinada com uma maior inativação bacteriana na presença de antibiótico, e a elevada sobrevivência dos fagos em urina, abre o caminho para estudos mais aprofundados para controlar a UTI e o desenvolvimento de resistências em E. coli, a bactéria mais frequentemente isolada em UTI ao nível da comunidade e em ambientes hospitalares.

Gli stili APA, Harvard, Vancouver, ISO e altri

40

Rivera, Hector. "Cloning and immunogenicity of a Chlamydia Trachomatis 36 kilodalton recombinant gene product in Escherichia Coli". CSUSB ScholarWorks, 1991. https://scholarworks.lib.csusb.edu/etd-project/839.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

41

Barletta, Francesca, Theresa J. Ochoa, Erik H. Mercado, Joaquim Ruiz, Lucie Ecker, Giovanni Lopez, Monica Mispireta, Ana I. Gil, Claudio F. Lanata e Thomas G. Cleary. "Quantitative real-time polymerase chain reaction for enteropathogenic Escherichia coli: a tool for investigation of asymptomatic versus symptomatic infections". Oxford University Press, 2015. http://hdl.handle.net/10757/556075.

Testo completo

Abstract (sommario):

theresa.j.ochoa@uth.tmc.edu
Article
BACKGROUND: Enteropathogenic Escherichia coli (EPEC) strains are pediatric pathogens commonly isolated from both healthy and sick children with diarrhea in areas of endemicity. The aim of this study was to compare the bacterial load of EPEC isolated from stool samples from children with and without diarrhea to determine whether bacterial load might be a useful tool for further study of this phenomenon. METHODS: EPEC was detected by polymerase chain reaction (PCR) of colonies isolated on MacConkey plates from 53 diarrheal and 90 healthy children aged <2 years. DNA was isolated from stool samples by cetyltrimethylammonium bromide extraction. To standardize quantification by quantitative real-time PCR (qRT-PCR), the correlation between fluorescence threshold cycle and copy number of the intimin gene of EPEC E2348/69 was determined. RESULTS: The detection limit of qRT-PCR was 5 bacteria/mg stool. The geometric mean load in diarrhea was 299 bacteria/mg (95% confidence interval [CI], 77-1164 bacteria/mg), compared with 29 bacteria/mg (95% CI, 10-87 bacteria/mg) in control subjects (P = .016). Bacterial load was significantly higher in children with diarrhea than in control subjects among children <12 months of age (178 vs 5 bacteria/mg; P = .006) and among children with EPEC as the sole pathogen (463 vs 24 bacteria/mg; P = .006). CONCLUSIONS: EPEC load measured by qRT-PCR is higher in diarrheal than in healthy children. qRT-PCR may be useful to study the relationship between disease and colonization in settings of endemicity.

Gli stili APA, Harvard, Vancouver, ISO e altri

42

Khandaker, MD Shahjahan Ali. "Economic analysis of diseases caused by VTEC (verotoxin producing e.coli) in Australia /". St. Lucia, Qld, 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17335.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

43

Horvath, Dennis John Jr. "The Impact of Phagocyte-UPEC Interactions Upon Pathogenesis of Urinary Tract Infections". The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316282102.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

44

Lai, YuShuan (Cindy). "EspFU, an Enterohemorrhagic E. Coli Secreted Effector, Hijacks Mammalian Actin Assembly Proteins by Molecular Mimicry and Repetition: A Dissertation". eScholarship@UMMS, 2014. https://escholarship.umassmed.edu/gsbs_diss/715.

Testo completo

Abstract (sommario):

Enterohemorrhagic E. coli (EHEC) is a major cause of food borne diarrheal illness worldwide. While disease symptoms are usually self-resolving and limited to severe gastroenteritis with bloody diarrhea, EHEC infection can lead to a life threatening complication known as Hemolytic Uremic Syndrome (HUS), which strikes children disproportionately and is the leading cause of kidney failure in children. Upon infection of gut epithelia, EHEC produces characteristic lesions called actin pedestals. These striking formations involve dramatic rearrangement of host cytoskeletal proteins. EHEC hijacks mammalian signaling pathways to cause destruction of microvilli and rebuilds the actin cytoskeleton underneath sites of bacterial attachment. Here, we present a brief study on a host factor, Calpain, involved in microvilli effacement, and an in depth investigation on a bacterial factor, EspFU, required for actin pedestal formation in intestinal cell models. Calpain is activated by both EHEC and the related pathogen, enteropathogenic E. coli (EPEC), during infection and facilitates microvilli disassembly by cleavage of a key membrane-cytoskeleton anchoring substrate, Ezrin. Actin pedestal formation is facilitated by the injection of two bacterial effectors, Tir and EspFU, into host cells, which work in concert to manipulate the host actin nucleators N-WASP and Arp2/3. EspFU hijacks key host signaling proteins N-WASP and IRTKS by mimetic displacement and has evolved to outcompete mammalian host ligands. Multiple repeats of key functional domains of EspFU are essential for actin pedestal activity through proper localization and competition against the an abundant host factor Eps8 for binding to IRTKS.

