Дисертації з теми "Gram Negative Baterial Infections"
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Skovbjerg, Susann. "Inflammatory mediator response to Gram-positive and Gram-negative bacteria in vitro and in middle ear infections." Göteborg : Clinical Bacteriology Section, Dep. of Infectious Medicine, Sahlgrenska Academy , University of Gothenburg, 2010. http://hdl.handle.net/2077/21533.
Повний текст джерелаKarvanen, Matti. "Optimization of Colistin Dosage in the Treatment of Multiresistant Gram-negative Infections." Doctoral thesis, Uppsala universitet, Infektionssjukdomar, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-197724.
Повний текст джерелаCodjoe, Francis Samuel. "Detection and characterisation of carbapenem-resistant gram-negative bacilli infections in Ghana." Thesis, Sheffield Hallam University, 2016. http://shura.shu.ac.uk/15577/.
Повний текст джерелаPhee, Lynette. "Unorthodox antimicrobial combination therapies for the treatment of multi-drug resistant Gram-negative infections." Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/44695.
Повний текст джерелаJooste, Marius Johannes. "The in vitro antimicrobial activity of amikacin and ceftazidime against multiple resistant gram-negative bacilli in nosocomial infections." Thesis, Cape Town : Cape Technikon, 1988. http://dk.cput.ac.za/cgi/viewcontent.cgi?article=1018&context=td_ctech.
Повний текст джерелаDawes, Maisie W. "A series of in vitro studies investigating the role of lactoferrin in calf innate immunity." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4394.
Повний текст джерелаTitle from title screen of research.pdf file (viewed on December 22, 2006). The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. "May 2006" Vita. Includes bibliographical references.
Folkesson, Anders. "On extrinsic and intrinsic organizational themes in gram-negative bacteria and their role in evolution and virulence of the bacterial genus Salmonella spp /." Stockholm : [Karolinska institutets bibl.], 2002. http://diss.kib.ki.se/2002/91-7349-375-9/.
Повний текст джерелаAkinyele, Taiwo Adesola. "Assessment of the antibacterial properties of n-Hexane extract of Cocos Nucifera and its interactions with some conventional antibiotics." Thesis, University of Fort Hare, 2011. http://hdl.handle.net/10353/416.
Повний текст джерелаSilva, Josefa Bezerra da. "Papel das citocinas e quimiocinas na resposta imunológica murina na infecção por Leptospira interrogans sorovar Copenhageni." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-18062012-095355/.
Повний текст джерелаLeptospirosis is a worldwide zoonosis caused by Leptospira. The pathogenesis in humans is mainly observed in lungs, livers and kidneys. In this work the role of innate immune response in protection against leptospirosis is being studied using different mice models. The animals were infected intraperitoneally with virulent cells of L. interrogans serovar Copenhageni and the development of the disease was followed, being observed mortality of C3H/HeJ mice, whereas C3H/HePas presented jaundice and BALB/c mice remained asymptomatic. Samples of liver, kidney, lungs and sera were analyzed following the profiles of mRNA and protein of the cytokines TNF-α and TGF-b and chemokine MCP-1, MIP-1α, MIP-2 and CXCL1/IL-8. We showed that Leptospira infection stimulates early expression of cytokine TNF-α and TGF-b and chemokine MCP-1, MIP-1α, MIP-2 and IL-8 in the resistant mice strain BALB/c. Histological analysis indicates that the expression of those molecules can be related to the influx of distinct immune cells, which play a role in the naturally acquired protective immunity.
Amhaz, Juliana Mota Khalil. "Alterações na resposta imune inata e adaptativa induzidas por Escherichia coli enteroinvasora em modelo murino." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-07062016-173218/.
Повний текст джерелаDuring an infection, a complex sequence of events in iniciated after invasion of the host by pathogenic microorganisms. Enteroinvasive Escherichia coli (EIEC) and Shigella cause dysentery by means of invading the colonic mucosa, leading to tissue destruction and inflammation. In arder for an infectious process to occur, inocula of 102 Shigella are necessary incontrast to e 106 EIEC. The infection of J774 macrophages by EIEC resulted in phagocytosis of the bacterium, a hindering of the viability of the macrophage and in the production of cytokines. Macrophages obtained from C57BU6 mice infected with EIEC produced NO, which seems to be important for the control if infection. We observed that in iNOS knockout mice, both the production of proinflammatory cytokines and lethality were higher than that observed in wild-type mice. EIEC induced the migration of granulocytes and monocytes to the peritoneum as well as the secretion of cytokines by these cells. We observed a proliferation of Iymphocytes in response to inoculation with soluble EIEC antigens, however, in this case, the production of cytokines was not detected. Compared to Shigella, EIEC was slower in escaping from the macrophage, and induced a shyer production of pro-inflammatory cytokines and NO, as well as promoted a smaller activation of T Iymphocytes. These data suggest that when challenged with EIEC, the host produces a less severe response than that elicited by Shigella, which might explain why the infectious process with EIEC produces a milder form of dysentery with a quicker resolution.
Melo, Keyde Cristina Martins de. "Escherichia coli enteropatogênica (EPEC) atípica sorotipo O55:H7: descrição da antifagocitose a partir de um fator secretado." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-24032011-091904/.
Повний текст джерелаAtypical enteropathogenic Escherichia coli (aEPEC) causes diarrhea mainly in children and presents a high heterogeneity of virulence factors. The objective of this work was to study the behavior of aEPEC regarding its interaction with professional phagocytes. Two samples of aEPEC serotype O55:H7 were able to reduce phagocytosis, The culture supernatants were submitted to SPE and HPLC and the active fractions were tested and analyzed by mass spectrometry. The results show that the fraction with bacterial antiphagocytic activity also reduces phagocytosis of Saccharomyces cerevisiae. In addition to demonstrating that aEPEC can induce antiphagocytosis, this work shows that it is due to a secreted antiphagocytic factor that is soluble in aqueous medium, is thermo-stable, has a low molecular weight, is not bactericide or cytotoxic and, finally, possibly presents a glycosidic region. These findings suggest that the antiphagocytic factor may, though maybe not alone, play an important role in the adaptability and pathogenicity of aEPEC.
