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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Genome evolution in Streptococcus pneumoniae

Wyres, Kelly L. January 2012 (has links)
Streptococcus pneumoniae (the pneumococcus) is a bacterial pathogen responsible for >1.6 million annual deaths globally. Pneumococcal penicillin-resistance is conferred by acquisition of ‘altered’ penicillin-binding protein (pbp) genes. The first penicillin-nonsusceptible pneumococci were identified in the late 1960s. Global pneumococcal penicillin-nonsusceptibility rates rapidly increased in the 1980s/90s. Since 2000, protein-conjugate vaccines, targeting 7, 10 or 13 of the ≥94 different pneumococcal capsule types (serotypes), have been introduced in many countries. Following vaccine implementation there has been a decline in vaccine-type pneumococcal disease and an increase in non-vaccine-type disease. These epidemiological changes result from “serotype replacement” and/or “serotype switching”. The former describes the expansion of non-vaccine-type clones in the absence of vaccine-type pneumococci. The latter describes serotype change following recombination at the capsule polysaccharide synthesis (cps) locus. To fully understand how pneumococci respond to vaccine- and antibiotic-induced selective pressures, we must better understand the evolutionary history of this pathogen. This thesis describes the study of a global collection of 426 pneumococci, dated 1937 - 2007. Serotype, genotype and penicillin-susceptibility data were collected. Nucleotide sequences of three pbp genes (for 389 isolates) and whole-genome sequences (for 96 isolates) were also generated. The data demonstrated the long-term persistence of certain clones within pneumococcal populations, and that pbp and large-fragment (>30 kb) cps ± pbp recombination was occurring prior to both widespread antibiotic use and vaccine implementation. The data highlighted the promiscuous nature of the globally-distributed PMEN1 clone and its contribution to the spread of pneumococcal penicillin-resistance. PMEN1 also donated multiple, large regions (1.7 - 32.3 kb) of its genome to at least two un-related clones. Finally, six “Tn916-like” genetic elements, conferring resistance to non-penicillin antibiotics, were newly identified. These included two of the oldest ever described. These results provided a unique insight into the history of pneumococcal evolution and the importance of genetic recombination.
92

Aspectos fenotípicos e epidemiológicos de cepas de Neisseria gonorrhoeae produtora de penicilinase (ngpp) isoladas na cidade de São Paulo / Phenotypic and epidemiological aspects of strains of penicillinase-producing Neisseria gonorrhoeae (ngpp) isolated in the city of São Paulo

