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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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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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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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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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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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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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Nayak, Rajesh R. "Foodborne pathogens in poultry production and post-harvest control." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1266.
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Thesis (Ph. D.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains x, 180 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
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Khachatryan, Artashes Ruben. "Mechanisms responsible for the maintenance of high prevalence of antimicrobial drug resistant Escherichia coli in dairy calves." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Dissertations/Fall2005/a%5Fkhachatryan%5F121205.pdf.
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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.
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Paiva, e. Brito M. A. V. "Use of B subunit of Escherichia coli thermo-labile enterotoxin as a vehicle of mucosal immune stimulation." Thesis, University of Bristol, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234873.
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Månsson, Lisa. "Visualizing the dynamic interplay between the host and bacterial pathogen : a real-time study of renal infection /." Stockholm, 2007. http://diss.kib.ki.se/2007/978-91-7357-218-7/.
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Mariano, Valeria. "A study of tetracycline resistant Escherichia coli in impala (Aepyceros melampus) and their water sources." Diss., Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-02192009-140903/.
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Barbato, Leandro. "Detecção e caracterização de bactérias gram-negativas produtoras de b-lactamases de espectro estendido (ESBL) e AmpC plasmidial isoladas de animais de companhia e búfalos no Estado de São Paulo." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/42/42132/tde-18062013-114347/.
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O presente trabalho teve como objetivo realizar um estudo de vigilância epidemiológica de bactérias MR em isolados obtidos de amostras de búfalo de bubalinocultura e em animais de estimação apresentando sinais e sintomas clínicos de infecção urinária. O estudo relata resultados inéditos referentes à disseminação de bactérias MR, com alto índice de resistência a antimicrobianos de uso clínico e do agronegócio, constituindo o primeiro reporte mundial da emergência de cepas de Escherichia coli produtoras de b-lactamases de amplo espectro (ESBL) do tipo CTX-M-8 e AmpC plasmidial (pAmpC) CMY-2 na bubalinocultura e a presença de cepas de E. coli produtoras de ESBL do tipo CTX-M-15, CTX-M-8 e CTX-M-2, e pAmpC CMY-1, CMY-2 e DHA-1 em animais de companhia é relatada pela primeira vez no Brasil. Nos isolados de E. coli ESBL positivos, não foi constatada relação clonal. As cepas isoladas de búfalos pertencem aos grupos A e B1 e em animais de companhia foram identificados predominantemente os grupos filogenéticos de alta virulência B2 e D.This study aimed to conduct an epidemiological surveillance on MDR among Gram-negative bacilli recovered from samples from buffalo and in pets exhibiting signs and symptoms related to urinary tract infection. The study reports the spread of MDR bacteria exhibiting a high resistance profile to veterinary- and human-use b-lactams and quinolones, in livestock of buffalos and in pets, constituting the first worldwide report of CTX-M-8-type extended-spectrum b-lactamase (ESBL)- and CMY-2-type plasmid AmpC (pAmpC)-producing E. coli strains in buffalo. Moreover, to the best of knowledge, this is the first report of CTX-M-15-, CTXM-8-, CTX-M-2, CMY-1, CMY-2- and DHA-1-producing E. coli strains in pets in Brazil. With respect to the origin of resistance, we found no clonal relatedness among MDR. E. coli isolates from buffalos belonging to groups A and B1 and in companion animals, the phylogenetic analysis of virulence in E. coli denoted the predominance of the highly virulent phylogenetic groups B2 and D.
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Moura, Rodrigo Assunção. "Estudo das relações clonais entre amostras de Escherichia coli enteropatogênica atípica de origem animal e humana." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/42/42132/tde-02022010-100915/.