Dube, Callote. "Prevalence and risk factors for Helicobacter pylori transmission in the Eastern Cape Province application of immunological molecular and demographic methods." Thesis, University of Fort Hare, 2010. http://hdl.handle.net/10353/265.
Повний текст джерелаMilivojevic, Milica. "Dissecting the signaling pathways controlling inflammation during Gram-negative bacterial infections : the role of ALPK1, TIFA and TRAF6 during Shigella flexneri infection." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCB061/document.
Повний текст джерелаEpithelial cells represent the first line of defense against pathogens and play an active role in innate immunity. Via local secretion of cytokines, they are able to orchestrate the immune response against invading pathogens. The activation of both intracellular and extracellular pathogen recognition receptors leads to a complex signaling cascade, resulting in the activation of the transcription factor nuclear factor kB(NF-kB)and the subsequent production of pro-inflammatory cytokines. However, the molecular mechanisms governing this process have not been fully elucidated. The Gram-negative bacterium Shigella flexneriis an important human pathogen and the causative agent of bacillary dysentery. This disease is characterized by acute inflammation of the colon resulting in the destruction of the intestinal tissue and, in severe cases, death. S. flexneri can invade and replicate within colonic epithelial cells. Following detection of the bacteria, both infected and uninfected bystander cells initiate inflammatory signaling pathways, which result in massive interleukin-8 (IL-8) production by the latter. Using S. flexneri as a model of infection, we have identified a novel signaling pathway, which is central to the activation of NF-kB and the subsequent production of IL-8 during Gram-negative bacterial infections. Following the cytosolic detection of bacteria, the protein TRAF-interacting factor with forkhead-associated domain (TIFA) forms oligomers, a process dependent on its threonine at position 9 and theforkhead-associated domain. These oligomers interact withTNF receptor associated factor (TRAF)6, leading to its oligomerization and the subsequent activation of NF-kB. In addition, we show that oligomerization of TIFA is dependent on the kinase alpha-kinase(ALPK)1 and that this pathway is activated in response to the detection of the bacterial metabolite heptose-1, 7-bisphosphate (HBP). These observations could be extended to the enteroinvasive pathogen Salmonella typhimurium as well as the extracellular bacteria Neisseria meningitidis. Our results therefore demonstrate the central role of the ALPK1-TIFA-TRAF6 signaling pathway in response to HBP of both intracellular and extracellular Gram-negative bacterial pathogens, and offer a better understanding of the molecular mechanisms governing the epithelial cell immune response to pathogenic bacteria
Ramirez, Priscilia Aguilar. "Caracterização imunológica e genética da deficiência do componente C5 do sistema complemento humano." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/42/42133/tde-19102007-155013/.
Повний текст джерелаThe deficiency of the C5 component of the complement system is rare with 38 described cases in the literature. This deficiency is frequently associated with severe infections, especially caused by Neisseria. Our objective is to characterize immunologically and genetically this deficiency, the first of its type described in the Brazilian population.We noted that C3, C4, C6, C7, C8, C9, Factor B, Factor H and Factor I have expressive levels in all the individuals sera of this family. C5 was absent in individuals II:4, II:5 and II:9. By ELISA a C5 concentration in this individuals were 0,9; 1,0; 1,3 µg/ml (normal: 45 - 190 µg/ml). Their serum doesn´t present hemolytic activity mediated by complement system. The C5 cDNA from individuals I:1, I:2, II:4 and II:9 has éxon 30 deleted. Caused by the substitution of GAG4028 for a GAA4028 in the last codon of exon 30. This defect was responsible for the deficiency of C5 in this family and this deletion would probably produce an unstable protein destined for degradation.
Roxo, Inês Abrantes Cravo. "Epidemiology of β-lactamase producing isolates". Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14879.
Повний текст джерелаMultidrug resistant bacteria are an emerging problem worldwide, associated with prolonged stays in the hospital and inherent increased costs. Widely studied ESBL-producers, and the not so considered AmpC-producers are of extreme importance, and its epidemiology should be closely followed. The epidemiology of ESBL-producing isolates from patients over 65 attending the ER and diagnosed with a UTI, as well as the epidemiology of AmpC-producing isolates were assessed by the Vitek2® procedure of identification. For the AmpC positive isolates, confirmatory phenotypic test were performed, searching for the presence of an AmpC enzyme. High numbers of ESBL-producing isolates, detected in UTI patients over 65 years old are the main motive of concern, since these are recurrent visitors of hospitals and frequently live in nursing homes, which makes them potential carriers of multiresistant strains. The earlier hospital restricted problem has now become widely spread in the community, and requires further attention. As for the AmpC, although less frequent than ESBLs, its presence often masks the ESBL phenotype. Misevaluation and false reports induces wrong medication procedures and the consequent emergence of selected resistant strains. Also, the possibility of identifying both resistance mechanisms in one organism has become more common, rising the need of complementary methods to distinguish them, which the automated method is unable to do. Cefoxitin disc was found to be the right complementary test to perform in order to detect these kinds of multiresistant strains. xii This study shows the importance of following the epidemiology of β-lactamases, providing a realistic view on its dissemination trough the community and its implications in the health care system in our region.