Luiz Fernando de Goes Siqueira 29 April 1994 (has links)
A gonorréia permanece até os dias atuais como um problema de saúde pública. A resistência plasmidial à penicilina, em cepas de Neisseria gonorrhoeae, constitui um problema crescente, preocupando autoridades sanitárias em todo o mundo. O conhecimento das características epidemiológicas e da dinâmica destas cepas na população é imperativo, para o sucesso de intervenções de combate e controle da gonorréia no Brasil e no mundo. Os fenômenos de instalação, manutenção e propagação da Neisseria gonorrhoeae produtora de penicilinase são ainda pouco conhecidos. Este trabalho estudou as características fenotípicas (comportamento de sensibilidade às drogas antimicrobianas, características do plasmídio de resistência, auxotipo e sorotipo), da Neisseria gonorrhoeae produtora de penicilinase (NGPP), objetivando fornecer conhecimentos quanto aos fenômenos de instalação, manutenção e propagação destas cepas, de forma a contribuir com o programa de combate e controle da gonorréia na cidade de São Paulo e no Brasil. Foram estudadas 15 cepas de Neisseria gonorrhoeae produtora de penicilinase (NGPP) e 50 de Neisseria gonorrhoeae não produtora penicilinase (não NGPP), isolados no serviço de Doenças Sexualmente Transmissíveis (DST) da Faculdade de Saúde Pública da Universidade de São Paulo, no período de abril de 1985 a abril de 1990. Com uma incidência de 3,11 por cento de cepas de NGPP, os resultados permitiram colaborar para formação de perfil epidemiológico das cepas produtoras de penicilinase na cidade de São Paulo. Quanto as características de sensibilidade aos antimicrobianos, foram observados altos níveis de resistência a tetraciclina. As demais características fenotípicas, plasmídios, auxotipo e sorotipo, demonstram que a cidade de São Paulo é uma região geográfica \"aberta\" ao fenômeno de \"importação\", tendo sido observadas características epidemiológicas descritas em várias outras localidades no mundo. Os resultados obtidos neste trabalho reforçam a necessidade da instalação de um programa de vigilância epidemiológica, visando manter sob controle a dinâmica da Neisseria gonorrhoeae, colaborando com o programa de combate e controle da gonorréia na cidade de São Paulo e no Brasil. / Gonorrhoea has been considered as a public health problem up to these days. The plasmid penicilin resistance, in Neisseria gonorrhoeae strains, is an increasing problem which concerns authorities from the whole world. The Knowledge on the epidemiological characteristics and on the dynamics of these strains in the populations is extremely important for the success of interventions and gonorrhoea contrai programmes in Brazil and in the world. The onset phenomena, maintenance and proliferation of the penicilin producing Neisseria gonorrhoeae (PPNG) are not well known yet. This study presents the phenotype characteristics (sensibility to antimicrobial drugs, plasmid resistance characteristics, auxotype and serotype) of the PPNG. The objectives of the study are to contribute to the knowledge related to the onset phenomena, maintenance and proliferation of these strains, so that we can contribute to the gonorrhoea contrai programme in the city of São Paulo and in Brazil. We studied 15 strains of penicilin producing Neisseria gonorrhoeae (PPNG) and 50 of non penicilin producing Neisseria gonorrhoeae (non PPNG), which were isolated in the Sexually Transmitted Disease Service of the Faculty of Public Health of the University of São Paulo, from April 1985 to April 1990. With an incidence rate of 3.11 per cent of Neisseria gonorrhoeae, the results allowed us to design an epidemiological profile of the penicilin producing strains in São Paulo. Regarding the antimicrobial sensibility characteristics, we observed high leveis of resistance to tetracycline. The other phenotype characteristics (plasmid, auxotype, and serotype) show that the city of São Paulo is a geographic region open to \"importation\" phenomenon, since we have observed epidemiologic charactéristics described in several places in the world. The results of this reinforce the necessity of setting up an epidemiological surveillance programme with the objective of controlling the Neisseria gonorrhoeae dynamics and, in this way, to colaborate with the gonorrhoea control programme in the city of São Paulo and in Brazil.
93

Aspectos fenotípicos e epidemiológicos de cepas de Neisseria gonorrhoeae produtora de penicilinase (ngpp) isoladas na cidade de São Paulo / Phenotypic and epidemiological aspects of strains of penicillinase-producing Neisseria gonorrhoeae (ngpp) isolated in the city of São Paulo

Siqueira, Luiz Fernando de Goes 29 April 1994 (has links)
A gonorréia permanece até os dias atuais como um problema de saúde pública. A resistência plasmidial à penicilina, em cepas de Neisseria gonorrhoeae, constitui um problema crescente, preocupando autoridades sanitárias em todo o mundo. O conhecimento das características epidemiológicas e da dinâmica destas cepas na população é imperativo, para o sucesso de intervenções de combate e controle da gonorréia no Brasil e no mundo. Os fenômenos de instalação, manutenção e propagação da Neisseria gonorrhoeae produtora de penicilinase são ainda pouco conhecidos. Este trabalho estudou as características fenotípicas (comportamento de sensibilidade às drogas antimicrobianas, características do plasmídio de resistência, auxotipo e sorotipo), da Neisseria gonorrhoeae produtora de penicilinase (NGPP), objetivando fornecer conhecimentos quanto aos fenômenos de instalação, manutenção e propagação destas cepas, de forma a contribuir com o programa de combate e controle da gonorréia na cidade de São Paulo e no Brasil. Foram estudadas 15 cepas de Neisseria gonorrhoeae produtora de penicilinase (NGPP) e 50 de Neisseria gonorrhoeae não produtora penicilinase (não NGPP), isolados no serviço de Doenças Sexualmente Transmissíveis (DST) da Faculdade de Saúde Pública da Universidade de São Paulo, no período de abril de 1985 a abril de 1990. Com uma incidência de 3,11 por cento de cepas de NGPP, os resultados permitiram colaborar para formação de perfil epidemiológico das cepas produtoras de penicilinase na cidade de São Paulo. Quanto as características de sensibilidade aos antimicrobianos, foram observados altos níveis de resistência a tetraciclina. As demais características fenotípicas, plasmídios, auxotipo e sorotipo, demonstram que a cidade de São Paulo é uma região geográfica \"aberta\" ao fenômeno de \"importação\", tendo sido observadas características epidemiológicas descritas em várias outras localidades no mundo. Os resultados obtidos neste trabalho reforçam a necessidade da instalação de um programa de vigilância epidemiológica, visando manter sob controle a dinâmica da Neisseria gonorrhoeae, colaborando com o programa de combate e controle da gonorréia na cidade de São Paulo e no Brasil. / Gonorrhoea has been considered as a public health problem up to these days. The plasmid penicilin resistance, in Neisseria gonorrhoeae strains, is an increasing problem which concerns authorities from the whole world. The Knowledge on the epidemiological characteristics and on the dynamics of these strains in the populations is extremely important for the success of interventions and gonorrhoea contrai programmes in Brazil and in the world. The onset phenomena, maintenance and proliferation of the penicilin producing Neisseria gonorrhoeae (PPNG) are not well known yet. This study presents the phenotype characteristics (sensibility to antimicrobial drugs, plasmid resistance characteristics, auxotype and serotype) of the PPNG. The objectives of the study are to contribute to the knowledge related to the onset phenomena, maintenance and proliferation of these strains, so that we can contribute to the gonorrhoea contrai programme in the city of São Paulo and in Brazil. We studied 15 strains of penicilin producing Neisseria gonorrhoeae (PPNG) and 50 of non penicilin producing Neisseria gonorrhoeae (non PPNG), which were isolated in the Sexually Transmitted Disease Service of the Faculty of Public Health of the University of São Paulo, from April 1985 to April 1990. With an incidence rate of 3.11 per cent of Neisseria gonorrhoeae, the results allowed us to design an epidemiological profile of the penicilin producing strains in São Paulo. Regarding the antimicrobial sensibility characteristics, we observed high leveis of resistance to tetracycline. The other phenotype characteristics (plasmid, auxotype, and serotype) show that the city of São Paulo is a geographic region open to \"importation\" phenomenon, since we have observed epidemiologic charactéristics described in several places in the world. The results of this reinforce the necessity of setting up an epidemiological surveillance programme with the objective of controlling the Neisseria gonorrhoeae dynamics and, in this way, to colaborate with the gonorrhoea control programme in the city of São Paulo and in Brazil.
94

Etude structurale de PBP3 et localisation des six « Penicillin-Binding Proteins » de Streptococcus pneumoniae : implication dans la croissance et la division bactérienne.

Morlot, Cecile 17 November 2003 (has links) (PDF)
L'objectif de ma thèse était de réaliser une étude de la synthèse de la paroi de Streptococcus pneumoniae, paroi qui participe à la croissance et la division bactérienne et fait intervenir les « Penicillin-Binding Proteins » (PBPs). J'ai étudié la localisation du répertoire complet des six PBPs au cours du cycle cellulaire de S. pneumoniae, ce qui a révélé des similitudes inattendues entre les mécanismes de division des bactéries de type bacille et coque. J'ai déterminé le rôle spécifique de chaque PBP dans la synthèse de la paroi et mis en valeur la contribution de PBP3, une D,D-carboxypeptidase, dans la régulation de la division bactérienne. J'ai par ailleurs déterminé la structure tridimensionnelle de PBP3 à 2.8 Å de résolution, ce qui m'a permis de contraindre les modèles de synthèse de la paroi chez le pneumocoque.
95

Pharmacokinetics of ampicillin, gentamicin, amikacin, and omeprazole in llamas

Kasiwong, Srirat 28 May 1997 (has links)
Graduation date: 1998
96

A study of the reactivity of benzyl-penicillin toward the components of human blood