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Quarenta e nove amostras EPEC típica (tEPEC) e atípica (aEPEC) pertencentes a diferentes sorotipos, isoladas de humanos e animais (cães, gatos, bovinos, ovinos, coelhos e sagüis) foram investigadas quanto ao perfil de virulência pela PCR e similaridade clonal por Multilocus Sequence Typing (MLST) e Pulsed-Field Gel Electrophoresis (PFGE). O objetivo deste estudo foi verificar se animais atuam como reservatório e fonte infecção de aEPEC para humanos. Os marcadores de virulência analisados revelaram que cepas aEPEC isoladas de animais possuem potencial para causar diarréia em humanos. As técnicas MLST e PFGE revelaram que amostras isoladas de animais e humanos compartilham relações clonais próximas ou idênticas. Estes resultados indicam que os animais estudados atuam como reservatório de aEPEC e representam fonte de infecção para humanos. Pelo fato de humanos, também atuarem como reservatório de aEPEC, ciclos de infecção cruzada animal-humano não podem ser descartados, pois a dinâmica de transmissão entre reservatórios de aEPEC não é muito bem compreendida.Forty-nine typical and atypical EPEC strains belonging to different serotypes, isolated from humans, pets (cats and dogs), farm (bovines, sheep and rabbits) and wild animals (monkeys) were investigated for virulence markers and clonal similarity by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The virulence markers analyzed revealed that atypical EPEC strains isolated from animals have the potential to cause diarrhea in humans. Close clonal relationship between human and animal isolates was found with MLST and PFGE. These results indicate that these animals act as atypical EPEC reservoirs and may represent sources of infection for humans. Since humans also act as a reservoir of atypical EPEC strains, the cycle of mutual infection of atypical EPEC between animals and humans, mainly pets and their owners, cannot be ruled out, since the transmission dynamics between the reservoirs are not yet clearly understood.
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Franco, Andreia da Silva. "Infeção do trato urinário por Escherichia coli em cães e gatos : mecanismos moleculares de resistência aos antibióticos β-lactâmicos." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2017. http://hdl.handle.net/10400.5/13676.
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Dissertação de Mestrado Integrado em Medicina VeterináriaA infeção do trato urinário (ITU) é uma afeção frequentemente observada em clínica de animais de companhia, sendo uma das razões mais comuns para instituição de terapêutica antimicrobiana. Escherichia coli é o principal agente patogénico bacteriano associado a ITU. A resistência antimicrobiana de E. coli aos antibióticos β-lactâmicos representa um problema de saúde pública emergente uma vez que estes são frequentemente utilizados tanto em medicina veterinária como humana. O objetivo deste estudo foi caracterizar estirpes de E. coli isoladas de animais de companhia com ITU quanto aos mecanismos moleculares de resistência aos antibióticos β-lactâmicos e grupos filogenéticos, marcadores de urovirulência/comensalismo. Além disso, pretendeu-se investigar a tendência temporal de resistência à amoxicilina/ácido clavulânico (AMC) e cefalosporinas de terceira geração (C3G) durante um período de 16 anos (1999-2014). A suscetibilidade antimicrobiana de 415 estirpes de E. coli foi determinada pelo método de difusão em disco. Os breakpoints clínicos foram aplicados de acordo com as orientações do Clinical and Laboratory Standards Institute (CLSI). A análise estatística das tendências temporais da resistência antimicrobiana foi determinada pelo modelo de regressão logística do SAS. Um total de 303 estirpes de E. coli foram caracterizadas. O grupo filogenético foi determinado por multiplex-PCR. As estirpes resistentes à AMC foram rastreadas por PCR para deteção de genes que codificam β-Lactamases de Espectro Alargado (Extended-Spectrum Beta-Lactamases, ESBL) (blaTEM, blaSHV, blaOXA-1) enquanto que as estirpes resistentes às C3G foram ainda rastreadas para a presença de ESBL (blaCTX-M) e AmpC (blaMOX, blaCIT, blaDHA, blaFOX, blaMIR, blaACT). Considerando o período de tempo de 1999 a 2014, 16,8% e 11,2% das estirpes eram resistentes à AMC e C3G, respetivamente. Além disso, foi observado um aumento estatisticamente significativo da resistência à AMC (p <0,0001) e C3G (p <0,0001) durante o período do estudo. Nas estirpes de E. coli resistentes a AMC, os genes mais frequentemente detetados foram blaTEM e blaOXA-1. A resistência às C3G deveu-se, principalmente, à presença dos genes blaCTX-M e blaCMY. O filogrupo patogénico B2 foi o mais frequente. O aumento da resistência de E. coli à AMC e C3G observada neste estudo é preocupante, especialmente porque estes são compostos antimicrobianos criticamente importantes (Critically Important Antimicrobials, CIA) para o Homem. Este estudo destaca a importância de uma monitorização contínua dos padrões de resistência, a fim de uma utilização antimicrobiana prudente, uma vez que a resistência bacteriana tem um impacto não só na qualidade de vida do animal de estimação, mas também na saúde humana.