As bactérias multirresistentes são um problema emergente por todo o mundo, associado a estadias prolongadas nos hospitais, e ao inerente aumento de custos. As bactérias produtoras de β-lactamases de espectro alargado, amplamente estudadas, e as produtoras de enzimas AmpC, não tão mencionadas, são objecto de grande importância, e a sua epidemiologia deve ser seguida de perto. A epidemiologia de bactérias produtoras de β-lactamases de espectro alargado de pacientes com mais de 65 anos que recorrem à Urgência com diagnóstico de infecção urinária, bem como a epidemiologia de estirpes produtoras de AmpC, foram avaliadas através do processo de identificação automática Vitek2®. Para os isolados AmpC positivos, testes fenotípicos confirmatórios foram usados para detectar a presença de enzimas AmpC. Os valores elevados de isolados produtores de β-lactamases de espectro alargado detectados em pacientes com infecção urinária e mais de 65 anos são o maior motivo de preocupação. Uma vez que estes recorrem frequentemente à Urgência ou vivem em lares, estes doentes são potenciais veículos de transmissão destas bactérias multirresistentes. Um problema que estava confinado ao ambiente hospitalar é, hoje em dia, foco de atenção por se encontrar espalhado por toda a comunidade. Quanto às bactérias produtoras de AmpC, embora sejam menos frequentes do que as produtoras de β-lactamases de espectro alargado, a sua presença pode mascarar a presença do fenótipo característico destas. A avaliação incorrecta induz à prescrição errada de medicamentos e ao consequente surgimento x de estirpes resistentes. Para além disso, existe a possibilidade de se detectarem ambos os mecanismos de resistência na mesma estirpe, aumentando a necessidade de se usarem métodos complementares que as distingam, uma vez que o método automático não é capaz de o fazer. O disco de Cefoxitina é o teste indicado para complementar a identificação da presença da enzima AmpC. Este estudo mostra a importância de estudar a epidemiologia das β-lactamases, e fornece uma visão realista da sua disseminação pela comunidade, bem como das suas implicações no sistema de saúde da região de Aveiro.
Okeleye, Benjamin Ifeoluwa. "In vitro activity of bioactive compounds of selected South African medicinal plants on clinical isolates of Helicobacter pylori." Thesis, University of Fort Hare, 2011. http://hdl.handle.net/10353/310.
Повний текст джерелаRodrigues, Fernanda Saad. "Fatores associados à aquisição nosocomial de bacilos gram-negativos no Hospital das Clínicas da Faculdade de Medicina de Botucatu em diferentes estações do ano um estudo tipo caso-controle /." Botucatu, 2018. http://hdl.handle.net/11449/153211.
Повний текст джерелаResumo: Seasonality of healthcare-associated infections (HCAIs) has been recently reported, especially involving Gram-negative bacilli (GNB). Factors underlying this phenomenon were not elucidated. It is theoretically conceivable it reflects seasonal variations in traditional risk factors for those infections. With this in mind, we conducted a study to analyze the interplay of season, weather and usual predictors of healthcare-associated bloodstream infections caused by Gram-negative bacilli (GNB-BSI). The study had a retrospective, case-only desing. It was conducted in the teaching hospital from Botucatu School of Medicine (450 beds). The study enrolled 446 patients with GNB-BSI caused by Escherichia coli, Enterobacter spp., Klebsiella spp., Pseudomonas aeruginosa or Acinetobacter baumannii, diagnosed from July 2012 through June 2016. Demographic data, comorbidities, invasive procedures and use of antimicrobials were reviewed in medical charts. The season in which GNB-BSI occurred, as well as weather parameters of the day of diagnosis, were recorded. We analyzed factors associated with occurrence of GNB-BSI in different seasons (with winter as reference category) and caused by different GNB (reference category, E. coli). Univariate and multivariable models of polytomous (multinomial) logistic regressions were used for analysis. In multivariable analysis, GNB-BSI diagnosed in summer were more likely to be caused by Klebsiella spp. (OR, 5.33; 95%CI, 2.04-13.96) or A. baumannii (OR, 2.... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Seasonality of healthcare-associated infections (HCAIs) has been recently reported, especially involving Gram-negative bacilli (GNB). Factors underlying this phenomenon were not elucidated. It is theoretically conceivable it reflects seasonal variations in traditional risk factors for those infections. With this in mind, we conducted a study to analyze the interplay of season, weather and usual predictors of healthcare-associated bloodstream infections caused by Gram-negative bacilli (GNB-BSI). The study had a retrospective, case-only desing. It was conducted in the teaching hospital from Botucatu School of Medicine (450 beds). The study enrolled 446 patients with GNB-BSI caused by Escherichia coli, Enterobacter spp., Klebsiella spp., Pseudomonas aeruginosa or Acinetobacter baumannii, diagnosed from July 2012 through June 2016. Demographic data, comorbidities, invasive procedures and use of antimicrobials were reviewed in medical charts. The season in which GNB-BSI occurred, as well as weather parameters of the day of diagnosis, were recorded. We analyzed factors associated with occurrence of GNB-BSI in different seasons (with winter as reference category) and caused by different GNB (reference category, E. coli). Univariate and multivariable models of polytomous (multinomial) logistic regressions were used for analysis. In multivariable analysis, GNB-BSI diagnosed in summer were more likely to be caused by Klebsiella spp. (OR, 5.33; 95%CI, 2.04-13.96) or A. baumannii (OR, 2.... (Complete abstract click electronic access below)
Mestre
Adeyemi, Oluwatosin Oluwakemi. "Comparative in-vitro activities of trimethoprimsulfamethoxazole and the new fluoroquinolones against confirmed extended spectrum beta-lactamase producing Stenotrophomonas maltophilia in Nkonkobe Municipality, Eastern Cape environment." Thesis, University of Fort Hare, 2012. http://hdl.handle.net/10353/d1007576.
Повний текст джерелаBaeta, Tiago. "Activité régulée d'une machinerie de transenveloppe bactérienne : le système de transport du LPS." Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALV037.
