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1
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.
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Ranfaing, Jérémy. "Etudes des activités anti-adhérentielles et anti-bactériennes de la canneberge (Vaccinium macrocarpon) et de la propolis." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT122.
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L’infection urinaire (IU) est un problème majeur de Santé publique. La cystite aiguë touchant principalement les femmes est la plus fréquente des IU. La bactérie la plus fréquemment isolée au cours de ces IU est Escherichia coli. Une des particularités de la cystite est sa propension à récidiver. Le traitement préconisé pour ces infections est la prise d’antibiotiques, qui peut être fréquente en cas de cystites récidivantes. C’est dans ce contexte que de nouvelles stratégies doivent être développées afin de prévenir et traiter les IU récidivantes. Parmi ces différentes stratégies, l’utilisation de produits naturels tels que la canneberge (Vaccinium macrocarpon) apparaît comme prometteuse. En effet, des études précédentes ont montré que la canneberge a un effet négatif sur l’adhésion des bactéries aux cellules superficielles de l’épithélium vésical facilitant l’élimination des bactéries par le flux urinaire. Cette activité est portée par la proanthocyanidine de type A (PAC-A). D’autre part, une étude menée par notre équipe a montré que l’effet de la canneberge sur l’adhésion et la virulence de souches d’E. coli uropathogènes pouvait être potentialisé par l’ajout d’un autre composé naturel : la propolis. Depuis l’Antiquité ses propriétés anti-bactériennes sont reconnues et des études plus récentes ont démontré son impact sur des bactéries à Gram positif mais également sur deux bactéries à Gram négatif : E. coli et Pseudomonas aeruginosa. Ce travail de thèse a permis : i) de décrire l’impact de la canneberge, de la propolis et de leur association sur le transcriptome d’une souche clinique d’E. coli uropathogène (G50). Cette analyse transcriptomique a montré que la canneberge entrainait une sous-expression de gènes liés à l’adhésion, mais également de gènes liés à la mobilité et à la formation de biofilm. En revanche, la canneberge augmentait l’expression des gènes liés au métabolisme du fer ainsi qu’à la réponse au stress. Ces effets étaient potentialisés par l’ajout de la propolis. En parallèle, des tests phénotypiques menés sur une collection de souches d’E. coli uropathogènes sur la mobilité et la formation de biofilm ont confirmé les résultats précédents ; ii) de développer un test, basé sur les précédents travaux de transcriptomique, permettant une évaluation standardisée de l’effet de la PAC-A sur E. coli, indépendamment de sa concentration car il n’existe pas de techniques standardisées pour doser cette molécule. C’est ainsi que 4 gènes (tsr, ftnA, fecB, feoB) ont été sélectionnés, le suivi de leur expression permettant une mesure de l’activité anti-bactérienne de la canneberge; iii) de mesurer l’effet potentialisateur de la propolis sur l’activité des antibiotiques utilisés dans le traitement des IU. C’est ainsi qu’il a été montré que l’ajout de la propolis permettait d’augmenter l’activité bactéricide des antibiotiques testés et de diminuer les concentrations minimales inhibitrices de ces antibiotiquesUrinary Tract Infection (UTI) is a major problem of public health. Acute cystitis which touches mostly women is the most common form of UTI. The bacteria which is mostly isolated in an UTI is Escherichia coli. A particularity of cystitis is to come back. In this context news strategies have to be developed to prevent and cure recurrent UTI. One of these strategies is the utilization of natural products like the cranberry (Vaccinium macrocarpon) which is promising. Indeed, previous studies showed the negative impact of cranberry on the adhesion of bacteria on the superficial cells of bladder which help the elimination of bacteria by the urinary flux. This activity is carried by the type A proanthocyanidin (PAC-A). Moreover, a study lead by our team has demonstrated an improvement of the activity of cranberry on the adhesion and the virulence of uropathogenic E. coli (UPEC) by another natural product: the propolis. Since Antiquity its antibacterial activities have been recognize and more recent studies have demonstrated its impact of Gram positive bacteria and also on two Gram negative bacteria: E. coli and Pseudomonas aeruginosa. This thesis has allowed for: i) the description of the impact of cranberry, propolis and its association on the transcriptome of a clinical strain of UPEC (G50). This transcriptomic analyze have shown that the cranberry down regulated genes linked to the adhesion and also genes linked to the motility and biofilm formation. However the cranberry up regulated genes linked to the iron metabolism and the stress response. These effects are improve by the addition of propolis. Concurrently phenotypics tests have been conducted on a collection of UPEC on the motility and the biofilm formation and they confirmed the previous results; ii) the development of a test, based on our transcriptomic results, enable to performed a standardized evaluation of the impact of PAC-A on E. coli, independently of its concentration. Indeed, this molecule cannot be measure in a standard way. Four genes have been selected (tsr, ftnA, fecB, feoB), the monitoring of their expression allow us to measure the anti-bacterial efficiency of the cranberry; iii) the measurement of the potential effect of the propolis of the antibiotic’s activities used to treat UTIs. Thus it have been observed that the addition of propolis improve the bactericide activity of the antibiotics tested and reduces the minimal inhibitory concentration of these antibiotics
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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.