ABSTRACT - Escherichia coli urinary tract infection in dogs and cats: molecular resistance mechanisms to β-lactam antibiotics - Urinary tract infection (UTI) is a frequent clinical problem in companion animals and among the most common reasons for antimicrobial therapy. Escherichia coli is the main bacterial pathogen associated with UTIs. Antimicrobial resistance of E. coli to β-lactam antibiotics is an emerging public health concern since β-lactams are frequently used in veterinary and human medicine. The aim of this study was to characterize E. coli strains isolated from companion animals with UTI for the molecular resistance mechanisms to β-lactam antibiotics and phylogenetic groups, markers of urovirulence/commensalism. Furthermore, it aimed to investigate the temporal trends of antimicrobial resistance to amoxicillin/clavulanate (AMC) and third-generation cephalosporin (3GC) over a period of 16 years (1999-2014). Antimicrobial susceptibility of the 415 E. coli isolates was determined by disk diffusion method. Clinical breakpoints were applied according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Statistical analysis of antimicrobial resistance temporal trends was determined by logistic regression model of SAS. A total of 303 E. coli were further characterized. The determination of E. coli phylogenetic group was conducted by multiplex PCR. AMC resistant isolates were screened by PCR for ESBL (blaTEM, blaSHV, blaOXA-1) and 3GC resistant isolates were further screened for the presence of Extended-spectrum β-lactamases (ESBL) (blaCTX-M) and AmpC (blaMOX, blaCIT, blaDHA, blaFOX, blaMIR, blaACT). Considering the 1999-2014 time period, 16.8% and 11.2% were resistant to AMC and 3GC, respectively. Furthermore, statistically significant increase of the resistance to AMC (p<0.0001) and 3GC (p<0.0001) was observed during the study period. Among AMC resistant E. coli, blaTEM and blaOXA-1 were the most detected genes. 3GC resistance was mainly due to the presence of blaCTX-M and blaCMY. The pathogenic phylogroup B2 was the most frequent. The significant increase in E. coli AMC and 3GC resistance over time observed in the study is worrying, especially because these are critically important antimicrobials (CIA) for humans. This study highlights the importance of a continuous monitoring of the resistance patterns in order to use antibiotics prudently, since bacterial resistance has an impact not only on companion animal’s quality of life, but also on human health.
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Mallick, Emily M. "A New Murine Model For Enterohemorrhagic Escherichia coli Infection Reveals That Actin Pedestal Formation Facilitates Mucosal Colonization and Lethal Disease: A Dissertation." eScholarship@UMMS, 2012. https://escholarship.umassmed.edu/gsbs_diss/601.
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Enterohemorrhagic Escherichia coli (EHEC) colonizes the intestine and produces the phage-encoded Shiga toxin (Stx) which is absorbed systemically and can lead to hemolytic uremic syndrome (HUS) characterized by hemolytic anemia, thrombocytopenia, and renal failure. EHEC, and two related pathogens, Enteropathogenic E. coli (EPEC), and the murine pathogen, Citrobacter rodentium, are attaching and effacing (AE) pathogens that intimately adhere to enterocytes and form actin “pedestals” beneath bound bacteria. The actin pedestal, because it is a unique characteristic of AE pathogens, has been the subject of intense study for over 20 years. Investigations into the mechanism of pedestal formation have revealed that to generate AE lesions, EHEC injects the type III effector, Tir, into mammalian cells, which functions as a receptor for the bacterial adhesin intimin. Tir-intimin binding then triggers a signaling cascade leading to pedestal formation. In spite of these mechanistic insights, the role of intimin and pedestal formation in EHEC disease remains unclear, in part because of the paucity of murine models for EHEC infection. We found that the pathogenic significance of EHEC Stx, Tir, and intimin, as well as the actin assembly triggered by the interaction of the latter two factors, could be productively assessed during murine infection by recombinant C. rodentium expressing EHEC virulence factors. Here we show that EHEC intimin was able to promote colonization of C. rodentium in conventional mice. Additionally, previous in vitro data indicates that intimin may have also function in a Tir-independent manner, and we revealed this function using streptomycin pre-treated mice. Lastly, using a toxigenic C. rodentium strain, we assessed the function of pedestal formation mediated by Tir-intimin interaction and found that Tir-mediated actin polymerization promoted mucosal colonization and a systemic Stx-mediated disease that shares several key features with human HUS.
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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.
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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
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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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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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Hunter, Jane Elizabeth Bryson. "Apramycin-resistant Escherichia coli in farm animals and man." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358989.
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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.
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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.
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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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Silva, Pedro Guilherme Braz Pinto. "Dynamics of companion animal to human transmission of antimicrobial resistance, during skin and soft tissue companion animal infection." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2021. http://hdl.handle.net/10400.5/21490.
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Dissertação de Mestrado Integrado em Medicina VeterináriaABSTRACT - Objective: This study aims to characterize the dynamics of antibiotic resistance gene transmission in dogs with skin and soft tissue infections (SSTI) and human beings co habiting with them. We also aim to evaluate the gut colonization of these individuals for the presence of extended spectrum beta-lactamases (ESBL’s) in Enterobacteriaceae and to assess the effect of antibiotherapy on the selection of MDR bacteria from human and canine gut microbiota. Methods: Two types of biological samples were gathered in a teaching veterinary hospital in Portugal, at the dermatology department, from twelve dogs diagnosed with SSTI and their household members. Collections included a swab from the infection site (ISS) and a faecal sample (FS). Gathering of samples was performed at two different times. The ISS were cultured and an AST was performed. The FS was also cultured, and the bacteria isolated subjected to molecular analysis. Antibiotic resistance patterns were obtained by disk diffusion antimicrobial susceptibility’s testing and Enterobactereaceae ESBL’s production was confirmed by amplification of the specific gene by PCR and sequencing. Results: High levels of Methicillin resistant Staphylococcus pseudintermedius (MRSP) were isolated, and high levels of other multidrug resistant bacteria (MDR) as well. One family was suspected of carrying the same E. coli clone, shared by two humans and one dog of the same household, with a blaCTX-M-15 gene. All of the isolated Enterobactereaceae displayed susceptibility to carbapenems. The most common ESBL genes found were from the blaCTX-M group, followed by blaOXA-1 and then blaTEM, no gene from the blaSHV gene was found. Conclusions: There is a high prevalence of ESBL-producing E. coli. Interspecies transmission of antimicrobial resistance is real. This issue should be addressed with introduction of antimicrobial stewardship strategies on a wider scale and better use of antimicrobials like chlorohexidine, especially in SSTI.
RESUMO - Esta dissertação enquadra-se nos objetivos de um projeto muito maior e ainda mais ambicioso, chamado PetRisk. Pretende-se analisar o impacto e as interações dos genes de resistência aos antibióticos, percebendo de que forma as barreiras interespécie podem ser ultrapassadas. Assim sendo, o estudante integrou o núcleo desse mesmo empreendimento em Portugal, o Laboratório de Resistência aos Antibióticos da FMV-UL, liderado pela Professora Doutora Constança Pomba. Objetivo: Este estudo teve como objetivo principal compreender a dinâmica de transmissão de genes de resistência aos antibióticos, entre cães com infeção de pele e tecidos moles e as pessoas com quem vivem em regime de co-habitação. Pretendeu-se avaliar a colonização do tubo digestivo desses mesmos indivíduos quanto à presença de Enterobactereacea produtoras de beta-lactamases de largo expectro e verificar o efeito da antibioterapia na seleção de estirpes multiresistentes da microbiota intestinal canina e humana. Outro obejtivo da realização deste trabalho é o de aumentar os recursos biológicos – com isto subentende-se, bactérias de diferentes agregados familiares e o seu perfil de resistência aos antimicrobianos – para o projeto mãe, o PetRisk. Métodos: Para tal, recolheram-se dois tipos de amostras biológicas no departamento de dermatologia do hospital veterinário escolar da FMV-ULisboa. A amostra inclui doze cães com infeções de pele e tecidos moles, assim como os restantes membros do seu agregado familiar. Os materiais recolhidos foram zaragatoas do local de infeção (ZLI) e amostras fecais (AF). As colheitas decorreram em dois tempos diferentes. Às ZLI após cultura microbiológica realizaram-se testes de suscetibilidade aos antibióticos de rotina. Os isolados provenientes das AF foram sujeitos a cultura microbiológica e análise molecular. Os padrões de resistência aos antibióticos foram obtidos pelo método de difusão de discos e a confirmação da produção das beta-lactamases de largo expectro pelas Enterobactereaceae por amplificação do respetivo gene por PCR e sequenciação. Resultados: Foram encontrados elevados níveis de Staphylococcus resistentes à meticilina, assim como a resistência a multiplos antibióticos. Também as nas Escherichia coli provenientes das AF foram encontrados elevados nívreis de resistência a múltiplos antibióticos. Uma familia foi suspeita de partilhar o mesmo clone de E.coli (duas pessoas e um cão) com o mesmo filogrupo e o gene blaCTX-M-15. Todas as Enterobactereaceae isoladas demonstraram suscetibilidade aos carbapenemos. Os genes de beta-lactamases de largo expectro detetados foram (da maior para a menor frequência): blaCTX-M , blaOXA-1 e blaTEM, com nenhum registo de blaSHV. Conclusões: Existe uma elevada prevalência de E. Coli produtoras de beta-lactamases de largo expetro. A transmissão de informação genética inter-espécies é uma realidade. A prática clínica beneficiaria de uma administração mais prudente e integrada de antibióticos, com uma equipa a trabalhar apenas para a gestão destes recursos num hospital, assim como maior atenção ao uso de antisséticos como a clorohexidina, especialmente em infeções de pele e tecidos moles onde os produtos disponivéis são de fácil aplicação.
N/A
25
Wong, Chun-wai. "Antimicrobial resistance in Escherichia coli isolated from food animals and humans." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557935.
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Wong, Chun-wai, and 黃振威. "Antimicrobial resistance in Escherichia coli isolated from food animals and humans." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557935.
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Chan, Jane, and 陳曉婷. "Molecular epidemiology of fosfomycin-resistant Escherichia coli from humans and animals." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/197077.
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The diminishing choice of effective antibiotics against resistant pathogens has forced clinicians to revive the use of old antibiotics. Hence, fosfomycin has been frequently suggested for alternative therapies given its track record of low resistance rates despite extensive use. However, there have been recent reports of plasmid-mediated fosfomycin resistance among animals and healthy humans in Asia. Accordingly, comparison of shared fosfomycin resistance mechanisms between animals and humans will shed light on the spread of resistance and guide future use of antimicrobials.
This study aimed to investigate plasmid-mediated fosfomycin resistance in E. coli isolates collected from patients and animals in Hong Kong. Non-duplicate E. coli isolates were cultured from 1711 urinary isolates and 167 blood clinical samples collected from multiple centres during 1996-2008 and from fecal samples of 210 cattle, 214 pigs, 460 chickens, 398 stray cats, 368 stray dogs and 456 wild rodents during 2008-2010.
A total of 2106 animal samples yielded 1693 E. coli isolates of which 831 were ESBL-producers. Fosfomycin-resistant isolates were more likely than fosfomycin-susceptible isolates to be ESBL-producers and multidrug resistant (≥3 antimicrobial classes). Of the 101 fosfomycin-resistant isolates, 97 (96.0%) were fosA3 positive and 94 (93.1%) were blaCTX-M positive. Of the 1878 clinical isolates, 18 were fosfomycin-resistant of which six were fosA3-positive and two were positive for another fosA variant (designated fosKP96). All but one fos-carrying clinical isolate was ESBL-producing. The majority of the fos-carrying E. coli strains belonged to diverse clones under two main clonal complexes CC58 accounting for 38 (36.2%) strains and CC10 for 32 (30.5%) strains.
PCR mapping showed that all fosA3-containing regions were followed by a downstream IS26. In all clinical isolates and 81 (83.5%) of animal isolates, an IS26 was also found upstream. In 14 (14.4%) of animal isolates, the fosA3 gene was preceded by an upstream blaCTX-M-14-containing transposon-like structure (ΔISEcp1-blaCTX-M-14-ΔIS903 or ISEcp1-IS10-blaCTX-M-14-ΔIS903). For the remaining two animal isolates, the upstream region could not be defined.
In a random subset of 18 animal isolates, fosA3 was carried on transferable plasmids with sizes of 50–200 kb and the following replicons: F2:A-:B- (n = 3), F16:A1:B- (n = 2), F24:A-B- (n = 1), IncHI2 (n = 3), IncN (n = 2), IncI1 (n = 1), B/O (n = 1) and untypeable (n = 5). Among six fosA3-carrying clinical isolates, the distributions were: F2:A-:B- (n = 2), IncN (n = 1), multi-replicon F-:A-:B1/IncN (n = 1) and untypeable (n = 2). Both fosKP96-carrying plasmids belonged to IncN. Restriction fragment length polymorphism analysis showed that the four F2:A-:B- plasmids carrying fosA3 and blaCTX-M-3 genes from a pig, dog and two patients shared an almost identical pattern. The complete plasmid sequences further demonstrated their homology.