Повний текст джерелаBacteria display several intrinsic mechanisms which confers them the ability to cope with disadvantageous situations, such as nutrient deprivation, environmental inter/intra-species competition, managing adaptation to detrimental conditions, and handling effects of antibacterial compounds.In a global context of antibiotic resistance accelerated by anthropogenic activities, gram negative bacteria display intrinsic resistance mechanisms. The complex and dynamic multilayered envelope, coated with lipopolysaccharides (LPS), confers these bacteria increased survivability. Biosynthesis of these complex glycolipids is initiated in the cytoplasm, and its transport proceeds along the inner membrane, periplasm, until reaching the outer membrane, with a dedicated biosynthetic pathway and transport machinery.The Lipopolysaccharide Transport (Lpt) machinery comprises 7 fundamental proteins (LptA to LptG) that span the entire envelope. More specifically, at the inner membrane, LptB2FG ABC transporter couples ATP hydrolysis with LPS extraction. LptB2 cycles ATP while LptF/G interact with LPS and carry it towards LptC and LptA in the periplasm.This machinery uses a conserved architecture with dedicated jellyroll domains present on LptF, LptG, LptC and LptA that assemble into a bridge that allow LPS flow to the outer membrane.Molecules that would disrupt protein-protein interactions between the different jellyroll domains of the Lpt system could become potent cell wall inhibitors. Thanatin, a natural occurring antimicrobial peptide, has been described as targeting the jellyroll domains of the machinery. We screened its effect in the disruption of LptC-LptA complex. Thanatin binds to LptA but not LptC and inhibits the assembly of the complex at low nM concentrations, showing the potential of targeting Lpt Jellyroll-jellyroll interactions.The network of interactions between the Inner membrane complex, LptB2FG and periplasmic LptC and LptA is not fully understood. LptB2FG was produced in detergent micelles and within nanodisc particles, to probe interactions with LptC and LptA at an atomic scale, using Nuclear Magnetic Resonance (NMR) and biophysical techniques.In the assembly of the LptB2FGCA bridge, LptC and LptF interact mostly through the jellyroll domains. A mutation in the LptF jellyroll (R212 residue) rendered LptC presence facultative in vivo.Biophysical and biochemical characterization showed unaltered interaction of mutant LptB2FG with LptC and LptA, whereas ATPase activity showed lack of regulation by presence of its partners. This led us to propose that R212 is a checkpoint in the LptF jellyroll, acting as a hub for LptB2FG to sense proper assembly of the machinery.When LptB2FGCA complex is assembled in vitro, LptB2 was found capable of catalyzing phosphotransfer between ADP molecules, generating ATP and AMP, a novel activity (Adenylate Kinase) previously undescribed for this protein. Being a topic of very recent interest in the literature, the role of dual-function transporters is not understood. To characterize the balance between ATPase and AK, we mutated LptB2 on key ABC motifs to probe possible location for AK activity. LptB2FG studied in nanodisc particles, suggests that balance between activities depends on the dynamic assembly of LptB2FGCA, with regulatory mechanisms possibly not being shared between both activities. Structural characterization of LptB2 in apo and nucleotide bound-state was initiated .This project, focused on the essential Lpt system, sheds light on the importance of protein-protein interactions as targets for designing future antimicrobial compounds. It could also be worth evaluating if dual-function transporters, involved in cell wall synthesis and drug export, are valid targets for future drug screenings
Barbato, Leandro. "Detecção e caracterização de bactérias gram-negativas produtoras de b-lactamases de espectro estendido (ESBL) e AmpC plasmidial isoladas de animais de companhia e búfalos no Estado de São Paulo." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/42/42132/tde-18062013-114347/.
Повний текст джерелаThis study aimed to conduct an epidemiological surveillance on MDR among Gram-negative bacilli recovered from samples from buffalo and in pets exhibiting signs and symptoms related to urinary tract infection. The study reports the spread of MDR bacteria exhibiting a high resistance profile to veterinary- and human-use b-lactams and quinolones, in livestock of buffalos and in pets, constituting the first worldwide report of CTX-M-8-type extended-spectrum b-lactamase (ESBL)- and CMY-2-type plasmid AmpC (pAmpC)-producing E. coli strains in buffalo. Moreover, to the best of knowledge, this is the first report of CTX-M-15-, CTXM-8-, CTX-M-2, CMY-1, CMY-2- and DHA-1-producing E. coli strains in pets in Brazil. With respect to the origin of resistance, we found no clonal relatedness among MDR. E. coli isolates from buffalos belonging to groups A and B1 and in companion animals, the phylogenetic analysis of virulence in E. coli denoted the predominance of the highly virulent phylogenetic groups B2 and D.
Desai, Devika J. "Characterisation of Biofilm-Forming Ability and Haemolytic Activity of Clinical Group B Streptococcus (GBS) Isolates From the Urinary Tract." Thesis, Griffith University, 2020. http://hdl.handle.net/10072/398419.
Повний текст джерелаThesis (Masters)
Master of Medical Research (MMedRes)
School of Medical Science
Griffith Health
Full Text
Filho, Mário Augusto Heluany. "Uso de simbiótico para descolonização de pacientes hospitalizados portadores de bacilos Gram-negativos multidrogarresistentes." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/17/17139/tde-29082016-114807/.
