Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 55 for “"β-lactam"”.
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Mechanisms of resistance to β-lactam antibiotics in Streptomycetes
… of penicillin G is not directly related to β-lactamase production in the panel of isolates examined. There was no correlation between the MICs of penicillin G and the growth rate in these isolates. Likewise, there was no association between the position of beta-lactamase producing and …
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Evaluation of the Interplay between β-Lactamase Expression and Porin Loss in β-Lactam Susceptibility Profiles in Escherichia coli
… driven by the acquisition of Extended-Spectrum β-Lactamases (ESBLs) and carbapenemases. However, β-lactam resistance in E. coli is often multifactorial, arising from different mechanisms such as the combined effects of β-lactamase production, alterations in outer membrane permeability, and …
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Discovery and optimization of inhibitors and probes that target New Delhi metallo-[beta]-lactamase
Since the discovery of penicillin in 1928, β-lactam antibiotics have been used worldwide to treat a broad spectrum of bacterial infections. However, the rise of bacterial resistance through the evolution of β-lactam hydrolyzing enzymes, known as β-lactamases, threatens their clinical efficacy. …
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THE ROLE OF BACTERIA AND ß-LACTAM ANTIBIOTICS IN CANDIDA ALBICANS INFECTION
… albicans hyphal growth. Here, we report that β-lactam antibiotics cause bacteria to release large quantities of hyphal-inducing PGN subunits into the environment, including culture media and the GI tract of mice. Of high importance, massive hyphal growth in the GI tract of treated mice due to …
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Palladium-Catalysed Carbonylation of Aliphatic Amines and its Application in the Total Synthesis of Cylindricine C
… aliphatic amines to form synthetically useful β-lactam building blocks. Amines exhibiting a range of substitution patterns around the nitrogen functionality, and bearing a wide variety of functional groups, could be tolerated in the reaction. The desired β-lactam products were delivered in high …
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Characterization of β-lactamases and Porins in Uropathogenic E. coli
… increasingly resistant to commonly utilized β-lactam antibiotics leading to higher medical costs, prolonged treatment from persistent infections, and increased mortality. This rising resistance is primarily caused by the dissemination of acquired resistance mechanisms, namely plasmid-encoded …
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Elucidation of the Molecular Mechanisms That Contribute to Variation in Susceptibility Testing Show the Need for Alternative Detection Methods of KPC-producing Gram-negative Bacteria
… have been associated with high levels of β- lactam resistance, in addition to other antibiotic drug classes. This, in addition to the lack of novel antimicrobials with activity against Gram-negative bacteria, forces physicians to treat infections caused by KPC-producing pathogens with …
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Beyond MICS: Determining the Role of Porin Production and β-Lactamase Expression in Resistance and Cellular Physiology of Klebsiella pneumoniae
… K. pneumoniae is capable of resistance to β-lactam antibiotics through expression of β-lactamases and downregulation of outer membrane porins. However, the extent to which these mechanisms interplay in a resistant phenotype is not well understood. β-lactamase expression has long been presumed …
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Mechanisms Involved in the Expression of the AmpC Beta-lactamase Gene blaCMY-2 in Escherichia coli
… that express plasmid-encoded AmpC β-lactamases can be resistant to third generation cephalosporins and β-lactam/β-lactamase inhibitor combinations. Infections by these bacteria are associated with increased patient morbidity and mortality. Little is known about how plasmid-encoded …
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Structural characterization of superbug proteins involved in regulating beta-lactam resistance
The widespread use of β-lactams has undermined their effectiveness as chemotherapeutic agents by fueling the evolution and dissemination of multiple resistance mechanisms, including: (1) production of hydrolytic β-lactamase enzymes that inactivate β-lactams, (2) expression of PBPs with …
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Enabling early stage drug discovery targeting high molecular mass penicillin-binding proteins in <i>Yersinia pestis</i>
… to this family of proteins, the history of β-lactam antibiotics and the organism of interest are given in Chapter one. High molecular mass (HMM) PBPs are well-established targets of β-lactam antibiotics. However, only in the past two decades has information about their structure started to …
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Antibiotic resistance in the gut microbiota
… prevalence and diversity of aminoglycoside and β-lactam resistance genes in the adult gut microbiota and highlighted the merits of the approach adopted. Using infant faecal samples, we constructed and screened a second fosmid metagenomic bank for the same families of resistance genes and …
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Proteomic comparison of Amoxicillin resistant and susceptible periodontal Provotella Intermedia and Provotella Nigrescens clinical isolation with Matrix-Assisted Laser Disportion Ionization Time-Of-/flight mass spectrometry
… and P. nigrescens may exhibit resistance to β-lactam antibiotics prescribed in periodontal therapy via expression of β-lactamase enzymes. Conventional methods of in vitro antibiotic susceptibility testing entail cultivation of targeted bacterial species, with evaluations of whether or not the …
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Synthesis of 4-(trifluoromethyl)azetidin-2-one building blocks and their transformation into novel CF3-substituted amines and heterocyclic systems
… light of the versatile synthetic potential of β-lactams on the one hand and the beneficial impact of fluorine on biological properties on the other hand, β-lactams bearing a trifluoromethyl group comprise interesting entities for the construction of novel targets with promising bioactivities. In …
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Studying the riboregulatory role of Hfq in Klebsiella pneumoniae using CLASH (crosslinking, ligation and sequencing of hybrids)
… which interact with genes that modulate β-lactam susceptibility. A significant discovery of my thesis is the phenotype obtained due to the interaction between Spf and mrdA (encodes Penicillin Binding Protein 2). Spf deletion mutants exhibited decreased susceptibilities to β-lactam …
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Combatting β-lactamase-mediated antimicrobial resistance: from novel assays for inhibitor discovery to new diagnostics
The clinical utility of β-lactams, the most prescribed antibiotics worldwide, is endangered due to the production of β-lactamase enzymes by pathogenic bacteria. Collectively, these enzymes can inactivate every clinically available β-lactam antibiotic via a hydrolytic mechanism. Thus, infections …
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Outer Membrane Porin Regulation among Different Sequence Types of Escherichia coli Clinical Isolates
… pandemic clone associated with the spread of β-lactam and fluoroquinolone resistance. However, the reasons for the global dominance of this clone are largely unknown. It has been suggested that the success of ST131 E. coli is due to the resistance and virulence genes it possesses. Additionally, …
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GENOMIC SURVEILLANCE AND RISK-BASED ASSESSMENT OF ANTIBIOTIC RESISTANCE TRANSMISSION ACROSS TROPICAL AQUATIC ENVIRONMENTS
… poorly understood. This thesis investigates β-lactam resistance transmission across Singapore's tropical aquatic continuum—from hospital sewage and community wastewater to freshwater, aquaculture, and coastal environments—using integrated metagenomic and whole-genome sequencing approaches …
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Metallo-β-lactamase-like enzymes from non-pathogenic organisms: an illustration of functional promiscuity
… of antibiotic-degrading enzymes, the metallo-β-lactamases (MBLs). MBLs are a family of Zn(II)-dependent enzymes that inactivate most of the commonly used β-lactam antibiotics. In Chapter 1 a detailed review of the properties of these enzymes is presented. Novel MBLs are continuously discovered …
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