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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.
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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.
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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 C5To 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
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Bourlioux, Marc. "Nouvelle méthodologie permettant la mise en évidence rapide des infections urinaires." Paris 5, 1988. http://www.theses.fr/1988PA05P259.
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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.
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Stevenson, Sam M. L., and 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.
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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.
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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.
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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.
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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.
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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.
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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.
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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 ostéoblastiquesGram-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
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Söderhäll, Mats. "The importance of Escherichia coli fimbriae in urinary tract infection /." Stockholm : Karolinska Univ. Press, 2001. http://diss.kib.ki.se/2001/91-7349-067-9/.
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COINTRE, DECRE ISABELLE. "Epidemiologie de l'infection urinaire a e. Coli au service des urgences du c. H. U. De nantes (mars-avril-mai 1989)." Nantes, 1990. http://www.theses.fr/1990NANT066M.
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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.
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Plummer, Kathleen Hope. "Cancer and Infection." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5293.
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E. coli is the most frequently isolated Gram negative pathogen from bacteremia in cancer patients and is repeatedly recovered from many other extraintestinal illnesses. These infections are commonly endogenous in nature and interfere with the treatment of cancer resulting in increased healthcare costs, morbidity, and mortality rates. Cancer and the treatments related to cancer cause alterations in the microbiome of the gut and other organs. Despite this point, there is a serious lack of knowledge about the genetic types of E. coli infecting cancer patients. This gap results in vague prevention strategies and limited treatment options for cancer patients. Multi Locus Sequence Typing (MLST) was used to successfully genotype 105 sequentially collected E. coli isolates from patients admitted to H. Lee Moffitt Cancer Center (HLMCC, Tampa, FL) with confirmed extraintestinal infections between 2010 and 2012. In total, 24 distinct genotypes (STs) have been identified in this dataset using EcMLST (STEC Reference Center). Of these, ST34 constituted 39% of the isolates and may represent a disseminating clone at HLMCC. Furthermore, 17 isolates not found in the EcMLST database have been identified. Importantly, phylogenetic analysis of DNA sequence data for MLMCC E. coli revealed only 22% of HLMCC E. coli clustered with ECOR reference strains commonly attributed to the B2 phylogroup of extraintestinal pathogenic E. coli (ExPEC). Four HLMCC E. coli belonging to ST171 and attributed to life-threatening blood infections clustered with Shiga toxin (Stx) producing E. coli (STEC) strain TW06296. HLMCC E. coli belonging to ST34 clustered with enteroaggregative E. coli (EAEC) strain TW10263. Importantly, these non-B2 phylogroup strains demonstrated more pathogenic potential than HLMCC E. coli clustered with B2 ExPEC,which included a higher incidence of bacteremia and sepsis, as well as resistance to first-line antibiotics. Upon further investigation, ST34 may equate to ST131 by another MLST database. These findings suggest that isolates previously characterized as commensal and intestinal pathogenic E. coli have an increased ability to cause infection outside of the gastrointestinal tract in cancer patients and that selective pressures are contributing to increased antibiotic resistance. These findings may change the approach to clinical management of E. coli infections at cancer centers.