Повний текст джерелаIn recent decades the incidence of multidrug resistant (MDR) Gram-negative nosocomial infections has been dramatically raising in the whole world. The World Health Organization (WHO) recently recognized nosocomial infections due to MDR pathogens as a global concern due to its negative impact on patients, health-care workers and health-care institutions, affecting developed countries as well as developing ones. They negatively impact in-hospital mortality and health-care related costs. Hand hygiene promotion, antibiotic stewardship and contact precautions are the main available measures to control such MDR Gram-negative organisms in hospitals. However, they are only partially effective as well as difficult to be implemented and expensive. Therefore, simpler and more effective actions are thought to be helpful and urgent. In the present study, we analyzed the impact of the administration of a symbiotic product on patients harboring Gram-negative multidrug-resistant bacteria upon the subsequent rates of decolonization of these pathogens from the gastro-intestinal tract.This is a double-blinded and placebo controlled randomized clinical trial evaluating the oral/enteral daily administration of 1010 units of Lactobacillus bulgaricusplus 1010 units of Lactobacillus rhamnosus associated with fructo-oligosacharide (FOS), or placebo, for 7 days, to 101 patients previously colonized by MDR Gram-negative bacteria, identified through selective culture of rectal swab. The primary study outcome was the rate of complete decolonization of the MDR microorganism from the gastro-intestinal tract following the intervention. In the \"modified intention to treat\" analysis, decolonization rates observed were 16.7% (8/48) in the experimental group and 20.7% (11/53) in the placebo group (p=0,600). In the \"per protocol\" analysis, decolonization rates were 18.9% (7/37) in the experimental group and 23.3% (7/30) in the placebo group (p=0,659). In a logistic regression model, symbiotic use did not produce any impact on the chance of decolonization (OR=0.80, CI95%=0.28-2.27, p=0.678). Mild to moderate adverse events occured similarly in both the placebo (7.55%) and the experimental group (6.25%), (p=1,000). No severe adverse event potentially related to the medications was detected during the study period. In the present study conditions, the results obtained lead to the conclusion that the studied symbiotic proved to be ineffective to decolonize patients harboring multidrug resistant Gram-negative bacilli.
Nyenje, Mirriam E. "Phytochemical analysis and bioactivity of the stem bark of Combretum Molle on some selected bacterial pathogens." Thesis, University of Fort Hare, 2011. http://hdl.handle.net/10353/391.
Повний текст джерелаPetitjean, Marie. "Évolution génotypique et phénotypique d'une souche épidémique de Pseudomonas aeruginosa au cours des 11 ans de sa diffusion hospitalière." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCE019/document.
Повний текст джерелаP. aeruginosa is an opportunistic pathogen responsible of hospital-acquired infections in immunocompromised patients. Although in-host evolution of P. aeruginosa is well documented, little is known about this pathogen evolution during its spread on a hospital scale. The high-risk multidrug resistant clone ST395 spread among more than 300 patients in the University Hospital of Besançon between 1997 and 2008. We used a WGS approach to identify the origin of the outbreak, the features that could have helped its implantation in our hospital and those associated with the end of the epidemics. The genomes of 54 representative isolates were fully sequenced. The phylogenetic tree indicated two distinct clusters corresponding to two parallel outbreaks. The ancestor of the ST395 clone possibly contaminated our hospital water network during its construction in 1979. This hypothesis is supported by the fact that the ST395 strain had a specific genomic island carrying 6 copper transporter genes implicated in copper resistance, correlated with the resistance to this metal which water supply network is made of. The late isolates displayed independent genomic signatures of chronic adaptation in patients (altered LPS and porin OprD, and extinction of MexAB-oprM efflux pump overproduction). Some of these mutations were associated with a decreased in vitro fitness. We hypothesize that the independent emergence of isolates adapted to chronic infection, and thus the accumulation of epidemiological dead-ends, participated to the end of the hospital outbreak of P. aeruginosa ST395
Wright, Claire Louise. "Investigation of the prevalence of opportunistic gram negative pathogens in the water supply of a haematology unit, and the application of point-of-use filtration as an intervention." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5692.
Повний текст джерелаMoura, Rodrigo Assunção. "Estudo das relações clonais entre amostras de Escherichia coli enteropatogênica atípica de origem animal e humana." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/42/42132/tde-02022010-100915/.
Повний текст джерелаForty-nine typical and atypical EPEC strains belonging to different serotypes, isolated from humans, pets (cats and dogs), farm (bovines, sheep and rabbits) and wild animals (monkeys) were investigated for virulence markers and clonal similarity by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The virulence markers analyzed revealed that atypical EPEC strains isolated from animals have the potential to cause diarrhea in humans. Close clonal relationship between human and animal isolates was found with MLST and PFGE. These results indicate that these animals act as atypical EPEC reservoirs and may represent sources of infection for humans. Since humans also act as a reservoir of atypical EPEC strains, the cycle of mutual infection of atypical EPEC between animals and humans, mainly pets and their owners, cannot be ruled out, since the transmission dynamics between the reservoirs are not yet clearly understood.
Hernández, Jessica. "Design et synthèse de nouveaux inhibiteurs de la résistance bactérienne ciblant la pompe d'efflux AcrAB-ToIC chez Enterobacter aerogenes." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM5508.
Повний текст джерелаOverexpression of Resistance-Nodulation-Division (RND) efflux pumps (EP) is a major contributor in multidrug resistance (MDR) and pathogenicity in Gram-negative bacteria. These transporters are able to expel out of the bacterial cell clinically important antibiotic classes, contributing in a significant manner to the treatment failure of infectious diseases. With the worrying levels of bacterial resistance reported worldwide and the continuous spreading of MDR pathogens, EPs are interesting targets for the discovery of new antimicrobial drugs. Therefore, to overcome this mechanism, efflux pump inhibitors (EPIs) are being developed as adjuvants in order to restore or improve the activity of usual antibiotics. The AcrAB-TolC archetype is particularly widespread in Enterobacter spp. presenting clinical relevance (ESKAPE pathogens). In this study, we described the drug design strategy based on fluoroquinolone antibiotic analogs, against the AcrB pump of E. aerogenes. Thus, synthesis and microbiological evaluation of quinazolin-4(3H)-one derivatives were performed. The structural and molecular properties of the tested compounds (i. e. rigidity and flexibility) were also investigated. In this purpose, a scaffold hopping of the quinazolinone core to homologous benzoquinazolinones and precursors benzamides were carried out. Several molecules increased the bacterial susceptibility towards norfloxacin and chloramphenicol. The obtained results, supported by molecular modeling, suggest that molecular flexibility and the nature of chemical functions play a critical role to improve activity and selectivity on fluoroquinolone potentiation targeting AcrB efflux pump
Junior, Silvio Marciano da Silva. "Caracterização de Escherichia coli uropatogênicas isoladas de crianças com infecção urinária." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-05072012-104130/.