This study demonstrated the emergence of fosA3-mediated fosfomycin resistance among E. coli isolates from multiple sources. Highly similar IncFII plasmids and IS26 transposon-like structures appear to be the main vehicles for dissemination. This study also highlighted occurrence of plasmids carrying fosKP96 that may have been overlooked by others as this variant could not be detected by established PCR markers.published_or_final_version
Microbiology
Master
Master of Philosophy
28
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.
30
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
31
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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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.
33
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.
34
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.
Full textAbstract:
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
35
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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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.
37
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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Duan, Rongshuai. "Extended-spectrum beta-lactamases in fecal isolates of Escherichia coli from human and food animals." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B35301648.
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Leung, Lai-ming, and 梁麗明. "Molecular epidemiology of 16S rRNA methylase genes in Escherichia colifrom humans and animals." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48334091.
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Background
Aminoglycosides are one of the clinically relevant antibiotics. Plasmid-encoded 16S rRNA methylase enzymes have emerged in clinical isolates of Gram-negative bacteria worldwide. The spread of these resistance determinants has become a great concern.
Objectives
The objectives of this study were to investigate the prevalence of 16S rRNA methylases and aminoglycoside modifying enzyme, AAC(3)-II in Escherichia coli isolated from human blood cultures and faecal samples of animals. E. coli isolates with unexplained aminoglycoside resistance phenotypes were investigated by detection of four aminoglycoside modifying enzymes, AAC(6’)-I, ANT(2”)-I, ANT(4’)-II and APH(3’)-VI.
Methodology
This study included 188 E. coli clinical isolates obtained from blood cultures of patients in one regional hospital between January 2004 and September 2010 and 81 E. coli isolates obtained from faecal samples of chickens, pigs, cattle, cats, dogs and rats between September 2008 and August 2011. All 269 E. coli isolates in this study were screened for the aac(3)-II gene and six 16S rRNA methylase genes(armA, rmtA, rmtB, rmtC, rmtD and rmtE)by two individual sets of multiplex PCR assays. A subset of 88E. coli isolates with aminoglycoside resistance phenotypes, which could not be explained by the genes detected, were subjected to detection of the aac(6’)-Ib, ant(2”)-Ia, ant(4’)-IIaand aph(3’)-Via genes by four individual PCR assays. The transfer of resistance of the rmtB gene was studied by conjugation experiments. The clonal relationship between rmtB-producing strains was investigated by pulsed-field gel electrophoresis.
Results
67.6% (25/37) and 63.4% (26/41) of the Gen-R/Amk-NS group isolates from human and animal sources, respectively, were found to possess the aac(3)-IIgene. The aac(3)-IIgene was also found in 96.7% (146/151) Gen-R/Amk-S group human isolates. 21.6% (8/37) and 61%(25/41) of the Gen-R/Amk-NS isolates from human and animal sources, respectively, were found to possess the rmtB gene. The armA gene was found in one human and one animal isolates, which were both resistant to gentamicin and amikacin. No rmtA, rmtC, rmtD orrmtE genes were found in this study. Among 88E. coli isolates with unexplained aminoglycoside resistance phenotypes, the aac(6’)-Ib gene was found in51.2%(22/43) and 10% (4/40) of the Gen-R/Amk-NS group and the Gen-S/Amk-NS group, respectively. The ant(2”)-Ia gene was found in 11.6% (5/43) of the Gen-R/Amk-NS group E. coli isolates. No ant(4’)-IIa or aph(3’)-Via genes were found. No major PFGE cluster was observed among 32 rmtB-positive isolates by pulsed-field gel electrophoresis.In addition, amikacin resistance could be transferred by conjugation from 12rmtB-positive donors.
Conclusion
The present study showed that the rmtB gene was the most prevalent 16S rRNA methylase gene in both human and animal E. coli isolates. A high incidence of the aac(3)-IIgene was found among gentamicin-resistant strains. The spread of 16S rRNA methylases has aroused clinical concern and become a major therapeutic threat in the future.published_or_final_version
Microbiology
Master
Master of Medical Sciences
40
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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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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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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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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Duan, Rongshuai, and 段榮帥. "Extended-spectrum beta-lactamases in fecal isolates of Escherichia coli from human and food animals." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B35301648.
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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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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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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.
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Mestrado em MicrobiologiaEscherichia 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.
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Lo, Wai-u., and 羅慧瑜. "Epidemiology of CTX-M type extended-spectrum beta-lactamases in escherichia coli isolates from human and animals." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46923184.
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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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