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Lemaître, Chloé. "Région conservée des plasmides ColV/ColBM de Escherichia coli : mise en évidence d'un facteur de virulence auxiliaire des sidérophores et dissémination au sein des souches de E. coli responsables d'infections intra et extraintestinales." Paris 7, 2013. http://www.theses.fr/2013PA077091.
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Le plasmide ColV pS88 joue un rôle majeur dans la virulence du clone de Escherichia coli O45:K1:H7 responsable de méningite néonatale. Ce plasmide est caractérisé par une région de virulence conservée CVP qui comprend des facteurs de virulence connus comme les systèmes de capture du fer ainsi que des gènes de fonction inconnue. Les objectifs de ce travail étaient d'identifier de nouveaux gènes de virulence et de mieux caractériser la distribution de la région CVP au sein des E. Coli extraintestinaux. Par analyse transcriptionnelle, nous avons identifié des gènes de fonction inconnue parmi lesquels le gène csbLp dont la transcription était fortement induite en situation de carence martiale. Ce gène apparaît toujours associé au sidérophore salmochéline. Par mutagénèse, spectrométrie de masse et modèle expérimental, nous avons montré qu'il était impliqué dans la virulence de pS88 en agissant comme booster de la synthèse de certains sidérophores via la voie métabolique du shikimate. Par ailleurs, nous avons montré une forte prévalence de la région CVP au sein du sous-groupe phylogénétique C, récemment isolé du groupe majeur B1, ce qui pourrait expliquer la virulence paradoxale de certaines souches B1 habituellement considérées comme commensales. Enfin, nous avons mis en évidence la présence d'une région CVP dans une souche productrice de shigatoxine responsable d'un syndrome hémolytique et urémique associé à une bactériémie. L'analyse fonctionnelle et épidémiologique de la région CVP a permis d'élaborer le concept de facteur de virulence auxiliaire des sidérophores et d'évaluer sa dissémination au sein des E. Coli responsables de pathogénicité intra et extraintestinaleThe ColV plasmid pS88 plays a major role in the virulence of the neonatal meningitis Escherichia coli clone O45:K1:H7. This plasmid is characterized by a conserved virulence plasmidic (CVP) region including several known virulence factors as the iron uptake systems as well as genes of unknown function. The aims of this study were to identify new virulence genes and to better characterize the distribution of the CVP region within extraintestinal pathogenic E. Coli. Transcriptional analysis identified genes of unknown function including the gene csbLp whose transcription was strongly induced in iron-depleted conditions. This gene was present only in strains harboring the iro locus encoding salmochelins. By mutagenesis, mass spectrometry and experimental model, we showed that it was involved in the virulence of pS88 acting as a booster of catecholate/phenolate siderophores synthesis via the shikimate pathway. Furthermore, we have shown a high prevalence of the CVP region in the phylogenetic subgroup C, closely related to major group B1, which could explain the unexpected virulence of some B1 strains usually considered as commensal. Finally, we showed the presence of a CVP region in a Shiga toxin-producing E. Coli responsible for a hemolytic-uremic syndrome associated with bacteremia. The functional and epidemiological analysis of the CVP region pointed the concept of siderophore auxiliary virulence factors and showed its dissemination within extraintestinal and intestinal pathogenic E. Coli
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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.
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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.
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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.
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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.
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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.
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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.
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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/.
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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/.
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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.
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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
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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.
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Ellis, Samuel. "Investigating enteroaggregative Escherichia coli virulence factors in human intestinal infection." Thesis, University of East Anglia, 2018. https://ueaeprints.uea.ac.uk/69931/.
