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Jucker, Markus Thomas. "Relationship of plasmids in Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum". Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/39450.
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Bacteria of the Mycobacterium avium, M. intracellulare, and M. scrofulaceum group (MAIS) are opportunistic human pathogens and widespread in the environment. The first objective of this study was to demonstrate that plasmids from clinical isolates are closely related to plasmids from environmental MAIS isolates. A 12.9 kb plasmid, pVT2, from a clinical M. avium isolate, MDl, was cloned and used a a DNA probe to examine the relationship of MAIS plasmids. The pVT2 probe hybridized with plasmids isolated from MAIS strains from the environment, from patients without AIDS with pulmonary infections, and from AIDS patients with disseminated MAIS infections. Similar results were seen with a second probe derived from pLR 7, a 15.3 kb plasmid from clinical M. intracellulare strain LR 113. The similarity of plasmids from environmental and clinical isolates supports the hypothesis that the environment is a source of MAIS infection in humans.Ph. D.
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Narbonne-Nguyen, The Tich Valérie. "Analyse de plusieurs marqueurs moléculaires de mycobactéries : applications épidemiologiques (doctorat : sciences de la vie et de la santé)". Brest, 2000. http://www.theses.fr/2000BRES3102.
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Redford, Paul Stuart. "Regulatory mechanisms inhibiting anti-mycobacterial immunity following Mycobacterium tuberculosis infection". Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1445023/.
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The work reported in this thesis addresses the regulatory factors that function to limit the initiation of protective immune responses following exposure to the bacterium Mycobacterium tuberculosis (MTb). Control and clearance of intracellular pathogens, such as MTb, is dependent on the cytokine Tumour Necrosis Factor (TNF) and induction of a T-helper 1 (Thl) response, which is characterised by production of IFN-gamma driven by interleukin (IL)-12. In other infection models the presence of the immunosuppressive cytokine IL-10 in the local milieu has been shown to down-regulate Thl responses thus limiting detrimental host induced immune-pathology. To determine a role for IL-10 following murine infection, we examined its function during acute and chronic infections with two strains of H37Rv obtained from either i) National Institute for Medical Research (NIMR) or ii) London School of Hygiene and Tropical Medicine (LSHTM). IL-10 receptor blockade during the chronic phase of MTb infection reduced bacterial burdens in mice infected with H37Rv NIMR, but not mice infected with H37Rv LSHTM. However, despite the lack of effect of IL-10 blockade on the bacterial load during chronic infection with H37Rv LSHTM, immune cells obtained from MTb infected mice produced elevated levels of IFN-gamma when stimulated in vitro in the presence of IL-10 blocking antibodies. In addition, neutralisation of IL-10 before and during acute MTb infection with H37Rv LSHTM resulted in a transient reduction in bacterial burdens and enhanced IFN-gamma production, suggesting that IL-10 plays a role in regulating the early immune response to MTb. Additional regulators that may function together with or in parallel to IL-10 to limit bacterial clearance such as regulatory T cells (Tregs) have been shown to be regulators of autoimmunity, atopy and infectious disease. Using flow cytometric analysis of the Treg specific transcription factor FoxP3, we observed an early increase in the number of lung Tregs following aerosol MTb infection of mice. However, when addressing the effect on bacterial clearance in the absence of Tregs by either i) antibody depletion or ii) adoptive transfer approaches into immuno-deficient mice, a suppressive role for Tregs on bacterial burdens could not be found. Finally this work evaluated the role of plasmacytoid precursor DC (pDC) during MTb infection, which is in contrast their normal function as mediators of the anti viral response. Upon in vitro exposure to viable MTb, plasmacytoid pDC could not be infected and did not produce pro-inflammatory cytokines. Using flow cytometry, we observed no increase in plasmacytoid pDC in either the lung or spleen during the early stages of aerosol or intravenous infection. In addition, antibody depletion of plasmacytoid pDC during the early stages of MTb infection did not affect bacterial load. In summary, the data suggests that plasmacytoid pDC play only a minor role during the early immune response to MTb.
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Mpongoshe, Vuyiseka. "Gene expression changes in macrophages infected with pathogenic M. tuberculosis and non-pathogenic M. smegmatis and M. bovis BCG". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86729.
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Thesis (MScMedSc)--Stellenbosch University, 2014.ENGLISH ABSTRACT: The current anti-TB drugs have had success in decreasing the number of deaths caused by TB, however, this success is limited by the emergence of drug resistant TB strains. Therefore, a novel TB therapy that limits the development of resistance has become necessary in an attempt to effectively control TB. The anti-TB drugs directly target mycobacterial enzymes, and potentiate the development of this resistance, and have therefore provided the rationale for this study. The aim was therefore to identify host macrophage genes that affect M. tb intracellular survival. The proposed alternative anti-TB therapy potentially involves the application of RNA interference (RNAi) and RNA activation (RNAa) biological processes that will target host genes, thereby inducing an indirect bactericidal effect. We hypothesized that macrophage genes that are differentially expressed by pathogenic and non-pathogenic mycobacterial species may be important in the regulation of M. tb intracellular survival. The lipid-rich mycobacterial cell wall is implicated in the excessive clumping of the mycobacterial cells in liquid culture. In order to minimize this, Tween 80 detergent was supplemented (mycobacteriaT). However, due to substantial evidence emphasising the detrimental effects of Tween 80 on the mycobacterial cell wall, mycobacteria were also cultured without Tween 80 (mycobacteriaNT), in order to investigate if the perturbed mycobacterial cell wall induced by Tween 80 affects the transcriptional response of macrophages. We endeavoured to develop a new method to culture mycobacteria without Tween 80 that will still generate single cells. We further hypothesized that the macrophage gene expression profile induced by mycobateriaNT differs from the response induced by mycobacteriaT. Differentiated THP-1 (dTHP-1) cells were infected with pathogenic and non-pathogenic mycobacteria (for 3 h, 24 h and 48 h with M. tb and M. bovis BCG, and 3 h and 8 h with M. smegmatis) cultured in the presence or absence of Tween 80. The expression of 12 macrophage genes, selected based on their involvement in the phagocytic pathway and autophagy, as well as their general involvement in the immune response, was determined by qRT-PCR and further analysed on the REST programme. The expression of each target gene was normalised relative to the expression of the reference gene (Beta actin). We observed that out of the 12 genes, TLR7 and VAMP7 were consistently downregulated in dTHP-1 cells infected with M. tbNT and upregulated in dTHP-1 cells infected with M. smegmatisNT. Their response to M. bovis BCG was inconsistent and not significantly different, and therefore could not be interpreted. Furthermore, CCL1 was upregulated by all the mycobacterial species. However, its expression was more pronounced in response to mycobacteriaNT, when compared to mycobacteriaT. Differential gene expression of TLR7 and VAMP7 in response to pathogenic and non-pathogenic mycobacteriaNT suggests that these 2 genes may be potential targets for RNAa-based anti-TB therapy, even though we could not conclude whether their response was specific to macrophages. In addition, the observed difference in the expression of CCL1 induced by mycobacteriaNT, compared to mycobacteriaT suggests that the perturbation caused by Tween 80 on the mycobacterial cell wall most likely affected the response of macrophages to infection with mycobacteria. Furthermore, this study has demonstrated a feasible method by filtration to generate single cells from mycobacteriaNT, which should be considered for future mycobacterial infection studies.
AFRIKAANSE OPSOMMING: Die huidige anti-tuberkulose middels se sukses lê daarin dat dit die aantal sterftes verminder maar hierdie sukses word weer beperk met die ontstaan van middel-weerstandige M.tb stamme. Daarom is nuwe middels nodig wat die ontwikkeling van middel-weerstandigheid beperk in ʼn poging om effektiewe TB behandeling te bewerkstellig. Anti-tuberkulose middels teiken hoofsaaklik mycobakteriële ensiemsisteme en ontlok sodoende weerstandigheid in M.tb stamme en dit vorm die rasionale vir hierdie studie. Die doel was om gasheer makrofaag gene te identifiseer wat M.tb oorlewing intrasellulêr bewerkstellig. Die voorgestelde alternatiewe anti-TB behandeling sal dan behels die toepassing van RNA intervensie (RNAi) en RNA aktivering (RNAa) tegnologie wat gasheer selgene teiken (inaktiveer) en sodoende ʼn bakterisidiese respons induseer. Die kanse is skraal dat mycobakterieë weerstandigheid sal kan ontwikkel onder hierdie omstandighede. Ons hipotetiseer dus dat makrofaag gene wat differensieel uitgedruk word deur patogeniese en nie-patologiese mycobakteriële spesies belangrik mag wees vir die oorlewing van M.tb intrasellulêr. Die lipiedryke selwand van mycobakterieë word geïmpliseer in die oormatige sameklomping van die bakterieë in vloeistofkulture. Om hierdie effek te minimaliseer word Tween 80 normaalweg tot die medium gevoeg (mycobakterieëT). Maar weens genoegsame bewyse dat Tween-80 die selwand van bakterieë nadelig beïnvloed, is mycobakterieë ook in die afwesigheid van Tween 80 gekultureer (mycobakterieëNT) om te bepaal of die nadelige effek van Tween 80 op die selwand die transkripsionele respons in makrofage beïnvloed post-infeksie. Dit was daarom ook ons doelstelling om ʼn nuwe tegniek te ontwikkel om mycobakterieë te kultureer in die afwesigheid van Tween 80 wat ook enkelselle sal genereer vir beter gekontroleerde makrofaag infeksie. Ons hipotetiseer ook verder dat makrofaag geenuitdrukking-profiele verskil afhangende of infeksie gedoen is met mycobakterieë wat in die afwesigheid of teenwoordigheid van Tween 80 gekultureer is. Gedifferensieerde THP-1 (dTHP-1) was geïnfekteer met patogeniese en nie-patogeniese mycobakterieë (vir 3 h, 24 h en 48 h met M.tb en M.bovis BCG, en 3 h en 8 h met M.smegmatis) gekultureer in die teenwoordigheid en afwesigheid van Tween 80. Die uitdrukking van 12 makrofaag gene, geselekteer op grond van hul betrokkenheid in die fagositose meganisme en in outofagie asook hul betrokkenheid in die immuunrespons, is gekwantifiseer met qRT-PCR en daaropvolgens geanaliseer met die REST-program. Die uitdrukking van elke geen is genormaliseer relatief tot die uitdrukking van die verwysingsgeen (Beta actin). Daar is bevind dat van die 12 gene, TLR7 en VAMP7 deurlopend afgereguleer was in dTHP-1 selle geïnfekteer met M.tbNT en opgereguleer was in dTHP selle geïnfekteer met M.smegmatisNT. Selrespons met M.bovis BCG was onbeduidend en derhalwe kon geen gevolgtrekking hier gemaak word nie. Ook, CCL1 was opgereguleer met infeksie deur enige van die mycobakteriële spesies, maar CCL1 se uitdrukking was groter in respons tot mycobakterieëNT wanneer vergelyk word met respons tot mycobakterieëT. Differensiële geenuitdrukking van TLR7 en VAMP7 in respons tot patogeniese en nie-patogeniese mycobakterieëNT impliseer dat hierdie twee gene potensiële teikens kan wees vir RNAa-gebaseerde anti-TB behandeling, alhoewel ons nie kon beslis of hierdie respons spesifiek vir makrofage was nie. Ook, die verskille waargeneem in die uitdrukking van CCL1 geïnduseer deur mycobakterieëNT, vergeleke met mycobakterieëT, impliseer dat die steuring in die selwand veroorsaak deur Tween 80, heelwaarskynlik die respons van die makrofaag beïnvloed het. Hierdie studie beskryf ook ʼn filtrasiemetode om enkele mycobakteriële selle te genereer wat oorweeg moet word by toekomstige mycobakteriële infeksiestudies.