Talbert, Madonna L. 03 June 2011 (has links)
Benzylpenicillin is incubated with whole human blood. The degree of reactivity of 14C-benzylpenicillin to the components of this blood is determined via a Beckman LS-100C Liquid Scintillation Counter.The oxygen carrying capacities of penicillin treated adult normal and sickled hemoglobin are measured spectrophotometrically and compared to untreated adult normal and sickled hemoglobin.Ball State UniversityMuncie, IN 47306
97

An investigation of the irreversible binding of penicillin to serum protein

Truex, Lewis L. 03 June 2011 (has links)
The irreversible binding of penicillin to serum protein was investigated by incubating 14C-benzyl-penicillin with reconstituted lyophilized human serum and dialyzing away the non-bound penicillin. Binding appeared in each protein fraction as was observed by polyacrylamide gel electrophoresis and liquid scintillation counting.The nature of penicillin binding was investigated by preincubating reconstituted human serum with specicific blocking reagents.Ball State UniversityMuncie, IN 47306
98

Improving the enzymatic synthesis of semi-synthetic beta-lactam antibiotics via reaction engineering and data-driven protein engineering

Deaguero, Andria Lynn 16 August 2011 (has links)
Semi-synthetic β-lactam antibiotics are the most prescribed class of antibiotics in the world. Chemical coupling of a β-lactam moiety with an acyl side chain has dominated the industrial production of semi-synthetic β-lactam antibiotics since their discovery in the early 1960s. Enzymatic coupling of a β-lactam moiety with an acyl side chain can be accomplished in a process that is much more environmentally benign but also results in a much lower yield. The goal of the research presented in this dissertation is to improve the enzymatic synthesis of β-lactam antibiotics via reaction engineering, medium engineering and data-drive protein engineering. Reaction engineering was employed to demonstrate that the hydrolysis of penicillin G to produce the β-lactam nucleus 6-aminopenicillanic acid (6-APA), and the synthesis of ampicillin from 6-APA and (R)-phenylglycine methyl ester ((R)-PGME), can be combined in a cascade conversion. In this work, penicillin G acylase (PGA) was utilized to catalyze the hydrolysis step, and PGA and α-amino ester hydrolase (AEH) were both studied to catalyze the synthesis step. Two different reaction configurations and various relative enzyme loadings were studied. Both configurations present a promising alternative to the current two-pot set-up which requires intermittent isolation of the intermediate, 6-APA. Medium engineering is primarily of interest in β-lactam antibiotic synthesis as a means to suppress the undesired primary and secondary hydrolysis reactions. The synthesis of ampicillin from 6-APA and (R)-PGME in the presence of ethylene glycol was chosen for study after a review of the literature. It was discovered that the transesterification product of (R)-PGME and ethylene glycol, (R)-phenylglycine hydroxyethyl ester, is transiently formed during the synthesis reactions. This never reported side reaction has the ability to positively affect yield by re-directing a portion of the consumption of (R)-PGME to an intermediate that could be used to synthesize ampicillin, rather than to an unusable hydrolysis product. Protein engineering was utilized to alter the selectivity of wild-type PGA with respect to the substituent on the alpha carbon of its substrates. Four residues were identified that had altered selectivity toward the desired product, (R)-ampicillin. Furthermore, the (R)-selective variants improved the yield from pure (R)-PGME up to 2-fold and significantly decreased the amount of secondary hydrolysis present in the reactions. Overall, we have expanded the applicability of PGA and AEH for the synthesis of semi-synthetic β-lactam antibiotics. We have shown the two enzymes can be combined in a novel one-pot cascade, which has the potential to eliminate an isolation step in the current manufacturing process. Furthermore, we have shown that the previously reported ex-situ mixed donor synthesis of ampicillin for PGA can also occur in-situ in the presence of a suitable side chain acyl donor and co-solvent. Finally, we have made significant progress towards obtaining a selective PGA that is capable of synthesizing diastereomerically pure semi-synthetic β-lactam antibiotics from racemic substrates.
99