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Enteroaggregative Escherichia coli (EAEC) are a major cause of diarrhoeal illness in children, travellers, and the immunocompromised, and associated with foodborne outbreaks worldwide. However, EAEC is a heterogeneous pathotype with frequent asymptomatic carriage and a diversity of virulence factors. Previous studies have been unsuccessful in identifying genetic virulence markers. In this study, two complimentary approaches were applied using intestinal infection models to investigate bacterial factors contributing to EAEC pathogenesis in the human gut. Firstly, the influence of intestinal environmental signals on the expression of putative EAEC virulence genes was evaluated using a vertical diffusion chamber (VDC). Aerobic oxygen levels increased expression of the adhesins aggregative adherence fimbriae II (AAF/II) and E. coli common pilus, the colonisation factor dispersin, and the global transcriptional activator AggR in prototype strain 042. Furthermore, adherence to polarised T84 intestinal epithelial cells significantly enhanced the expression of adherence factors (AAFs and dispersin), toxins (HlyE, EAST-1, Pet) and the Pic mucinase. This induction required host cell binding and was independent of AggR regulation. Based on these findings, it is proposed that EAEC adherence factors are induced by proximity to the oxygen diffusion gradient across the gut epithelium, while epithelial cell contact activates expression of further virulence factors. As an alternative approach to identify EAEC pathogenicity markers, virulence-associated phenotypes and genotypic profiles were determined for EAEC sequence types associated with disease (ST40) or carriage (ST31). ST40 isolates exhibited significantly higher biofilm formation and adherence to T84 cells and human colonic biopsies. The genotype comparison identified differences in virulence genes associated with epithelial colonisation and induction of host inflammatory responses between both sequence types. Overall, this project has revealed that EAEC virulence gene expression is modulated by intestinal environmental signals and identified phenotypic and genotypic traits specific for EAEC sequence types associated with disease or carriage.
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Nunes, Kamila Oliveira. "Relações filogenéticas entre Escherichia coli enteroagregativa e uropatogênica." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/42/42132/tde-16082016-141428/.
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Escherichia coli isoladas de infecções do trato urinário (ITU) são conhecidas como E. coli uropatogênicas (UPEC). Dentre as E. coli diarreiogênicas, o patótipo denominado E. coli enteroagregativa (EAEC) é definido pela produção do padrão de adesão agregativa em células epiteliais cultivadas. Estudos recentes mostraram que algumas cepas de UPEC albergam propriedades de virulência de EAEC, indicando que cepas de EAEC podem causar ITU. Assim sendo, o objetivo deste estudo foi analisar as relações filogenéticas entre cepas de EAEC que apresentam marcadores genéticos de E. coli extraintestinais (ExPEC) e cepas de UPEC com e sem marcadores genéticos de EAEC. Para tal, foram selecionadas 92 EAEC, 8 UPEC com e 10 sem marcadores de EAEC. As 92 EAEC foram analisadas quanto à presença dos genes considerados como marcadores de cepas de ExPEC (papA/papC, sfa/foc, afa/dra, iutA, kpsMT II), detectando 30 (32,6%) cepas com esse perfil. Estas 30 cepas foram selecionadas para análises de filogrupos e multilocus sequence type (MLST) junto às cepas de UPEC. Foi observado que 17 (54,4%) cepas de EAEC e 3 (16,6%) de UPEC pertenceram ao filogrupo A, 2 (6,45%) EAEC e 1 (5,5%) UPEC ao filogrupo B1, 3 (9,68%) EAEC e 8 (44,4%) UPEC ao filogrupo B2, 6 (19,35%) EAEC e 2 (11,1%) UPEC ao filogrupo D, 1 (3,2%) EAEC e 4 (22,2%) UPEC ao filogrupo E, 1 (3,2%) EAEC ao filogrupo F e 1 EAEC (3,2%) não pôde ser classificada de acordo com esta metodologia. Comparando os dois grupos de UPEC notou-se que dentre as cepas com marcadores de EAEC 3 (37,5%) pertenceram ao filogrupo E, 2 (25%) aos filogrupos A e D e 1 (12,5%) ao filogrupo B1. Dentre as cepas sem marcadores de EAEC 1 (10%) pertenceu ao filogrupo A, 1 (10%) ao filogrupo E e 8 (80%) ao filogrupo B2. As análises de MLST através do sequenciamento dos genes recA, fumC, icd, mdh, purA, adk e gyrB permitiram determinar 42 sequence types (ST) distintos, dos quais 22 foram descritos neste estudo. Os mais comuns foram o ST 10 (5 cepas) e ST 95 e ST 746 (ambos com 2 cepas cada). A árvore filogenética gerada confirmou esses dados, mostrando o grupamento das cepas de EAEC com marcadores de ExPEC com as cepas de UPEC com marcadores de EAEC. Em resumo, o presente estudo mostrou que um subgrupo de cepas de EAEC está inserido nos mesmos grupos filogenéticos de cepas de UPEC com marcadores de EAEC apresentando, portanto, correlação filogenética. Houve diferenças de distribuição filogenética entre cepas de UPEC com e sem marcador de EAEC. Concui-se que cepas de EAEC podem apresentar potencial uropatogênico, tanto no curso de uma infecção diarreica, quanto em carreadores assintomáticos.Escherichia coli isolated from urinary tract infections (UTI) are known as uropathogenic E. coli (UPEC). Among the diarrheagenic E. coli, the enteroaggregative E. coli (EAEC) pathotype is defined by the production of the aggregative adherence on cultured epithelial cells. Recent studies have shown that some UPEC strains harbor virulence properties of EAEC, indicating that EAEC strains can cause UTI. Therefore, the aim of this study was to analyze the phylogenetic relationships among EAEC strains that have genetic markers of extraintestinal E. coli (ExPEC) and UPEC strains, with and without genetic markers of EAEC. For that reason, we selected 92 EAEC, 8 UPEC with and 10 without EAEC markers. The 92 EAEC were analyzed for the presence of genes considered as markers for ExPEC strains (papA/papC, sfa/foc, afa/dra, iutA, kpsMT II), detecting 30 (32.6%) strains with that profile. These 30 strains were selected for phylogroup and multilocus sequence type (MLST) analysis with the UPEC strains. It was observed that 17 (54.4%) EAEC and 3 (16.6%) UPEC belonged to the phylogroup A, 2 (6.45%) EAEC and 1 (5.5%) UPEC to the phylogroup B1, 3 (9.68%) EAEC and 8 (44.4%) UPEC to the phylogroup B2, 6 (19.35%) EAEC and 2 (11.1%) UPEC to the phylogroup D, 1 (3.2%) EAEC and 4 (22.2%) UPEC to the phylogroup E, 1 (3.2%) EAEC to the phylogroup F and 1 (3.2%) EAEC could not be classified according to this methodology. Comparing the two groups of UPEC it was observed that among the UPEC strains with EAEC markers, 3 (37.5%) belonged to the phylogroup E, 2 (25%) to the phylogroups A and D and 1 (12.5%) to the phylogroup B1. Among the UPEC strains without EAEC markers, 1 (10%) belonged to the phylogroup A, 1 (10%) to the phylogroup E and 8 (80%) to the phylogroup B2. The MLST analysis by sequencing of recA, fumC, icd, mdh, purA, adk and gyrB genes allowed to determine 42 distinct sequence types (ST), of whom, 22 were described in this study. The most common were ST 10 (5 strains), and ST 95 and ST 746 (both with two strains each). The phylogenetic tree generated confirmed that data, showing the clustering of EAEC strains (harboring ExPEC markers) with the UPEC strains (harboring EAEC markers). In summary, the current study showed that a subgroup of EAEC strains are clustered in the same phylogenetic groups of UPEC strains with EAEC markers and, thus, present phylogenetic correlation. Also, there were differences in phylogenetic distribution among UPEC strains with and without EAEC markers. In conclusion, EAEC strains may have uropathogenic potential, either in the course of a diarrheal infection or in asymptomatic carriers.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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, αs1-casein, immunoglobulin chains, and MFGM polypeptides in sow milk and colostrum were shown to be able to bind K88ab pili. Additionally, αs1-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 αs1-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.
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Chu, Pui-shan, and 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.
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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
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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.
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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.
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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.
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Barletta, Francesca, Theresa J. Ochoa, Erik H. Mercado, Joaquim Ruiz, Lucie Ecker, Giovanni Lopez, Monica Mispireta, Ana I. Gil, Claudio F. Lanata, and 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.
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theresa.j.ochoa@uth.tmc.eduArticle
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.
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Jenkins, Claire. "The human antibody response to infection with verocytotoxin-producing Escherichia coli." Thesis, Open University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340706.
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Junior, Silvio Marciano da Silva. "Caracterização de Escherichia coli uropatogênicas isoladas de crianças com infecção urinária." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-05072012-104130/.
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Infecção do Trato Urinário (ITU) é o segundo tipo de infecção bacteriana mais comum em crianças. Nesse estudo amostras de urina de 6012 pacientes pediátricos foram analisadas, a prevalência de ITU foi determinada, os uropatógenos foram identificados e o perfil antimicrobiano dos mesmos foi determinado. Os resultados mostraram que a prevalência de ITU varia de acordo com o sexo e a idade do paciente. Bactérias Gram-negativas foram responsáveis por 89 % de todos os casos de ITU e Escherichia coli foi a espécie mais prevalente. Os uropatógenos foram resistentes a ampicilina 63 %, a nitrofurantoina 37 % e ao trimethoprim-sulfamethoxazole 28 %. Todavia, 99 % deles foram sensíveis a cefalexina e 96 % ao cloranfenicol. Resultados obtidos com a caracterização de 90 isolados de E. coli, mostraram que todas as amostras foram positivas para os marcadores fimA e fimH, 53 % para pap, 32 % para sfa, 10 % para o marcador genético da toxina pic e 29 % foram capazes de produzir hemolisina-a. Esses isolados se distribuíram entre os grupos filogenéticos da seguinte maneira: B2 42 %, D 25 %, A 21 % e B1 11 %. Dessas amostras 19 % não foram tipáveis (ONT), 15,56 % pertenceram ao sorogrupo O2 e 12,22 % aos sorogrupos O6 e OR. A maioria dos isolados de E. coli aderiu às células epiteliais, poliestireno e PVC.Urinary Tract Infection (UTI) is the second most common type of bacterial infection in children. In this study, 6012 urine samples from pediatric patients were analyzed, the prevalence of UTI was determined, the uropathogens were identified and their antimicrobial profile was determined. The results have shown that the prevalence of UTI varies according to the sex and age of the patient. Gram negative bacteria were responsible for 89 % of all cases of UTI and E. coli was the most prevalent species. The uropathogens were resistant to: ampicillin 63 %, nitrofurantoin 37 % and trimethoprim-sulfamethoxazole 28 %. However, 99 % of them were sensitive to cephalexin and 96 % to chloramphenicol. Results obtained with the characterization of 90 isolates of E. coli showed that all of them were positive for fimA and fimH, 53 % were positive for pap, 32 % were positive for sfa, 10 % were positive for the genetic marker of pic and 29 % were able to produce hemolysin-a. These isolates were distributed between the phylogenetic groups as follows: B2 42 %, D 25 %, A 21 % and B1 11 %. Nineteen percent of these samples were untypeable (ONT), 15.56 % belonged to O2 serogroup and 12,22 % belonged to the O6 and OR serogroups. Most E. coli isolates were able to adhere to epithelial cells, polystyrene and PVC.
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Colby, Susan Mary. "Pathogenicity studies on verocytotoxin-producing Escherichia coli : bacterial adhesion, toxin expression and uptake." Thesis, University of Warwick, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387370.
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Rochon, Kateryn, and University of Lethbridge Faculty of Arts and Science. "Persistence and significance of E. Coli in house flies (Musca Domestica) and stable flies (Stomoxys Calcitrans)." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2003, 2003. http://hdl.handle.net/10133/233.