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Dumartin, Catherine. "Activité de l'antiseptique chloré amukine Rsur "Mycobacterium fortuitum", "Mycobacterium tuberculosis" et "Mycobacterium avium"". Paris 5, 1994. http://www.theses.fr/1994PA05P185.
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Hasan, Zehra. "Mycobacterium - host interactions : trafficking of mycobacteria within the host cell". Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264976.
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Millar, Douglas Spencer. "Mycobacterium paratuberculosis, mycobacteria and chronic enteritis in humans and animals". Thesis, St George's, University of London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308932.
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Muhammed, Ameen Sirwan. "Re-evaluation of older antibiotics in the area of resistant mycobacteria". Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM5058.
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Chez les patients traités par un régime posologique, La concentration sérique moyenne et l'écart type de la concentration SMX était 161,01 ± 69,154 mg/L et de 5,788 ± 2,74 mg/L pour le TMP. La concentration minimale inhibitrice 90% (CMI 90) était de 10 mg/L pour le cotrimoxazole et la sulfadiazine contre Mycobacterium tuberculosis. Toutes les mycobactéries étaient inhibées par 20 mg/L de cotrimoxazole et de sulfadiazine. Les CMI de l'ivermectine contre 13 souches complexe M. tuberculosis ont varié entre 10 et 40 mg/L. En outre, tous isoler M. tuberculosis étaient résistants à la squalamine avec CMI > 100 mg/L. Dans une autre partie nous avons montré que tous les isolats du complexe Mycobacterium avium étaient résistants au triméthoprime avec une CMI > 200 mg/mL. Le cotrimoxazole, le sulfaméthoxazole et la sulfadiazine ont montré une CMI respectivement de 10 mg/L, 25 mg/L et 20 mg/L, à l'exception de Mycobacterium chimaera qui présentait une CMI de 10 mg/L pour ces molécules. La comparaison de la séquence du gène de la dihydroptéroate synthase de M. intracellulare et M. chimaera a montré seulement quatre changements d'acides aminésFirstly, we measured the serum concentration of Sulfamethoxazole (SMX)-Trimethoprim (TMP) in patients treated with high dosage regimen. The mean values and standard deviation for SMX concentration was 161.01± 69.154 mg/L and of 5.788 ± 2.74 mg/L for TMP. Susceptibility testing yielded a minimum inhibitory concentration 90% (MIC90) of 10 mg/L for cotrimoxazole and sulfadiazine. All M. tuberculosis complex mycobacteria (MTC) were inhibited by 20 mg/L cotrimoxazole and sulfadiazine. Also, the MICs of ivermectin varied between 10 and 40 mg/L, against 13 MTC mycobacteria. Moreover, all M. tuberculosis isolate were resistant to squalamine with MIC > 100 mg/L. Also, all Mycobacterium avium complex (MAC) isolates were resistant to trimethoprim with MIC > 200 mg/L. Cotrimoxazole, sulfamethoxazole and sulfadiazine exhibited MIC of 10 mg/L, 25 mg/L and 20 mg/L, respectively against all tested MAC isolates except for Mycobacterium chimaera which exhibited MICs of 10 mg/L for these molecules. Comparing the DHPS gene sequence in M. intracellulare and M. chimaera type strains and clinical isolates yielded only four amino acid changes
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Vorwieger, Stefan [Verfasser], i Dirk [Akademischer Betreuer] Wagner. "Efflux-Inhibition bei Mycobacterium smegmatis und Mycobacterium avium". Freiburg : Universität, 2012. http://d-nb.info/1123467102/34.
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Agustí, Adalid Gemma. "Caracterització d'un nou polièster present en les soques llises de Mycobacterium vaccae, Mycobacterium aurum, Mycobacterium obuense, Mycobacterium parafortuitum, Mycobacterium chubuense i Mycobacterium gilvum. Implicació en la morfologia colonial, motilitat i formació de biofilms". Doctoral thesis, Universitat Autònoma de Barcelona, 2009. http://hdl.handle.net/10803/3928.
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Els micobacteris són un grup de microorganismes de gran importància clínica, ja que existeixen múltiples espècies que són agents causals de diverses malalties humanes amb unes importants morbiditat i mortalitat. Entre aquest grup de micobacteris patògens cal destacar Mycobacterium tuberculosis i Mycobacterium leprae, agents causals de la tuberculosi i la lepra, respectivament. D'altra banda, a part dels microorganismes que constitueixen els complexes M. tuberculosis i M. leprae trobem un grup nombrós de micobacteris, format per micobacteris atípics o micobacteris ambientals (MNT). Aquest grup engloba la resta d'espècies micobacterianes no incloses en els dos grups anteriors. De les més de 130 espècies descrites de MNT, aproximadament un terç podrien estar relacionades amb malalties en humans i ser les responsables de les anomenades micobacteriosis, encara que, a diferència del complex M. tuberculosis i M. leprae, les espècies de MNT no són patògens obligats.
Els MNT tenen una gran capacitat de prevalença en aigües de distribució i això és degut principalment a la seva capacitat de créixer en un ampli rang de condicions ambientals i, sobretot, a la seva capacitat de colonitzar superfícies. La motilitat i la capacitat d'adherir-se a superfícies són algunes de les respostes funcionals que es manifesten en el procés de colonització d'una superfície. Per tant l'estudi de la motilitat, la hidrofobicitat i la capacitat d'adhesió a diferents materials ens pot ajudar a entendre i determinar els mecanismes de colonització, persistència i transmissió dels MNT en el medi ambient.
En el gènere Mycobacterium, els efectes de la morfologia colonial en les funcions biològiques són múltiples. Diferents estudis, en Mycobacterium avium, Mycobacterium abcessus i Mycobacterium smegmatis, mostren una relació directa entre la morfologia colonial, la motilitat, la hidrofobicitat, l'adhesió cel·lular i la formació de biopel·lícules en superfície, a més a més de relacionar aquestes funcions biològiques amb la presència en la paret cel·lular d'aquests micobacteris d'un tipus específic de glicolípids anomenats glicopeptidolípids.
Aquesta tesi s'ha centrat a estudiar i relacionar la morfologia colonial amb les funcions biològiques (motilitat, hidrofobicitat, adhesió cel·lular i formació de biopel·lícules en superfície), descrites inicialment en M. avium, M. abcessus i M. smegmatis, en un altre grup de micobacteris ambientals, Mycobacterium aurum, Mycobacterium chubuense, Mycobacterium gilvum, Mycobacterium obuense, Mycobacterium parafortuitum i Mycobacterium vaccae. Aquestes espècies micobacterianes tenen en comú que són de creixement ràpid, presenten originàriament una morfologia colonial llisa i, segons els estudis comparatius del 16S ARN, són filogenèticament properes entre elles, a la vegada que filogenèticament distants de les espècies micobacterianes ja estudiades.
En aquest sentit, ens vem proposar obtenir de forma espontània, a partir de les colònies llises de M. aurum, M. chubuense, M. gilvum, M. obuense, M. parafortuitum i M. vaccae, variants rugoses estables les quals van ser aïllades en cultiu pur. Posteriorment, ens vem centrar en analitzar els lípids i glicolípids de la paret cel·lular d'aquests micobacteris mitjançant cromatografia de capa fina per a comprovar si s'observaven diferències en la composició lipídica i glicolipídica entre les dues variants morfològiques. A més, es va dur a terme l'estudi comparatiu de la capacitat de motilitat, de les característiques hidrofòbiques, de l'adhesió cel·lular i de la formació de biopel·lícules en la interfase líquid-aire entre les dues morfologies colonials en les diferents espècies estudiades. I, finalment, es van fer estudis genètics per determinar les bases moleculars relacionades amb els canvis de morfologia colonial en M. vaccae.
Mycobacteria are a clinically important group of microorganisms due to the fact that there are some species which are causal agents of human diseases with high morbidity and mortality. Among this group of pathogenic mycobacteria it has to be highlighted Mycobacterium tuberculosis and Mycobacterium leprae, which are, respectively, the causal agents for tuberculosis and leprosy.
Besides, apart from the microorganisms which constitute the complexes M. tuberculosis and M. leprae, there is a large group of mycobacteria species which includes atypical or environmental mycobacteria (NTM). This group comprises the other mycobacteria species which have not been included in both groups before mentioned. At least a third out of the 130 NTM described could be related to human diseases and could be responsible for mycobacteriosis, although, unlike complex M. tuberculosis and M. leprae, NTM species are not obligated pathogens.
NTM have a great capacity to remain in the environment, and this is mainly due to their capacity to grow in a wide range of environmental conditions and, overall, due to their capacity to colonize surfaces. The motility and the capacity to adhere to many different surfaces are some of the functional responses which appear in a surface colonization process. That is why the study of motility, hydrophobicity and adhesion to many materials can help us to understand and determine the colonization, persistence and transmission mechanisms of NTM in the environment.
In Mycobacterium genus, the effects of colonial morphology in the biological functions are numerous. Different studies in Mycobacterium avium, Mycobacterium abcessus and Mycobacterium smegmatis, show a direct connection among colonial morphology, motility, hydrophobicity, cellular adhesion and biofilm formation. These biological functions are also connected with the presence in these mycobacteria cell wall of a specific type of glycosylated peptidolipids named glycopeptidolipids (GPLs).
This thesis has been focused on studying and connecting colonial morphology with biological functions (motility, hydrophobity, cellular adhesion and the biofilm formation), which have been described previously in M. avium, M. abcessus and M. smegmatis, in another environmental mycobacteria group, Mycobacterium aurum, Mycobacterium chubuense, Mycobacterium gilvum, Mycobacterium obuense, Mycobacterium parafortuitum and Mycobacterium vaccae. These species have in common that they are fast growing, show an originally smooth colonial morphology and, according to comparative 16S ARN studies, they are phylogenetically nearby among them but phylogenetically distant of the other mycobacteria species already studied. Moreover, none of these last species possess GPLs in their cell wall.
In this sense, we proposed to obtain spontaneous rough variants from the original smooth colonies of M. aurum, M. chubuense, M. gilvum, M. obuense, M. parafortuitum and M. vaccae. Afterwards, we analyzed and compared the lipid and glycolipid composition of the cell wall between both morphological variants by thin layer chromatography. In addition, we carried out the comparative study about the motility capacity, hydrophobical characteristics, cellular adhesion and biofilm formation in liquid-air interface between both colonial morphologies studied. And, finally, genetic studies were realized in order to determine the molecular bases connected with the changes in the colonial morphology in M. vaccae.
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Nakedi, Kehilwe Confidence. "Comprehensive definition of Ser/Thr/Tyr phosphorylation in mycobacteria: towards understanding reprogramming of normal macrophage function by pathogenic mycobacteria". Doctoral thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29707.