Gli stili APA, Harvard, Vancouver, ISO e altri

45

Lai, YuShuan (Cindy). "EspFU, an Enterohemorrhagic E. Coli Secreted Effector, Hijacks Mammalian Actin Assembly Proteins by Molecular Mimicry and Repetition: A Dissertation". eScholarship@UMMS, 2004. http://escholarship.umassmed.edu/gsbs_diss/715.

Testo completo

Abstract (sommario):

Enterohemorrhagic E. coli (EHEC) is a major cause of food borne diarrheal illness worldwide. While disease symptoms are usually self-resolving and limited to severe gastroenteritis with bloody diarrhea, EHEC infection can lead to a life threatening complication known as Hemolytic Uremic Syndrome (HUS), which strikes children disproportionately and is the leading cause of kidney failure in children. Upon infection of gut epithelia, EHEC produces characteristic lesions called actin pedestals. These striking formations involve dramatic rearrangement of host cytoskeletal proteins. EHEC hijacks mammalian signaling pathways to cause destruction of microvilli and rebuilds the actin cytoskeleton underneath sites of bacterial attachment. Here, we present a brief study on a host factor, Calpain, involved in microvilli effacement, and an in depth investigation on a bacterial factor, EspFU, required for actin pedestal formation in intestinal cell models. Calpain is activated by both EHEC and the related pathogen, enteropathogenic E. coli (EPEC), during infection and facilitates microvilli disassembly by cleavage of a key membrane-cytoskeleton anchoring substrate, Ezrin. Actin pedestal formation is facilitated by the injection of two bacterial effectors, Tir and EspFU, into host cells, which work in concert to manipulate the host actin nucleators N-WASP and Arp2/3. EspFU hijacks key host signaling proteins N-WASP and IRTKS by mimetic displacement and has evolved to outcompete mammalian host ligands. Multiple repeats of key functional domains of EspFU are essential for actin pedestal activity through proper localization and competition against the an abundant host factor Eps8 for binding to IRTKS.

Gli stili APA, Harvard, Vancouver, ISO e altri

46

Privat, Pascale. "Anguillulose maligne et méningites récidivantes à escherichia coli dans le cadre d'un syndrome d'immunodéficience acquise". Montpellier 1, 1993. http://www.theses.fr/1993MON11193.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

47

Salo, J. (Jarmo). "Long-term consequences and prevention of urinary tract infections in childhood". Doctoral thesis, Oulun yliopisto, 2012. http://urn.fi/urn:isbn:9789514298707.

Testo completo

Abstract (sommario):