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The persistance of Escherichia coli in the larval, pupal and adult stages of both house flies, Musca domestica (L.), and stable flies, Stomoxys calcitrans (L). was examined. Abundance of E.coli declined over time in immature house flies, but remained constant in immature stable flies, suggesting house fly larvae digest E. coli but stable fly larvae do not. Survival of house fly and stable fly larvae averaged 62% and 25% respectively when reared on pure E. coli cultures. E. coli load in pupae decreased significantly one day before emergence of adult house flies, but remained constant until stable fly emergence. Nevertheless, E. coli was detected in 78% of emerging house flies and in 28% of emerging stable flies. House flies are more important E. coli vectors as adults, whereas stable flies may be overlooked vectors of E. coli during immature development.ix, 89 leaves ; 28 cm.
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Aimutis, William R. "The role of mucin in establishment of Escherichia coli in porcine small intestine." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/53860.
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Mucin was isolated for incorporation in bacteriological media by reduction and proteolysis of mucous gel from porcine small intestine. Mucin prepared in this study contained (by weight) 37.2% protein, 58.7% carbohydrate (4.6% fucose, 9.4% mannose, 10.7% sialic acid, 13.5% galactose, and 20.5% hexosamine), and 3.7% ester sulfate. Fractionation of mucin on Sepharose CL-4B yielded one peak which eluted at the void volume. However, sodium dodecyl sulfate gel electrophoretic patterns contained 9 polypeptide bands of which 6 stained with periodic acid—Schiff reagent. Proline, serine, and threonine residues accounted for 26% (by weight) of the total protein in the preparation. Half-cysteine residues made up another 1%. Intrinsic viscosity of mucin prepared by reduction and proteolysis was 135 ml/g.
Mucin was incorporated into a minimal bacteriological medium as the sole-source of carbon and nitrogen. Enterotoxigenic and non-enterotoxigenic Escherichia coli grew equally well in mucin medium at levels comparable to growth in 3 mM glucose medium. Growth did not appear to be limited by availability of metabolizable substrates. Spent mucin medium supported growth in comparable numbers. E. coli P-155 produced heat-stable and heat-labile enterotoxins during growth in both mucin medium and fresh mucosal scrapings medium. E. coli utilized total hexose and protein in mucin medium at comparable levels (6 to 10%). Increases in reducing end groups (0.28 μ moles/ml) and free amino sugar end groups (0.04 μmoles/ml) during growth were detected. E. coli used approximately 15% of the total carbohydrate in mucin medium including 36% of the galactose, 15% of the fucose, and 27% of the mannose. Utilization of mucin by QL ggli produced minor changes in gel filtration patterns on Sepharose CL-4B.
Twelve strains of E. coli were examined for glycosidase activity during growth on mucin. All twelve produced a cell-bound and an extracellular α-fucosidase although the majority of activity was cell-bound. Although α-fucosidase was a constitutive enzyme of E. coli P-155, maximum activity was observed during exponential growth in mucin medium. Eleven strains produced cell-bound α-galactosidase. No extracellular activity of this enzyme was detected. Maximum levels of induced α-galactosidase activity were obtained in late exponential to early stationary growth of E. coli. E. coli ATCC 23723, a mutant of E. coli K12 lacking the galactoside permease gene, did not produce α-galactosidase activity during growth on mucin. No α-mannosidase activity was detected using nitrophenylmannoside as substrate.
Porcine small intestinal mucin was a positive chemoattractant for E. coli in capillary assays. Optimal chemotactic response by E. coli P-155 in capillary experiments was obtained at a mucin concentration of 1 mg dry wt/ml at a pH of 7.0. Spent mucin was still a positive chemoattractant for E. coli P-155 and 123 despite losing 15% of the total mucin carbohydrate.Ph. D.
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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.
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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 uropathogensTiivistelmä 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
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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.
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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 INFECTIONSSACCHAROMYCES 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
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Ree, Johannes Mathijs de. "Molecular and serological characterization of p fimbriae from uropathogenic escherichia coli." Maastricht : Maastricht : Rijksuniversiteit Limburg ; University Library, Maastricht University [Host], 1986. http://arno.unimaas.nl/show.cgi?fid=5322.
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Launay, Adrien. "Etude de l'émergence de la diversité d'Escherichia coli in vivo par séquençage de génomes complets." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066692/document.