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Mycobacterium tuberculosis, the causative agent for the disease Tuberculosis, is a serious public health problem that is responsible for 1.6 million deaths each year. The WHO’s recent report on Tuberculosis estimates that a third of the world’s population is latently infected with the bacteria, and, of those, 10% will progress to active disease. M. tuberculosis is a successful pathogen mainly due to its ability to adapt and survive in changing environments. It can survive a dormant state with limited metabolic activity during latent infection, while also being able to escape the macrophage and disseminate into active disease. Efforts to eradicate the disease must be based on understanding the biology of this organism, and the mechanisms it uses to infect, colonize, and evade the immune system. Understanding the behaviour of pathogenic mycobacteria in the macrophage is also important to the discovery of new drug targets. In this thesis, we employed state of the art mass spectrometry techniques, which allowed us to unpack the biology of this bacterium in different growth environments and expand our understanding of the mechanisms it employs to adapt and survive. We investigated protein regulation by the process of phosphorylation, through sensory kinases, which add a phosphate group to a protein of interest, thereby regulating its function. First, we interrogated the phosphoproteomic landscape between M. bovis BCG and M. smegmatis to explain how differential protein regulation results in the differences between slow and fast growth of mycobacteria. Second, we focused on Protein Kinase G (PknG), which plays an important role in bacterial survival by blocking phagosome/lysosome fusion. We identified the in vivo physiological substrates of this kinase in actively growing M.bovis BCG culture. Our results revealed that this kinase is a regulator of protein synthesis. We then examined the mechanisms of survival in murine RAW 246.7 macrophages mediated by PknG, using M. bovis BCG reference strain and PknG knock-out mutant. Our results indicated strong evidence that pathogenic mycobacteria disrupt the macrophagic cytoskeleton, through phosphorylation of proteins that are involved in cytoskeleton rearrangement. These results explain the strategies that pathogenic mycobacteria employ mediated by PknG to block phagosome-lysosome fusion and evade the host immune system and survive for prolonged periods in the macrophages. The findings of this thesis contribute to our understanding of the physiology of pathogenic mycobacteria and their interaction with the host.
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Veyrier, Frédéric. "The evolution of «Mycobacterium tuberculosis»: the mycobacterial SigK-RskA regulatory system". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86905.
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The mycobacteria genus comprises bacteria pathogenic for humans and animals, including M. tuberculosis complex (MTC). In the past decade, considerable research has focused on genomic studies differences between MTC strains and sub-species. These data largely address the devolution of MTC organisms, through a process of reductive genomics and single nucleotide polymorphisms. We hypothesized that these findings present an incomplete evolutionary scenario for the pathogen M. tuberculosis. To test this possibility, we have conducted comparative genomic analysis among sequenced mycobacteria to look for evidence of horizontal gene transfers during the evolution of the genus. Using a bioinformatic screen, we predicted a number of foreign genes acquisitions during the step-wise genesis of M. tuberculosis. Along with others, this study emphasizes another side of the evolution of M. tuberculosis and demonstrates that before the process of genomic decay, M. tuberculosis had acquired foreign genes.The description of the M. tuberculosis evolution is strengthened when accompanied by functional characterization of these evolutionary events. Therefore, we have focused on an already-known example of micro-evolution to determine its role in M. tuberculosis biology. Our laboratory had previously established that MTC members exhibit variable production of eleven proteins due to mutations in the anti-sigma factor of SigK (RskA). As a consequence, in M. tuberculosis, their expression is low in vitro but strongly induced during infection; in contrast, M. bovis and the Oryx bacillus constitutively express these proteins. We first determined which genes are SigK-regulated and described the SigK promoters using luciferase technology. We then used these tools for a detailed study of the function of RskA from different MTC organisms. These experiments demonstrated that the anti-sigma factor RskA is not only an inhibitor of SigK but also presents an activator function. Finally, the activating property of RskA was used to generate M. tuberculosis strains over-expressing the SigK regulon, enabling us to test the effect of over-expression on the host pathogen relationship during in vivo infections. These experiments reproducibly demonstrated that over-expressing SigK-regulated genes results in increased bacterial dissemination from the site of infection along with increased survival of the host.
Over-all, this study has provided new and complementary understanding on M. tuberculosis evolution. Additionally, our evolutionary approach has contributed to a better understanding of two major areas of research, specifically Sigma factor signaling and M. tuberculosis pathogenesis.
Le genre bactérien des mycobactéries comprend des espèces pathogènes pour les animaux mais aussi pour les humains comme les bactéries du groupe de Mycobacterium tuberculosis (MTC). Dans les dernières années, la recherche dans ce domaine à largement donné la priorité aux études des différences génomiques entre les sous-espèces et souches du MTC. Celles-ci ont alors permis d'observer que les organismes du MTC avaient évolué grâce à des délétions géniques et des mutations ponctuelles. Cependant, nous avons émis l'hypothèse que ces observations ne décrivent qu'en partie l'évolution de M. tuberculosis. En effet, en utilisant la comparaison bioinformatique des génomes des mycobactéries séquencées, nous avons décrit l'acquisition séquentielle de gènes étrangers par l'ancêtre de M. tuberculosis durant l'évolution du genre. Cette étude, additionnée à d'autres, démontre que l'évolution de M. tuberculosis a été ponctuée d'acquisition de gènes étrangers avant d'être suivi d'une période de dévolution génomique.
L'étude de l'évolution de M. tuberculosis ne serait pas complète sans la caractérisation fonctionnelle de ces évènements évolutifs. C'est pourquoi nous avons tenté de comprendre un exemple déjà connu de microévolution et de déterminer le rôle de cet évènement dans la biologie de M. tuberculosis. Notre laboratoire a déjà établi que les membres du MTC expriment de façon variable onze protéines suite à des mutations dans l'anti-sigma facteur de SigK (RskA). Par conséquent, si M. tuberculosis n'exprime pas ces protéines in vitro mais durant l'infection, M. bovis et le Bacille de l'antilope les expriment de façon constitutive incluant in vitro. Nous avons commencé par décrire les promoteurs régulés par SigK en utilisant la luciférase comme rapporteur. Ces données et ces outils nous ont alors permis d'étudier plus en détail la fonction des différentes versions de RskA provenant des membres du MTC. Nous avons démontré que RskA est non seulement un inhibiteur de SigK mais aussi un activateur. La découverte des propriétés activatrices de RskA nous a permis de construire des souches de M. tuberculosis qui surexpriment le regulon SigK et donc de tester l'effet de cette surexpression sur la relation hôte-pathogène lors d'une infection. Ces expériences ont démontré de façon répétée que la surexpression du regulon SigK accroit d'une part les capacités disséminatrices des bactéries et d'autre part le temps de survie de l'hôte.
En conclusion, cette étude a permis une meilleure description de l'évolution de M. tuberculosis. De plus, notre approche de l'évolution a contribué à une meilleure compréhension de deux domaines de recherche majeure à savoir la régulation de gènes par les Sigma facteurs mais aussi la pathogenèse de M. tuberculosis.
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Mullis, Summer. "Adherence and Biofilm Formation of Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium abscessus in household plumbing". Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/44778.
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Nontuberculous mycobacteria (NTM) are ubiquitous in the environment and found in drinking water distribution systems and household plumbing. They are opportunistic pathogens of humans, causing lung disease. Their ability to adhere and form biofilm is attributed to a waxy, lipid-rich, cell envelope. This highly hydrophobic envelope also contributes to the characteristic antibiotic-, chlorine-, and disinfectant- resistance of NTM.
NTM in household plumbing reside primarily in biofilms and the ability to form biofilm has been linked to virulence. Shedding of cells from biofilm and the subsequent aerosolization of microorganisms through showerheads presents a significant public health risk, particularly to those individuals with associated risk factors.
Three species of NTM, Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium abscessus, were examined for adherence and biofilm formation on surfaces common to household plumbing systems, including glass, copper, stainless steel, polyvinyl chloride, and galvanized steel. All experiments were conducted with sterile, Blacksburg tap water in a CDC Biofilm Reactor.
Highest adherence was observed by M. avium on galvanized steel surfaces, reaching 15,100 CFU/cm2 surface at 6 hours incubation at room temperature. After 3 weeks incubation at room temperature, biofilm formation of M. avium was also highest on galvanized steel surfaces, reaching 14,000,000 CFU/cm2 surface. Lowest adherence was observed by M. abscessus on polyvinyl chloride (PVC) surfaces, reaching 40 CFU/cm2. Lowest biofilm formation was observed by M. intracellulare on glass surfaces, reaching 5,900 CFU/cm2.
Surfaces, such as galvanized (zinc), on which high adherence and biofilm formation was observed, should be avoided in household plumbing systems of NTM patients and individuals at risk for developing NTM disease. Additionally, surfaces such as copper, harbor fewer NTM and may provide a safer alternative for household plumbing of NTM patients.Master of Science
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Mathie, Heather. "Early macrophage response to Mycobacterium avium subspecies paratuberculosis". Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31378.
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Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of Johne's disease, a chronic enteritis that has a damaging economic and welfare impact on the livestock industry. Johne's disease in cattle is known to reduce milk yield and carcass value, making it of economic concern to both dairy and beef farmers. In addition, there is cause for concern regarding zoonotic transmission, as there is an unconfirmed but potential relationship between MAP infection and human Crohn's disease, which presents similar clinical symptoms. MAP is most often contracted by neonates through the faecal-oral route, but can also be spread through contact with contaminated milk and colostrum, as well as in utero. Once the host receives an oral dose, the bacteria traverse the gut epithelium and are phagocytosed by gut macrophages residing in the lamina propria and Peyer's patches. MAP are able to evade the macrophage response by resisting intracellular degradation within phagosomes. Infected macrophages respond to the infection by secreting several pro-inflammatory cytokines that drive the downstream immune response and granuloma formation. This work aimed to elucidate key early responses of bovine monocyte derived macrophages (MDM) to MAP infection, and determine the reliability of using the reference strain, K10 (which is likely to have undergone lab adaptation) to model the infection in vitro, by comparing the MDM response to K10 with the response to a recent clinical isolate, C49. At a multiplicity of infection of 5 (MOI 5), there was a significant decrease in K10 intracellular survival (~90%), compared to C49 intracellular survival, over a 24 hour infection time-course. This suggests that K10 may have lost some virulence mechanism through lab adaptation. Understanding the mechanisms of how MDM respond to these two strains could be informative for the design of targeted vaccines When further investigating the MDM response to both strains, it was found that, at MOI 5, MDM infected with K10 secreted higher levels of IL-1β and IL-10, compared to MDM infected with C49. Both cytokines are associated with mycobacterial infection and could perhaps indicate that MDM are more responsive to the K10 strain at early time-points. In addition, MDM infected with K10 produced significantly higher levels of reactive nitrogen species (RNS). RNS are antimicrobial products that can destroy invading pathogens, and have been shown to have bactericidal effects on MAP. The production of RNS could, therefore be a potential mechanism by which MDM are able to kill K10 more efficiently than C49. An additional aim of this project was to understand the importance of the route of phagocytosis in determining the outcome of MAP infection. MDM express several phagocytic receptors, including Fc receptors (FcRs), complement receptors (CR), Ctype lectin receptors and scavenger receptors. This project mainly focused on the role of the mannose receptor (MR) on bacterial uptake and downstream immune responses, as past studies have suggested that other species of mycobacteria such as M. tuberculosis, target the mannose receptor in order to regulate macrophage immune responses. Blocking the MR reduced intracellular survival for both strains of MAP; however, the mechanism by which the MR influences intracellular survival remains poorly understood The effect of opsonisation on MAP prior to uptake by phagocytic cells was also investigated, as presence of opsonins, such a complement proteins and antibody, can change the mechanism by which pathogens are phagocytosed. MAP were incubated in serum from either MAP- negative or MAP- positive cattle, prior to infection and the percentage uptake and survival assessed by performing colony counts. Opsonisation in serum from Johne's negative cattle resulted in marked increase in MAP uptake but not intracellular survival, whereas opsonisation in serum from Johne's positive cattle did not increase uptake but decreased the intracellular survival rate by 24 HPI. This finding highlights a potential protective role of antibody early in the infection process, and could significantly impact how the infection is modelled in future, as anti-MAP antibody may be present in contaminated milk at the point of infection. Taken together, the data presented in this thesis show that bacterial strain has a significant impact on MDM response to MAP infection, which may have important implications for the interpretation of previous studies and the design of future studies investigating host-pathogen interactions in the context of paratuberculosis. Additionally, this work has shown that RNS production and the mechanism of uptake can affect intracellular survival rates, and although this needs further investigation, the findings could have implications for the design of future vaccines.
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Warek, Ujwala. "Action of clofazimine on Mycobacterium avium and Mycobacterium intracellulare". Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03042009-040856/.
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Sales, Mariana Lázaro. "Identificação de Mycobacterium bovis e Mycobacterium tuberculosis por PCR". Universidade Federal de Minas Gerais, 2012. http://hdl.handle.net/1843/SMOC-9L2PT7.
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Mycobacterium bovis and Mycobacterium tuberculosis are the causative agents of bovine and human tuberculosis, respectively. The standard diagnosis is based on the isolation and identification of bacterial colonies through biochemical methods. These methodologies in addition to being costly, require an environment with high level of biosecurity and a great time of cultivation and tests to obtain the results. The molecular tests based on the principles of real-time PCR using the fluorophore Eva Green were efficient in the identification of M. bovis and M. tuberculosis. In addition, analyses were performed with primers and molecular markers, described in the literature, able to differentiate the M. bovis of M. tuberculosis by PCR. The results showed that some of the molecular markers are found in both microorganisms. The work of this dissertation has enabled the development of real-time PCR techniques able to identify colonies of M. bovis and M. tuberculosis.O Mycobacterium bovis e o Mycobacterium tuberculosis são os agentes causadores da tuberculose bovina e humana, respectivamente. O diagnóstico padrão se baseia no isolamento bacteriano e a identificação das colônias através de métodos bioquímicos. Estas metodologias além de serem onerosas, requerem um ambiente com alto nível de biossegurança e um grande tempo de cultivo e testes para obtenção dos resultados. Os testes moleculares baseados nos princípios da PCR em tempo real utilizando-se o fluoróforo Eva Green foram eficientes na identificação do M. bovis e M. tuberculosis. Além disso, foram realizadas análises com iniciadores e marcadores moleculares, descritos na literatura, capazes de diferenciar o M. bovis do M. tuberculosis por PCR. Os resultados mostraram que alguns dos marcadores moleculares são encontrados em ambos os micro-organismos. O trabalho dessa dissertação permitiu o desenvolvimento de técnicas de PCR em tempo real capazes de identificar colônias de M. bovis e M. tuberculosis, em substituição aos testes bioquímicos.
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Whiteford, Danelle. "Stress survival in Mycobacterium tuberculosis and Mycobacterium bovis and the role of hup in Mycobacterium smegmatis". Pullman, Wash. : Washington State University, 2008. http://www.dissertations.wsu.edu/Dissertations/Fall2008/D_Whiteford_100908.pdf.
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Taylor, Robert Henry. "Disinfectant Susceptibility of Mycobacterium avium". Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36018.
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Mycobacterium avium, an opportunistic human pathogen, infects between 25 and 50% of advanced-stage acquired immuno-deficiency syndrome (AIDS) patients in the United States. M. avium has been isolated from many environmental sources including: natural waters, soils, and aerosols. M. avium has also been recovered from within municipal and hospital drinking water systems. Rhesus macaques (Macaca mulatta) infected with the simian HIV analog, SIV, have been shown to acquire M. avium infections from potable water.
Reduced-aggregate fractions (cell suspensions free of large aggregates) of Mycobacterium avium were exposed to chlorine, monochloramine, chlorine dioxide, and ozone and kinetics of disinfection measured. Chlorine disinfection kinetics was also measured in M. avium cultures grown in biofilms.
M. avium exhibited a high resistance to chlorine compared to E. coli. M. avium CT99.9% (disinfectant concentration x time to 3 logs cell inactivation) values were between 571- and 2318 -times those of E. coli. Clinical isolates of M. avium showed 0.24 and 2.5-fold increase in resistance to chlorine compared to their pulsed-field-gel-electrophoresis- (PFGE) matched environmental isolates.
M. avium strains exhibited a mixed response to exposure to monochloramine. The CT99.9% values of three strains (2 clinical, 1 environmental) were between 6.3- and 23.5- times that of E. coli. Two strains (1 clinical, 1 environmental) exhibited CT99.9% values approximately the same as E. coli, a difference from all the other disinfectants which were much less effective on M. avium than on E. coli.
M. avium strains exhibited a high resistance to chlorine dioxide when compared to E.coli. M. avium CT99.9% values of between 133- and 706- times higher that that of E. coli. In the paired isolates tested, the clinical isolate was 5.3 times more resistant than the matched environmental isolate.
M. avium exhibited a high resistance to ozone when compared to E. coli. M. avium strains exhibited a CT99.9% value of between 52 and 90 times higher that that of E. coli. In the paired isolates tested, the clinical isolate was nearly identical as judged by CT99.9% values. M. avium strain 5002 exhibited an unusual disinfection kinetics curve. Disinfection rate increased by a non-logarithmic factor, indicating that inactivation efficiency was increasing over time.
M. avium strain 1060 showed between a 17% decrease to a 265% increase in CT99.9% value when grown as biofilms as opposed to suspension. Due to the large variance in biofilm density and and CT99.9% values, any conclusions based on these experiments should be considered tentative at best.
M. avium's resistance to chlorine and chlorine dioxide approaches that of the protozoan cysts of Giardia muris and Entamoeba hystolytica. M. avium is much less resistant, relatively, to monochloramine possessing values similar to E. coli. Ozone resistance of M. avium is two orders of magnitude greater than E. coli and one order of magnitude of less than G. muris cysts.
A critical concentration threshold level for chlorine dioxide was found. That is, there was no linear relationship between concentration of chlorine dioxide and cell inactivation. Initial experiments using a range of concentrations from 0.1 ppm to 0.5 ppm chlorine dioxide showed a biphasic curve with the inflection point (indicating the critical concentration) between 0.3 and 0.4 ppm chlorine dioxide.
Master of Science
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Jönsson, Bodil. "Epidemiological and immunological studies of environmental mycobacteria : with focus on Mycobacterium abscessus /". Göteborg : Clinical Bacteriology Section, Dept of Infectious medicine, Sahlgrenska Academy, University of Gothenburg, 2009. http://hdl.handle.net/2077/19060.
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Hoza, Abubakar Shaaban. "Molecular characterization of Mycobacterium tuberculosis complex and prevalence of nontuberculous mycobacteria and other potential pathogenic bacteria from Tubercolisis suspents in Northeastern, Tanzania". Doctoral thesis, Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-211093.
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Molecular typing is increasingly essential to tuberculosis (TB) control programmes, providing public health practitioners with a tool to characterize transmission patterns, track the emergence and spread of strains of M. tuberculosis complex (MTC) in populations. While molecular typing is already used extensively as a tool for TB control in many developed settings across the globe, its use in resource-poor settings is still limited. Moreover, information on the role, contribution and burden of nontuberculous mycobacteria (NTM) and other pathogens in aetiology of TB-like syndromes is also lacking in such settings.
The broad objective of this dissertation was to determine the genetic diversity of MTC and their drug resistance profiles as well as the prevalence of NTM and other potentially pathogenic bacteria among TB suspects in Northeastern, Tanzania in order to generate insights that may inform the design of a rational TB control programmes.
A total of 18 distinct spoligotypes were identified in this study area, with CAS1-KILI and EAI8 being the most predominant families. Major lineages prediction by conformal Bayesian network (CBN) revealed that 70% of TB infections in this area is due to modern lineages, whereas 30% of TB infections is due to the ancestral lineages mainly of Indo-oceanic lineage.
The study also revealed that the overall proportions of any drug resistance and MDR-TB were 12.7% and 6.3% respectively. With the prevalence of any drug resistance and MDR-TB among new cases being 11.4% and 4.3% respectively, among previously, treated cases were 22.2%. The prevalence of NTM was found to be 9.7 %, with HIV being a significant predictor of NTM detection (P < 0.001). Four out of 30 patients with NTM diagnosed by culture received 1st line anti-TB treatment suggesting that a proportion of patients diagnosed by smear microscopy (4/65, 6.2%) were mistreated as TB patients. Our findings further showed that 17 (4.6%) out of 372 TB suspects were due to pulmonary nocardiosis.
Overall this dissertation has revealed that TB is still a major problem in Tanga and is characterized by a diverse array of MTB strains. Additionally, modern MTB strains contribute significantly to TB infections in this area. High proportions of anti-TB drug resistance among new treated cases observed suggest that more efforts need to be done to identify individual cases at facility level for improved TB control programmes. Inefficient screening of TB patients and a prevalent increase of NTM may contribute to both unrealistic and mismanagement of TB cases. A diverse array of pathogenic Nocardia species among TB suspects further indicates that they are likely cause of human disease in this population.
Therefore, need to integrate NTM and pathogens causing TB-like syndromes in diagnosis and management of TB is urgent. Results of these investigations contribute to the understanding of the dynamics of TB transmission in resource poor settings of Tanzania and highlight key factors that should be considered in the development of rational approaches to design effective TB prevention and control programmes in the country.
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Djomkam, Leopold Tientcheu. "Differences between host immune responses to `Mycobacterium tuberculosis' and 'Mycobacterium africanum'". Thesis, London School of Hygiene and Tropical Medicine (University of London), 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.590516.
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Daffé, Mamadou Madani. "Les lipides dans la taxonomie des mycobacteries : application a l'etude de mycobacterium leprae". Toulouse 3, 1986. http://www.theses.fr/1986TOU30138.
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Martinot, Amanda Jezek. "Mycobacterial Metabolic Syndrome: Triglyceride Accumulation Decreases Growth Rate and Virulence of Mycobacterium Tuberculosis". Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:14226055.
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Mycobacterium tuberculosis (Mtb) mutants lacking the operon Rv1411c-1410c encoding a lipoprotein, Rv1411c (LprG) and a putative transporter, Rv1410c (Rv1410) are dramatically attenuated for growth in mice. Previous work in our lab, using the model organism Mycobacterium smegmatis, suggested that this operon regulated the lipid content of the cell wall. Work in other laboratories characterizing LprG as a lipid-binding lipoprotein lead us to hypothesize that these bacteria grew poorly due to loss of a key lipid important in the host-pathogen interaction. Based on structural and biochemical studies we hypothesized that this attenuation was due to a lipid transport defect. Using whole cell lipidomic analysis, we found changes in LprG-1410 mutants including accumulation of triacylglyceride (TAG) species in the absence of the transport system. We have identified TAG in outer membrane fractions and supernatants of Mtb, have demonstrated the ability of LprG to transport TAG in an in vitro vesicle transfer assay, and have co-crystallized LprG with TAG. Moreover, accumulation of intracellular TAG substantially decreases growth under carbon stress in vitro and in vivo in the mouse model. Our results suggest a far different model – that TAG is ordinarily transported out of the cell and, in the absence of a transporter, limits cell proliferation independent of the host immune response. This suggests that TAG is a key metabolic regulator of cellular growth within the host.
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Fujita, Kohei. "Association between polyclonal and mixed mycobacterial Mycobacterium avium complex infection and environmental exposure". Kyoto University, 2014. http://hdl.handle.net/2433/188673.
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Lamrabet, Otmane. "Modifications génétiques de Mycobacterium tuberculosis : interactions avec les organismes hôtes". Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM5027/document.
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Les mycobactéries sont classées parmi les bactéries contenant des acides mycoliques dans leur paroi et un haut GC% dans leur génome. Elles peuvent être isolées à partir du sol ou d'environnement d'eau douce où vivent aussi les protozoaires libres. Plusieurs études ont montré une possibilité de co-isolement des mycobactéries et des amibes à partir de ces sources environnementales. Il a été montré également que la plupart des mycobactéries de l'environnement ont la capacité à survivre dans les trophozoites et les kystes d'amibes et dans certaines cellules eucaryotes, y compris les macrophages. Les manipulations génétiques des mycobactéries en général et des mycobactéries du complexe Mycobacterium tuberculosis en particulier sont compliquées et aucune étude de modification génétique des mycobactéries (pathogènes ou non pathogènes) n'avait été réalisée dans notre laboratoire avant notre travail de thèse. Dans notre travail de thèse, nous avons montré que les amibes ou d'autres organismes phagocytaires peuvent servir comme sources et lieu de transfert des gènes chez les mycobactéries. Ce transfert des gènes peut avoir contribué à l'adaptation des mycobactéries à un mode de vie intracellulaire. Nous avons développé ensuite deux systèmes de coculture: Mycobacterium smegmatis-Acanthamoeba polyphaga et Mycobacterium gilvum-A. polyphaga et nous avons clarifié le spectre des interactions des mycobactéries à croissance rapide avec les amibes. Ce modèle d'interaction mycobactéries-amibes a été utilisé pour tester l'hypothèse contraire au paradigme dominant que l'addition des gènes réduit la virulence des bactériesMycobacteria are mycolic-acid containing, high GC% bacterial organisms which can be recovered from soil and fresh water environments where free-living protozoa also live. Co-isolation of mycobacteria and amoeba collected from such environmental sources has been reported. Several experiments further demonstrated the ability of most environmental mycobacteria to survive in the amoebal trophozoites and cysts and in some eukaryotic cells including macrophages. Genetic modification of mycobacteria in general and mycobacteria belonging to Mycobacterium tuberculosis complex in particular are complicated and no studies using genetic modification of mycobacteria (pathogenic or non-pathogenic) had been performed in our laboratory prior to our work. In our thesis work, we showed that amoebae or other phagocytic organisms can serve as sources and places for gene transfers in mycobacteria. Gene transfers may have contributed to the adaptation of mycobacteria to an intracellular lifestyle. In addition, we developed two co-culture systems: Mycobacterium smegmatis-Acanthamoeba polyphaga and Mycobacterium gilvum-A. polyphaga and we clarified the spectrum of rapid-growing mycobacteria and amoeba interactions. This model of mycobacteria-amoeba interactions was then used to test another hypothesis according to which unlike the prevailing paradigm, the addition of genes does not reduce the virulence of bacteria. For the first time in our laboratory we modified two species of the M. tuberculosis complex, M. tuberculosis H37Rv and Mycobacterium bovis BCG to observe the effect of these changes on their pathogenicity and survival
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Gcebe, Nomakorinte. "The occurrence and molecular characterization of non-tuberculous mycobacteria in cattle, African buffalo (Syncerus caffer) and their environments in South Africa and genomic characterization and proteomic comparison with Mycobacterium bovis". Thesis, University of Pretoria, 2015. http://hdl.handle.net/2263/58682.
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The aim of this study was to investigate the diversity and prevalence of non-tuberculous mycobacteria (NTM) in cattle, African buffaloes and their environments in South Africa and the potential of these NTM to elicit cross- reactive immune responses in these animal species which may in turn lead to false diagnosis of bovine tuberculosis. A total of 40 NTM species were identified during a countrywide survey. Mycobacterium terrae, Mycobacterium nonchromogenicum, Mycobacterium vaccae/ Mycobacterium vanbaalenii and a group of isolates closely related to Mycobacterium moriokaense (M. moriokaense-like isolates) were the four most frequently isolated species. Further characterization of M. moriokaense- like isolates revealed two novel NTM species which were named Mycobacterium malmesburii sp.nov. and Mycobacterium komanii sp.nov. respectively. Genomes of M. nonchromogenicum, M. malmesburii sp. nov., M. komanii sp. nov., and M. fortuitum ATCC 6841 were elucidated and investigated for genes encoding homologues of M. bovis predominant immunogenic proteins. These included genes encoding for the Esx family proteins (esx genes), mpb70, mpb63, mpb64, hspX, tpx, Rv1120c, canA and dnaK. The esx gene orthologs encoded in ESX-1 (esxA and esxB), ESX-3 (esxH and esxG), esxR, and ESX-4 (esxT and esxU) loci were identified in the NTM genomes while those encoded in ESX-2 locus were absent in all the four NTM genomes and only esxN (encoded in the ESX-5 locus) and its homologue, esxK were present in M. nonchromogenicum. Gene orthologs encoding for MPB70 (M. malmesburii sp.nov. and M. komanii sp.nov.), DnaK (all four NTM species), CanA (all four NTM species), MPB64 (all four NTM species), Rv1120c (in all four NTM species), TpX, MBP63 and HspX (all in M. nonchromogenicum and M. fortuitum), were found in the NTM genomes. In contrast orthologs of mpb83 and espC were not detected in any of the four NTM. We could not judge just based on the overall protein sequence homologies of the antigens whether the NTM homologues will give rise to cross-reactive immune responses. We consequently checked the existence in NTM of epitopes shown to be immunogenic in M. bovis and M. tuberculosis. Amino acid sequence alignment of the EsxA and EsxB of the NTM sequenced in this study as well as M. smegmatis, M. bovis and M. tuberculosis respectively was done to investigate their similarities at “immunogenic” epitope level. In this analysis, we found that the six bovine T-cell recognized epitopes of M. bovis ESAT-6 described by Vordermeier et al., 2003 and 2007 had similarities to those of M. fortuitum and M. nonchromogenicum (showing sequence similarity of as high as 81.28% and as low as 52.9% ). Likewise a certain degree of sequence similarity between the six M. bovis CFP 10 immunogenic epitopes and those of the NTM species (highest similarity of 75% observed between all NTM and M. bovis and lowest similarity of 50% between M. komanii sp.nov, M. malmesburii sp.nov and M. bovis.) was observed. Still, with sequence homologies of less than 100% between the M. bovis immunogenic epitopes and those of the NTM, it was difficult to unambiguously predict T-cell cross-recognition. Comparison of the EsxR and EsxH amino acid sequences at immunogenic epitope level, revealed higher sequence similarities in the epitopes of NTM and those of M. bovis than the predicted protein sequences of EsxA and EsxB. A sequence similarity of 100% was observed between two of the five M. bovis immunogenic epitopes of EsxR and those of M. fortuitum, M. malmesburii sp. nov. and M. komanii sp.nov. Full cross- recognition of these NTM EsxR epitopes is therefore highly likely, and may lead to misdiagnosis of bovine Tuberculosis (BTB). The other three EsxR/EsxH epitopes shown to be immunogenic in M. bovis also exist in the three NTM showing similarity of as low as 77.7%.Thesis (PhD)--University of Pretoria, 2015.
WOTRO Science for Global Development
Genomics Research Institute (GRI)
Veterinary Tropical Diseases
PhD
Unrestricted
27
Baron, Vincent. "Phenotypic discrimination of Mycobacterium tuberculosis by Raman spectroscopy". Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/16562.
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TB remains a major health issue worldwide causing around 1.5 deaths each year. The recent phase III clinical trials of shortened TB treatment failed to show superiority compared to the current regimen and this mainly because of relapse. Relapse is thought to be caused by dormant bacteria. Dormancy in Mycobacterium species has been shown to be associated with the accumulation of intracellular lipids, defining two phenotypes: the lipid rich (LR) cells (associated with dormancy) and the lipid poor (LP) cells (non-dormant). LR cells were shown to have a higher phenotypic antibiotic resistance compared to LP cells. Studying these two phenotypes is therefore central in tuberculosis research to understand better the disease and also potentially start to reveal the bacteriology of relapse. We investigated the power of Raman spectroscopy, a label-free and non-destructive technique, to discriminate LR and LP bacteria both in-vitro and ex-vivo. This represents the first Raman spectroscopy study that tries to discriminate the phenotypes of M. tuberculosis and investigate them directly at the site of the disease. Using total lipid extract of M. tuberculosis, we showed the location of the main lipid bands in the Raman spectrum. The two major lipid peaks were located around 1300 cm⁻¹ and 1450 cm⁻¹. Raman spectroscopy can discriminate LR and LP cells with high sensitivity and specificity. The main differences between the two groups are located in the two major Raman lipid peaks, the lipid band A (1300 cm⁻¹) and lipid band B (1440 to 1450 cm⁻¹). The two phenotypes were successfully discriminated in TB infected guinea pig lung tissue sections also from in-vitro culture using wavelength modulated Raman (WMR) spectroscopy combined with fluorescence imaging. We developed a protocol to perform both Raman spectroscopy and immunohistochemistry on the same tissue sample. We studied the evolution of LR and LP proportion in mycobacterial population as the growth conditions changed and showed that LR cells could rapidly convert to LP cells as they face favourable growth conditions. The results presented in this thesis showed that LR M. tuberculosis cells could be predominant at the site of infection. This would suggest that drug sensitivity testing should be performed on culture presenting both LR and LP cells in high proportion.
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Guhan, N. "Mycobacterium tuberculosis RecA intein, a novel LAGLIDADG homing endonuclease, displays dual target specificity in the presence of alternative cofactors". Thesis, Indian Institute of Science, 2002. https://etd.iisc.ac.in/handle/2005/117.
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Mobile inteins and introns are genetic elements capable of self-propagation by “homing” into host genes and occur in entire taxonomy: eubacteria, eukarya, archaea and viruses. The process of “homing” is promoted by an endonuclease encoded by the open reading frame (ORF) embedded within the genetic element. Homing endonucleases are encoded by group I and group II introns, archaeal introns, inteins, and free standing ORFs. They are believed to play a central role in rearrangement of organelle as well as nuclear genomes. Inteins are genetic elements present within protein-coding genes with dual function: protein-splicing and homing endonuclease activities. One hallmark of homing endonucleases is their ability to recognize and cleave extended degenerate asymmetric sequences (14 - 40 bp) in intein- or intron-less alleles. Homing endonucleases are classified into four families based on the presence of LAGLIDADG, GIY-YIG, His-Cys box, or H-N-H conserved motifs. Among these, LAGLIDADG family is the largest, widespread and well-studied class. Structural and biochemical studies have demonstrated that homing endonucleases with one LAGLIDADG motif act as homodimers, whereas enzymes with two such motifs function as monomers during catalysis. In vitro, these enzymes are extremely specific for their recognition sites and they prefer Mg2+ as the metal-ion cofactor.
Unlike Escherichia coli, recA of Mycobacterium tuberculosis and Mycobacterium leprae contain in-frame insertion of an intein-coding sequence. In addition to recA,scrutiny of M. tuberculosis genome revealed that intein-coding sequences are present in the ORFs of dnaA and Rv1461 (pps1). M. tuberculosis recA encodes a 85 kDa precursor
protein. Amino acid sequence comparison between M. tuberculosis RecA precursor and the prototype E. coli RecA displayed high degree of homology at the amino-terminal (1 -254 amino acid residues) and carboxyl-terminal (694 - 790 amino acid residues)domains of the RecA precursor. The central domain comprising 440 amino acid residues
showed significant homology to the members of the LAGLIDADG super-family of intein homing endonucleases. Following the synthesis of precursor protein, RecA intein and active RecA are generated by protein splicing reaction. The protein splicing reaction of RecA intein has been studied extensively; however, its endonuclease activity remained obscure.
To identify the biochemical function of M. tuberculosis RecA intein (PI-MtuI), the
intervening sequence from recA was cloned, overexpressed in E. coli and purified to
homogeneity. The identity of PI-MtuI was ascertained by sequencing 10 amino acid
residues at the amino-terminal end and by Western blot analysis using polyclonal antibodies raised against precursor RecA.
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Guhan, N. "Mycobacterium tuberculosis RecA intein, a novel LAGLIDADG homing endonuclease, displays dual target specificity in the presence of alternative cofactors". Thesis, Indian Institute of Science, 2002. http://hdl.handle.net/2005/117.
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Mobile inteins and introns are genetic elements capable of self-propagation by “homing” into host genes and occur in entire taxonomy: eubacteria, eukarya, archaea and viruses. The process of “homing” is promoted by an endonuclease encoded by the open reading frame (ORF) embedded within the genetic element. Homing endonucleases are encoded by group I and group II introns, archaeal introns, inteins, and free standing ORFs. They are believed to play a central role in rearrangement of organelle as well as nuclear genomes. Inteins are genetic elements present within protein-coding genes with dual function: protein-splicing and homing endonuclease activities. One hallmark of homing endonucleases is their ability to recognize and cleave extended degenerate asymmetric sequences (14 - 40 bp) in intein- or intron-less alleles. Homing endonucleases are classified into four families based on the presence of LAGLIDADG, GIY-YIG, His-Cys box, or H-N-H conserved motifs. Among these, LAGLIDADG family is the largest, widespread and well-studied class. Structural and biochemical studies have demonstrated that homing endonucleases with one LAGLIDADG motif act as homodimers, whereas enzymes with two such motifs function as monomers during catalysis. In vitro, these enzymes are extremely specific for their recognition sites and they prefer Mg2+ as the metal-ion cofactor.
Unlike Escherichia coli, recA of Mycobacterium tuberculosis and Mycobacterium leprae contain in-frame insertion of an intein-coding sequence. In addition to recA,scrutiny of M. tuberculosis genome revealed that intein-coding sequences are present in the ORFs of dnaA and Rv1461 (pps1). M. tuberculosis recA encodes a 85 kDa precursor
protein. Amino acid sequence comparison between M. tuberculosis RecA precursor and the prototype E. coli RecA displayed high degree of homology at the amino-terminal (1 -254 amino acid residues) and carboxyl-terminal (694 - 790 amino acid residues)domains of the RecA precursor. The central domain comprising 440 amino acid residues
showed significant homology to the members of the LAGLIDADG super-family of intein homing endonucleases. Following the synthesis of precursor protein, RecA intein and active RecA are generated by protein splicing reaction. The protein splicing reaction of RecA intein has been studied extensively; however, its endonuclease activity remained obscure.
To identify the biochemical function of M. tuberculosis RecA intein (PI-MtuI), the
intervening sequence from recA was cloned, overexpressed in E. coli and purified to
homogeneity. The identity of PI-MtuI was ascertained by sequencing 10 amino acid
residues at the amino-terminal end and by Western blot analysis using polyclonal antibodies raised against precursor RecA.
30
Michell, Stephen Lloyd. "Molecular characterisation of a novel lipoglycoprotein from Mycobacterium tuberculosis and Mycobacterium bovis". Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/7477.
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In Great Britain a recent independent scientific review into bovine tuberculosis concluded that the best prospect for control of TB in the national herd is to develop a vaccine. The secreted antigens of the Mycobacterium tuberculosis complex have received much interest as possible vaccine candidates due to their ability to confer protection against tuberculosis in small animal models. The recent discovery that some of these mycobacterial antigens are glycosylated, a modification ubiquitous in eukaryotic proteins, may provide some novel insights into the properties of these antigens. The antigen MPB70 is the major secreted protein of Mycobacterium bovis, the causative agent of tuberculosis in cattle. It has previously been reported that this antigen, encoded for by the gene mpb70, is present in at least two forms, a 22 kDa unglycosylated form and a 25 kDa glycosylated form. A clone was isolated from an M. tuberculosis H37Rv mycobacterial shuttle cosmid library which expressed both the 22 and 25 kDa antigens. Genetic analysis of this cosmid revealed that the two antigens were encoded by separate genes. The gene encoding the 25 kDa antigen (MPT83), subsequently designated mpt83, is situated 2.4 kb upstream of mpt70 and transcribed in the same direction. Using a mycobacterial expression system and alkaline phosphate (PhoA) fusions, it was shown that MPT83 but not MPT70 is glycosylated by Mycobacterium smegmatis. Moreover, neither fusion protein was glycosylated in E. cW demonstrating that glycosylation of MPT83 was specific to the mycobacterial species. The use of site directed mutagenesis in conjunction with the PhoA reporter system identified both 0 and N-linked glycosylation sites within MPT83. Preliminary investigations into the role of glycosylation in the alteration of immune recognition showed a possible influence of cilycosylation on a T cell epitope of MPT83.
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Middleton, Andrew Mark. "The interaction of mycobacterium avium complex and mycobacterium tuberculosis with respiratory mucosa". Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252107.
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McNerney, Ruth. "Detection of mycobacterium tuberculosis". Thesis, London School of Hygiene and Tropical Medicine (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416621.
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Cochrane, Shaun Kevern Twyman. "Antitermination in Mycobacterium tuberculosis". Thesis, University College London (University of London), 2004. http://discovery.ucl.ac.uk/1446584/.
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Mycobacterium tuberculosis is the leading cause of death from a single infectious agent. The varying efficacy of the BCG vaccine and the emergence of multi-drug resistant strains of M. tuberculosis have made it essential that novel drug and vaccine targets are identified. The antitermination mechanism, probably used in transcriptional regulation of the single rrn operon, is one such target. Antitermination is a mechanism by which RNA polymerase is able to transcribe through both Rho-dependent and-independent terminators. Antitermination in association with Nus (N-utilising) factors was initially discovered within the ?-phage where it regulates the transcription of early and late genes. Subsequent investigations in Escherichia coli demonstrated antitermination and the Nus proteins were involved in transcriptional regulation of the seven rrn operons present in the genome. The presence of Nus homologs and Nut sequences (the assembly sites for the antitermination complex) within the M. tuberculosis genome indicate that antitermination may occur during rrn operon transcription. The aim of this project has thus been an understanding of the characteristics, functions and interactions of the Nus proteins within the M. tuberculosis antitermination complex. A definite, yet likely to be weak, interaction between NusB and NusE is shown. The stoichiometry of this interaction (NusB monomer or dimer bound to NusE monomer) was investigated and results may indicate a heterodimer. The dissociation equilibrium constant for the NusB dimer was estimated to be 8 x 10-8 M. The NusG protein was characterised and shown to be monomeric in solution with a highly elongated shape with approximately 20% ?-helical secondary structure. A C-terminal domain, containing the KOW rRNA binding motif, was identified by limited proteolysis. Lastly the Rho termination factor was over-expressed and purified and interactions with NusA and NusG investigated. No interactions have yet been detected.
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Dubée, Vincent. "Stratégies d'optimisation des bêta-lactamines pour le traitement des infections dues aux mycobactéries multirésistantes". Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066415.
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L’émergence de formes multirésistantes de tuberculose et la résistance intrinsèque de Mycobacterium abscessus à de nombreux anti-infectieux imposent l’identification de nouveaux antibiotiques et de nouvelles stratégies thérapeutiques. Les mycobactéries sont naturellement peu sensibles aux β-lactamines par production d’une β-lactamase et de cibles atypiques de faible affinité, les L,D-transpeptidases, qui sont efficacement inactivées par une seule classe de β-lactamines, les carbapénèmes. L’objectif de la thèse est d’étudier le mode d’action des β-lactamines afin de proposer des stratégies permettant d’optimiser ces antibiotiques. Pour comprendre la spécificité des L,D-transpeptidases vis-à-vis des carbapénèmes, nous avons étudié la cinétique et le mécanisme de la réaction d’inactivation de ces enzymes par différentes méthodes de spectroscopie en flux arrêté. Nos résultats indiquent que l’efficacité des carbapénèmes est due à leur capacité à former rapidement un intermédiaire tétrahédrique et à la stabilité de l’acylenzyme. La spécificité des L,D-transpeptidases pour les carbapénèmes ne dépend pas de leurs chaînes latérales, qui pourraient être modifiées pour améliorer les propriétés pharmacologiques de ces antibiotiques. Chez M. abscessus, nous avons identifié un inhibiteur de la β-lactamase, l’avibactam, qui augmente l’activité de certaines β-lactamines in vitro, en intracellulaire et dans un modèle d’infection du poisson zèbre. Nos résultats montrent que les β-lactamines peuvent être optimisées pour le traitement des infections dues aux mycobactéries multirésistantes par l’amélioration de l’inactivation des cibles ou l’inhibition des β-lactamasesThe emergence of multidrug-resistant tuberculosis and the intrinsic resistance of Mycobacterium abscessus to most antibiotics require the identification of new drugs and new therapeutic strategies. Mycobacteria are naturally poorly susceptible to β-lactam antibiotics due to production of a β-lactamase and of atypical low-affinity targets, the L,D-transpeptidases, which are effectively inactivated by a single class of β-lactams, the carbapenems. The aim of the thesis is to study the mode of action of β-lactams to propose strategies for the optimization of these antibiotics. To understand the specificity of L,D-transpeptidase for carbapenems, we have studied the kinetics and mechanism of inactivation of these enzymes using various stopped-flow spectroscopic methods. Our results indicate that the efficacy of carbapenems is due to their ability to rapidly form a tetrahedral intermediate and to the stability of the acylenzyme. The specificity of the L,D-transpeptidases for carbapenems does not depend upon the side chains of the drugs, which may be modified to improve their pharmacological properties. In M. abscessus, we have shown that the β-lactamase inhibitor avibactam increases the activity of various β-lactams in vitro, intracellularly, and in zebrafish model. Our results show that β-lactams can be optimized for the treatment of infections due to multidrug-resistant mycobacteria by improving inactivation of the targets and by inhibiting the β-lactamases
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Wei, Jun. "Identification and characterization of a Mycobacterium tuberculosis gene that enhances mycobacterial survival within macrophages". Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279898.