Abstract Urinary tract infections (UTIs) are among the most common bacterial infections in childhood and have a tendency to recur. The ability of uropathogens to form biofilm may be important in the pathogenesis of UTI. Although childhood UTIs are thought to increase the risk of chronic kidney disease (CKD), evidence showing this association is scarce. Cranberry juice has been shown to prevent UTIs in women, but evidence of its efficacy in children is lacking. The aim of this work was to evaluate the significance of biofilm formation for the clinical presentation of UTI, the long-term consequences of UTI in childhood and the efficacy, safety and acceptability of cranberry juice in the prevention of UTIs in children. The formation of biofilm in clinical samples was assessed in vitro with optical density measurements and verified by scanning electron microscopy and confocal scanning laser microscopy. A systematic literature search on the association between childhood UTIs and CKD was conducted, and data on patients with CKD treated or monitored at Oulu University Hospital were reviewed. The efficacy of cranberry juice in preventing recurrences of UTIs in children and its effects on the normal flora were evaluated with two randomized controlled trials. About one third of the uropathogenic E. coli strains were capable of forming biofilm, and the strains isolated from patients having pyelonephritis formed biofilm better than those from cystitis cases. We did not find any cases among the 1576 reviewed in the literature search or the 366 in our patient series who had structurally normal kidneys in their first kidney imaging and in whom childhood UTIs could have been the cause of subsequent CKD. The aetiological fraction of childhood UTIs as a cause of CKD was at most 0.3%. The administering of cranberry juice did not reduce the number of children who experienced a recurrence of UTI, but it did reduce the number of recurrences per person year at risk by 39% (0.25 vs. 0.41 episodes, 95% CI for difference -0.31 to -0.01) and the number of days on antimicrobials per patient year by 34% (11.6 vs. 17.6 days, 95% CI for difference -7 to -5). Cranberry juice was well accepted and tolerated by the children and did not cause harmful changes in the normal flora. The ability of bacteria to persist and grow in a biofilm seems to be one of the significant factors in the pathogenesis of UTIs. A child with normal kidneys is not at risk of developing CKD because of UTIs in childhood, so that imaging procedures after the first UTI can be focused on finding severe urinary tract abnormalities. Taking into account the relatively innocent nature of childhood UTIs, cranberry juice offers an alternative to antimicrobials for preventing UTIs in children. The mechanism of action of cranberry juice may be associated with biofilm formation by uropathogens
Tiivistelmä Virtsatieinfektio (VTI) on yksi tavallisimpia lasten bakteeri-infektioita, ja sillä on taipumus uusiutua. Bakteerien biofilminmuodostuskyky voi olla merkittävä tekijä VTI:n synnyssä. Lapsuudessa sairastetun VTI:n ajatellaan lisäävän kroonisen munuaisten vajaatoiminnan riskiä, mikä ei kuitenkaan perustu tieteelliseen näyttöön. Karpalomehu ehkäisee aikuisten naisten VTI:n uusiutumisia, mutta sen tehoa lapsilla ei tiedetä. Tämän väitöskirjatyön tavoitteena oli selvittää bakteerien biofilminmuodostuskyvyn yhteyttä VTI:n kliiniseen kuvaan, lapsuudessa sairastetun VTI:n pitkäaikaisvaikutuksia sekä karpalomehun tehoa, turvallisuutta ja käyttökelpoisuutta lasten VTI:n ehkäisyssä. Kliinisistä virtsanäytteistä viljeltyjen E. coli –kantojen muodostama biofilmi mitattiin optisen tiheyden perusteella, ja elävien biofilmirakenteiden muodostuminen varmistettiin elektronimikroskooppi- ja konfokaalimikroskooppikuvauksilla. Lapsena sairastetun VTI:n yhteyttä munuaisten vajaatoimintaan tutkittiin systemaattisella kirjallisuuskatsauksella ja selvittämällä OYS:ssa munuaisten vajaatoiminnan vuoksi hoidossa olevien potilaiden munuaissairauden etiologia. Karpalomehun tehoa, turvallisuutta ja käyttökelpoisuutta lasten VTI:n ehkäisyssä selvitettiin kahdella lumekontrolloidulla tutkimuksella. Kolmasosa E. coli –kannoista muodosti biofilmiä, ja pyelonefriittipotilailta eristetyt kannat olivat parempia biofilminmuodostajia kuin kystiittipotilailta eristetyt. Kirjallisuuskatsauksen 1576:n ja OYS:n 366:n tapauksen joukossa ei ollut potilaita, joilla olisi ollut ensimmäisessä kuvantamistutkimuksessa rakenteeltaan normaalit munuaiset ja lapsuuden VTI:t olisivat johtaneet munuaisten vajaatoimintaan. Lapsuuden VTI:n etiologinen fraktio munuaisten vajaatoiminnan syynä oli teoriassakin korkeintaan 0.3 %. Karpalomehu ei vähentänyt uusintainfektion saaneiden lasten määrää, mutta se vähensi uusintaepisodeja 39 % riskiaikaa kohti (0,25/vuosi vs. 0,41/vuosi) ja antibioottipäiviä 34 % potilasvuotta kohti (11,6 vs. 17,6 päivää). Lapset joivat karpalomehua mielellään, eikä sillä ollut haitallisia vaikutuksia normaaliflooraan. Aiheuttajabakteerien biofilminmuodostuskyky vaikuttaa olevan merkittävä tekijä VTI:n patogeneesissä. Lapsi, jolla on rakenteellisesti normaalit munuaiset, ei ole lapsuuden VTI:n vuoksi riskissä sairastua munuaisten vajaatoimintaan. Siten ensimmäisen VTI:n jälkeiset kuvantamistutkimukset voidaan suunnata toteamaan vaikeat rakenteelliset poikkeavuudet. Koska lapsuuden VTI on suhteellisen vaaraton sairaus, karpalomehu on hyvä vaihtoehto VTI:n ehkäisyyn myös lapsilla. Biofilminmuodostuksen esto on sen yksi mahdollinen vaikutusmekanismi

Gli stili APA, Harvard, Vancouver, ISO e altri

48

Hagman, Ragnvi. "New aspects of canine pyometra : studies on epidemiology and pathogenesis /". Uppsala : Dept. of Small Animal Clinical Sciences, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/v182.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

49

Wetzel, Amy Noel. "Studies in Shiga toxin-producing Escherichia coli O157:H7 determination of factors contributing to the dissemination of Escherichia coli O157:H7 among dairy farms /". Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1133239436.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

50

Chapman, Peter Alan. "Purification of the verotoxins of Escherichia coli and production of antitoxins for use in a diagnostic test". Thesis, University of Sheffield, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244433.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Tesi sul tema "Escherichia coli infections Pathogenesis"

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili