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COLOMBO, STEFANO. "DISCLOSING THE PHAGE-MEDIATED ANTIBIOTIC RESISTANCES IN THE FOOD CHAIN." Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/487927.
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The aim of this PhD project is to evaluate the presence and the role of viruses in food related environment with particular attention on the mobilization of antibiotic resistance genes (ARGs). During the last three years it has been investigated samples from different food related environments in order to fully characterize the respective microbial and viral communities with a focus on the identification of ARGs in virome and microbiomes. Water from aquaculture was the first sample analyzed (i) being a matrix that has a strong direct contact with the respective food; secondly, it has been analyzed water from Lambro river (ii) since it is used in the field’s irrigation so it directly came in contact with cereals and vegetables. Last project involved the analysis of air surrounding different moment of cheesemaking production (iii). Once again the viruses present in the air could deposit on the surface of the food and they can be ingested by humans. Shotgun metagenomic sequencing was used to study both microbes and viruses, while 16S rRNA profiling analysis completed the characterization of the bacterial community.
The three different projects showed how antibiotic resistance genes are wide spread in the viromes of different environments irrespective of the presence of associated anthropic activities. In this context, we hypothesize that the release of antibiotics molecules in the environment by the microbiota is a driving force able to maintain ARGs in the microbiome and, consequently, mobilize them in the virome. In addition, we should consider the effect of the intense environmental release of antibiotics by humans activities. For these reasons this novel approach even if really useful to collect a high amount of information on the sample, is insufficient to discriminate how ARGs have mobilized to the virome and from the virome to the microbiome. In this context, the development of mesocosms can be the turning point since this system let us to work with complex environmental samples but focusing the attention only at one variable at time as, for example, the supplementation of defined amount of antibiotics.
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Monchique, Cláudia Raquel Oliveira. "Evolução da resistência aos antibióticos em Staphylococcus spp. : 1999 a 2006." Master's thesis, Universidade de Lisboa. Faculdade de Medicina Veterinária, 2013. http://hdl.handle.net/10400.5/6229.
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Dissertação de Mestrado Integrado em Medicina VeterináriaO género Staphylococcus tem importância a nível clínico e económico, sendo que a emergência de estirpes meticilina resistente e multirresistentes tornam-no num assunto atual em Medicina Humana e Veterinária. As 383 amostras de infeções clínicas analisadas foram recebidas pelo Laboratório de Análises Clínicas da FMV-UL ao longo de um período de 8 anos (1999-2006). O teste de susceptibilidade aos antibióticos foi realizado por difusão de disco usando 37 antibióticos. As espécies de estafilococos foram identificadas por amplificação por PCR dos respetivos genes nuc. Os genes mecA e mecC foram pesquisados por PCR. No total, 293 isolados foram resistentes a pelo menos um antibiótico (76,50%), com as maiores frequências de resistência à penicilina e ampicilina (53%). A maior percentagem de resistência a um antibiótico verificou-se em S. pseudintermedius (80,84%), seguido dos S. aureus (75%), estafilococos coagulase-negativo (ECN) (68,18%) e S. schleiferi (63,44%). Globalmente, 132 isolados foram multirresistentes (34,36%) e apenas 23,50% dos isolados foram suscetíveis a todos os antibióticos testados. A resistência aumentou com o tempo, sendo 2004 o ano com maior percentagem de isolados resistentes de estafilococos (85%). Dez isolados eram resistentes à oxacilina, mas só oito eram mecA positivo (sete ECN e um S. aureus) e nenhum foi positivo para o mecC. Os nossos resultados confirmam a elevada resistência aos antibióticos em estafilococos e ressaltam a importância de uma monitorização contínua dos padrões de resistência para ajustamento da estratégia antimicrobiana.
ABSTRACT - Evolution in antibiotics resistance in Staphylococcus spp. – 1999 a 2006 - The genus Staphylococcus has importance at clinical and economic level, with the emergence of methicillin-resistant and multiresistant strains making it a current issue in Human and Veterinary Medicine. The 383 clinical samples analyzed were received by the Laboratory of Clinical Analysis of the FMV-UL over a period of 8 years (1999-2006). The antimicrobial susceptibility testing was performed by disk diffusion using 37 antibiotics. Staphylococcal species were identified by PCR amplification of the respective nuc gene. The mecA and mecC genes were screened by PCR. In total, 293 isolates were resistant to at least one antibiotic (76,50%), with higher frequencies of resistance to penicillin and ampicillin (53%). The highest resistance to one antibiotic was found in S. pseudintermedius (80,84%) followed by S. aureus (75%), coagulase-negative staphylococci (CNS) (68,18%) and S. schleiferi (63,44%). Overall, 132 isolates were multidrug resistant (34,46%) and only 23,50% of the isolates were susceptible to all the antibiotics tested. Resistance increased over time, with the highest level observed in 2004 (85%). Ten isolates were resistant to oxacilin, but only 8 were mecA-positive (seven CNS and one S. aureus) and none was mecC-positive. Our results confirmed that antimicrobial resistance is very frequent in staphylococci, and highlights the importance of a continuous monitoring of the resistance patterns for adjustment of antimicrobial strategy.
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Schmidt, K. "Evaluation of new diagnostic technologies for rapid detection of urinary pathogens and their antibiotic resistances." Thesis, University of East Anglia, 2017. https://ueaeprints.uea.ac.uk/66564/.
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Background: Most urinary tract infections (UTIs) are trivial; but complicated UTIs are a growing reason for hospitalisation in the UK, and are among the commonest sources of sepsis. Increasing resistance among uropathogens complicates treatment and drives wider empirical use of previously-reserved antibiotics. Rapid precise detection of pathogens and resistances, without culture, might better guide early therapy in deteriorating UTI patients. Methods: Two approaches were evaluated: i) MALDI-TOF mass spectrometry for direct identification of pathogens from urine together with multiplex, tandem PCR (MT-PCR) for resistance gene profiling. MALDI-TOF was also explored for rapid detection of β-lactamase activity in bacteria harvested from urine; ii) MinION sequencing for bacterial and resistance gene identification, again directly from urine. As background, an epidemiological surveillance of uropathogens from the Norfolk and Norwich University Hospital in July and November 2014 was performed. Results: Direct MALDI-TOF on urines could achieve rapid bacterial identification within 1.5 h and also allowed direct detection of extended-spectrum β-lactamase (ESBL) activity. MT-PCR showed satisfactory results in detecting the commonest resistance genes in Enterobacteriaceae directly from urines and cultivated isolates within 3 h. Weaker association was found between streptomycin resistance and aadA1/A2/A3 genes. Fluoroquinolone-susceptible and -resistant Escherichia coli were distinguished by the melting temperatures of their gyrA product. MinION sequencing correctly identified uropathogens and their resistances in all urine samples within < 5 h, without culture. Acquired resistance genes agreed with resistance phenotypes and closely matched Illumina sequencing, albeit with poor discrimination within some β-lactamase families (e.g. blaTEM). Epidemiological surveillance showed E. coli predominant in all age groups and location types, with high resistance rates to amoxicillin and trimethoprim. Conclusion: Either a MALDI-TOF plus PCR or a sequencing approach could significantly shorten the time required for microbiological investigation of urosepsis, allowing clinicians to adjust therapy before the second dose of a typical (i.e. q8h) antibiotic.
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Sutera, Vivien. "Francisella et antibio-resistance : aspects génétiques, phénotypiques et cliniques." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAV064/document.
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Francisella tularensis est une bactérie à Gram négatif intracellulaire facultative, agent causal de la tularémie. Cette zoonose est induite principalement par deux sous espèces : F. tularensis subsp. tularensis (type A) et F. tularensis subsp. holarctica (type B) retrouvées respectivement en Amérique du Nord et dans tout l’hémisphère Nord. Cette seconde sous espèce, moins virulente que la première induit majoritairement des formes cliniques de sévérité moyenne à modérée dites ganglionnaires. Leur traitement est basé sur l’utilisation des antibiotiques de la classe des fluoroquinolones ou des tetracyclines, l’utilisation des aminosides étant réservée aux formes graves. Les adénopathies évoluent cependant souvent vers la suppuration et la chronicité (20 à 40% des cas), malgré l’administration d’un traitement antibiotique adapté.Les travaux réalisés visent à étudier l’hypothèse de l’émergence de la résistance bactérienne chez Francisella, expliquant ces échecs thérapeutiques. Ils sont basés sur le développement et l’étude d’un modèle d’évolution in vitro de la bactérie en présence de ciprofloxacine, une fluoroquinolone. Nos travaux ont confirmé la capacité de la bactérie à évoluer vers un haut niveau de résistance à ces antibiotiques, corrélée à l’accumulation de mutations dans les gènes codant pour les topoïsomérases de type II. De plus, nous avons observé la présence sur l’ensemble des souches de F. tularensis subsp. holarctica d’un niveau de résistance cliniquement significatif induit par des mutations modifiant la sous-unité GyrA de l’ADN gyrase sur les acides aminés en position 83 et 87. La recherche de ce marqueur dans des prélèvements de patient en échec thérapeutique suite à divers traitements antibiotiques s’est avérée infructueuse.Après avoir vérifié l’action de l’antibiotique sur les bactéries dans le compartiment intracellulaire (fibroblates), nous avons recherché les autres mutations induites lors de l’évolution de Francisella en présence de fluoroquinolones. Cette étude a permis l’implication de plusieurs systèmes de transports transmembranaires dans la résistance antibiotique. Nous avons également révélé l’existence d’une seconde cible majeure impliquée dans le métabolisme du fer de la bactérie. L’altération de cette cible (FupA/B) en plus d’être associée à une augmentation de la résistance aux fluoroquinolones est corrélée à une forte diminution de la capacité de la bactérie à se multiplier dans les cellules phagocytairesFrancisella tularensis is a gram-negative facultative intracellular bacterium, causing tularemia. This zoonosis is mainly related to two subspecies: F. tularensis subsp. tularensis (type A) and F. tularensis subsp. holarctica (type B) in North America and throughout the Northern Hemisphere, respectively. Infections with this second subspecies, less virulent than the first one, predominantly induce glandular clinical forms of mild to moderate severity. Their treatment is based on antibiotherapy using a fluoroquinolone or a tetracycline. The use of aminoglycosides is reserved for severe clinical forms. The lymph nodes infection, however, often become chronic (20 to 40% of cases), despite administration of an appropriate antibiotic treatment.The aim of this study was to verify the hypothesis of the emergence of bacterial resistance in Francisella, which could explain treatment failures. It is based on the development and study of an in vitro evolutionary experiment of the bacterium in the presence of ciprofloxacin, a fluoroquinolone. Our work confirmed the bacterium's ability to evolve towards a high-level of resistance to fluoroquinolones, this evolution being correlated with the accumulation of mutations in the genes encoding for type II topoisomerases. In addition, we observed in all strains of F. tularensis subsp. holarctica resistant to fluoroquinolones at a clinically significant level, the presence of mutations altering the GyrA subunit of DNA gyrase at amino acids positions 83 and 87. The research of this marker in clinical samples from patients with treatment failure following appropriate antibiotic treatment was however unsuccessful.After checking the action of antibiotics on bacteria internalized in the intracellular compartment in fibroblast cells, we looked for other mutations induced during the evolution of Francisella to resistance to fluoroquinolones. This study unveiled the involvement of several transmembrane transport systems in antibiotic resistance. We also revealed the existence of a second major target involved in Francisella iron metabolism. The alteration of this target (FupA/B), in addition to being associated with an increase in fluoroquinolone resistance, is correlated with a sharp decrease in the ability of the bacteria to multiply in phagocytic cells
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Dodgen, Taylor L. "Escherichia coli and Antibiotic Resistance to Tetracycline Antibiotics." Lynchburg, Va. : Liberty University, 2008. http://digitalcommons.liberty.edu.