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The virulence of Mycobacterium tuberculosis (Mtb) depends on its ability to multiply and survive within host macrophages. In screening for Mtb genes that play a role in the intracellular survival, a Mtb gene ( eis) was identified that enhanced survival of Mycobacterium smegmatis in both human monocytes and in the human macrophage-like cell line U-937 when introduced on the multi-copy plasmid pOLYG. When a single chromosomal copy of eis was introduced into M. smegmatis, using an integrative vector, the construct still exhibited increased intracellular survival in U-937 cells. The eis gene was found in the genomic DNA of various M. tuberculosis strains and of Mycobacterium bovis BCG but not in that of M. smegmatis or 10 other mycobacterial species. Western blot analysis showed that the eis gene could produce a 42-kD protein product in both M. smegmatis and M. tuberculosis. The role of the eis gene in M. tuberculosis intracellular survival and multiplication was investigated by inactivation of the eis gene via allelic exchange. A mutated eis allele ( eis::hyg) was delivered at the eis locus, using the suicide vector pMJ10, in both Mtb strains H37Rv and H37Ra. Complemented mutants were also constructed by reintroducing a wild-type eis into the chromosome attB site. Southern and Western blot analysis demonstrated that the eis gene was disrupted and no Eis protein was produced, and that complemented strains regained the ability to produce Eis. Wild-type M. tuberculosis, eis knockout mutant and complemented strain were then evaluated for their capacity to survive and multiply within U-937 cells. The eis mutant survived and multiplied, as its parental strain, in U-937 cells over a 7-day period. These findings suggest that eis may not be required for the short-term multiplication of M. tuberculosis in U-937 cells. Further in vivo study needs to be done to clarify the role of eis in the pathogenesis of tuberculosis.
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Schiavo, Wesley. "Susceptibilidade antimicrobiana e tipagem molecular de Mycobacterium fortuitum isoladas de amostras clínicas de origem humana". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-01032013-093651/.
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Introdução: A revisão da literatura disponível no PubMed evidencia que há relatos de surtos de infecções por micobactérias de crescimento rápido ocorridos no Brasil, mas não há dados nacionais que permitam orientar o tratamento empírico até que o perfil de sensibilidade e a identificação da espécie estejam disponíveis. Não há estudo nacional com amostragem significativa de M. fortuitum nem tampouco análise da relação clonal entre isolados de vários pontos do território nacional. Este trabalho pretende trazer contribuições quanto ao entendimento da disseminação de clones de M. fortuitum no Brasil, assim como o perfil de sensibilidade dessa espécie no Brasil. Material e métodos: Foram utilizadas no estudo 121 isolados pertencentes ao banco de micobactérias do Fleury Medicina e Saúde, referentes ao período de janeiro de 2001 a dezembro de 2010. A identificação da espécie for determinada por sequenciamento parcial do gene rpoB, a clonalidade foi avaliada por eletroforese em campos alternados e a susceptibilidade antimicrobiana foi avaliada utilizando-se placas de microdiluição RAPMYCOI. Resultados e conclusões: Foram detectados três grupos clonais, sendo dois presentes na cidade de Campinas e o terceiro na cidade de Florianópolis. Foi observada a persistência do grupo clonal MFBRA2 na cidade de Campinas por seis anos. A maioria dos casos isolados em diferentes estados brasileiros pertence a grupos clonais distintos. O índice de similaridade de Dice mínimo para a identificação de um grupo clonal de M. fortuitum ao analisar fragmentos de restrição gerados por XbaI deve ser de 98%. Todos os isolados testados foram sensíveis à amicacina, tigeciclina, imipenem, ciprofloxacina, moxifloxacina, sulfametoxazol-trimetoprim e linezolida, o que permite seu uso no tratamento empírico das infecções por M. fortuitum. Houve uma baixa taxa de sensibilidade à doxiciclina o que não subsidia seu uso em tratamento empírico. A taxa de sensibilidade de 89% para claritromicina não permite seu uso empírico no tratamento das infecções por M. fortuitum.Introduction: The literature available on PubMed shows that there are reports of outbreaks of infections caused by rapidly growing mycobacteria occurred in Brazil, but there is no national data to guide empiric treatment until the susceptibility profile and identification of the species are available. No national study of significant sample of M. fortuitum nor analysis of the clonal relationship between isolates from various parts of the country. This work aims to bring contributions to the understanding of the spread of clones of M. fortuitum in Brazil, as well as the susceptibility pattern of this species in Brazil. Material and methods: We studied 121 isolates belonging to the mycobacteria collection from Fleury Medicina e Saúde, collected during the period from January 2001 to December 2010. Species identification was determined by partial sequencing of the rpoB gene, clonality was assessed by pulsed field gel electrophoresis and antimicrobial susceptibility was assessed using microdilution plates RAPMYCOI. Results and conclusions: There were three clonal groups, with two present in the city of Campinas and the third in Florianopolis. We observed the persistence of the clonal group MFBRA2 in Campinas for six years. Most cases isolated in different Brazilian states belong to different clonal groups. Our data indicate that Dice\'s similarity index for identification of a M. fortuitum clonal group should be at least 98% when analyzing restriction fragments generated by XbaI. All isolates tested were susceptible to amikacin, tigecycline, imipenem, ciprofloxacin, moxifloxacin, linezolid, and trimethoprim-sulfamethoxazole, which allows its use in the empirical treatment of infections caused by M. fortuitum. There was a low sensitivity to doxicycline which does not subsidize its use in empiric treatment. The rate of 89% sensitivity does not allow the empirical use of clarithromycin in the treatment of infections caused by M. fortuitum.
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Wallace, Paul Andrew. "Synthesis and structure of novel lipid antigens from Mycobacterium tuberculosis and Mycobacterium fortuitum". Thesis, University of Newcastle Upon Tyne, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386894.
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Tschiginewa, Valeria [Verfasser]. "Regulation der C-Quellenverwertung in Mycobacterium tuberculosis und Mycobacterium bovis BCG / Valeria Tschiginewa". Ulm : Universität Ulm. Fakultät für Naturwissenschaften, 2015. http://d-nb.info/1076828485/34.
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Trower, Carolyn Joy 1975. "A preliminary investigation of a sialidase activity associated with M. smegmatis". Monash University, Dept. of Medicinal Chemistry, 2003. http://arrow.monash.edu.au/hdl/1959.1/7646.
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Pedro, Heloisa da Silveira Paro. "Pesquisa do Mycobacterium sp. em uma população soropositiva para o HIV-1 do Noroeste Paulista /". São José do Rio Preto : [s.n.], 2008. http://hdl.handle.net/11449/94865.
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Orientador: Andréa Baptista RossitBanca: Daisy Nakamura Sato
Banca: Silvia Helena Vendramine
Resumo: São José do Rio Preto (SJRP), localizada na região Noroeste do Estado de São Paulo, Sudeste do Brasil, é considerada Município prioritário pelo Programa Nacional de Controle da Tuberculose e da AIDS. O objetivo deste trabalho foi avaliar retrospectivamente pacientes infectados pelo HIV com pelo menos um isolamento de Mycobacterium sp., atendidos em unidades de saúde de referência de SJRP e região, bem como descrever seus aspectos clínicos e sócio-demográficos. Foram avaliados no período de janeiro de 2000 a dezembro de 2006, 198 indivíduos soropositivos para o HIV com culturas positivas no Instituto Adolfo Lutz de SJRP. Houve uma correlação positiva entre a tuberculose e o registro de detenção (p=0.021). O uso do tabaco reduziu o tempo de vida entre o diagnóstico e o óbito (p=0.05). Houve associação entre o isolamento de M. tuberculosis (MT) e os níveis de linfócitos TCD4+ bem como o achado difuso para RX de tórax (p=0.014 e 0.000, respectivamente). Aproximadamente 11% de todas as cepas de MT mostraram resistência a pelo menos uma droga, enquanto 3.1% foram multiresistentes. Micobactérias não tuberculosas (MNT) totalizaram 35.19% de todos os isolamentos e a maioria das espécies pertence ao complexo Mycobacterium avium (MAC; 22.3%), seguido por M. fortuitum (5.2%) e M.gordonae (3.1%). Conclui-se que a população HIV estudada tem alta prevalência de colonização por MNT. Em um país com extensão continental como o Brasil, o conhecimento das diferenças regionais na distribuição de MNT em populações infectadas pelo HIV pode contribuir para o controle e tratamento dessas infecções oportunistas.
Abstract: São José do Rio Preto city (SJRP), Northwestern São Paulo State, Southeast Brazil, is considered "priority" by the National Programs of Tuberculosis and AIDS Control. Our purpose was to retrospectively evaluate Mycobacterium sp. isolated from HIV-infected patients attending the HIV/TB reference health care units from SJRP and region, as well as to describe their clinical and socio-demographic aspects. One hundred and ninetyeigth HIV-seropositive individuals provided 287 positives cultures from January 2000 to December 2006. There was a positive correlation between tuberculosis and prison record (p=0.021) and tobacco use reduced the mean lifetime from tuberculosis diagnosis to obit (p = 0.05). TCD4+ levels and a diffuse chest X-ray finding were associated to Mycobacterium tuberculosis (MT) isolation (p = 0.014 and 0.000, respectively). Approximately eleven percent of all MT strains showed resistance to at least one drug while 3.1% were multidrug resistant. Non-tuberculous mycobacteria (NTM) totalized 35.19% of all species and the most frequently isolated ones were Mycobacterium avium complex (MAC; 22.3%), M. fortuitum (5.2%) and M. gordonae (3.1%). We conclude that the HIV-infected population studied has a high prevalence of NTM colonization. In a wide country like Brazil, regional differences on NTM distribution in HIV-infected individuals must be further evaluated in order to improve control and treatment of these opportunistic infections.
Mestre
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Ngan, Chi-shing. "Rapid typing of mycobacterium tuberculosis in respiratory specimens using PCR-based mycobacterial interspersed repetitive units (MIRU) typing". Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B4378334X.
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Gilleron, Martine. "Structure et propriétés immunologiques de nouveaux glycolipides isolés de Mycobacterium kansasii et Mycobacterium gastri". Toulouse 3, 1991. http://www.theses.fr/1991TOU30221.
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Mycobacterium kansasii et mycobacterium gastri sont deux especes mycobacteriennes considerees par certains auteurs comme identiques. Pourtant, si m. Kansasii est l'agent etiologique de tuberculoses disseminees, frequemment rencontrees chez les porteurs sains du virus hiv, m. Gastri qui n'a jamais ete associee a une maladie est consideree comme non-pathogene. Les etudes precedentes ont montre dans la paroi de m. Kansasii de deux antigenes specifiques d'espece: les glycolipides phenoliques (phe gi) et les lipooligosaccharides (los). L'objectif de cette these concerne la recherche et l'analyse structurale de ces glycolipides immunoreactifs permettant la differenciation de ces deux especes et d'autre part l'approfondissement des connaissances au niveau moleculaire de la pathogenicite de m. Kansasii. Une nouvelle structure a ete proposee pour le glycolipide phenolique majeur de m. Kansasii: k-l. Ce compose antigenique et immunogene se caracterise par un haptene tres particulier, un monosaccharide pour la premiere fois decrit dans la nature. Grace a la synthese des 2 enantiomeres d et l de ce monosaccharide, nous avons montre le caractere immunodominant de ce monosaccharide distal, l'epitope ayant ensuite ete delimite au disaccharide terminal monoacetyle. Nous avons recherche et purifie les glycolipides phenoliques plus polaires que k-i et quantitativement mineurs: k-ii, k-iii et k-iv. Ces glycolipides se sont reveles etre partages par les deux especes. Un des membres de cette famille (k-iv) a fait l'objet d'une etude rmn 2d. Aucune structure specifique a l'espece m. Kansasii n'a donc ete mise en evidence parmi les glycolipides phenoliques et nous avons alors entrepris l'analyse des los. Une nouvelle famille de molecules a ete mise en evidence chez m. Gastri. L'analyse structurale de l'un de ses composes a ete realisee et repose essentiellement sur des donnees rmn et de spectrometrie de masse. Cette etude a notamment permis de caracteriser le monosaccharide distal de structure particuliere
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Seloma, Ngwanamohuba Mologadi. "Wild-type minimal inhibitory concentration distributions of secondline drugs in mycobacterium tubercolosis complex clinical isolated in relation to recommended critical concentrations in Limpopo Province, South Africa". Thesis, University of Limpopo, 2016. http://hdl.handle.net/10386/1712.
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Thesis (MSc. (Medical Sciences)) -- University of Limpopo, 2016.The reference phenotypic methods for Mycobacterium tuberculosis drug susceptibility testing are qualitative and based on drug critical concentrations. Limitations include lack of standardization and variations in laboratory preparation of drug stock solutions. The recommended critical concentrations are determined by consensus and experience rather than scientific data. Consequently incorrect and inadequate susceptibility breakpoints are used and patients receive ineffective antimicrobial therapy. The determination of wild-type minimal inhibitory concentration distribution is an important tool used by European Committee for antimicrobial susceptibility Testing (EUCAST) to establish clinical breakpoints in Europe. This could be applicable in South Africa. Aim To determine wild-type minimal inhibitory concentration distributions of first and secondline drugs against Mycobacterium tuberculosis complex clinical isolates and compare these with the recommended critical concentration in Limpopo province. Methods A sample of 101 Mycobacterium tuberculosis complex positive cultures were collected from National Health Laboratory Services in Polokwane (Limpopo province) and subcultured on BACTEC MGIT 960 system. The isolates were inoculated on MYCOTB MIC plates to determine the wild-type MIC distributions of first and second-line drugs. The data were compared with currently recommended critical concentrations. DNA was extracted and amplified by PCR. Genotypic drug susceptibility testing was performed using GenoType MTBDRplus version 2.0 and GenoType MTBDRsl version 2.0 for the first- and second-line drugs, respectively. Genotyping of clinical isolates was performed to determine M. tuberculosis strain families using spoligotyping. vi Results Wild-type MIC distributions range reported in this study are as follows rifampin (≤ 0.12 - 0.5 μg/μg/ml), isoniazid (≤ 0.3 - 2.00 μg/ml), rifabutin (≤ 0.12 - 0.25 μg/ml), ethionamide (≤ 0.12 - 5 μg/ml), ethambutol (≤ 0.5 - 2 μg/ml), streptomycin (≤ 0.25 - 0.5 μg/ml), paraaminosalicylic (≤ 0.5 - 4.0 μg/ml), cycloserine (≤ 2 -16 μg/ml), amikacin (≤ 0.12 - 0.5 μg/ml), kanamycin (≤ 0.6 -2.5 μg/ml), moxifloxacin (≤ 0.6 - 0.5 μg/ml), ofloxacin (≤ 0.25 - 1 μg/ml). GenoType MTBDRplus detected (n= 68, 67%) rifampin resistance (MUT 3=26, MUT 2=18, MUT 2B=8) on the rpoB gene. Isoniazid resistant (n=20, 19.8%) was detected katG MUT (n=20, 19.8%) on katG gene (S315T1). Genotypic resistance to second-line drugs determined by GenoType MTBRsl detected no mutations in (n= 98, 97%) isolates on gyrA, gyrB rrs and eis gene and (n=3, 2.9%) isolates non mycobacterium tuberculosis complex were detected. The frequency and percentage of Mycobacterium tuberculosis family strain were identified in (n= 81, 80%) of the clinical isolates which matched 18 pre-existing shared types. The results showed high genotype diversity with the Beijing strain (n= 30, 29.7%) and T family (n= 19, 18.8%) dominating. Twenty isolates (19.8%) had no shared types thus reported as orphan. Conclusion The findings obtained in this study suggest wild-type Minimal Inhibitory Concentration distributions may be considered when setting clinical breakpoints. Discordant results were observed between phenotypic and genotypic DST for rifampin, isoniazid, streptomycin, rifabutin and ethambutol, suggesting that breakpoint concentrations for some drugs are set too high while others are too low. The Mycobacterium tuberculosis clinical isolates displayed diverse family strain with Beijing and T strain predominate breakpoints for first-line and second-line drugs used in Mycobacterium tuberculosis treatments. Poster Presentations Poster presented at faculty of Health science first annual research day on Second-line drug susceptibility breakpoints for Mycobacterium tuberculosis using MYCOTB MIC plate. University of Limpopo Tiro hall 16th to 17th September 2014. Poster presented at National Health Laboratory Service Pathology Research and Development Congress (PathReD) on Determination of families strains of Mycobacterium tuberculosis circulating in Limpopo Province, South Africa. Emperors Palace 14th April-16th April 2015.
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Griffiths, Patricia A. "The resistance of Mycobacterium tuberculosis and other mycobacteria of increasing clinical importance to chemical agents". Thesis, Aston University, 1997. http://publications.aston.ac.uk/10956/.
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Tuberculosis is a major public health problem which has been compounded by the emergence of multi-drug-resistant strains of Myco. tuberculosis (MDR-TB), an increased use of immunosuppressive therapy and increasing numbers of HIV infection. To further complicate the infection control issues, many of the environmentally associated mycobacteria, commonly referred to as opportunistic pathogens, are being incriminated in human infection with increasing frequency. Information is required on the mycobactericidal effectiveness of disinfectants, especially those associated with heat sensitive equipment such as bronchoscopes, which may be contaminated with mycobacteria. The activity of disinfectants against Myco. tuberculosis is well documented. However, there is much variation in test methodology resulting in conflicting efficacy data. Therefore a standard, reproducible and practical method must be developed which will give useful and reliable data on the resistance of Myco. tuberculosis and other mycobacteria of increasing clinical importance to current disinfection procedures. A standard test method was developed for use in this study. Suspension and carrier tests were carried out in the presence and absence of 10% serum as the organiC load. The test organisms were type strains of Myco terrae, Myco chelonae, Myco. fortuitum and Myco. tuberculosis. 1\vo endoscope washer disinfector isolates of Myco. chelonae and a clinical isolate of Myco. avium-intraceUulare were also used. The type strains of Myco. chelonae and Myco. fortuitum were very sensitive to all disinfectants tested. My co. terrae was slightly more resistant than Myco. tuberculosis. This is in agreement with published data. Myco. avium-intraceUulare was without doubt the most resistant of all the test organisms. The two machine isolates of Myco. chelonae were extremely resistant to 2% glutaraldehyde. This prompted further work to assess if these two strains differed from the type strain in other ways.
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Thegerström, Johanna. "Mycobacterium avium infections in children". Doctoral thesis, Linköpings universitet, Klinisk immunologi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-53786.
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Mycobacterium avium belongs to a group of over 130 species of non-tuberculous mycobacteria (NTM) or environmental mycobacteria. The subspecies Mycobacterium avium avium was originally described as the causative agent of bird tuberculosis, but was later found to cause disease also in humans. Small children display a special form of infection that is seldom detected in other age groups. It manifests as a chronic lymphadenitis usually in the head and neck region. The incidence rate is approximately 1-5/100,000 children/year. However, exposure to this bacterium is high as judged by sensitin skin test studies. Even if a lot of persons are infected with M. avium, a majority of them do not develop disease and the bacterium is therefore considered to be of low virulence, causing disease mainly in immunocompromised persons. Children with M. avium lymphadenitis, however, usually do not have any known deficiencies in the immune system. This thesis elucidates why small children are prone to develop disease by M. avium. Investigation of a possible zoonotic spread of this bacterium to children involved analysis and comparison of different strains isolated from birds and other animals and from children, using the restriction fragment length polymorphism (RFLP) method on insertion sequence IS1245, resulting in the finding that the children were infected exclusively with the new proposed subspecies M. avium hominissuis. Animals in general and birds in particular were infected with the subspecies M. avium avium (using the more narrow definition). Moreover, when investigating the immunological response of human peripheral blood mononuclear cells (PBMCs) to stimulation with M. avium hominissuis and M. avium avium, respectively, it was found that the former subspecies induced lower IFN-γ and IL-17 than the latter, but higher levels of Il-10, which might contribute to explain the higher pathogenicity of M. avium hominissuis in humans. Through studies of the geographical distribution of cases of M. avium infection in children in Sweden and the seasonal variation of the disease, a fluctuation of the incidence over the year was detected, with higher numbers of cases in the autumn months and lower numbers in the late spring. There was a higher incidence rate in children living close to water than in those living in the inland or in the urban areas. Therefore, outdoor natural water is the most probable source of infection in children with M. avium lymphadenitis. Through a descriptive clinical retrospective study, complete surgical removal of the affected lymph node was found to lead to better results than treatment by incision and drainage of abscess or expectation only. Finally there might be several explanations as to why an individual develops disease after infection with M. avium, such as, exposure, bacterial virulence factors or possible specific deficiencies of the immune system of the host or a combination of these factors. Which are the more important factors regarding children with M. avium lymphadenitis is still an open question.
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Alteri, Christopher. "Novel Pili of Mycobacterium tuberculosis". Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1276%5F1%5Fm.pdf&type=application/pdf.
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Abate, Getahun. "Drug resistance in mycobacterium tuberculosis /". Stockholm, 1999. http://diss.kib.ki.se/1999/91-628-3833-4/.
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Ho, Timothy Boon Leong. "Pathogen polymorphisms of mycobacterium tuberculosis". Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399538.
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Roring, Solvig Mary Margaret. "DNA fingerprinting of Mycobacterium bovis". Thesis, Queen's University Belfast, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287426.
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Gurcha, Sudagar Singh. "Mannan biosynthesis in mycobacterium tuberculosis". Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324798.
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