Bacteriological aspects of treatment failures in streptococcal tonsillitis

Grahn, Eva January 1986 (has links)
ß-hemolytic streptococci persist in 10-25% of patients with acute streptococal tonsillitis (about 10.000-25.000 per year in Sweden) in spite of treatment with a recommended dosage and schedule of Phenoxymethylpenicillin. The aim of the study was to investigate different bacteriological factors involved in treatment failures of streptococcal tonsillitis. Patients included in the study were 33 patients who underwent tonsillectomy, 62 persons included in a tonsillitis epidemic outbreak, 267 tonsillitis patients contacting the ENT-clinic, Sahlgrenska Hospital, Göteborg, and 20 healthy volunteers taking Phenoxymethylpenicillin. It was found that the Steer's steel pin replicator was a useful tool to study interference between a- and ß-hemolytic streptococci and a guantitative differen ce in. the inhibitory capacity of the different a-strains was noted, a-streptococci with a strong inhibitory capacity on ß-streptococci were isolated mainly from individuals seemingly resistant to ß-streptococcal tonsillitis, while from patients with repeated tonsillitis no or low numbers of inhibiting a-streptococci were demonstrated. Patients with clinical treatment failure had less a-streptococci with inhibiting capacity on their own ß-streptococcal strain compared with the healthy carriers. These treatment failures also showed beta-lactamase activity in their saliva pellet significantly more often than patients in the control groups. In volunteers penicillin was released from ordinary sugar coated tablets already in the mouth resulting in a decrease of the a-strep- tococcal flora. A synergistic effect on ß-hemolytic killing by low concentration of penicillin and inhibition of a-streptococci was noted in vitro and in vivo. Penicillin tolerance was registered in most strains from the treatment failure group, but in none of the strains from the group of successfully treated patients. A co-operation between different bacteriological factors (bacterial interference, beta-lactamase production, penicillin tolerance) seems to be important in treatment failures of streptococcal tonsillitis. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1986, härtill 6 uppsatser</p> / digitalisering@umu
100

Steroidal estrogen mineralization in liquid swine manure, sewage sludge and biosolids in the prescence of antibiotics

Rose, Karin P. 12 March 2014 (has links)
Steroidal estrogens and antibiotics used in veterinary and human medicine are detected in livestock manure or sewage sludge and biosolids. Biodegradation is an important process by which estrogenic compounds are removed from organic amendments, but antibiotics have been shown to impede microbial communities. Although both compounds are often present in these media, the fate of estrogens in association with antibiotics has not been previously studied. In this study, both rates of tetracycline (40 and 200 mg kg-1) in liquid swine manure induced a lag phase of 40 to 50 days prior to the onset of a log phase of estrone and 17 β-estradiol mineralization, and tetracycline at 200 mg kg-1 significantly reduced maximum mineralization of estrone and 17 β-estradiol in manure. In soils amended with a high rate of manure, penicillin at 200 mg kg1 also significantly decreased maximum mineralization of estrone and 17 β-estradiol relative to soils free of antibiotics. Estrogen mineralization almost always significantly decreased in the order of: manure > soil amended with a low rate of manure = soil > soil amended with a high rate of manure. In order to examine the relationship between physical and chemical parameters of media and estrogen mineralization, sewage sludge and biosolid samples with vastly different characteristics were selected for a study of 17 β-estradiol and 17 α-ethinylestradiol mineralization in the presence of ciprofloxacin, an antibiotic commonly used to treat urinary and intestinal infections in humans. Ciprofloxacin was persistent in all media, as less than 0.05% mineralization was observed over 133 d. Despite this persistence, no significant effect of ciprofloxacin addition on 17 β-estradiol or 17 α-ethinylestradiol mineralization was observed at 133 days. Consistent with its chemical structure, maximum mineralization of 17 α-ethinylestradiol was always less than that of 17 β-estradiol, indicating resistance to microbial degradation. PCA analysis indicated that total nitrogen, ammonium-nitrogen and total carbon demonstrated a positive association with respiration and maximum mineralization of 17 β-estradiol, but a negative association with 17 α-ethinylestradiol maximum mineralization. Sorption of 17 α-ethinylestradiol was greater than 17 β-estradiol in all media, limiting maximum mineralization of 17 α-ethinylestradiol.

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