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Lee, Henry Hung-Yi. "A systems approach to the evolution of antibiotic resistance." Thesis, Boston University, 2012. https://hdl.handle.net/2144/31582.
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Thesis (Ph.D.)--Boston UniversityPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
Antibiotic-resistant bacterial strains continually arise and their increasing prevalence poses significant clinical and societal challenges. Functional analyses of resistant mutants and the study of general stress responses perturbed by antibiotic treatment have yielded valuable insights into how resistance arises through mutations. However, less is known about the population dynamics and communal interactions that underlie the development of resistance through mutations. In this work, we utilize systems approaches to study the functional dynamics of bacterial populations evolving antibiotic resistance. We follow a continuous culture of Escherichia coli facing increasing levels of antibiotic and show that the vast majority of isolates are less resistant than the population as a whole. We find that the few highly resistant mutants improve the survival of the populations less resistant constituents, in part, by producing indole, a signaling molecule generated by actively growing and unstressed cells. We show, through transcriptional profiling, that indole serves to turn on drug efflux pumps and oxidative stress protective mechanisms. The indole production comes at a fitness cost to the highly resistant isolates, and wholegenome sequencing reveals that this bacterial altruism is enabled by drug-resistance mutations unrelated to indole production. This work establishes a population-based resistance mechanism constituting a form of kin selection whereby a small number of resistant mutants can, at some cost to themselves, provide protection to other more vulnerable cells, enhancing the survival capacity of the overall population in stressful environments. Deeper studies into cooperative strategies bacteria use to evade antibiotics may prove critical for the rational design of more effective antimicrobial interventions.
2031-01-01
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Shadoud, Lubana. "Approches moléculaires de l'épidémiologie de la légionellose et de la résistance aux antibiotiques chez Legionella pneumophila." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENV008/document.
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Legionella pneumophila est une bactérie à Gram négatif, intracellulaire facultative, responsable de la légionellose (ou maladie des Légionnaires) chez l'Homme. Les fluoroquinolones et les macrolides sont utilisés en première intention dans le traitement antibiotique de cette maladie. Cependant, les échecs thérapeutiques sont fréquents, et le taux de mortalité demeure élevé (10-15% des cas, plus de 30% chez le patient immunodéprimé). Bien qu'aucune souche de L. pneumophila résistante à ces antibiotiques n'ait été isolée à ce jour, ces échecs peuvent faire évoquer la possibilité d'une sélection in vivo de mutants résistants. Le mécanisme génétique principal d'acquisition de la résistance aux fluoroquinolones correspond à l'accumulation de mutations au niveau des gènes codant pour l'ADN gyrase et la topoisomérase IV ; en particulier celles affectant les codons en positions 83 et 87 du QRDR (quinolone resistance determining region) du gène gyrA entrainent une résistance de haut niveau à ces antibiotiques. Le première aspect de notre projet était d'élaborer un test de PCR en temps réel permettant de détecter chez L. pneumophila des mutants gyrA résistants aux fluoroquinolones et de les différencier des souches sauvages par analyse des températures de fusion des amplifias obtenus. Après optimisation, ce test nommé qPCRgyrALp amplifie spécifiquement une portion du QRDR du gène gyrA de l'espèce L. pneumophila et permet de détecter et de différencier les mutations gyrA83 et gyrA87. Nous avons ensuite utilisé ce test pour la recherche de mutants gyrA directement dans divers prélèvements respiratoires provenant de 82 patients atteints de légionellose, certains en échec thérapeutique après traitement par une fluoroquinolone. Les résultats ont montré pour quatre patients un profil de courbe de fusion semblable à celui du mutant gyrA83. Le séquençage du QRDR de gyrA à partir de ces prélèvements respiratoires a confirmé cette mutation chez deux patients. L'utilisation de la technique de séquençage à haut débit a permis de quantifier ces mutants gyrA83 chez ces deux patients, permettant de montrer un remplacement progressif in vivo de la population de L. pneumophila sensible aux fluoroquinolones par une population résistante à ces antibiotiques. Le deuxième aspect de notre travail a été de développer des tests de PCR quantitative en temps réel (qPCR) permettant de quantifier la charge bactérienne à L. pneumophila dans les prélèvements cliniques des patients infectés, avant et au cours du traitement antibiotique, dans la but de prédire l'évolution clinique et le pronostic final de ces patients. Nous avons utilisé deux tests de qPCR, ciblant soit le gène codant pour l'ARNr16s (qPCR16S) soit le gène mip (qPCRmip) dans des prélèvements respiratoires de 116 patients atteints de légionellose. Chez certains patients, nous avons pu déterminer la cinétique de la charge bactérienne au cours du temps, alors que les patients recevaient une antibiothérapie adaptée. Les premières cinétiques recueillies montrent la possibilité de différencier les patients qui répondent rapidement au traitement antibiotique et évoluent favorablement au cours de la 1ère semaine d'hospitalisation, de ceux qui présentent une réponse modeste au traitement et nécessitent une hospitalisation prolongée, voire décèdent. La PCR en temps réel semble donc représenter un outil pronostique d'intérêt au cours de la légionellose. Le type de cinétique observé chez un patient donné semble pouvoir prédire l'évolution des patients et la nécessité d'ajuster le traitement antibiotiqueLegionella pneumophila is a Gram- negative, facultative intracellular bacterium responsible for legionellosis (or Legionnaires' disease ) in humans. The fluoroquinolones and the macrolides are used as first-line antibiotic treatment of this disease. However, treatment failures are common, and the mortality rates remain high (10-15 % of cases, more than 30% in immunocompromised patients). Although L. pneumophila strain resistant to these antibiotics have never been isolated, treatment failures may suggest the possibility of in vivo selection of resistant mutants. The main genetic mechanisms associated with acquired resistance to fluoroquinolones correspond to the accumulation of mutations in the genes encoding DNA gyrase and topoisomerase IV, especially those affecting codons 83 and 87 of the QRDR (quinolone resistance determining region) of the gyrA gene, which are associated with high level resistance to these antibiotics. The first aspect of our project was to develop a real-time PCR test to detect gyrA QRDR mutants and differentiate them from wild-type strains of L. pneumophila by analysis of melting temperatures of the amplified DNA. After optimization, the qPCRgyrALp test specifically amplified a portion of the gyrA QRDR of L. pneumophila and could detect and differentiate gyrA83 and gyrA87 mutations. Then, we checked the presence of gyrA mutants directly in respiratory samples collected in 82 legionellosis patients, including some after treatment failure with a fluoroquinolone. For four patients, results corresponded to a melting curve profile similar to that of the gyrA83 mutant. Amplification and sequencing of the gyrA QRDR directly from these respiratory samples confirmed this mutation in two patients. The use of high-throughput sequencing technology allowed us to quantify the gyrA83 mutants in these two patients, allowing demonstration of in vivo gradual replacement of the fluoroquinolones susceptible population of L. pneumophila by a resistant one. The second aspect of our work was to develop quantitative real-time PCR tests offering the possibility to quantify the L. pneumophila bacterial load in respiratory specimens before and during antibiotic treatment, in order to predict the clinical course and the final prognosis of these patients. We used two qPCR tests, either targeting the gene encoding 16S rRNA (qPCR16S ) or the mip gene (qPCRmip ) in respiratory samples from 116 patients with Legionnaires' disease. In some patients, we determined the kinetics of bacterial loads over time, while patients received appropriate antibiotic therapy. The kinetics we observed allowed differentiation of patients who respond quickly to antibiotic treatment and were released from hospital within the first week following admission, from those with a modest response to treatment and requiring prolonged hospitalization or finally died. Thus, our real-time PCR tests seem to be good prognostic tools for evaluation of legionellosis prognosis. The type of kinetics observed in a given patient may allow the clinician to predict the evolution of patients and the need to adjust the antibiotic treatment
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DeSilva, Malini. "Efficacy of Print Media Risk Communication About Antibiotic Resistance." Thesis, Boston College, 2003. http://hdl.handle.net/2345/427.
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Thesis advisor: Roche P. JohnThe growing threat of antibiotic resistance makes it extremely important that citizens be informed about the risks posed by antibiotic-resistant bacteria, and measures with which they can reduce these risks. The print media are major sources of such information for members of the public. In the present study, articles from major newspapers in the United States and Canada appearing between 1998 and 2002 were surveyed to determine the extent to which mention was made of antibiotic resistance and the risks associated with antibiotic resistance, the contextual precision with which this information was communicated, and the extent to which information was presented about causes, and risk-reduction measures, associated with antibiotic resistance. The majority of articles surveyed mentioned antibiotic resistance, but most failed to mention associated risks (i.e., the risk of illness and/or the risk of mortality). Articles that did report risks, did so only at a low level of contextual precision. A relatively low percentage of articles mentioned causes of antibiotic resistance, and even fewer mentioned risk reduction measures. These findings suggest that the print media could improve the efficacy with which they inform the public about issues associated with antibiotic resistance
Thesis (BS) — Boston College, 2003
Submitted to: Boston College. College of Arts and Sciences
Discipline: Biology
Discipline: College Honors Program
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Millar, Michael. "Antibiotics and antibiotic resistance : what do we owe to each other?" Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/4780/.
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There is a tension between the need to use antibiotics to prevent adverse outcomes from infection, and a consequence of their use, which is antibiotic (treatment) resistant infection. Actions taken to control the spread of antibiotic resistant microbes, and constraints on the use of antibiotics both give rise to ethical tensions. I consider the evaluative framework and the principles that might be used to decide a just distribution of burdens and benefits associated with the use of antibiotics. Nussbaum specifies a list of capabilities. A minimum sufficiency of each capability is required for a life of human dignity. Nussbaum’s approach provides a richer framework for the evaluation of the distribution of burdens and benefits associated with the use of antibiotics than prevailing health economic, or prevalence of disease measures. There are contexts in which we cannot assure a sufficiency of capabilities. I consider the potential for Scanlon’s contractualism to provide principles for deciding the distribution of burdens and benefits associated with the use of antibiotics under differing levels of resource constraint. Finally I consider the influence of metaphor and analogy in the context of the human relationship with microbes.
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Fisher, Morgane, (Dennison) Jaime Thomas, and Danielle Weimann. "Effects of an Educational Intervention on Parental Knowledge Regarding Antibiotic Resistance." The University of Arizona, 2008. http://hdl.handle.net/10150/624276.
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Class of 2008 AbstractObjectives: To evaluate changes in parental knowledge regarding antibiotic use and antibiotic resistance with an educational intervention given at elementary school parent-teacher association (PTA) meetings. Methods: This was an analytical pre-test/post-test study of an educational intervention given at two elementary schools in the Phoenix metro area. The primary dependent variable was a knowledge measure, calculated as a total score. The changes between the pre- and post-test total score means were compared using a dependent t-test. The a-priori alpha level used was 0.05. Results: The study sample consisted of 25 participants. Study data were collected between September 2007 and December 2007. The mean (SD) pre- and post-test scores were 33.7 (4.4) and 40.7 (2.7), respectively (p < 0.05). Conclusions: The educational intervention presented at elementary school PTA meetings resulted in a significant knowledge increase regarding the appropriate use of antibiotics when pre- and post-test scores were compared.
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Fermér, Elin. "Selection for Antibiotic Resistance Below Minimal inhibitory concentration in Biofilm." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-409806.
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Antibiotics are today one of the most important cornerstones in modern healthcare when it comes to treating bacterial infections. It is an asset human kind have been leaning on for the last century, but excessive and widespread misuse of antibiotics have left deep scars in the form of multi resistant pathogenic strains of bacteria that we soon will not be able to treat. A lot of research have been invested in understanding the mechanisms and spread of resistance within bacteria living in planktonic form, overlooking the fact that there are more lifestyles that causes problems. In this study, focus has been put on antibiotic resistance within bacteria living as biofilms, a lifestyle that causes problems in chronic infections and prosthetics/medical implants. By constructing resistant mutants derived from a biofilm forming strain of Escherichia coli, the minimal selection concentration has been investigated in both planktonic and biofilm assays for Streptomycin and Ciprofloxacin. By comparing the results, it is possible to evaluate if and how the antibiotic resistance properties differ between the two lifestyles. Focus has been put on concentrations of antibiotics below the minimal inhibitory concentration with the objective to see how selection of antibiotic resistant mutants take place with the susceptible strain still growing, although with reduced growth rate. The hope is that the results gained in this study will provide a foundation for future research regarding antibiotic resistance in biofilms, and be part of the solution to the excessive resistance problem before it is too late.
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Tangeman, Lorraine Susan. "Can Antibiotics From Recently Discovered Marine Actinobacteria Slow the Tide of Antibiotic Resistance?" Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1377522942.
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Wallace, Jeremy Iain. "Hyperinducible β-lactamase expression in gram-negative bacteria." Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295568.
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Hedin, Matthew Lowell. "The Effects of dairy cattle antibiotics on soil microbial community cycling and antibiotic resistance." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83227.
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Antibiotic use in agricultural ecosystems has the potential to increase resistance to antibiotics
in soil microbial communities since 40-95% of an antibiotic dose administered to livestock is
excreted intact or as metabolites. Exposure to antibiotics is also known to alter microbial
community composition, biomass, and physiology, but the potential influences of antibiotic
residues on the essential ecosystem processes that microbes regulate, e.g., carbon and
nitrogen cycling are not well understood. I investigated the effects of antibiotic residues
associated with dairy cattle operations on soil microbial communities and the ecosystem
processes they regulate. I examined the effects of antibiotic exposure on the biogeochemical
functioning of soil microbial communities by measuring the activity of extracellular enzymes
associated with organic matter processing and nutrient mineralization in soils collected from
dairy cattle operations across the United States. At each experimental station paired sites
were identified by local managers that represented sites with high and low stocking rates of
dairy cows who had been treated prophylactically with antibiotics to prevent mastitis.
Responses varied among individual enzymes, but I found an overall significant decrease in total
hydrolytic enzyme activity under high cattle stocking rates indicating a change in the
functioning of the microbial community in soils exposed to antibiotic laden manure. Principle
components analysis suggest that while some of the variation in enzyme activities are
associated with the abundance of antibiotic resistance genes, soil organic matter (total organic,
mineralizable, and particulate organic carbon) was the most significant variable accounting for
differences in enzyme activities. This reflects an inherent challenge in studies of antibiotic
exposure in agricultural landscapes: the difficulty of distinguishing direct effects of antibiotic
residues from the organic matter and nutrient subsidy associated with manure applications. To
address this concern I conducted a series of incubation experiments manipulating soils to
isolate the influences of antibiotics, manure resource subsidies, and bovine microbiome
inoculants into soils. Specifically, I examined soil respiration and antibiotic resistance gene
counts using qPCR following treatment with cephapirin, pirilimycin and a positive and negative
control. I found that pre-exposure to antibiotics and manure is important in modulating the
response of microbial communities (soil respiration, and gene copy numbers of AmpC and
TetO) to further antibiotic exposure. I conclude that antibiotics themselves have a direct effect
on soil communities and their functioning that is additive to the effect of manure (i.e., as a
resource subsidy). This effect is mediated by the history of previous exposure to antibiotics, i.e.,
cattle stocking density. These results suggest that antibiotic residues from dairy cattle
operation may have significant effects on microbial communities and the biogeochemical
cycling they regulate in agricultural ecosystems.Master of Science
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Santiago, Marina Joy. "New Genomics Tools and Strategies for Studying Antibiotics and Antibiotic-Resistance in Staphylococcus Aureus." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493460.
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Staphylococcus aureus is a gram positive coccoid pathogen that causes intractable infections in hospitals and communities around the world, and tens of thousands of people die of these infections every year. In order to combat these antibiotic-resistant infections, we need to better understand the genes involved in resistance to the cell stress caused by antibiotic treatment, which will enable the discovery of new antimicrobials and the development of novel therapeutic strategies. We chose to use an approach to this problem that utilizes a new phage-based high frequency of transposition system. In this work, we adapted this system so that transposon mutant libraries can be made and sequenced using next-generation sequencing (NGS) in any strain of S. aureus. We validated our new platform by performing a temperature screen and identifying mutants that are significantly resistant or sensitive to temperature-stress. Next, we created transposon libraries in two MRSA strains to show that this system can be broadly applied to other S. aureus strains, and we used one of these libraries to identify a new interaction between two genes involved in the secretion of sortase-anchored surface proteins. To better understand antibiotic-resistance, we performed Tn-Seq on transposon libraries treated with a small panel of six different antibiotics to identify intrinsic resistance factors to these antibiotics. We identified two new intrinsic resistance factors, SAOUHSC_01025 and SAOUHSC_01050, that sensitize to many cell envelope targeting antibiotics and may be involved in hemolysin regulation. Finally, we expanded this approach to sequence transposon libraries treated with 25 different antibiotics. Based on these data, we were able to develop methods for predicting the mechanism of action of new antibiotics. These methods involve identifying genes upregulated by transposon insertion and applying machine learning algorithms to identify similarities to a curated panel of well-studied antibiotics with known mechanisms of action. This work will enable many new functional genomics studies in S. aureus, and it will allow us to gain a better understanding of antibiotic resistance in this dangerous pathogen.Chemical Biology
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Ramstedt, Rebecka, and Susanna Ahnlund. "Health in the headlines : How two Indian newspapers treat antibiotic resistance." Thesis, Södertörns högskola, Institutionen för samhällsvetenskaper, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-19510.
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In India, there is no regulation of antibiotics and allegedly the use has doubled since 2006. Indiscriminate use of antibiotics gives rise to development of resistant bacteria. The media has, according to the theories used in this study, a responsibility to educate and empower the people to make personal judgments about health risks. This study focuses on the extent to which two of the largest English-language newspapers in India, the Hindu and Times of India, report on antibiotic resistance; and also, how the journalists and editors on these newspapers look upon their profession and responsibilities when it comes to reporting on health issues. In addition to the quantitative content analysis, which comprises 162 articles about antibiotic resistance published between 2006 and 2012, six in-depth interviews were conducted. The results show that the amount of coverage on antibiotic resistance increased 2010 when the Lancet published a report on new findings of multi-resistant bacteria in India. This indicates that an event was needed to qualify antibiotic resistance for the news pages. Our study also shows that preventive measures which can be taken to reduce the emerge of resistant bacteria are often included in the articles and that they are addressed to doctors as well as to the general public. On the other hand, information on the magnitude of the problem is rarely presented. Scientists are often quoted or referred to, and the journalists of the investigated newspapers state that they have a great confidence in them. Furthermore, the respondents express that they have a responsibility to report on health issues. They believe that their newspapers have a major influence on its readership, and that their reporting can make a difference in the health situation in India. Some of them mention, however, that their overall impact is limited since their newspapers only reach the literate middle-class.