Повний текст джерелаUrinary Tract Infection (UTI) is the second most common type of bacterial infection in children. In this study, 6012 urine samples from pediatric patients were analyzed, the prevalence of UTI was determined, the uropathogens were identified and their antimicrobial profile was determined. The results have shown that the prevalence of UTI varies according to the sex and age of the patient. Gram negative bacteria were responsible for 89 % of all cases of UTI and E. coli was the most prevalent species. The uropathogens were resistant to: ampicillin 63 %, nitrofurantoin 37 % and trimethoprim-sulfamethoxazole 28 %. However, 99 % of them were sensitive to cephalexin and 96 % to chloramphenicol. Results obtained with the characterization of 90 isolates of E. coli showed that all of them were positive for fimA and fimH, 53 % were positive for pap, 32 % were positive for sfa, 10 % were positive for the genetic marker of pic and 29 % were able to produce hemolysin-a. These isolates were distributed between the phylogenetic groups as follows: B2 42 %, D 25 %, A 21 % and B1 11 %. Nineteen percent of these samples were untypeable (ONT), 15.56 % belonged to O2 serogroup and 12,22 % belonged to the O6 and OR serogroups. Most E. coli isolates were able to adhere to epithelial cells, polystyrene and PVC.
Mathlouthi, Najla. "Déterminisme du support moléculaire et de l'épidémiologie de la résistance aux β-lactamines chez des bacilles à Gram négatif isolés dans des hôpitaux tunisiens et libyens". Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0079/document.
Повний текст джерелаThe increase and spread of β-lactam resistance in gram negative bacteria especially Enterobacteriaceae, Pseudomonas and Acinetobacter (E.P.A) species have become a major concern worldwide. The hospital-acquired infections caused by MDR bacteria have led to an increase in mortality, morbidity and cost of treatment. The frequent misuse of antibiotic drug has greatly contributed to worldwide dissemination of antibiotics resistance. Front of this worldwide concern, and various recommendations, several epidemiological and molecular studies have been reported in order to control the spread and the dissemination of these MDR. Unlike many parts of the world, there is little information concerning the molecular characterization of the β-lactam resistance genes of Gram-negative bacilli isolated in Tunisia and especially in Libya. Therefore, it is in this context that the project of this thesis was conducted with essential objectives: (i) highlight the prevalence of multi-resistant Gram negative bacilli isolated in Tunisian and Libyan hospitals (ii) identify the genetic support of resistance to β-lactams of these clinical strains (iii) study the clonal diversity of the multi-resistant strains by molecular typing (iii) study the molecular epidemiology of these BMRs in these countries in order to control the decision-making process of the treatment and the rapid identification of epidemics by implementing appropriate control measures for the spread of infections and especially developing new tools and software for the diagnosis and monitoring of potential MDR bacteria in Mediterranean countries
Al, Bayssari Charbel. "Etude des mécanismes moléculaires de la résistance aux antibiotiques dans le bassin méditerranéen." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM5028.
Повний текст джерелаThe detection, monitoring and dissemination of bacterial resistance to antibiotics are a major issue worldwide since the discovery and spread of multi-resistant bacteria, in particular resistance to carbapenems, specifically among Enterobacteriaceae and bacteria of the genus Pseudomonas and Acinetobacter.The emergence and dissemination of carbapenem-resistant Gram-negative pathogens is a significant contributor to patient morbidity and mortality. Despite radical efforts in infection control and improvements in molecular diagnostics, carbapenem-resistant Gram-negative bacilli remain a formidable threat as few antimicrobial agents are reliably active and very little is expected to be available in the near future.The origin and source of resistance genes in the world are not well known and recent works suggest that domestic and wild animals, the environment (soil, water, rivers ..) but also the digestive tract of mammals and humans could represent a reservoir and an important source of resistance genes that may be transmissible to humans.It is in this context that this thesis project articulates with the following objectives: (i) The achievement of molecular epidemiological studies on carbapenem-resistant clinical and animal isolates collected from countries in the Mediterranean basin (Lebanon, Libya, France) and the characterization of the genetic determinants of this resistance; (ii) the description of new resistance mechanisms to imipenem; and finally (iii) The genome sequencing of clinical isolates resistant to carbapenems, the analysis of these genomes and the identification of mechanisms and genetic supports of the resistance to carbapenems and other antibiotics
Kumar, Sumith. "Exploring the Roles of Phase Variable HpyAII Restriction-modification System in the Human Pathogen Helicobacter pylori." Thesis, 2016. http://etd.iisc.ac.in/handle/2005/4069.
Повний текст джерелаAgarwal, Mansi. "Risk of hospital-acquired infections and drug resistance caused by gram-negative bacteria in patients with multiple hospitalizations." Thesis, 2017. https://doi.org/10.7916/D8KW5TGC.
Повний текст джерелаGeorge, Divya. "Characterization of novel virulence factors of Shigella flexneri and development of Caenorhabditis elegans as an animal model for Shigella infection." Phd thesis, 2014. http://hdl.handle.net/1885/156384.
Повний текст джерелаFreire, Catarina Maria Boto. "Analogues of the antimicrobial peptide BP214." Master's thesis, 2017. http://hdl.handle.net/10451/36008.
Повний текст джерелаOne of the most concerning health problems present in the twenty-first century is antibiotic-resistant infections. The growing number of multi-resistant infections has led to complicated public health problems that require the most consideration. Simultaneously there are economic and regulatory barriers. Having all of these difficulties in mind, some researchers are trying to find new therapeutic classes that may became reliable alternatives to the therapeutics use nowadays. One of these new classes may be antimicrobial peptides. AMPs have demonstrated antimicrobial activity which makes them a good choice for research. Their cationic amino acids confer the molecule an attraction towards some components of the bacteria, this leads to the possibility of destroying the microorganism due to membrane rupture. The AMP studied on this work was BP214, which was characterised in some previous studies. BP214 has shown a similar antimicrobial activity to colistin (a last-line therapeutic) and a reduced hemolytic activity compared to other AMPs. Therefore, on this study, eleven different BP214s analogues were synthesised and studied in order to discover which amino acids are essential to its antimicrobial and hemolytic activities. Each of these analogues differs from BP214 only in one amino acid that was replaced by an alanine. The results demonstrated that only the peptides that had a lysine or an arginine replaced showed an improved antimicrobial activity but also an increase in their hemolytic activity. The remaining replacements resulted in a loss of antimicrobial and hemolytic activities of the peptide. It was also possible to associate the loss of activity to the low hydrophobicity of the molecule, which resulted from the amino acids replacement. The peptides where the lysine or the arginine were replaced, were also the ones that demonstrated the higher hydrophobicity. Both amino acids are basic and possess high values of pKa. This characteristic can be closely related with higher antimicrobial activity.
Um dos maiores problemas do século vinte e um tem sido a resistência aos antibióticos. O crescente número de infeções multirresistentes desencadeou um problema de saúde pública, o que requer uma enorme preocupação por parte da sociedade. Aliados a esta problemática estão os obstáculos a nível económico e regulatório. Tendo todas estas dificuldades em consideração, alguns investigadores estão a tentar encontrar novas classes terapêuticas que possam conferir alternativas às terapêuticas existentes de modo a podermos combater estas infeções com armas inovadoras e contra as quais os patogénicos ainda não possuam resistências. Uma das novas classes emergentes podem ser os péptidos antimicrobianos. Estes péptidos têm demonstrado uma atividade antimicrobiana que faz deles uma boa opção contra as bactérias resistentes. Os seus aminoácidos catiónicos conferem-lhes uma atração específica a determinados componentes das bactérias, levando depois à possibilidade de as eliminar por rotura da membrana. Estes péptidos têm também atividades imunomodulatórias em que são capazes de aumentar a resposta imunitária contra o patogénico, aumentar a quimioatração e ativar a resposta inata e adaptativa, antibiofilme em que conseguem impedir a sua formação mesmo abaixo da sua concentração mínima inibitória e anticancerosas pela sua atividade citolítica específica para tecido tumoral que, tal como as bactérias está carregado negativamente. Entre as várias vantagens dos péptidos antimicrobianos está a facilidade de síntese. Através de uma síntese bastante simples é possível manipulá-los aminoácido por aminoácido de modo a obter um híbrido o mais potente possível em comparação com o péptido original. Deste modo, é viável controlar a sua relação estrutura-atividade. De uma maneira tão simples, é também possível adicionar novos aminoácidos à sequência ou mutar o péptido de modo a torná-lo mais estável ou menos agressivo para o ser humano. Esta síntese pode ser feita em pequena escala no laboratório, mas também pode ser transferida para ser produzida numa grande escala de modo automatizado. Apesar de entre si poderem ser bastante diferentes, os péptidos antimicrobianos possuem algumas características que são transversais a todos eles. Por exemplo, possuem um comprimento médio de menos de 60 aminoácidos, são geralmente carregados positivamente (com carga entre +2 a +9) e as suas estruturas são flexíveis e anfipáticas, ou seja, parte da molécula é hidrofóbica e outra é hidrofílica. Vai ser esta última característica que vai permitir ao péptido passar da sua conformação em solução para a conformação que permite a sua entrada na membrana da bactéria. Esta particularidade vem dos seus aminoácidos catiónicos e hidrofóbicos. São estes aminoácidos catiónicos que desencadeiam uma atração electroestática para as moléculas aniónicas da membrana da bactéria, como os lipopolissacáridos das bactérias gram-negativas e os ácidos lipoteicóicos das gram-positivas. É também através desta peculiaridade que mantém um elevada especificidade para as células procariotas ao invés das eucariotas. A estrutura catiónica vai então levar a uma interação do péptido com a membrana da bactéria e também com os lípidos da membrana citoplasmática, ambos carregados negativamente. A sua carga positiva vai então estabilizar a carga dos fosfolípidos da membrana e causar a sua perturbação. A estrutura anfipática vai depois permitir a sua inserção na bicamada da membrana resultando na sua disrupção e posterior morte da bactéria. O mecanismo exato de como esta disrupção acontece ainda não é totalmente conhecido, sendo que existem diversas teorias para o explicar mas ainda nenhuma foi globalmente aceite. As teorias existentes até ao momento são o modelo “barrel-stove” (i) em que se assume que a inserção do péptido se dá com a orientação das regiões hidrofóbicas no core dos lípidos, levando à formação de um poro que causa a disrupção da membrana; o modelo “toroidal-pore” (ii) que supõe que a inserção do péptido na bicamada leva a que esta se dobre e forme um poro que permite a associação do péptido às cabeças polares dos fosfolípidos; o modelo “aggregate” (iii) em que se crê que vai ocorrer a formação de agregados péptido-lípido, agregados esses que levam a flutuações na condutância e translocações de péptidos na membrana; e, por último, o modelo “carpet” (iv) em que se supõe que a conformação anfipática do péptido leva à sua acumulação na membrana da bactéria formando uma espécie de carpete, causando a disrupção (Figura 1). Para além desta capacidade de disrupção da membrana da bactéria que os péptidos antimicrobianos possuem, eles possuem ainda alvos intracelulares. Apesar de precisarem de estar a uma determinada concentração para serem capazes de causar a lise das bactérias, com apenas concentrações muito baixas conseguem atingir os seus alvos no interior da bactéria, provando assim que estes fenómenos acontecem por mecanismos distintos. Estes péptidos vão