Dissertations / Theses on the topic 'Plasmid resistance'
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Udo, Edet Ekpenyong. "Characterisation and molecular studies of plasmids from Nigerian staphylococci." Thesis, Curtin University, 1991. http://hdl.handle.net/20.500.11937/1845.
Full textBERTINI, ALESSIA. "Plasmid-mediated antimicrobial resistance in Gram-negative bacteria." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2008. http://hdl.handle.net/2108/641.
Full textThe epidemiology of resistance plasmids is a major issue for the description of antimicrobial resistance diffusion. The identification of related plasmids associated to specific resistance genes may help to follow the spread of epidemic plasmids, opening new epidemiological scenarios on the mechanism of diffusion of antimicrobial resistance. This aspect is particularly interesting when applied to collections of plasmids that are playing a major role in the diffusions of Extended Spectrum Beta Lactamases (ESBLs) such as CTX-M, SHV, TEM. The aim of this thesis is the molecular characterization of plasmids conferring drug resistances in different collections of Enterobacteriaceae of human and animal origin. Several example of epidemic plasmids will be discussed: the IncHI2 plasmids carrying blaCTX-M-9 or blaCTX-M-2 genes identified from human and animal isolates of Escherichia coli and Salmonella from Spain, Belgium and UK; the IncI1 family of plasmids characterized by specific virulence factors, carrying the blaCMY-2, blaTEM-52 and blaCTX-M-1 genes from Salmonella and E. coli of human and animal origin; the IncN plasmids carrying the gene codifying the metallo-β-lacatamase VIM-1 from human isolates of Klebsiella pneumoniae and E. coli in Greece; the IncA/C2 plasmids carrying specific resistance genes such as blaCMY-2, blaCMY-4, blaVIM-4 and blaVEB-1 from different Enterobacteriaceae isolated worldwide; different plasmid replicons (IncFII, IncA/C1, IncI1) carrying the ESBL SHV-12 from human and animal origin. The comparative analysis of plasmid backbones allowed to ascertain the diffusion of common, emerging plasmids and helped to determine the evolution of these plasmids by acquisition of relevant resistance genes by a panoply of mobile genetic elements and illegitimate recombination events.
Chan, Helena. "Characterisation of a plasmid segregational stability determinant, par, of the staphylococcal multiresistance plasmid, pSK1." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17714.
Full textBottery, Michael J. "The sociality and evolution of plasmid-mediated antimicrobial resistance." Thesis, University of York, 2017. http://etheses.whiterose.ac.uk/19016/.
Full textUdo, Edet Ekpenyong. "Characterisation and molecular studies of plasmids from Nigerian staphylococci." Curtin University of Technology, School of Biomedical Sciences, 1991. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=15648.
Full textby plasmids.Conjugation experiments led to the isolation of three unique conjugative plasmids which have not been found to confer resistance to antimicrobials or to produce haemolysins or diffusible pigment (Dip). The three plasmids, pWBG620, pWBG637 and pWBG661, were indistinguishable by restriction endonuclease analysis and DNA-DNA hybridisation. However pWBG620, unlike pWBG637 and pWBG661, was not detected in the cytoplasm of its host and was only detected in transconjugants after it mobilised a non-conjugative Sm-resistance (SmR) plasmid. Further analysis indicated that it is integrated into the chromosome of its host, excises during conjugation and mobilises the SmR plasmid.These plasmids were studied further using pWBG637 as a representative. It was compared with representatives of the two groups of conjugative plasmids which have been reported in the staphylococci. These are the plasmids which encode resistance to Gm, Km and Nm and those which code for the production of diffusible pigment. The three types of conjugative plasmids were compared by restriction endonuclease analysis and DNA- DNA hybridisation and were found to be different. A preliminary restriction map of pWBG637 has also been constructed.However since pWBG637 has no resistance phenotype direct selection for it was not possible in transfer experiments and for incompatibility (Inc.). To study it further it was necessary to construct resistant derivatives which could be selected for in transfer experiments. This was achieved by labelling pWBG637 with resistance transposons to generate two conjugative plasmids, pWBG636 carrying an insert of Tn3851 (Gm- resistance) and pWBG642 carrying an insert of Tn551 (hn- resistance). It was found that transposon labelling had not changed the incompatibility of pWBG637 and therefore pWBG636 and pWBG642 were used in further experiments in place of pWBG637. Inc. ++
tests with the pWBG637 derivatives revealed that the pWBG637 type of plasmid is not only different from the other two types of conjugative plasmids but is different from any of the described staphylococcal Inc. groups and therefore the pWBG637 type of plasmids represent a new Inc. group 15. The pWBG637 type of plasmids were studied further using plasmids pWBG636 and pWBG642. They were able to transfer conjugatively to a capsulated S.aureus strain either by the polyethylene glycol method or on filter membranes. They also transferred by conjugation to S. epidermidis and Streptococcus faecalis and were able to transfer back from these strains to S.aureus indicating that they also replicate in these hosts. Consequently they have been used to mobilise non-conjugative plasmids from S.epidermidis and non phage typable S.aureus. Both plasmids failed to transfer conjugatively to Bacillus subtilis and Escherichia coli.pWBG637 transferred non-conjugative plasmids by mobilising them in a manner similar to mobilisation (donation) in E.coli or by recombining with them to form new resistance plasmids. In one case, pWBG628 which encodes Bla and resistance to Cd, Km, Nm and Sm and has no homology with pWBG637 recombined with it during conjugation to produce three new conjugative plasmids pWBG629, pWBG630 and pWBG631 carrying resistance determinants from pWBG628. One of these plasmids, pWBG629, was found to be pWBG637 which had acquired a 4.5 kb element encoding resistance to Km, Nm and Sm. This element was shown to be transposable in both rec+ and rec- backgrounds and has been designated Tn3854. It expressed Sm resistance in E.coli and differs on this account from the Gram-negative transposon Tn5 which expresses resistance to Km, Nm and Sm in non-enteric bacteria but only resistance to Km and Nm in E. coli.Where possible the non-conjugative plasmids encoding resistance to ++
antimicrobial agents were compared with phenotypically similar plasmids isolated from other parts of the world. It was found that the Tc and Sm resistance plasmids were closely related to other plasmids with the same phenotype whereas the Cm resistance plasmids were different.Although the majority of the Bla plasmids belonged to Inc. group 1 they demonstrated significant restriction enzyme fragment length polymorphism when compared with other Bla plasmids.This study has provided the first data on the genetics of antimicrobial resistance in Nigerian S.aureus. Although many of the plasmids studied were found to be similar to those previously described the isolates also contained some unique and previously undescribed plasmids.
Coons, Terry M. "Restriction mapping and expression of recombinant plasmids containing the arsenic resistance genes of the plasmid R45." PDXScholar, 1986. https://pdxscholar.library.pdx.edu/open_access_etds/3597.
Full textTavakoli, Norma Parvin. "Characterisation of the plasmid pUB2380 and in particular its transposition system." Thesis, University of Bristol, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386071.
Full textEvans, Jane E. "The conjugation system of Staphylococcus aureus." Thesis, University of Oxford, 1986. https://ora.ox.ac.uk/objects/uuid:1c1f5c11-f854-4af5-b9cf-34fdf279fb28.
Full textEldek, Ahmed. "Antibiotic-Regulated Plasmid Copy Number Variation: A Driver of Antibiotic Resistance?" Thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388523.
Full textKhan, Azra. "An investigation into the association of plasmid-borne qacAB and antimicrobial resistance in meticillin-resistant Staphylococcus aureus." Thesis, University of Portsmouth, 2013. https://researchportal.port.ac.uk/portal/en/theses/an-investigation-into-the-association-of-plasmidborne-qacab-and-antimicrobial-resistance-in-meticillinresistant-staphylococcus-aureus(49b2b0fc-936a-412a-b418-8d9d24d3b531).html.
Full textHamilton, Michelle Ann Elizabeth. "The relationship between plasmid presence, antibiotic resistance and surface structures in Bacteroides." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/28187.
Full textMoran, Robert A. "Characterisation of plasmids in commensal Escherichia coli from healthy Australian adults." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18199.
Full textSaial, Dolores Cristina Conceição. "Use of antimicrobials and cephamicin resistance in companion animals." Master's thesis, Universidade de Lisboa. Faculdade de Medicina Veterinária, 2013. http://hdl.handle.net/10400.5/6251.
Full textObjectives: This work includes two separate studies. In study 1 the aim was to investigate the use of antimicrobials in companion animals in Portugal while in study 2 the objective was to evaluate and characterize the prevalence of blaCMY-2 gene in Enterobacteriaceae and the phylogenetic relatedness among plasmids from companion animals and humans. Materials and Methods: In study 1 in order to understand the patterns of antimicrobial prescription a national survey was submitted to veterinarians. In study 2 plasmids harboring blaCMY-2 were transferred into GeneHog® E. coli by electroporation and typed by S1 endonuclease pulsed-field gel electrophoresis, PCR-based replicon typing, and plasmid multilocus sequence typing (pMLST). Results: In study 1, the use of amoxicillin-clavulanate (28%) and enrofloxacin (18%) were the most common antimicrobials used in dogs and cats, whereas clindamycin (3%) cefovecin (2%) and pradofloxacin (2%) were the less prescribed. In study 2, twenty three blaCMY-2 genes were plasmid encoded. Replicon typing demonstrated that from animal isolates, thirteen isolates were IncFII plasmids, five isolates were IncI1 plasmid, one isolate carried an A/C plasmid and the remaining isolate was non-typeable by PBRT. Regarding human isolates, one isolate was IncFII, one was IncI1 and the third isolate was also non-typeable. IncI1 blaCMY-2 plasmids showed that three were sequence type (ST2), three were non-typeable and fourteen IncFII plasmids were F2;FIA-;FIB- by pMLST. Conclusions and Clinical Importance: This work showed that in order to understand how antimicrobials are prescribed, further studies and implementation of a surveillance system for antimicrobial usage in these species would be recommended. Plasmid encoded resistant genes are an important factor for selection and dissemination of genes such as blaCMY-2. The transmission of resistant genes in humans and animals is due to plasmid encoding which is of great concern, and further research is still necessary to understand about the mechanisms which have led to the rapid spread of resistant bacteria worldwide.
RESUMO - USO DE ANTIMICROBIANOS E RESISTÊNCIA ÀS CEFAMICINAS EM ANIMAIS DE COMPANHIA - Objetivos: Este trabalho inclui 2 estudos. O objetivo do primeiro estudo consistiu em investigar o uso de antimicrobianos em animais de companhia em Portugal enquanto no segundo estudo, o objetivo consistiu na análise e caraterização da prevalência do gene blaCMY-2 em Enterobacteriaceas, ao mesmo tempo que pretendeu determinar a semelhança filogenética dos respetivos plasmídeos, em animais e humanos. Materiais e Métodos: No estudo 1, para compreender os hábitos de prescrição de antimicrobianos em Portugal foi realizado um inquérito nacional aos Veterinários. No estudo 2, os plasmídeos com o gene blaCMY-2 foram transferidos para uma célula electrocompetente GeneHog® E. coli por electroporação, e caraterizados por S1 endonuclease pulsed-field gel electrophoresis, PCR-based replicon typing e plasmid multilocus sequence typing (pMLST). Resultados: No estudo 1, os antimicrobianos mais utilizados em cães e gatos foram a amoxicilina/acido clavulânico (28%) e enrofloxacina (18%). Clindamicina (3%), cefovecina (2%) e pradofloxacina (2%) foram os menos utilizados em ambas as espécies. No estudo 2, vinte e três genes blaCMY-2 estavam codificados em plasmídeos. De acordo com o método replicon typing, os isolados de origem animal, treze pertenciam ao plasmídeo IncFII, cinco estavam codificados no plasmídeo IncI1, um estava presente no plasmídeo A/C e um isolado foi considerado “non-typeable”. Dos 3 isolados humanos, 1 estava incorporado num plasmídeo IncI1, 1 estava inserido no plasmídeo IncFII e o terceiro foi considerado “non-typeable”. Pelo método pMLST, os plasmídeos IncI1 foram caraterizados como ST2, e três foram considerados “non-typeable”. Catorze plasmídeos IncFII foram caraterizados como sendo F2;FIA-;FIB-. Conclusões e Importância Clínica: Para compreender os hábitos de prescrição de antimicrobianos, seriam recomendáveis estudos complementares e a implementação de um sistema de monitorização para o consumo de antimicrobianos nestas espécies. A presença de genes de resistência em plasmídeos é um fator importante para a seleção e disseminação de genes como o gene blaCMY-2. A transmissão destes genes em humanos e animais é mediada por plasmídeos, o que é preocupante. Investigação contínua é pois necessária para entender quais os principais mecanismos que conduziram à disseminação de bactérias com genes de resistência no mundo.
Risley, Claire. "The population dynamics of plasmid-mediated antibiotic resistance in salmonella typhimurium in chickens." Thesis, University of Oxford, 2002. http://ora.ox.ac.uk/objects/uuid:a70bda98-533f-41d0-b9a0-630457b3f982.
Full textArmbruster, Steven C. (Steven Christopher). "Characterization of the OCT Plasmid-Encoded Mercury Resistance Genetic Locus in Pseudomonas putida." Thesis, University of North Texas, 1989. https://digital.library.unt.edu/ark:/67531/metadc500381/.
Full textTatley, Fernanda Maria Palma Ribeiro da Silva. "Characterisation of a replicon of the conjugative, multiple drug resistance, moderately promiscuous, plasmid pGSH500." Thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/25668.
Full textGullberg, Erik. "Selection of Resistance at very low Antibiotic Concentrations." Doctoral thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-235225.
Full textLe, Vien Thi Minh. "Plasmid-mediated quinolone resistance determinants in Enterobacteriaceae isolated in Ho Chi Minh City, Vietnam." Thesis, University of Oxford, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559782.
Full textWang, Chien-Sao. "Molecular Cloning and Functional Analysis of Transposable Mercury Resistance Genes Encoded by the OCT Plasmid." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc501216/.
Full textBernardo, Nerea. "Prevention of the spread of antibiotic resistance via the structural and molecular study of pLS20 conjugative plasmid proteins." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/671044.
Full textLa resistencia a antibióticos está considerada una de las principales amenazas a la salud pública del siglo XXI por la OMS. Debido a su consumo excesivo e incorrecto, las bacterias desarrollan mecanismos para hacerles frente y así, ser capaces de sobrevivir en su presencia. Cuando una bacteria desarrolla el gen que le dota de resistencia, dispone de varios mecanismos para cederlo a las bacterias colindantes. Este proceso es conocido como transferencia horizontal de genes y es la principal causa de la propagación de los genes de resistencia a antibióticos. Podemos distinguir entre 3 subtipos, siendo la conjugación la más común. La conjugación es la transferencia activa de material genético desde una bacteria donante a otra receptora y requiere contacto directo entre células. La característica primordial es la presencia de un plásmido conjugativo. En este trabajo, se ha estudiado el plásmido conjugativo pLS20, de la bacteria Gram positiva Bacillus subtilis. Es una elección de estudio interesante ya que B. subtilis pertenece al filo Firmicutes, siendo este el filo predominante en el intestino humano. El intestino humano funciona como una reserva genética de resistencia a antibióticos. Además, pLS20 tiene interés biotecnológico debido a su existencia en B. subtilis natto, el cual es importante en producción alimentaria. Entender cómo se regula la conjugación y reunir información sobre las proteínas específicas que participan en el proceso conjugativo es muy importante para poder acabar con la propagación de la resistencia a antibióticos. Así, este trabajo está centrado en el estudio estructural y molecular de varias proteínas de pLS20. En primero lugar, se ha estudiado el circuito regulatorio que controla la expresión de genes del principal operon conjugativo, en el cual participan Rco, Rap y Phr*. Hemos caracterizado estructuralmente el dominio de tetramerización de Rco, descubriendo que comparte similitud con la familia de proteínas p53. Además, hemos determinado que Rco posee distintos estados de oligomerización en función al pH, probablemente debido a su interfaz de tetramerización compuesta de residuos cargados. Asimismo, la unión entre Rap y Rco a distintas estequiometrías y el efecto de Phr* en la formación del complejo han sido analizados por cromatografía de exclusión molecular. Respecto a Rap, se ha evaluado la posibilidad de regulación cruzada con otros sistemas de Rap mediante ensayos de unión. En segundo lugar, hemos trabajado con Reg576, una proteína que participa en la regulación de genes involucrados en el establecimiento del plásmido una vez transferido a la célula receptora. Hemos identificado su sitio de unión en el ADN y mutado un residuo conservado para concluir que la unión no se ve afectada. Hemos obtenido diferentes empaqueteamientos cristalinos y grupos espaciales de la proteína además de la que ya está depositada, lo cual revela que Reg576 es una proteína que cristaliza con relativa facilidad. Finalmente, hemos investigado P34, proteína involucrada en adhesión celular que juega un papel igualmente importante que la regulación en el proceso conjugativo. Hemos determinado que es una proteína TIE (tioéster, isopeptídico, éster) ya que hemos caracterizado estructuralmente su dominio tioéster, denominado TED. Mediante la introducción de la mutación de la cisteína que participa en el enlace tioéster, no hemos observado ningún cambio significativo en la estructura de la proteína, sin embargo, hemos medido cambios drásticos en la funcionalidad. En definitiva, estos resultados suponen un importante avance en la comprensión sobre la regulación de la conjugación y el contacto entre células para comenzar la transferencia de genes del plásmido pLS20. Dada la importancia de las proteínas estudiadas, no descartamos la opción de utilizar estas proteínas como futuras dianas de fármacos para detener la propagación de la resistencia a antibióticos.
Antibiotic Resistance is considered one of the most important public health threats of the 21st century by the WHO. Due to human overuse and misuse of antibiotics, bacteria develop new mechanisms to survive in the presence of antibiotics. Once one bacterium has evolved the gene that endows resistance to it, there are several ways by which this trait can pass to neighbouring bacteria. This process is known as horizontal gene transfer and it is the main reason for the spread of antibiotic resistance genes. We can distinguish between three subtypes, conjugation being the most common one. Conjugation is the active transfer of genetic material from a donor bacterium to a recipient bacterium, involving direct cell-to-cell contact. It is characterized by the presence of a conjugative plasmid. In this work, we have studied the pLS20 conjugative plasmid, from Gram positive bacteria Bacillus subtilis. It is an interesting choice of research as Bacillus subtilis belongs to the phylum Firmicutes, which is the predominant pylum in human gut. The human gut has favourable conditions for conjugative gene exchange and therefore is a pool of antibiotic resistance genes. Also, pLS20 has biotechnological interest because of its occurrence in B. subtilis natto, which is important in food production. Understanding how conjugation is regulated and gathering information of the specific proteins that take part in the conjugative process is of extreme importance in order to stop antibiotic resistance spread. Consequently, this work is focused on the structural and molecular study of various pLS20 proteins. Firstly, the regulatory circuit that controls the expression of the genes of the main conjugation operon has been studied, in which Rco, Rap and Phr* take part. We have structurally characterized the tetramerization domain of Rco and realized it shares high structural resemblance with p53 family proteins. Also, we have determined that Rco has different oligomerization states under distinct pHs, probably due to the charged tetramerization interface. Furthermore, binding between Rapp and Rco at different stoichiometries and the effect of Phr* in the complex formation has been analyzed by size exclusion chromatography. With regard to Rap, the possibility of cross-regulation with other Rap systems has been considered and evaluated by binding assays. Secondly, we have studied Reg576, which is also a transcriptional regulator that controls the transctiption of the genes involved in the establishment of the plasmid once it has been transferred to the recipient cell. We have identified its binding region in DNA and mutated a conserved residue of the protein and determined that binding is not affected. Moreover, we have obtained diverse crystal packings and space groups of the proteins, revealing that Reg576 is a protein that tends to crystallize with relative ease. Finally, we have investigated P34, a protein involved in cell adhesion, which plays an equally important part in the overall success of plasmid transfer as does gene regulation. We have determined it is a TIE (thioester, isopeptide, esther) type of protein as we have structurally characterized its TED domain. Also, from the structure of a mutant where the thioester bond-forming cysteine was mutated to a serine, we conclude that there are no significant structural changes. However, we have observed drastic functionality changes: conjugation is inhibited for the mutant. Together, these results bring new important insights into how conjugation in the pLS20 plasmid is regulated and how cells contact each other to start the transfer of the genes. Given the importance of the proteins characterized, we do not discard the option of using these proteins as future drug targets to stop antibiotic resistance spread.
Universitat Autònoma de Barcelona. Programa de Doctorat en Bioquímica, Biologia Molecular i Biomedicina
Li, Xinhui. "Effective Control of Antibiotic Resistance in Cheese and Characterization of a Dairy Enterococcus faecium Isolate Carrying a Persistent, TA-independent Tetracycline Resistance-encoding Plasmid." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1308294661.
Full textMassie-Schuh, Ella. "The Processing of Replication Initiation Protein PrgW in Enterococcus faecalis is Necessary for Activity and Stable Maintenance of pCF10." Master's thesis, Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/216595.
Full textM.S.
Enterococcus faecalis are Gram-positive bacteria that colonize the gastrointestinal tracts of mammals, birds and invertebrates and are also found in sewage, soil, food and water. In addition to being commensal organisms, Enterococci can also cause nosocomial infections in humans including urinary tract infections, septicemia and endocarditis. Hospital-acquired infections often present a challenge in treatment due to the emergence of multi-drug resistant strains. Enterococcal plasmids may act as extremely stable reservoirs for resistance genes and other virulence factors. Pheromone responsive plasmids such as pCF10 mediate efficient transfer of genetic material within the species E. faecalis but may also be capable of transferring resistance genes across species and genus boundaries. Polymicrobial environments often found in nosocomial infections may expose plasmid-harboring enterococci to pathogenic species, poising cells for this type of promiscuous horizontal gene transfer of resistance determinants. Previous studies showed that prgW, which encodes the pCF10 replication initiation protein PrgW, is the minimal origin of replication for this plasmid. The replicon, which is usually limited to Enterococcal spp., can replicate in Lactococcus lactis if it is engineered to produce pre-cCF10. Three conserved cysteines (C78/C275/C307) are important for plasmid stability and allow for replication of the pCF10 replicon in L. lactis in the absence of pre-cCF10. PrgW has a predicted molecular weight of 38,635. Four polyclonal antibodies targeting PrgW at the N-terminus (aa 1-20), C-terminus (aa 314-333) and two internal regions (aa 64-80 and aa 250-271) were used in current experiments and retrospective studies. When PrgW was overexpressed in E. faecalis, four different apparent approximate molecular weights were detected by Western blotting (p40*, p36*, p24* and p18*), suggestive of processing. In Enterococci where the replicon is active, p36* was consistently detected by all four antisera; when PrgW was overexpressed in Streptococcus mutans where the replicon is non-functional, p49* and p40* were detected but p36* was not observed. PrgW p24* was detected by a mixture of the internally targeting antibodies as well as the C-terminal targeting antibody, but not the N-terminal targeting antibody, suggesting that the N-terminal domain of PrgW has been cleaved off in p24*. The p24* form may play a role in pCF10 stability. Mutations to three cysteines in PrgW (C78/C275/C307), which reduce the stability of pCF10, result in the loss of p24*. Enterococcal conjugative plasmids have been previously implicated in the transfer of antibiotic resistance genes. The pCF10 plasmid contains the conjugative transposon Tn925, which possesses the tetM tetracycline resistance gene. Proximity of donor and recipient cells is a key part of pheromone-responsive conjugation. Aggregation substance allows for formation of clumps of E. faecalis in liquid mating experiments. E. faecalis forms biofilms; in contrast to filter mating experiments, polymicrobial biofilms provide an in vitro model of a natural scenario during which horizontal gene transfer may occur. Rates of cross-genus genetic transfer of tetM between E. faecalis OG1RF(pCF10) donor cells and Staphylococcus aureus recipient cells growing on glass coverslips as mixed-species biofilm populations were determined to be 10-8 after pheromone induction of pCF10 conjugation. This biofilm transfer model also holds potential to test the efficacy of synthetic peptides in the reduction or even prevention of pCF10 transfer, and the consequential dissemination of antibiotic resistance determinants throughout the genus Enterococcus and beyond.
Temple University--Theses
Morgan, Dale. "Molecular analysis of genes encoding resistance to Cationic Biocides in staphylococci." Thesis, Curtin University, 2007. http://hdl.handle.net/20.500.11937/2467.
Full textFreitas, Ana Raquel Pinho. "Ecology and evolution of antimicrobial resistance in Enterococcus: a multilayered molecular approach with emphasys in the plasmid diversity." Doctoral thesis, Faculdade de Farmácia da Universidade do Porto, 2010. http://hdl.handle.net/10216/63801.
Full textSaeed, Sadia. "Uncovering the molecular mechanism of ParG dimerization and its role in segrosome assembly of multidrug resistance plasmid TP228." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/uncovering-the-molecular-mechanism-of-parg-dimerization-and-its-role-in-segrosome-assembly-of-multidrug-resistance-plasmid-tp228(76dda7e1-a14c-4d85-9b10-6524e1fb9281).html.
Full textKrishnan, B. Rajendra Carleton University Dissertation Biology. "The incN antibiotic-resistance plasmid pCU1: bacterial host-range, nucleotide sequence, deletion and subcloning analysis of the replicon." Ottawa, 1989.
Find full textFreitas, Ana Raquel Pinho. "Ecology and evolution of antimicrobial resistance in Enterococcus: a multilayered molecular approach with emphasys in the plasmid diversity." Tese, Faculdade de Farmácia da Universidade do Porto, 2010. http://hdl.handle.net/10216/63801.
Full textVan, Thi Thu Hao, and thuhao2007@gmail com. "Detection of Enteric Bacteria in Raw Food Samples from Vietnam and Evaluation of Antibiotic Resistance." RMIT University. Applied Sciences, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20090407.141836.
Full textMorgan, Dale. "Molecular analysis of genes encoding resistance to Cationic Biocides in staphylococci." Curtin University of Technology, School of Pharmacy, 2007. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=17463.
Full textplasmids belonging to the pC194 rolling-circle replication family and has been redefined as repWBG1773. ORF2 was found to have no similarity to any proteins of known function in the GenBank database whereas ORF3 was found to have homology to the marR gene, a regulator of the multiple antibiotic resistance (mar) operon of Gram-negative organisms. MIC analysis of these ORFs found both ORF2 and ORF3 were essential for expression of resistance to cationic biocides. The exact ORF2 sequence required for resistance to be expressed was reduced to only 141 nt in size. This translated to a 47 aa sequence that contained a hydrophobic C-terminus indicating ORF2 to be a membrane-bound protein. The aa sequence of ORF3 contained a helix-turn-helix motif characteristic of the DNA binding domains of MarR-like proteins. Further analysis of pWBG1773 identified a putative 'marbox', a binding site for the homologous transcriptional activators of mar, within the ORF2 sequence. This indicated that ORF3 was binding to the 'marbox' sequence and activating transcription. Induction studies have not been able to ascertain any compounds capable of interacting with the ORF3 regulatory protein resulting in induction of cationic biocide resistance. Each ORF when analysed alone had no effect on the expression of cationic biocide resistance and it is thought that a efflux pump was not involved. This is further corroborated by the CCCP efflux experiments performed in an attempt to determine the mechanism of resistance. The unique ORFs of plasmid pWBG1773 appears to encode a novel cationic biocide resistance phenotype and mechanism.MRSA strains from all around the world were analysed to determine if they possessed sequences homologous to ORF2 and ORF3. Sequences sharing a high degree of homology to ORF2 and/or ORF3 were detected in several MRSA strains including strains sensitive to all cationic ++
biocides tested. These findings suggest that the appearance of ORF2 and ORF3 sequences in MRSAs was not an isolated event and the fact that some MRSAs do not carry both ORF2 and ORF3 sequences simultaneously indicates that these genes have another role that does not involve expression of resistance to cationic biocides.Bacteria are noteworthy for their remarkable ability to adapt to changes in their environments and possess an impressive set of tools with which to adjust the blueprint of the cell to this change. The acquisition of a single system that may decrease a potential pathogenic organisms susceptibility to a wide range of cationic biocides, such as seen in pWBG1773, poses a clinical threat, one that needs to be thoroughly investigated.
Muhammad, Ghulam. "Staphylococci of bovine mammary gland : conventional and molecular dynamics of infections, plasmid stability, reproducibility, and interspecific conjugal transfer of antibiotic resistance /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487780393268973.
Full textBarge, Madhuri. "Role of the unstructured N-terminus of the centromere binding protein ParG in mediating segregation of the multidrug resistance plasmid TP228." Thesis, University of York, 2015. http://etheses.whiterose.ac.uk/8902/.
Full textPrével, Renaud. "Mécanismes de dissémination des Entérobactéries productrices de bêta-lactamase à spectre élargi en médecine intensive réanimation." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0315.
Full textIntroduction: Extended-spectrum beta-lactamase producing Enterobacteriales (ESBL-E) are a leading cause of antimicrobial resistance dissemination in Europe. ESBL-E can lead to inadequate antimicrobial treatment, especially in intensive care units (ICU). A better understanding of ESBL-E mechanisms of dissemination, including colonization diffusion and the link between colonization and infection, is needed to improve ESBL-E containment. The aims of this work are to investigate the roles of clonal and plasmidic disseminations and of gut microbiota in ESBL-E spread.Materiels and Methods: ESBL-E isolates from ICU patients between January and May 2015 were collected. Clonal dissemination was assessed by mean of pulsed-field gel electrophoresis and plasmidic one by mean of incompatibility groups determination by polymerase-chain reaction. Microbiota analysis were performed on rectal swabs by 16SrRNA coding gene and ITS2 coding gene sequencing. Assignation was performed thanks to DADA-2 pipe-line and statistical analysis on Phyloseq R package (version 3.6.0).Results: Among 508 screened patients, 55 (8%) were ESBL-E fecal carriers, 49 (8%) imported- and 6 (1%) acquired-fecal carriage. Among those 6 patients who acquired ESBL-E fecal carriage in ICU, only one case of cross-transmission was found. Among those 55 ESBL-E fecal carriers, 38 were infected during their stay in ICU but only 6 (16%) had a subsequent ESBL-E infection. To be an ESBL-E fecal carrier had a positive predictive value of 40% and a negative predictive value of 100% to have a subsequent ESBL-E ventilator-associated pneumonia. ESBL genes carrying plasmids were those usually described and we did not find any hegemonic plsmid. The plasmidic impact on the link between ESBL-E colonization and subsequent ESBL-E infection was not assessed. We did not find any difference regarding gut bacteriobiota and mycobiota alpha and beta diversities based on ESBL-E carriage status and regarding gut bacteriobiota based on subsequent ESBL-E infection. We found a statistically significant difference regarding gut mycobiota alpha diversity but not beta diversity based on subsequent ESBL-E infection.Conclusion: Clonal dissemination seems to be involved in the link between ESBL-E carriage and subsequent ESBL-E infection but poorly in ESBL-E cross-transmission. Our results do not permit to draw any conclusion regarding plasmidic dissemination. Qualitative alterations of gut microbiota could participate to ESBL-E fecal carriage but further studies are needed to better understand the underlying mechanisms. Further quantitative alterations seem to be associated with the occurrence of subsequent ESBL-E infections but, once again, further studies are nedded to decipher the causative mechanisms. These studies could pave the way to tailored probiotics to eradicate ESBL-E fecal carriage
Duplay, Quentin. "La galle du collet chez la vigne : de la diversité des pathogènes à l'étude des plasmides et du quorum sensing d'Allorhizobium vitis S4." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1041/document.
Full textCrown gall disease, characterized by the formation of a tumor, represents the most widespread bacteriosis in the vineyard and causes significant economic losses throughout the world. The causing agent is the Ti plasmid (pTi) which confers pathogenicity to their bacterial hosts, such as Allorhizobium vitis. In addition to pTi, A. vitis harbours other plasmids whose functions and ways of dissemination are poorly documented. In order to study the peculiar adaptation of A. vitis strains to grapevine, we studied the diversity of these pathogens as well as the role of plasmids and the regulation of their dissemination.First, we analyzed the diversity of isolates from vineyards of Morocco affected by crown gall. We highlighted that all the pathogenic isolates (e.g. carrying a pTi) form 4 genetic groups that are distinguished by the type of opine produced and the ability to induce a hypersensitive response. We then focused on strain A. vitis S4, which contains 5 plasmids, including 3 possessing a transfer mechanism that can be regulated by a bacterial communication system called quorum sensing (QS). We demonstrated that the QS system of plasmid p130 (renamed pApi) controls not only the conjugative transfer of the pApi but also other uncharacterized plasmid-encoded functions. This QS system requires the synthesis of a N-acyl-homoserine lactone signal molecule with an atypical structure. In addition, genomic analyzes combined with copper resistance assays allowed us to identify, on plasmid p79 of A. vitis S4, a genomic island that is likely involved in copper resistance of this strain.Through analyzes of diversity and study of a model strain, our work provides insight into adaptation of Allorhizobium vitis to its unique host plant, grapevine
Chisholm, Ian Alexander. "The relationship between copper and nickel resistance and the presence of plasmid DNA in isolates of Thiobacillus ferrooxidans recovered from mine tailings effluents." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0025/MQ31418.pdf.
Full textGatignol, Anne. "Expression de genes plasmidiques de resistance a la phleomycine chez les eucaryotes." Toulouse 3, 1987. http://www.theses.fr/1987TOU30257.
Full textAlexandra, Olivia. "Potential Application of Multiplex Automated Genome Engineering (MAGE) and One-Step Curing Plasmid System for Environmental Cambodian Enterobacterial Isolates." Thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-449082.
Full textCard, Galen Edward. "The Diversity Found Among Carbapenem-Resistant Bacteria." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/6949.
Full textPepper, Karen. "Etude de la localisation et de la dispersion des genes de resistance aux antibiotiques chez les streptocoques et les enterocoques." Paris 7, 1987. http://www.theses.fr/1987PA077144.
Full textSousa, Rafaela Rogério Floriano de. "Pesquisa de genes de resistência a quinolonas em bacilos Gram negativos de origem clínica e ambiental." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/6/6135/tde-27032014-091736/.
Full textIntroduction. Quinolones are synthetic antimicrobial agents that inhibit DNA gyrase and topoisomerase IV enzymes resulting in bacterial death. They are highly effective in the treatment of bacterial infections, especially the ones caused by Gram negative bacteria, as well as for prophylaxy. Therefore they are widely used in human and veterinary medicine. However, indiscriminate and improper use led to an increase of bacteria resistance to these compounds. This resistance can be due to mutations in DNA gyrase and topoisomerase IV enzymes and also by genes contained in plasmids, which are mainly responsible for the spread and transmission of resistance between the environment and the hospital set. Objectives. To search for genes of resistance to quinolone antimicrobial agents in Gram-negative bacteria from clinical and environmental strains that present phenotypic resistance to this group. Material and Methods. 73 strains of Enterobacteriaceae and Aeromonas spp., from clinical and environmental origin, were selected for this study, and evaluated for antimicrobial susceptibility of quinolone and search of resistance genes in this same group and also for mutations in the gene encoding the enzyme DNA gyrase by PCR and sequencing. Results. Of the 73 strains previously selected to compose this study, 65 were used, due to the exclusion of similar clonal profiles. In these, genes qnrS1 (1.5 per cent ), qnrS2 (26.2 per cent ) qnrB1 (3.1 per cent ), qnrB19 (12.3 per cent ) qnrD1 (1.5 per cent ) aac(6\')-Ib-cr (10.8 per cent ) oqxA (43.1 per cent ) and oqxB (41.5 per cent ) were observed, and two variants were named as qnrB-like (3.1 per cent ) and qnrB69-like (1.5 per cent ). The qnrA, qnrC and qepA genes were not identified. Mutations in DNA gyrase enzyme were observed in 97.9 per cent of the positive strains for at least one of the genes studied. It was possible to establish the association of aac(6\')-Ib-cr with class 1 integron gene in four strains. Complete sequencing and characterization of plasmid qnrD1, where the gene was inserted, was performed. Conclusions. This study reports, for the first time in Brazil, the occurrence of qnrS2, oqxA and oqxB genes, the association between genetic element integron class 1 gene and the aac (6 \')-Ib-cr, and qnrD1 gene and the characterization of the complete plasmid where this was inserted. qnrB1, qnrB19, and aac(6\')-Ib-cr genes, previously only reported in clinical strains, were observed in environmental strains. The results of this study show a high frequency of quinolone-resistance genes for both clinical and environmental isolates, warning about the spread of resistance through different sources, and the possible maintenance of these genes by environmental strains.
Dotto, Giorgia. "L'antibiotico-resistenza in ceppi di E. coli isolati da specie aviari e cunicole commerciali e selvatiche." Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3423395.
Full textIl fenomeno dell’antibiotico-resistenza rappresenta un grave problema per la sanità pubblica e la sua diffusione è attribuita principalmente alla capacità dei batteri di scambiarsi orizzontalmente materiale genetico attraverso plasmidi, spesso associati agli integroni (Sunde and Nor-strom, 2006). Questo studio nasce con l’obiettivo di definire i profili fe-notipici e genotipici di antibiotico-resistenza, in particolare la presenza e la caratterizzazione degli integroni di classe 1 e 2 in E. coli isolati sia da volatili che da lagomorfi domestici e selvatici campionati in Italia tra il 2006 e il 2012. I ceppi isolati da quest’ultima categoria di animali sono stati sottoposti anche a tipizzazione molecolare mediante Multilocus Se-quence Typing (MLST) e del contenuto plasmidico. Mediante PCR-Based Replicon Typing (PBRT). Inoltre sono stati ricercati i geni Plasmid Mediated Quinolone Resistance (PMQR) responsabili di una ridotta sensibilità ai chinoloni e fluorochinoloni. La presenza degli integroni di classe 1 è stata riscontrata in ceppi con profili di multifarmaco-resistenza isolati sia da volatili che da lagomorfi domestici e selvatici. Gli integroni di classe 2 sono stati invece rilevati soltanto negli E. coli di origine aviare. Le cassette geniche riscontrate di frequente sono state varie combinazioni dei geni aadA, sat e dfrA, responsabili della resistenza agli aminoglicosidi e al trimethoprim. Il 12,2% degli isolati da lagomorfi domestici e selvatici è risultato positivo ai geni oqxAB e, ad eccezione di 3, isolati da conigli di allevamento. La maggior parte dei ceppi oqxAB-positivi apparteneva al CC17 e presentava nel proprio corredo da 1 a 7 classi di plasmidi diversi, quali IncF, IncHI1, IncI1, IncR, IncN, IncP, IncX1, IncY, e ColE. Questo studio fornisce un importante contributo sulla diffusione degli integroni e dei geni PMQR in ceppi isolati da animali sia domestici che selvatici e indica l’importante ruolo giocato da queste specie come reservoir di determi-nanti genetici di antibiotico-resistenza e quali possibili fonti di batteri antibiotico-resistenti per l’uomo
Jackson, David. "A plasmid-based reverse genetics system for influenza B viruses : studies of resistance to neuraminidase inhibitors and the proteins unique to influenza B viruses, NB and BM2." Thesis, University of Reading, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402916.
Full textSantos, Andressa Liberal. "Perfil fenotípico e genotípico de enterobactérias resistentes aos beta-lactâmicos." Universidade Federal de Goiás, 2018. http://repositorio.bc.ufg.br/tede/handle/tede/8780.
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Enterobacteria are microorganisms involved with bacteria and the health of women with care. Treatment of bacterial infections is most often done with the use of antibiotics and one of the major classes of antimicrobials is one of the β-lactams. Among the main mechanisms of resistance to the observational β-lactam antibiotics: alteration of the antimicrobial target; alteration of β-lactam permeability; Flow pumps and the entry of enzymatic signals that destroy the β-lactate totally or with the development of an alternative metabolic pathway. These enzymes are known as beta-lactamases and are encoded by specific genes. Thus, the objective of this study was to correlate the resistance profile of enterobacteria, using phenotype methodologies and identifying 14 genes that encode as beta-lactamase enzymes: blaOXA genes; blaIMP; blaNDM; blaSME; blaDHA; blaCMY, blaTEM, blaKPC, blaSPM, blaCTX-M, blaVIM, blaSIM, blaGim and blaSHV. The phenotypic methodologies used were the Antimicrobial Sensitivity Test for Disk-Diffusion (antibiogram), and complementary tests for the detection of resistance mechanisms of beta-lactamases (ESBL, MBL, AmpC and Carbapenemase). The molecular methodology used was Real Time PCR using the Sybr Green system. Among the results found in the tests it was observed that 74.28% were resistant to ampicillin, 34.28% were resistant to aztreonam, 62.85% were resistant to amoxicillin associated with clavalunate, 51.42% were resistant to ceftazidime, 41 , 42% were resistant to cefoxitin, 54.28% were resistant to cefazolin, 44.28% were resistant to cefepime, 41.42% were resistant to cefuroxime, 8.57% were resistant to cefuroxime, 35.71% were resistant an imipenem and 41.42% were resistant to piperacillin associated with tazobactam. Among the total samples, the mechanism of resistance that presented the highest expression was ESBL (17.14%). The genes studied that were detected in a greater number of genera were blaGIM and blaSIM (66.66% of the samples). The gene that was amplified in a smaller number of samples was blaVIM (16.66%). It is concluded that although there is a low correlation between the methodologies analyzed, the levels of antimicrobial resistance in enterobacteria are high and worrying, and a way to minimize the accelerated emergence of resistance includes the development or improvement of techniques that generate diagnoses with high efficiency and speed.
As enterobactérias são microrganismos envolvidos com infecções bacterianas adquiridas na comunidade e nos ambientes dos cuidados com a saúde. O tratamento das infecções bacterianas na maioria das vezes é realizado com a utilização de antibióticos e uma das maiores classes de antimicrobianos é a dos β-lactâmicos. Entre os principais mecanismos de resistência aos antimicrobianos β-lactâmicos observa-se: alteração do alvo antimicrobiano; alteração da permeabilidade ao β-lactâmico; bombas de e-fluxo e a presença de mecanismos enzimáticos que destroem o β-lactâmico totalmente ou parcialmente com desenvolvimento de uma via metabólica alternativa. Essas enzimas são conhecidas como beta-lactamases e são codificadas por genes específicos. Dessa forma, o objetivo deste estudo foi o de correlacionar o perfil de resistência das enterobactérias, utilizando metodologias fenotípicas e identificar 14 genes que codificam as enzimas beta-lactamases: genes blaOXA; blaIMP; blaNDM; blaSME; blaDHA; blaCMY, blaTEM, blaKPC, blaSPM, blaCTX-M, blaVIM, blaSIM, blaGIM e blaSHV. As metodologias fenotípicas utilizadas foram o Teste de Sensibilidade aos Antimicrobianos por disco-difusão (antibiograma), e testes complementares para detecção dos mecanismos de resistência das beta-lactamases (ESBL, MBL, AmpC e Carbapenemase). A metodologia molecular utilizada foi a PCR em Tempo Real, utilizando o sistema Sybr Green. Entre os resultados fenotípicos encontrados nas bactérias observou-se que 74,28% foram resistentes a ampicilina, 34,28% foram resistentes a aztreonam, 62,85% foram resistentes a amoxicilina associado ao clavalunato, 51,42% foram resistentes a ceftazidima, 41,42% foram resistentes cefoxitina, 54,28% foram resistentes a cefazolina, 44,28% foram resistentes a cefepime, 41,42% foram rsistentes a ceftriaxona, 8,57% foram resistentes a cefuroxima, 35,71% foram resistentes a imipenem e 41,42% foram resistentes a piperacilina associada tazobactam. Entre o total de amostras, o mecanismo de resistência que apresentou maior expressão foi o ESBL (17,14%). Os genes estudados que foram detectados em um maior número de gêneros foram o blaGIM e o blaSIM (66,66% das amostras). O gene amplificado em menor número de amostras foi o blaVIM (16,66%). Conclui-se que apesar de haver baixa correlação entre as metodologias analisadas, os níveis de resistência a antimicrobianos em enterobactérias são altos e preocupantes e uma maneira de minimizar a acelerada emergência de resistência é desnvolver e aprimorar técnicas de diagnósticos com alta eficiência e rapidez.
GUGLIELMETTI, ELENA. "Antibiotico resistenza in batteri lattici: basi molecolari e trasferibilità." Doctoral thesis, Università Cattolica del Sacro Cuore, 2009. http://hdl.handle.net/10280/404.
Full textThe discovery and subsequent widespread use of antibiotics have rendered many bacterial species of human and animal origin resistant to some antibiotics. Antibiotic resistance gene may be transferred via food chain, from animals into fermented and other food or in the human gastrointestinal tract. The transferability of some plasmids that harbor the tetracycline or erythromycin resistance genes to animal and human pathogens was assessed using electrotrasformation and conjugation. The present study describes the proprieties of some new plasmids, originally isolated from fish intestinal Lactococcus lactis ssp. lactis and from fermented sausage Lactobacillus brevis, Lb. plantarum and Lb. reuteri. In particular, here I report the potentially of transferable antibiotic resistance determinants to human pathogenic bacterial like Listeria monocytogenes and Staphylococcus spp. and to an etiologic agent of Lactococcus infection like Lc. garvieae. The possibility of transferring natural Lactococcus and Lactobacillus plasmids into pathogenic bacterial strains involved the characterization of these elements, like comobilization and plasmid stability. These data suggest that lactic acid bacteria (LAB) might be reservoir organism for acquired resistance genes that can be spread both to fish and human pathogens, posing a risk to aquaculture and human health.
GUGLIELMETTI, ELENA. "Antibiotico resistenza in batteri lattici: basi molecolari e trasferibilità." Doctoral thesis, Università Cattolica del Sacro Cuore, 2009. http://hdl.handle.net/10280/404.
Full textThe discovery and subsequent widespread use of antibiotics have rendered many bacterial species of human and animal origin resistant to some antibiotics. Antibiotic resistance gene may be transferred via food chain, from animals into fermented and other food or in the human gastrointestinal tract. The transferability of some plasmids that harbor the tetracycline or erythromycin resistance genes to animal and human pathogens was assessed using electrotrasformation and conjugation. The present study describes the proprieties of some new plasmids, originally isolated from fish intestinal Lactococcus lactis ssp. lactis and from fermented sausage Lactobacillus brevis, Lb. plantarum and Lb. reuteri. In particular, here I report the potentially of transferable antibiotic resistance determinants to human pathogenic bacterial like Listeria monocytogenes and Staphylococcus spp. and to an etiologic agent of Lactococcus infection like Lc. garvieae. The possibility of transferring natural Lactococcus and Lactobacillus plasmids into pathogenic bacterial strains involved the characterization of these elements, like comobilization and plasmid stability. These data suggest that lactic acid bacteria (LAB) might be reservoir organism for acquired resistance genes that can be spread both to fish and human pathogens, posing a risk to aquaculture and human health.
Babosan, Anamaria. "Description d'un mécanisme, à l'origine de l'induction de la réponse SOS par les aminosides chez Escherichia coli, favorisant l'émergence de la résistance aux fluoroquinolones." Thesis, Reims, 2018. http://www.theses.fr/2018REIMS024/document.
Full textThe emerging plasmid-mediated quinolones resistance (PMQR) determinants significantly participate in the selection of high-level of resistance to the major antibiotics fluoroquinolones, leading to numerous clinical failures. In this study, we reported for the first time that PMQR expression could be triggered by the fluoroquinolones but also by another major class of antibiotics, the aminoglycosides. We were able to show that this unique cross selection of antibiotic resistance was the consequence of the PMQR determinant qnrD being SOS-regulated in a RecA-LexA dependent manner. We demonstrated that sub inhibitory concentration of aminoglycoside induced nitric oxide formation associated with the repression of the Hmp-mediated detoxification pathway, resulting in the induction of the SOS response and thus up-regulation of the PMQR. Overall, our findings revealed an unexpected antibiotic resistance cross-selection with low aminoglycosides concentrations promoting emergence of fluoroquinolones resistance
Guerreiro, Lara Sofia Fernandes. "Influência do uso de enrofloxacina no aparecimento de resistência às quinolonas mediada por plasmídeos em Escherichia coli de vitelos." Master's thesis, Universidade Técnica de Lisboa. Faculdade de Medicina Veterinária, 2012. http://hdl.handle.net/10400.5/4589.
Full textO conhecimento sobre a presença e frequência de genes de resistência às quinolonas mediada por plasmídeos (RQMP) em estirpes comensais de Escherichia coli de origem bovina é escasso a nível mundial. Foram estudadas um total de 237 amostras de E. coli de vitelos saudáveis previamente isoladas após pressão selectiva in vivo de enrofloxacina (ENR) e caracterizadas quanto à resistência aos antibióticos: 101, 79 e 57 isolados relativos a T0, T1 (6 semanas após administração de ENR) e T2 (10 semanas após administração de ENR), respectivamente. Os isolados foram caracterizados fenotipicamente por determinação da Concentração Inibitória Mínima (CIM) para os antimicrobianos ácido nalidíxico (AN), ciprofloxacina (CIP) e levofloxacina (LEV) e os resultados interpretados segundo os critérios epidemiológicos (ECOFF) estabelecidos pelo EUCAST. A frequência de genes de RQMP (qnr, aac(6’)-Ib-cr e qepA) foi determinada através de amplificação por PCR e sequenciação nucleotídica. A proporção de isolados de E. coli resistentes ao AN em T0, T1 e T2 foi de, respectivamente: 52,5% (n=53; CIM 64->256 μg/ml), 100% (n=79; CIM 128->256 μg/ml) e 82,5% (n=47; CIM 128->256 μg/ml). A resistência à CIP em T0, T1 e T2 foi de, respectivamente: 52,5% (n=53; CIM 0,125->256 μg/ml), 100% (n=79; CIM 0,25-128 μg/ml) e 89,5% (n=51; CIM 0,25-64 μg/ml). A resistência à LEV em T0, T1 e T2 foi de, respectivamente: 46,5% (n=47; CIM 0,5-64 μg/ml), 100% (n=79; CIM 0,5-64 μg/ml) e 87,7% (n=50; CIM 0,5-32 μg/ml). No que respeita aos determinantes de RQMP nos 237 isolados estudados, foram identificados: 11,8% (n=28) positivos para genes qnr (qnrB2, n=4; qnrD, n=11; qnrS1, n=13); e 0,8% (n=2) isolados positivos para o gene aac(6’)-Ib-cr. Da análise da frequência dos genes de RQMP nos isolados de E. coli observou-se: em T0, 3% de genes qnr (todos qnrS1) e 2% do gene aac(6’)-Ib-cr; em T1, 15,2% de genes qnr (10,1% qnrD e 5,1% qnrS1); em T2, 22,8% de genes qnr (7% qnrB2, 5,3% qnrD e 10,5% qnrS1). Os dados obtidos evidenciam um aumento significativo da prevalência de isolados resistentes ao longo do tempo de colheita, sugerindo que a pressão selectiva imposta pela exposição à ENR tem influência no aparecimento de resistência às quinolonas. Observou-se um aumento significativo da frequência de genes de RQMP ao longo do estudo longitudinal e mais de 80% dos isolados positivos para RQMP foram resistentes às quinolonas. Este é, para o nosso conhecimento, o primeiro estudo que descreve a identificação de resistência às quinolonas por qnrD em isolados de E. coli de bovinos.