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Bronson-Lowe, Daniel. "Impact of an Environmental Hygiene Intervention on Illness and Microbial Levels in Child Care Centers." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195257.
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Pathogens on surfaces in child care centers can contribute to illness among attendees and may thereby contribute to medical visits as well. This intervention study was conducted to assess the effect of using specific sanitizing products and cleaning protocols in child care centers on the incidences of lower respiratory infections, diarrheal illness, antibiotic use, and medical visits among children attending the centers and on the levels and antibiotic resistance of indicator bacteria in those centers. During the ten-week study period, children from twelve centers were observed. Six of the centers were randomly assigned to the intervention. The other six were controls. Intervention centers were given cleaning protocols and sanitizing products. Control centers were asked to retain their original procedures and products.Acute illness was determined from records kept by the center directors and telephone calls made to parents of ill children. A call was also made to one randomly selected healthy child's parents for every two ill children recorded. Parents were given a questionnaire requesting information including bedroom sharing status, environmental tobacco smoke exposure, and chronic illnesses.After controlling for within-center clustering and zero-inflation, statistically non-significant trends of reduction were seen in the weeks of lower respiratory infections, diarrheal illness, and medical visits. Multivariable zero-inflated Poisson regression revealed that the number of weeks intervention center children were using antibiotics was 32% lower than among the control center children. This was a statistically significant reduction (95% CI = 0.54-0.86; p = 0.001).Bacterial samples were collected from ten sites within each center at the beginning and the end of the study period to determine the effect of the intervention on the microbial population. The study determined the heterotrophic plate count bacteria numbers and the rates of resistance to ampicillin and cephalothin. Neither heterotrophic bacterial concentrations nor antibiotic resistance rates significantly changed over the course of the study.
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Norgren, Benjamin. "What role does aquaculture play in the global rise of antibiotic-resistant bacteria?" Thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-182602.
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In a world where the human population is increasing, new innovations to produce enough food are required. Aquaculture’s part of the global animal protein production has increased in recent years and could be a possible solution. However, if aquaculture is poorly managed, it can result in negative consequences and one such consequence is the development of antibiotic resistance. In this review, I examine how aquaculture affect antibiotic resistance by studying what the literature says on accumulation of antibiotics in different organisms and sediment, if antibiotics can be transferred to humans through consumption of antibiotic treated products, and if human pathogens in aquaculture farms may acquire antibiotic resistance. Furthermore, I examine what factors are contributing to irresponsible antibiotic use and how such use is managed. The result of this review indicate that antibiotics are able to accumulate in organisms and sediment. It is not clear however how consumption of these affect human microbiomes. In contrast, it is clear that antibiotic resistance can be transferred from antibiotic-resistant bacteria to human pathogens. Regarding antibiotic use, irresponsible use foremost exists in low-income countries and the main drivers behind such use are socioeconomic ones, such as lack of knowledge, poverty and food security. Finally, I propose possible solutions that might improve future management.I en värld där den mänskliga befolkningen ökar krävs nya innovationer för att producera tillräckligt med mat. Vattenbrukets andel av den globala animaliska proteinproduktionen har ökat de senaste åren och kan ses som en potentiell lösning. Om vattenbruk dock hanteras ansvarslöst kan det uppstå negativa konsekvenser. En sådan konsekvens är utveckling av antibiotikaresistens hos skadliga bakterier. I denna litteraturstudie undersöker jag vattenbrukets påverkan på antibiotikaresistens genom att studera vad litteraturen säger om ackumulation av antibiotika i olika organismer och sediment, om antibiotika kan överföras till människor genom konsumtion av antibiotikabehandlade produkter, och om mänskliga patogener i vattenbruksodlingar kan förvärva antibiotikaresistens. Jag undersöker också vilka faktorer som bidrar till ansvarslös antibiotikaanvändning och hur den hanteras ur ett hållbarhetsperspektiv. Resultaten i denna studie tyder på att antibiotika kan ackumuleras i organismer och sediment men att det råder oklarheter huruvida konsumtion av antibiotikabehandlad mat påverkar mänskliga bakteriekulturer. Antibiotikaresistens kan dock överföras från antibiotikaresistenta bakterier till mänskliga patogener. Ansvarslös antibiotikaanvändning sker huvudsakligen i fattigare länder och det är förmodligen i stor utsträckning till följd av socioekonomiska faktorer som okunskap, fattigdom och livsmedelstrygghet. Slutligen föreslår jag lösningar som möjligen kan bidra till bättre hantering av framtida antibiotikaanvändning.
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Bergfeldt, Vendela. "Microbes that never sleep : A multidisciplinary study of the antibiotic resistance management in Sweden." Thesis, Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-30623.
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The hypotheses of this study are that reduction and rational usage of antibiotics reduces development of antibiotic resistance. In Sweden, the trends do not follow this pattern. Despite a decrease in prescriptions of antibiotics, there is an increase in the number of patients infected with Methicillin-resistant Staphylococcus Aureus (MRSA), Extended Spectrum Beta-Lactamases (ESBL) and ESBL selecting for carbapenem-resistance (ESBLCARBA). This study aims to study factors affecting antibiotic resistance management. An additional aim is to use a multidisciplinary approach for a subject that has mostly been studied with quantitative methods. First, linear regressions investigated any possible significant changes of prescription rates in outpatient care, hospital usage of antibiotic groups and antibiotic resistance. After this, nine interviews were conducted with physicians in outpatient care, hospital care and with representatives from the Swedish Strategic Programme for the Rational Use of Antimicrobial Agents and Surveillance of Resistance (Strama), a network working for Swedish prevention against antibiotics resistance. There was a significant decrease in the number of prescriptions of antibiotics in outpatient care among all Swedish counties and a small, but significant increase of antibiotics used in hospitals. The number of patients infected with multidrug resistant bacteria also show a significant increase. The interviews revealed that health care workers in all counties follow the same guidelines and try to be as specific as possible in choosing antibiotics to hit specific bacteria. The respondents suggested migration and extended travelling as explanations to the growing number of cases of multidrug resistant bacteria. Further, two major factors emerged as important for an efficient antibiotic resistance management; Education/knowledge and Discussion. The results indicate a need for further research on rational usage of antibiotics and the use of broad-spectrum antibiotics in hospital care, rather than the reduction through prescriptions. The results indicate that rational usage has a bigger impact than reduction. Using a multidisciplinary approach gave a broader perspective on the issue and future studies should see the possibilities of mixing quantitative and qualitative studies.
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Anjuli, Borgonha. "Communicating Antibiotic Resistance to the Public: How effective was Public Health England’s 2018 ‘Keep Antibiotics Working’ campaign TV advertisement at increasing public understanding of antibiotic resistance and motivating a change in antibiotic seeking behaviours?" Thesis, Malmö universitet, Fakulteten för kultur och samhälle (KS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-21079.
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Antibiotic resistance is one of the greatest global threats we face today. Human overuse ofantibiotics is a contributing factor and major behaviour change around antibioticconsumption is needed, but several challenges exist in communicating antibiotic resistanceto the public. In 2018 the UK Government relaunched a national television advertisement aspart of the ‘Keep Antibiotics Working’ campaign which aimed to raise awareness of antibioticresistance and reduce public demand for antibiotics. This study evaluates what role theframing of antibiotic resistance in the advertisement played in increasing publicunderstanding of antibiotic resistance and motivating behaviour change. The study isgrounded in behaviour change and health communication theory from the field ofCommunication for Development, and health and social psychology theory, reflecting theneed for multidisciplinary approaches to addressing antibiotic resistance. A textual analysisidentified how the issue was framed in the advertisement and surveys and interviews wereconducted with members of the target audience groups to analyse what effect theadvertisement had on their understanding of, and attitude towards antibiotic resistance.The findings show that the framing of antibiotic resistance in the TV advertisement led to anincrease in misunderstandings of what becomes resistant to antibiotics. The advertisementwas helpful in highlighting the vulnerability of antibiotics and for creating a new social normaround being a responsible antibiotic user, however was interpreted as childish byparticipants. It did not communicate the severity of antibiotic resistance or specific risk ofantibiotic overuse to the audience, or accurately reflect the audience’s existing knowledge ofantibiotic resistance and current behaviours. As the severity of antibiotic resistance was notconveyed, the advertisement did not motivate a change in antibiotic seeking behaviours orattitude amongst the majority of participants. The findings did highlight knowledge gapsamongst study participants including the importance of completing a course of antibiotics asprescribed, and that it is the bacteria itself, not the person, that develops resistance, andhopes this research can inform the development of future campaigns.
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POLKA, JUSTYNA URSZULA. "Caratterizzazione di lactobacilli di origine intestinale." Doctoral thesis, Università Cattolica del Sacro Cuore, 2012. http://hdl.handle.net/10280/1316.
Full textAbstract:
I lactobacilli sono considerati dei microorganismi non-patogeni. Molti di loro appartengono al gruppo batterico GRAS e/o sono nell’elenco QPS. Dal momento che i lactobacilli intenzionalmente aggiunti agli alimenti possono agire come reservoir di geni di resistenza, la valutazione del rischio deve essere continuamente aggiornata. Lo scopo di questa tesi era la valutazione di alcuni metodi usati per testare e caratterizzare le specie del genere Lactobacillus per quanto riguarda la sicurezza e la potenziale attività probiotica.
Nella prima parte due metodi di micro diluzione, il metodo ISO e CLSI, soni stati comparati testando la resistenza agli antibiotici di 54 ceppi L. plantarum. Sulla base di risultati ottenuti il metodo ISO era più adatto per valutare la resistenza di questa specie.
Il test del limite di sensibilità della PCR per 8 paia di primers specifici per il rilevamento dei lactobacilli e bifido batteri da feci ha confermato i loro diversi livelli di efficacia.
La seconda parte della tesi descrive un progetto di ricerca mirato sulla identificazione di nuovi ceppi probiotici fra diversi ceppi di Lactobacillus paracasei e Lactobacillus rhamnosus identificando dei geni o loci responsabili della interazione con l’ospite, immunomodulazione, e l’inibizione della crescita dei patogeni. Le analisi fenotipiche dei 40 ceppi hanno confemato una grande variabilità fra di loro, che può servire per associare delle caratteristiche fenotipiche a quelle genotipiche. Tra i ceppi dello stesso progetto è stato individuato un ceppo di L. mucosae. Dal momento che questa è una specie relativamente nuova, le sue caratteristiche sono state analizzate comparandole con altri 3 ceppi appartenenti alla stessa specie. In questo modo sono state confermate alcune informazioni su L. mucosae, ma soprattutto sono stati forniti dei dati nuovi sulle proprietà di questa specie.The species of the Lactobacillus genus are generally believed to be microorganisms with no pathogenic potential. Many of them have granted GRAS and QPS status. Non-pathogenic bacteria as lactobacilli-intentionally added or accidentally present in food-are under evaluation, as they could act as reservoir of resistant genes. This thesis was aimed to evaluate some methods used for testing and to characterize some Lactobacillus species, as regards their safety and potential probiotic activity. The first part of the research focused on the comparison of two broth microdilution methods: ISO and CLSI, in order to assess the resistance of 54 L. plantarum strains to antimicrobial agents. The results suggest better performances of the phenotypic assay developed by ISO, at least for strains belonging to L. plantarum species.Then the assessment of the PCR detection limit for 8 sets of primers for the detection of lactobacilli and bifidobacteria from infant faeces confirmed different levels of effectiveness for the primers. Next part of the thesis was the research project aimed at identifying genes or genetic loci of different strains of two Lactobacillus species (i.e. Lactobacillus paracasei and Lactobacillus rhamnosus) involved in the interaction with the host, immune-modulation of host cells and pathogen growth inhibition in order to find new probiotic strains. The phenotypic analysis of 40 selected strains demonstrated large variability between strains of these species, which could serve to the association of phenotypic differences to genome specificities. A strain of Lactobacillus mucosae was found within the framework of the same project. As it is a relatively new species, it was chosen to further investigate its properties, comparing it with three other L. mucosae strains. This study led to confirm some information but first and foremost it has provided new data on the examined species.
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POLKA, JUSTYNA URSZULA. "Caratterizzazione di lactobacilli di origine intestinale." Doctoral thesis, Università Cattolica del Sacro Cuore, 2012. http://hdl.handle.net/10280/1316.
Full textAbstract:
I lactobacilli sono considerati dei microorganismi non-patogeni. Molti di loro appartengono al gruppo batterico GRAS e/o sono nell’elenco QPS. Dal momento che i lactobacilli intenzionalmente aggiunti agli alimenti possono agire come reservoir di geni di resistenza, la valutazione del rischio deve essere continuamente aggiornata. Lo scopo di questa tesi era la valutazione di alcuni metodi usati per testare e caratterizzare le specie del genere Lactobacillus per quanto riguarda la sicurezza e la potenziale attività probiotica.
Nella prima parte due metodi di micro diluzione, il metodo ISO e CLSI, soni stati comparati testando la resistenza agli antibiotici di 54 ceppi L. plantarum. Sulla base di risultati ottenuti il metodo ISO era più adatto per valutare la resistenza di questa specie.
Il test del limite di sensibilità della PCR per 8 paia di primers specifici per il rilevamento dei lactobacilli e bifido batteri da feci ha confermato i loro diversi livelli di efficacia.
La seconda parte della tesi descrive un progetto di ricerca mirato sulla identificazione di nuovi ceppi probiotici fra diversi ceppi di Lactobacillus paracasei e Lactobacillus rhamnosus identificando dei geni o loci responsabili della interazione con l’ospite, immunomodulazione, e l’inibizione della crescita dei patogeni. Le analisi fenotipiche dei 40 ceppi hanno confemato una grande variabilità fra di loro, che può servire per associare delle caratteristiche fenotipiche a quelle genotipiche. Tra i ceppi dello stesso progetto è stato individuato un ceppo di L. mucosae. Dal momento che questa è una specie relativamente nuova, le sue caratteristiche sono state analizzate comparandole con altri 3 ceppi appartenenti alla stessa specie. In questo modo sono state confermate alcune informazioni su L. mucosae, ma soprattutto sono stati forniti dei dati nuovi sulle proprietà di questa specie.The species of the Lactobacillus genus are generally believed to be microorganisms with no pathogenic potential. Many of them have granted GRAS and QPS status. Non-pathogenic bacteria as lactobacilli-intentionally added or accidentally present in food-are under evaluation, as they could act as reservoir of resistant genes. This thesis was aimed to evaluate some methods used for testing and to characterize some Lactobacillus species, as regards their safety and potential probiotic activity. The first part of the research focused on the comparison of two broth microdilution methods: ISO and CLSI, in order to assess the resistance of 54 L. plantarum strains to antimicrobial agents. The results suggest better performances of the phenotypic assay developed by ISO, at least for strains belonging to L. plantarum species.Then the assessment of the PCR detection limit for 8 sets of primers for the detection of lactobacilli and bifidobacteria from infant faeces confirmed different levels of effectiveness for the primers. Next part of the thesis was the research project aimed at identifying genes or genetic loci of different strains of two Lactobacillus species (i.e. Lactobacillus paracasei and Lactobacillus rhamnosus) involved in the interaction with the host, immune-modulation of host cells and pathogen growth inhibition in order to find new probiotic strains. The phenotypic analysis of 40 selected strains demonstrated large variability between strains of these species, which could serve to the association of phenotypic differences to genome specificities. A strain of Lactobacillus mucosae was found within the framework of the same project. As it is a relatively new species, it was chosen to further investigate its properties, comparing it with three other L. mucosae strains. This study led to confirm some information but first and foremost it has provided new data on the examined species.
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Steuart, Rebecca. "Antibiotic Prescribing and Subsequent Antibiotic Resistance of Respiratory Cultures in Children with Tracheostomies." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1623170006733706.
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Pietsch, Franziska. "Evolution of Antibiotic Resistance." Doctoral thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-265018.
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The emergence of antimicrobial resistance is a major global threat to modern medicine. The rapid dissemination of resistant pathogens and the associated loss of efficacy of many important drugs needs to be met with the development of new antibiotics and alternative treatment options. A better understanding of the evolution of resistance could help in developing strategies to slow down the spread of antimicrobial drug resistance. In this thesis we investigated the evolution of resistance to two important antibiotics, rifampicin and ciprofloxacin, paying special attention to the resistance patterns occurring with high frequency in clinical isolates. Rifampicin is a first-line drug in tuberculosis treatment and resistance to this valuable drug limits treatment options. Our work on rifampicin resistance helps to explain the extreme bias seen in the frequency of specific resistance mutations in resistant clinical isolates of M. tuberculosis. We identified an important interplay between the level of resistance, relative fitness and selection of fitness-compensatory mutations among the most common resistant isolates. Fluoroquinlones are widely used to treat infections with Gram-negatives and the frequency of resistance to these important drugs is increasing. Resistance to fluoroquinolones is the result of a multi-step evolutionary process. Our studies on the development of resistance to the fluoroquinolone drug ciprofloxacin provide insights into the evolutionary trajectories and reveal the order in which susceptible wild-type E. coli acquire multiple mutations leading to high level of resistance. We found that the evolution of ciprofloxacin resistance is strongly influenced by the mutation supply rate and by the relative fitness of competing strains at each successive step in the evolution. Our data show that different classes of resistance mutations arise in a particular, predictable order during drug selection. We also uncovered strong evidence for the existence of a novel class of mutations affecting transcription and translation, which contribute to the evolution of resistance to ciprofloxacin.
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Laxminarayan, Ramanan. "Economics of antibiotic resistance /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/7412.
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Larsson, Mattias. "Antibiotic use and resistance : assessing and improving utilisation and provision of antibiotics and other drugs in Vietnam /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-630-8/.
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Börjesson, Stefan. "Antibiotic Resistance in Wastewater : Methicillin-resistant Staphylococcus aureus (MRSA)and antibiotic resistance genes." Doctoral thesis, Linköpings universitet, Medicinsk mikrobiologi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17709.
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A large part of the antibiotics consumed ends up in wastewater, and in the wastewater the antibiotics may exert selective pressure for or maintain resistance among microorganisms. Antibiotic resistant bacteria and genes encoding antibiotic resistance are commonly detected in wastewater, often at higher rates and concentrations compared to surface water. Wastewater can also provide favourable conditions for the growth of a diverse bacterial community, which constitutes a basis for the selection and spread of antibiotic resistance. Therefore, wastewater treatment plants have been suggested to play a role in the dissemination and development of antibiotic resistant bacteria. Methicillin-resistant Staphylococcus aureus (MRSA) is a large problem worldwide as a nosocomial pathogen, but knowledge is limited about occurrence in non-clinical environments, such as wastewater, and what role wastewater plays in dissemination and development of MRSA. In this thesis we investigated the occurrence of MRSA in a full-scale wastewater treatment plant (WWTP). We also investigated the concentration of genes encoding resistance to aminoglycosides (aac(6’)-Ie+aph(2’’)), β-lactam antibiotics (mecA) and tetracyclines (tetA and tetB) in three wastewater-associated environments: (1) soil from an overland flow area treating landfill leachates, (2) biofilm from a municipal wastewater treatment plant, and (3) sludge from a hospital wastewater pipeline. In addition, concentrations of mecA, tetA and tetB were investigated over the treatment process in the WWTP. These investigations were performed to determine how the prevalence and concentration of MRSA and the antibiotic resistence genes are affected in wastewater and wastewater treatment processes over time. The occurrence of MRSA was investigated by cultivation and a commercially available real-time PCR assay. In order to determine concentrations of the genes aac(6’)-Ie+aph(2’’), mecA, tetA and tetB in wastewater we developed a LUXTM real-time PCR assay for each gene. Using cultivation and real-time PCR we could for the first time describe the occurrence of MRSA in wastewater and show that it had a stable occurrence over time in a WWTP. MRSA could mainly be detected in the early treatment steps in the WWTP, and the wastewater treatment process reduced the number and diversity of cultivated MRSA. However, our results also indicate that the treatment process selects for strains with more extensive resistance and possibly higher virulence. The isolated wastewater MRSA strains were shown to have a close genetic relationship to clinical isolates, and no specific wastewater lineages could be detected, indicating that they are a reflection of carriage in the community. Taken together, these data indicate that wastewater may be a potential reservoir for MRSA and that MRSA are more prevalent in wastewater than was previously thought. The real-time PCR assays, for aac(6’)-Ie+aph(2’’), mecA, tetA, and tetB that we developed, were shown to be sensitive, fast, and reproducible methods for detection and quantification of these genes in wastewater environments. The highest concentrations of all genes were observed in the hospital pipeline, and the lowest in the overland flow system, with tetA and aac(6´)-Ie+aph(2´´) detected in all three environments. In the full-scale WWTP, we continuously detected mecA, tetA and tetB over the treatment process and over time. In addition, it was shown that the treatment process reduces concentrations of all three genes. The data presented in this thesis also indicate that the reduction for all three genes may be connected to the removal of biomass, and in the reduction of tetA and tetB, sedimentation and precipitation appear to play an important role.
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Leszcynski, Robert A. "Determination of the Relationship Between Bacterial Coculturing, Antibiotic Resistance and Bacterial Growth." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1591787505690696.
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Gravander, Nikkinen Anna, and Ellen Haglund. "Sjuksköterskans potentiella roll i antimicrobial stewardship : En litteraturöversikt." Thesis, Högskolan Väst, Avdelningen för omvårdnad - grundnivå, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-16790.
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Background The antimicrobial stewardship is developed to provide a guide on the responsible use of antimicrobial drugs. Thus, slowing down the development of antimicrobial resistance. However, the nurse's role in antimicrobial stewardship is not clarified. Failure toinclude the nurse within the antimicrobial stewardship guidelines may result in poor execution of antimicrobial stewardship.Aim To explore the role of nurses in antimicrobial stewardship and how it can be practically implemented within the medical field.Method This is a literature review where seven qualitative studies, two quantitative studies and a mix-methods study examines the nurse's role in antimicrobial stewardship.Results Two main themes and five sub-themes were created. The two main themes were clinical role and collaboration. The clinical role described the nurse's role as a patient advocate and the nurse's contribution to antimicrobial stewardship through monitoring and evaluation of the patient and treatment, as well as through safe sampling, drug administration and hygiene. The collaboration showed and identified the nurse's role as a communicator and educator. Conclusion Conclusions that can be drawn from the literature review are that the potential roles the nurse may have in antimicrobial stewardship are many and those we have identified are already included in the nurse's daily work.
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Glassford, Ian Michael. "Addressing Antibiotic Resistance: The Discovery of Novel Ketolide Antibiotics Through Structure Based Design and In Situ Click Chemistry." Diss., Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/410231.
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ChemistryPh.D.
Antibiotic resistance has become and will continue to be a major medical issue of the 21st century. If not addressed, the potential for a post-antibiotic era could become a reality, one that the world has not been familiar with since the early 1900’s. Multidrug-resistant hospital-acquired bacterial infections already account for close to 2 million cases and 23,000 deaths in the United States, along with 20 billion dollars of additional medical spending each year. The CDC released a report in 2013 regarding the seriousness of antibiotic resistance and providing a snapshot of costs and mortality rates of the most serious antibiotic resistant bacteria, which includes 17 drug resistant bacteria, such as carbapenem-resistant Enterobacteriaceae, vancomycin-resistant Enterococcus and Staphylococcus aureus, and multidrug-resistant Acinetobacter and Pseudomonas aeruginosa. The development of antibiotic resistance is part of bacteria’s normal evolutionary process and thus impossible to completely stop. To ensure a future where resistant bacteria do not run rampant throughout society, there is a great need for new antibiotics and accordingly, methods to facilitate their discovery Macrolides are a class of antibiotics that target the bacterial ribosome. Since their discovery in the 1950’s medicinal chemistry has created semi-synthetic analogues of natural product macrolides to address poor pharmacokinetics and resistance. Modern X-Ray crystallography has allowed the chemist access to high resolution images of the bacterial ribosome bound to antibiotics including macrolides which has ushered in an era of structure-based design of novel antibiotics. These crystal structures suggest that the C-4 methyl group of third generation ketolide antibiotic telithromycin can sterically clash with a mutated rRNA residue causing loss of binding and providing a structural basis for resistance. The Andrade lab hypothesized that the replacement of this methyl group with hydrogen would alleviate the steric clash and allow the antibiotic to retain activity. To this end, the Andrade lab set out on a synthetic program to synthesize four desmethyl analogues of telithromycin by total synthesis that would directly test the steric clash hypothesis and also provide structure-activity relationships about these methyl groups which have not been assessed in the past. Following will contain highlights of the total synthesis of (-)-4,8,10-didesmethyl telithromycin, (-)-4,10-didesmethyl telithromycin, and (-)-4,8-desmethyl telithromycin and my journey toward the total synthesis of (-)-4-desmethyl telithromycin Traditional combinatorial chemistry uses chemical synthesis to make all possible molecules from various fragments. These molecules then need to be purified, characterized, and tested against the biological target of interest. While high-throughput assay technologies (i.e., automation) has streamlined this process to some extent, the process remains expensive when considering the costs of labor, reagents, and solvent to synthesize, purify, and characterize all library members. Unlike traditional combinatorial chemistry, in situ click chemistry directly employs the macromolecular target to template and synthesize its own inhibitor. In situ click chemistry makes use of the Huisgen cycloaddition of alkyne and azides to form 1,2,3-triazoles, which normally reacts slowly at room temperature in the absence of a catalyst. If azide and alkyne pairs can come together in a target binding pocket the activation energy of the reaction can be lowered and products detected by LC-MS. Compounds found in this way generally show tighter binding than the individual fragments. Described in the second part of this dissertation is the development of the first in situ click methodology targeting the bacterial ribosome. Using the triazole containing third generation ketolide solithromycin as a template we were able to successfully show that in situ click chemistry was able to predict the tightest binding compounds.
Temple University--Theses
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Bruinsma, Nienke. "Antibiotic resistance in the community." [Maastricht : Maastricht : Universiteit Maastricht] ; University Library, Maastricht University [Host], 2002. http://arno.unimaas.nl/show.cgi?fid=7242.
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Karlsson, Märit. "Antibiotic resistance in Brachyspira hyodysenteriae /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-5947-8.pdf.
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Groot, Ronald de. "Antibiotic resistance in Haemophilus influenzae." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 1991. http://hdl.handle.net/1765/10478.
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Powell, James Patrick. "Antibiotic Diversity and Bacterial Resistance." Available to users online at:, 2007. http://hdl.handle.net/10156/1303.
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Wong, Kin-man Gilman, and 黃健文. "Antibiotic resistance in laribacter hongkongensis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B42182347.
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Chatsuwan, Tanittha. "Antibiotic resistance in Helicobacter pylori." Thesis, University of Edinburgh, 2003. http://hdl.handle.net/1842/24320.
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Helicobacter pylori is a gram negative, microaerophilic bacteria that plays an important role in chronic gastritis and peptic ulcer disease. Multiple antimicrobial therapies including combinations of clarithromycin, metronidazole or amoxycillin and proton pump inhibitor have been used to eradicate H. pylori. Antimicrobial resistance in H. pylori has been associated with treatment failure. In this study, antimicrobial susceptibility patterns of amoxycillin, ciprofloxacin, clarithromycin, erythromycin, tetracycline and metronidazole were evaluated in 110 H. pylori strains isolated from 454 antral biopsies of patients undergoing endoscopy at the Royal Infirmary, Edinburgh. The MICs were determined by E-test. Resistance to clarithromycin and erythromycin was found in 8.2% (9/110) and 9.1% (10/110) respectively. Metronidazole resistance was demonstrated in 8 isolates (7.3%). Tetracycline resistance was found in one of the isolates (0.9%). Two isolates were resistant to ciprofloxacin (1.8%). Resistance to amoxycillin was not detected. Molecular mechanisms of fluoroquinolone, macrolide and metronidazole resistance in H. pylori were investigated. Resistant to fluoroquinolone has been associated with alterations in the Quinolone Resistance-Determining Region (QRDR) of gyrA gene. Mutation at position 91, leading to an amino acid change from Aspartic acid to Asparagine was found in 2 ciprofloxacin-resistant isolates. One isolate had a mutation at Asparagine-87 to Lysine. Mutations in the 23S rRNA conferring macrolide resistance were investigated. Mutations at position 2143 (A to G) were shown in seven of the ten macrolide-resistant isolates. Two of the seven isolates carried an additional T to C mutation at either position 2182 or 1934. Of the ten macrolide-resistant isolates, two had a single mutation at either position 2182 or 2195. Mutation at position 2182, however, has previously been identified not to be associated with macrolide resistance. The mutations at position at 1934 (T to C) and position 2195 (C to T) have not previously been reported. One of the ten isolates (MIC > 256 mg/L) had no alteration in the 23S rRNA. The results indicate that different mechanisms play a role in macrolide resistance in these H. pylori strains. Metronidazole resistance has been reported to be associated with mutations in the rdxA gene, encoding oxygen-insensitive nitroreductase. To investigate the role of rdxA, sequencing analysis of rdxA of metronidazole-resistant isolates was determined. The results showed that no particular amino acid substitution was associated with metronidazole resistance. One isolate contained a nonsense mutation, generating a stop codon. However, two metronidazole-sensitive strains had alterations in rdxA by insertions of a mini-IS605 sequence. These results suggest that alterations in rdxA are not the sole mechanism of metronidazole resistance and other mechanisms are required in the development of resistance. Since the prevalence rate of metronidazole resistance is variable, ranging from 11 to 70%, it is possible that some variation in reported resistance levels derives from difficulties in the method of sensitivity testing. To set a standard for susceptibility testing for metronidazole in H. pylori, the optimum conditions for sensitivity testing were evaluated. Activation of metronidazole requires an anaerobic environment. It was found that incubation under microaerophilic conditions elevated metronidazole MIC, suggesting that microaerophilic conditions cannot activate metronidazole to its active form. Pre-incubation of H. pylori in anaerobic conditions for 24 hours prior to incubation under microaerophilic conditions for 72 hours was found to be necessary to achieve accurate susceptibility results. This can explain why some centres report high levels of metronidazole resistance. To investigate the development of fluoroquinolone resistance in H. pylori, ciprofloxacin-resistant mutants were selected in vitro by exposing sensitive strains to serial increments of ciprofloxacin in Columbia blood agar plate. The QRDR of gyrA gene was analysed for mutations. Reduced susceptibility to ciprofloxacin was associated with either a single or double amino acid changes in gyrA gene. Mutations at position 85, 87 and 91 were found to be associated with ciprofloxacin resistance. The results also demonstrated that gyrA mutations are not sole contributors for the mechanism of ciprofloxacin resistance in H. pylori. As no parC gene has not yet been identified in H. pylori, any contribution from topoisomerase IV cannot be quantified. To investigate the DNA gyrase activity in H. pylori, gyrA and gyrB were separately cloned and overexpressed by using a T7 promoter vector, which contain a fusion tag of six histidine residues. GyrA and GyrB were purified by affinity chromatography using nickel-chelating resins. The ability of DNA gyrase to supercoil relaxed DNA was determined.
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Amos, Gregory C. A. "Environmental reservoirs of antibiotic resistance." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/58024/.
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Emerging antibiotic resistance mechanisms threatens the foundation of modern medicine. Growing evidence suggests anthropogenic inputs such as agriculture could form reservoirs of resistant bacteria which could directly or indirectly transfer to humans. Waste Water treatment plants (WWTPs) are an input which contains waste from several sources including that of human, animal and industry, providing a hot-spot for horizontal gene transfer to occur between bacteria from many origins. In this project we evaluated the role of WWTPs in creating environmental reservoirs of antibiotic resistance. An initial study investigated the impacts of WWTP effluent on the antibiotic resistant bacterial load in downstream rivers, particularly focusing on the class 1 integron as a marker for resistance. WWTP effluent was responsible for significantly higher levels of resistant bacteria in downstream river sediments compared to upstream, a result of the introduction and/ or selection for a diverse range of class 1 integrons. A second study investigated the effects of effluent on the clinically important antibiotic resistance gene blaCTX-M-15. Numerous examples of blaCTX-M-15 carried on new genetic contexts in association with new pathogenicity determinants were recovered, as was evidence for transfer of blaCTX-M-15 between diverse bacteria. The prevalence of blaCTX-M-15 as well as the diversity of its carriage were both increased greatly by WWTP effluent. The final study was on the Thames River basin in the UK, where we developed a model with the ability to predict antibiotic resistance load and exposure. This work suggests that WWTP effluent contributes to environmental reservoirs of resistant bacteria which could be of clinical importance. There is a danger that continued expansion of environmental reservoirs of antibiotic resistance will lead to increased therapeutic failure in the clinic and ultimately the end of the antibiotic era.
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Huang, Ying. "Antibiotic Resistance in Aquaculture Production." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417709599.
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Stone, Laura. "Drugs That Thwart Antibiotic Resistance." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467532.
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Antibiotics are often credited with being one of the major forces behind the expansion of human life expectancy in the past 60 years. Yet at the root of this advancement lies its potential undoing: using antibiotics promotes the emergence and spread of resistant strains, reducing the efficacy of the drugs. Now, rising antibiotic resistance threatens to undo much of the progress of modern medicine. To halt the rise of resistance and preserve the activity of antibiotics, we must find ways to neutralize, modulate, or even invert the evolutionary advantage of resistant strains. Chapter 1 reviews three strategies to overcome antibiotic resistance through the sequential or concurrent use of multiple drugs: resistance mechanism inhibitors, synergistic, antagonistic, and suppressive drug interactions, and collateral sensitivity.
Collateral sensitivity occurs when a bacterium acquires a mutation or gene that provides resistance to one drug, but makes them more susceptible to others. This new vulnerability can therefore be exploited to select against resistance mechanisms. Chapter 2 describes a screening strategy, based on direct competition between antibiotic resistant and susceptible strains, for identifying compounds that select against antibiotic resistance genes and cassettes. Using this approach we identified two compounds—β-thujaplicin and disulfiram—that select against the TetA tetracycline resistance pump in E. coli. Furthermore, we demonstrate a two-phase treatment paradigm in which β-thujaplicin drives a tetracycline resistant population back to susceptibility, allowing successful second-phase treatment with tetracycline.
Chapter 3 examines the consequences of linking two antibiotics—ciprofloxacin and neomycin—into one hybrid compound. We compared the cross-resistance and genotypic profiles of strains evolved in the hybrid to those evolved in mixtures of its two components. We find that the hybrid inhibits bacterial growth through its ciprofloxacin moiety, but prevents resistance through its neomycin moiety by avoiding a common multiple antibiotic resistance pathway. As a result, strains evolved in the hybrid gain less resistance than those evolved in an unlinked mixture. This indicates that linking two drugs can surpass traditional unlinked combination therapy in its ability to prevent resistance.
Finally, Chapter 4 discusses the implications of this work and possible directions for future research in treating antibiotic resistance.Chemical Biology
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Wong, Kin-man Gilman. "Antibiotic resistance in laribacter hongkongensis." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B42182347.
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Mohrs, Simone. "Factors influencing the use of antibiotics and knowledge about antibiotic resistance in Jakarta : A qualitative study on the perceptions of stakeholders involved in Yayasan Orangtua Peduli’s Smart Use of Antibiotics campaign in Indonesia." Thesis, Uppsala universitet, Internationell mödra- och barnhälsovård (IMCH), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-303379.
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Introduction: Southeast Asia has among the highest rates of antibiotic resistance worldwide, particularly in Indonesia, where paediatricians prescribed antibiotics to 94% of children, knowing that the infection was viral. Relevance: There is a gap in understanding of the reasons behind the irrational use of antibiotics by healthcare professionals and patients. Aim: This research aims to explore factors that influence the use of antibiotics and knowledge about antibiotic resistance in Jakarta, Indonesia. Methods: In December 2014, the researcher conducted thirteen semi-structured interviews with four stakeholder groups, which are involved in the “Smart Use of Antibiotics” campaign in Jakarta. Qualitative Content Analysis was used to identify the theme “unite our voice to address antibiotic resistance from all angles” as well as the five categories: Education, Media, Policy, Culture and Trust. Results: Each category presented one factor, which was divided into the sub-factors education of patients and professionals; online and offline media; policy and guidelines, drug availability and accessibility and stakeholder involvement; habit and behaviour, doctor-patient relationship, environment / surroundings; and trust in the system, in the healthcare professionals, among professionals and in medicine. Conclusion: All stakeholders need to unite their voices together to achieve a smarter use of antibiotics and increase the knowledge about antibiotic resistance.
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Torres, Monique A., and Monique A. Torres. "An Evaluation of the Prevalence of Antibiotic Resistance among Salmonella and Staphylococcus Aureus Isolated from Various Food Animals." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/622894.
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Within the last decade antibiotic resistant bacteria have become a major public health concern. A possible major contribution to this problem is thought to be the overuse of antibiotics in food animals. An estimated 70% of antibiotics dispensed yearly throughout the United States are distributed to the livestock industry as growth promoters, prophylactic, and therapeutic treatments, according to the Center for Disease Control and FDA. When food animals are exposed to low doses of antibiotics frequently over a long period of time the bacteria are able to develop resistance to antibiotics. Livestock harbor foodborne pathogens that are generally commensal bacteria in the animals themselves but can cause illness to the people exposed. The problem occurs when treatment becomes difficult, there is some speculation that livestock animals are a main contributor to the increase in antibiotic resistant foodborne pathogens. Salmonella spp. and Staphylococcus aureus are pathogens that can be isolated from livestock and cause serious illness in humans. Objectives of this study include isolating S. aureus and Salmonella from samples collected from food animals, investigating the prevalence of antibiotic resistance in the confirmed S. aureus and Salmonella isolates from animals raised in various areas of Southern New Mexico and Arizona. In this study, samples were collected from various food animals post-harvest at a USDA inspected, non-commercial animal harvest facility in Arizona, and evaluated for the presence of S. aureus and Salmonella. Samples were collected from 129 animals of the following types: Bovine (cow), Caprine (goat), Ovine (sheep), and Porcine (pig). S. aureus and Salmonella were isolated from three different types of samples per animal including hide samples, sub iliac and mesenteric lymph nodes, and nasal swabs. Each sample was cultured separately in enrichment media followed by selective/differential media. Once the pathogen was confirmed via 16s rRNA PCR for S. aureus, invA3 PCR for Salmonella, gel electrophoresis, DNA Sequencing, and other biochemical tests, an antibiotic susceptibility test was performed to check the resistance characteristics of each isolate. The pathogen was exposed to eight different antibiotics- Ampicillin, Cefoxitin, Chloramphenicol, Ciprofloxacin, Erythromycin, Streptomycin, Sulfamethoxazole/Trimethoprim, and Tetracycline; commonly used among animals and humans via the disc diffusion assay. A total of 59 and 60 of 369 samples were confirmed positive for S. aureus and Salmonella, respectively. The animal type that harbored the most Salmonella overall were Bovine/cattle and the sample type that harbored the most Salmonella overall were lymph nodes. The animal type that harbored the most S. aureus overall were porcine/pigs and the sample type that harbored the most S. aureus overall were lymph nodes. 18 out of 129 livestock animals sampled in this study were found to carry both Salmonella and S. aureus and were isolated from: 6-Porcine, 5-Bovine, 5-Caprine, and 2-Ovine. The overall antibiotic resistance prevalence in S. aureus and Salmonella were 22.88% and 32.71%, respectively. Antibiotic resistance patterns were seen in both S. aureus and Salmonella isolated from all different livestock and sample types. Of these S. aureus isolates 43 showed resistance to at least one type of antibiotic, and the most resistance was seen to Ampicillin. 53 Salmonella isolates showed resistance to at least one type of antibiotic, and the most resistance was seen to Erythromycin. The implications of this study indicate that there are antibiotic resistant Staphylococcus aureus and Salmonella found in various food animals and sample types. Most of these Salmonella and S. aureus isolates were resistant to more than one antibiotic. Appropriate control measures are needed to mitigate the problem of antibiotic resistant bacteria among food animals. These control measures could also reduce the spread of resistance from one bacterium to another and possibly lessen the antibiotic resistance problem and infections.