então ser capazes de inibir o material genético da bactéria ao nível do ADN, do ARN, da síntese proteica e também da atividade citosólica das suas enzimas. O péptido estudado neste trabalho foi o BP214 que já foi estudado em trabalhos anteriores e que demonstrou uma atividade antimicrobiana semelhante à colistina (uma terapêutica de última linha para o tratamento de infeções bacterianas multirresistentes) e uma atividade hemolítica reduzida quando comparado com outros péptidos antimicrobianos, tendo assim menos efeitos indesejados. Tendo esses estudos em conta, neste trabalho foram sintetizados onze análogos do péptido BP214 e, posteriormente, estudados ao nível da atividade antimicrobiana e hemolítica. Este trabalho foi realizado no sentido de poder descobrir quais os aminoácidos da sequência deste péptido que são essenciais para a sua atividade antimicrobiana e hemolítica e quais podem vir a ser alterados de modo a podermos aumentar a atividade antimicrobiana mas diminuir a atividade hemolítica, de modo a torna-los viáveis ao nível comercial. Cada um dos análogos vai diferir do BP214 apenas num único aminoácido que é consecutivamente substituído por uma alanina, um aminoácido bastante simples. Os resultados demonstraram que apenas os péptidos em que uma lisina ou uma arginina foram substituídas resultaram num aumento da atividade antimicrobiana mas também num aumento da atividade hemolítica. As restantes substituições levaram à perda de atividade antimicrobiana e também hemolítica. Foi também possível associar essa perda de atividade à diminuição do carácter hidrofóbico da molécula, resultado da substituição que foi feita. Este parâmetro foi avaliado pela percentagem de eluente B, o eluente hidrófobo, utlizado no HPLC. Os péptidos em que se trocaram a lisina ou a arginina eram também aqueles que tinham maior hidrofobicidade e nos quais ocorreu um aumento das atividades, quer hemolítica quer antimicrobiana. Quer a lisina como a arginina são aminoácidos básicos que conferiram um carácter mais básico à molécula. Esta característica pode estar intimamente relacionada com o aumento das suas atividades antimicrobianas e hemolíticas.
Messina, Angeliki Phroso. "A retrospective review of colistin utilization and patient outcomes across four private sector hospitals in South Africa to identify opportunities to optimise colistin stewardship in hospitalised patients with multi-drug resistant Gram-negative infections." Thesis, 2018. https://hdl.handle.net/10539/25414.
Повний текст джерелаThe increased prevalence of multi-drug resistant (MDR) Gram-negative infections in critically ill patients has resulted in the re-introduction of colistin as rescue therapy. Various guidelines for colistin administration have led to confusion in establishing the appropriate dose which has potential for adverse consequences including treatment failure or toxicity. Colistin, also known as Polymixin E, is a concentration-dependent bactericidal antibiotic considered to be highly nephrotoxic and neurotoxic. Colistin is used either intravenously to treat life threatening systemic infections or by nebulisation for the treatment of respiratory tract infections. Although colistin resistance has been documented in South Africa, there is no local evidence as to why and how colistin is used in hospitals and similarly compliance with current dosing guidelines is unknown. This study aimed to evaluate the utilization of colistin in order to identify stewardship opportunities regarding its’ appropriate use in the future. A retrospective electronic record review of adult patients treated with intravenous (IV) and aerosolised colistin therapy in four Gauteng private hospitals was conducted between 1 September 2015 - 30 June 2016. The following data were collected on a standardized template; patient demographics including: age, gender, weight and hospital location; laboratory indicators including: renal function markers of creatinine and estimated Glomerular Filtration Rate (eGFR), as well as, culture specimens taken and their corresponding results. With regards to the colistin therapy: the indication for use, admitting diagnosis, the prescribed dose, frequency and route of administration, duration of treatment and if prescribed in combination with another Gram-negative antibiotic was considered. The following stewardship principles were monitored in addition to appropriate dose and duration; if a culture was taken prior to the initiation of treatment, if therapy was de-escalated and if a loading dose was prescribed. Outcome measures included overall in-hospital mortality, intensive care unit length of stay and overall hospital length of stay. Furthermore, compliance to two local colistin dosing guidelines was measured and a colistin stewardship bundle was developed, including nine process measures, to enhance the appropriate use of IV colistin. A total of 237 patients were included in the study of which 212 received colistin IV and, 25 via nebulisation. The results of patients who received IV colistin therapy demonstrated an 81.2% overall compliance to the proposed colistin stewardship bundle developed from this study. Non-compliance was mainly due to incorrect maintenance doses prescribed (50%), ‘hang time’ (66%) and poor de-escalation practices (69%). Significantly shorter durations of treatment were found in patients who received higher loading doses (p=0.040) and in those that received maintenance doses of 4.5 Million Units (MU) twice daily vs 3 MU three times daily (p=0.0027). In addition, more of the patients that demised received the 3 MU three times daily maintenance doses, compared to those who survived (p=0.0037). Aerosolised colistin was only prescribed in one of the four hospitals studied. Of those patients who received aerosolised colistin, 13 were for cystic fibrosis and 12 for other nosocomial lower respiratory tract infections (LRTI’s). Compliance to appropriate dose for the cystic fibrosis patients was good at 92.3%, however, for other LRTI’s was poor at only 41.7%. This study demonstrated that there is noteworthy prevalence of MDR Gram-negative infections in South African hospitals which requires the use of colistin. In addition, the study identified many stewardship related opportunities to improve appropriate colistin utilization in particular relating to dose for both routes of administration. The implementation of a colistin stewardship bundle is necessary, as a matter of urgency, to preserve the efficacy of this last resort antibiotic.
LG2018
Um, Nlend Ingrid. "New insights into small molecules inhibitors and protein-protein interactions of VirB8 : a critical conserved component of the type IV secretion system." Thèse, 2015. http://hdl.handle.net/1866/13799.
Повний текст джерелаPhillips, Aaron M. "Investigation of peptide nucleic acid fluorescence in situ hybridization for diagnosis of ventilator-associated pneumonia in bronchoalveolar lavage specimens." Thesis, 2014. http://hdl.handle.net/1805/3803.
Повний текст джерела