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Escherichia coli est une espèce commensale du tube digestif, mais elle peut aussi se révéler être un dangereux pathogène intra ou extra intestinal. Un même clone pouvant passer d'un état commensal à pathogène, la compréhension des mécanismes impliqués dans la diversification d'E. coli dans ces deux habitats représente un enjeu majeur de santé publique. Des expériences d'évolution expérimentale utilisant E. coli ont permis de révéler différentes facettes de l'adaptation bactérienne. Cependant, ces expériences de laboratoire utilisant des conditions artificielles, on peut s'interroger sur la pertinence des observations qui en découlent en milieu naturel et plus globalement s’interroger sur la part de la sélection naturelle dans la diversification de E. coli dans la nature. Pour répondre à ces questions, j'ai analysé les profils génomiques de diversification de E. coli au cours (1) d’une adaptation au tube digestif de souris ou (2) dans des infections extra-intestinales. Dans les deux cas, j’ai pu montrer une importante convergence au niveau du gène : un même gène étant muté plusieurs fois indépendamment, un signe que l’adaptation est active. Dans les infections aigues, des mutations touchant des régulateurs globaux ont été retrouvées, alors que dans le tube digestif les cibles de l’adaptation semblaient plus spécifiques. Enfin, les échantillons issus des infections incluant des souches a fort taux de mutation dites mutatrices, j'ai pu documenter pour la première fois la génomique de l'émergence de bactéries mutatrices en milieu naturel.En conclusion, mes travaux montrent que l’adaptation joue un rôle important dans la diversification de E. coli en milieu naturel et que ce processus s’apparente à celui observé dans des milieux artificiels de laboratoire. L’adaptation semble néanmoins plus active en conditions d’infections aigues que dans le tube digestif de sourisEscherichia coli is a commensal species living in the digestive tract of vertebrates, but can also be a harmful pathogen involved in both intra and extraintestinal diseases. As clones can behave both as commensals and pathogens, the comprehension of the mechanisms involved in the diversification of E. coli in those two habitats represents a major public health concern. In vitro experimental evolution studies using E. coli have unraveled the different faces of bacterial adaptation. However, as those experiments used artificial conditions, the relevance of these observations and more generally the contribution of adaptation to the diversification of E. coli in the wild remain questionable. To answer these questions, I analyzed the genomic profiles of diversification of E. coli during (1) adaptation to the mice digestive tract or (2) during acute extraintestinal infections. In both cases, I found a strong convergence at the gene level, i.e. observation of several impendent mutations in the same gene, suggesting a dynamic adaptation. In acute infections, mutations in global regulators were recovered, while more specific genes were recruited in the mice gut. Finally, the existence of clones with high mutation rate in the infections, allowed me to document for the first time the genomics of mutator emergence in the wild. In conclusion, my work shows that adaptation is playing an important role in the diversification of E. coli, and that this process is fairly similar to the one observed in the laboratory. Nevertheless, adaptation seems more active during infections than in the mice gut
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Takahashi, Akira. "Molecular epidemiological studies of Escherichia coli isolates obtained from lower urinary tract infections." Kyoto University, 2010. http://hdl.handle.net/2433/120579.
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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/.
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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.
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GAUDIN, MARIELLE. "L'infection urinaire basse, non compliquee, chez la femme en periode d'activite genitale : audit sur la conduite a tenir aupres de 30 medecins generalistes des pays de loire." Angers, 1993. http://www.theses.fr/1993ANGE1072.
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VALERO, MARIA. "Portage sain d'escherichia coli chez le nouveau-ne en maternite : opportunite du traitement antibiotique." Toulouse 3, 1993. http://www.theses.fr/1993TOU31011.
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Bernier-Febreau, Christine. "Identification et caractérisation de facteurs de pathogénicité produits par les Escherichia coli entéroagrégatifs." Paris 7, 2003. http://www.theses.fr/2003PA077012.
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Wilt, Heather Dawn. "Supplementation of zinc and biotin : effect on growth performance, plasma and fecal zinc concentrations, and metabolic capacities and biochemcal phenotypes of fecal flora in nursery pigs /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426115.
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