ABSTRACT - The current knowledge about the presence and frequency of pasmid-mediated quinolone resistance (PMQR) genes in commensal Escherichia coli strains from cattle is scarce. Two hundred and thirty seven E. coli samples isolated from healthy calves were studied after in vivo enrofloxacin (ENR) selective pressure and previously characterized regarding antimicrobial susceptibility, including: 101, 79 and 57 isolates from T0, T1 (six weeks after ENR administration) and T2 (10 weeks after ENR administration), respectively. The phenotypic characterization was performed using Minimum Inhibitory Concentration (MIC) determinantion for nalidixic acid (NAL), ciprofloxacin (CIP) and levofloxacina (LEV) by the microdilution method and the results were interpreted according to EUCAST definitions of epidemiological cut-off values (ECOFF). PMQR genes (qnr, aac(6’)-Ib-cr and qepA) frequency was performed by PCR amplification and nucleotide sequencing. NAL resistant E. coli isolates in T0, T1 and T2 were, respectively: 52,5% (n=53; MICs 64 to >256 μg/ml), 100% (n=79; MICs 128 to >256 μg/ml) and 82,5% (n=47; MICs 128 to >256 μg/ml). CIP resistant isolates in T0, T1 and T2 were, respectively: 52,5% (n=53; MICs 0,125->256 μg/ml), 100% (n=79; MICs 0,25-128 μg/ml) and 89,5% (n=51; MICs 0,25-64 μg/ml). LEV resistant isolates in T0, T1 and T2 were, respectively: 46,5% (n=47; MICs 0,5-64 μg/ml), 100% (n=79; MICs 0,5-64 μg/ml) and 87,7% (n= 50; MICs 0,5-32 μg/ml). From the 237 E. coli isolates tested: 11,8% (n=28) harboured qnr genes (qnrB2, n=4; qnrD, n=11; and qnrS1, n=13) and 0,8% (n=2) were found positive for the aac(6’)-Ib-cr gene. The analysis of PMQR genes in E. coli at the different sampling times showed that: at T0, qnr genes were detected in 3% of the isolates (all found to be qnrS1) and 2% carried the aac(6’)-Ib-cr gene; at T1, 15,2% of the isolates carried qnr genes (10,1% qnrD and 5,1% qnrS1); and at T2, 22,8% of the isolates were found positive for qnr genes (7% qnrB2, 5,3% qnrD and 10,5% qnrS1). The results reveal an increased prevalence of resistant isolates along the time, suggesting that ENR selective pressure influences the emergence of quinolone resistance. A significant increased frequency of PMQR genes along the longitudinal study was observed and more than 80% of PMQR positive isolates were quinolone resistant. This is to our knowledge the first report on PMQR qnrD gene in E. coli isolates from cattle.
Drieux, Laurence. "Succès plasmidique : transmission inter-espèce d'un plasmide portant un gène de métallo-bêta-lactamase." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA114816/document.
Full textAcquired metallo-b-lactamases (MBLs) represent a threat for the treatment of infections caused by Gram-negative bacteria, particularly by enterobacteria that already produce extended-spectrum b-lactamases (ESBL). VIM-1 MBL, which is a carbapenemase that can hydrolyze all classes of β-lactam antibiotics except monobactams, has emerged in Greece and is now commonly found in Enterobacteriaeae. Six carbapenemase-producing strains of Gram-negative bacilli were isolated from a unique patient transferred from Greece to a French hospital. Three of these strains, Providencia stuartii (Ps), Proteus mirabilis (Pm) and Escherichia coli (Ec) strains, were shown to produce the MBL VIM-1 and the ESBL SHV-5. In each of these three strains, the blaVIM-1 gene was carried by a plasmid transferable by in vitro conjugation. The plasmids extracted from the transconjugants displayed a unique restriction profile and harboured identical VIM-1-containing class 1 integrons. Considering the hypothesis that this VIM-1 plasmid had probably been transferred from the Ps strain to the Ec and Pm strains, we performed in vivo conjugation assays in the digestive tract of gnotobiotic mice colonized with E. coli J53, to demonstrate that the VIM-1 plasmid harboured by strain Ps was transferable in vivo, in absence of antibiotic pressure. We determined the complete nucleotide sequence of the VIM-1-encoding plasmid pTC2, which was isolated in a Greek Providencia stuartii multiresistant strain. This 180-kb plasmid was found to be a multireplicon plasmid (IncA/C, IncR), with a large IncA/C backbone and a mosaic multidrug resistance (MDR1) region, in which was inserted a 13-kb IncR fragment. A CD-search-based annotation of the plasmid allowed the identification of a complete IncA/C-type transfer system and of several putative maintenance modules, either on the IncA/C backbone, and on the IncR fragment. The complex MDR1 region contained nine insertion sequences (seven copies of the IS26, one IS1 and one IS6100), 10 resistance genes and a mercury resistance operon integrated either into unit transposons, composite transposons or integrons. The broad-host range, the transfer capacities, the stability, the high plasticity of the MDR1 region combined to the variety of resistance genes make pTC2 a superspreader of resistance determinants
Bonot, Sébastien. "Persistance et dissémination du plasmide pB10, vecteur de gènes de résistance aux antibiotiques, dans des biomasses issues de stations d'épuration d'eaux usées urbaines." Thesis, Nancy 1, 2010. http://www.theses.fr/2010NAN10050/document.
Full textThe widespread use of antibiotics since the 50s, generates a significant release of these molecules in the environment (excretion via urine and feces) which can be found at concentrations ranging from 1-100 ng/L in wastewater. Due to the high microbial biomass and the abundance of nutrients, wastewater treatment plants (WWTP) represent a suitable habitat for horizontal gene transfer. Because they occupy a key position between human activities and the environment, WWTP may play a major role in limiting the dissemination of antibiotic resistance genes, therefore contributing to the preservation The parameters which influence these transfers in wastewater treatment plants are still poorly known, especially because of methodological limitations. Therefore the aim of our study was to identify environmental factors affecting the stability and transfer of a mobile genetic element model, the plasmid pB10 in bacterial communities (biomass from wastewater treatment plants and river sediments) maintained in microcosms. So far, the transfer of resistance genes have been studied mainly with methods based on the cultivation of microorganisms on selective media that we know now they underestimate the observed phenomena. Also, an approach based on quantitative PCR was developed for detecting the release of a mobile DNA template from the host bacterium E. coli DH5α. Couples of designed primers/probes were very specific and have been developed by taking advantage of the mosaic structure of the bacterial genome. The proposed approach is based on the over time measurements of the number of plasmids pB10 and its bacterial host DH5α, where an increased ratio (pB10/DH5α) implies a release of the plasmid to the indigenous bacteria. This method was used to assess the impact of some environmental parameters on the release of DNA in complex microbial communities. Two groups of factors could be distinguished according to whether they influence the persistence of plasmid pB10 in communities in microcosms (oxygenation / mixing, addition of antibiotics at sub-inhibitory concentrations as amoxicillin and sulfamethoxazole frequently found in treatment plant) and / or they favor his release in bacterial communities (biofilms, sediments). Without inducing genes transfers, the antibiotics tested, even at sub-lethal concentrations, could participate in the dissemination of resistance genes by facilitating their persistence
Zwanzig, Martin [Verfasser], Uta [Gutachter] Berger, Uta [Akademischer Betreuer] Berger, Thomas U. [Akademischer Betreuer] Berendonk, Jan-Ulrich [Gutachter] Kreft, and Susann [Gutachter] Müller. "Modelling the spread of plasmid-encoded antibiotic resistance in aquatic environments considering evolutionary modifications, individual heterogeneity and complex biotic interactions / Martin Zwanzig ; Gutachter: Uta Berger, Jan-Ulrich Kreft, Susann Müller ; Uta Berger, Thomas U. Berendonk." Dresden : Technische Universität Dresden, 2020. http://d-nb.info/1227196873/34.
Full textSANCHEZ-LOPEZ, ROSANA. "Partie i : etude des mecanismes impliques dans la resistance au sel chez une bacterie halophile- partie ii : etude des relations structure-fonction de metalloproteinases de la famille collagenase." Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR13020.
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