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Rietmeyer, Lauriane. "Étude fonctionnelle et structurale des transférases de la famille Fem de Staphylococcus aureus." Electronic Thesis or Diss., Sorbonne université, 2022. https://theses.hal.science/tel-03935194.
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La résistance aux antibiotiques constitue aujourd’hui l’une des plus graves menaces de santé publique à l’échelle mondiale et nécessite le développement urgent de nouveaux antibiotiques. La biosynthèse du peptidoglycane (PG), un composant majeur de la paroi bactérienne, est la cible des deux familles d’antibiotiques utilisées en thérapeutique humaine, les β-lactamines et les glycopeptides. Le PG est constitué de chaînes glycanes liées à des tiges peptidiques branchées entre elles par des ponts interpeptidiques. Chez de nombreuses bactéries à Gram positif, les chaînes latérales constituant ces ponts, sont synthétisées par les transférases de la famille Fem. Ces enzymes ont la particularité d’utiliser des ARNt aminoacylés comme substrats, qui sont des molécules également utilisées dans d’autres mécanismes biologiques importants, comme par exemple la synthèse des protéines via le ribosome. S. aureus possède trois transférases de la famille Fem (FmhB, FemA et FemB) qui catalysent le transfert séquentiel de cinq résidus glycyles des Gly-ARNtGly vers les précurseurs cytoplasmiques du peptidoglycane (lipide II). Ces enzymes, qui sont essentielles à la viabilité de la bactérie et qui n’ont pas d’équivalent chez les cellules eucaryotes, constituent des cibles thérapeutiques de choix pour le développement de nouvelles molécules antibactériennes actives sur des souches résistantes aux antibiotiques. De façon à comprendre le fonctionnement de ces enzymes, nous avons développé des méthodes de semi-synthèse d’ARNt aminoacylés, d’analogues de lipides II et de molécules bi-substrats. Ces outils, associés à des études structurales par rayons X et des tests enzymatiques in vitro nous ont permis de mieux comprendre les mécanismes catalytiques de ces enzymes, de comprendre le mode de reconnaissance des transférases Fem pour leurs substrats (ARNt et lipides) et enfin de synthétiser des inhibiteurs puissants de ces enzymesAntibiotic resistance is one of the most pressing global health issues and urgently requires the development of new antibiotics. The biosynthesis of peptidoglycan (PG), a major component of the bacterial wall, is targeted by two families of antibiotics used in humans, the β-lactams and the glycopeptides. PG is composed of glycan strands bearing peptide stems which are crosslinked by interpeptide bridges. In many Gram-positive bacteria, interpeptide bridges are synthesized by Fem transferases whose substrates comprise aminoacylated tRNAs which are broadly implicated in cellular metabolism e.g. protein synthesis. S. aureus produces three Fem transferases (FmhB, FemA and FemB) which catalyze the sequential transfer of five glycyl residues from Gly-tRNAGly to cytoplasmic precursors of peptidoglycan (lipid II). These enzymes are essential and specific to bacteria which makes them prime targets for the development of new antibiotics active against resistant strains. In order to explore the function of Fem transferases, we have developed methods for semi-synthesis of aminoacylated tRNAs, lipid II analogues and bi-substrate molecules. Using these molecular tools in X-ray crystallography and in vitro enzymatic assays, we were able to better understand the Fem catalytic mechanisms, to explore substrate recognition of Fem transferases (tRNAs and lipids) and finally, to synthesize a potent Fem inhibitor
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Dahlin, Kretz Karin, and Signe Harlén. "Registered nurses’ experience caring for patients subscribed antibiotic treatment in The Philippines : An interview study." Thesis, Högskolan i Borås, Akademin för vård, arbetsliv och välfärd, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-8705.
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Background: Antibiotic treatment of humans was introduced in 1930. The drug improved the living conditions globally due to the fact that bacterial diseases now could be treated. The development of antibiotic resistant bacteria is undeniable and globalization increases the spread of the resistant bacteria. The main reason for the emergence of resistant bacteria are incorrect and excessive use of antibiotics. Aim: The aim of the study is to investigate registered nurses’ experiences when caring for patients that have been subscribed antibiotic treatment. Method: A qualitative study with a semi-structured interview design based on interviews with eight nurses from one private hospital in The Philippines. The interviews were transcribed and analyzed using a qualitative content analysis. Result: Three themes were identified in the study, “To increase compliance”, “Nurses’ knowledge of antibiotic treatment” and “The nurses’ reflections on antibiotic treatment”. The first theme describes how the nurses provide a safe and open-minded environment for the patients, how to support and encourage the patient during treatment and how to give comprehensible information to the patient. The second theme describes the nurses’ knowledge of the emergence of antibiotic resistance, reasons for antibiotic treatment, the manifestation of antibiotic resistance and also the effects of antibiotic resistance. The third theme describes the nurses’ reflections and thoughts concerning antibiotics as well as how they perceive the population’s knowledge of antibiotics. Discussion: All of the nurses highlighted the poverty in The Philippines as the main reason for poor compliance. A large part of the population cannot afford to consult a doctor which results in people treating themselves without the proper knowledge. A majority of the nurses therefore request health education provided from the government. A private hospital also strives to please the patient which can result in doctors prescribing a lot of antibiotics to please their patients.
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Khan, Ghazanfar Ali. "Monitoring anti-infectives and antibiotic resistance genes : with focus on analytical method development, effects of antibiotics and national perspectives." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-61682.
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Antibiotics are biologically active and are globally used in humans and animal medicine for treatment and in sub-therapeutic amounts as growth promoters in animal husbandry, aquaculture and agriculture. After excretion, inappropriate disposal and discharge from drug production facilities they enter into water bodies either as intact drugs, metabolites or transformed products. In water environments they promote development of antibiotic resistance genes (ARGs) which could serve as a reservoir and be horizontally transferred to human-associated bacteria and thus contribute to AR proliferation. Measurement of antibiotics has been revolutionized with the usage of solid phase extraction (SPE) for enrichment followed by Liquid chromatography mass spectrometry (LC-MS). On-line SPE coupled to LC-MS/MS has the advantages of high sample throughput, low sample preparation time and minimal solvent utilization. Constructed wetlands (CWs) are potential alternatives to conventional treatment plants to remove organic pollutants. A study at Plönninge, Halmstad was performed to assess the impact of bacterial community pattern and development of resistance in spiked (n=4) and control (n=4). CWs were spiked with antibiotics at environmentally relevant concentrations continuously for 25 days. Shannon Index (H’) were used to determine the bacterial diversity and real-time PCR detected and quantified antibiotic resistance genes (ARGs) sulI, tetA, tetB, erm, dfrA1, qnrS and vanB and class 1 integrons intI1. No significant differences in bacterial compositions or in ARGs or integron concentrations could be discerned between exposed and control wetlands. A study conducted in Northern Pakistan showed that the antibiotic levels in most studied rivers were comparable to surface water measurements in unpolluted sites in Europe and the US. However, high levels of antibiotics were detected in the river in close vicinity of the 10 million city Lahore, e.g. 4600 ng L−1 sulfamethoxazole. Highest detected levels were at one of the drug formulation facilities, with measured levels up to 49000 ng L−1 of sulfamethoxazole for example. The highest levels of ARGs detected, sul1 and dfrA1, were directly associated with the antibiotics detected at the highest concentrations, sulfamethoxazole and trimethoprim. In the study in UK, sewage epidemiology surveillance is used to measure the oseltamivir carboxylate (OC), metabolite of oseltamivir (parent drug) in twenty four time proportional hourly influent samples from two WWTPs and then back-calculations were made to assess the compliance of drug. Predicted users of oseltamivir, based on measured OC in waste water, ranged from 3-4 and 120-154 people for the two WWTP catchments, respectively, which are consistent with the projected use from national antiviral allocation statistics, 3-8 and 108-270, respectively. Scenario analysis suggests compliance was likely between 45-60% in the study regions.
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Whiteley, Rosalind. "Effect of multiple antibiotic treatments on the evolution of antibiotic resistance in Pseudomonas aeruginosa." Thesis, University of Oxford, 2014. https://ora.ox.ac.uk/objects/uuid:ee7c9dd7-bdcf-481b-b16c-9bb7b99f5328.
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To combat the ever-growing clinical burden imposed by antibiotic-resistant pathogens, multiple-antibiotic treatments are increasingly being considered as promising treatment options. The impact of multiple-antibiotic treatments on the evolution of resistance is not well understood however, and debate is ongoing about the effectiveness of various multiple-antibiotic treatments. In this thesis, I investigate how aspects of multiple-antibiotic treatments impact the rate of evolution of antibiotic resistance in the opportunistic human pathogen Pseudomonas aeruginosa. In particular, I look at the impact of interactions between antibiotics in combination on the evolution of resistance, and how creating heterogeneity in the antibiotic environment by rotating the antibiotics used may change the rate of evolution of resistance. I characterise the interactions present in 120 combinations of antibiotics and find that the type of interaction can be predicted by the mechanism of action of the antibiotics involved. I investigate the effect of a subset of these combinations on the evolution of antibiotic resistance. My results refute the influential but poorly-evidenced hypothesis that synergistic combinations accelerate the evolution of resistance, even when synergistic combinations have the same inhibitory effect on sensitive bacteria as additive or antagonistic antibiotic combinations. I focus on a combination of the antibiotics ceftriaxone and sulfamethoxazole and test whether it is more effective in preventing the evolution of resistance than predicted by the inhibitory effect of the combination on sensitive bacteria. I do not find the combination to be more effective than predicted. Finally, I create heterogeneous antibiotic environments by rotating the antibiotic present at different rates. For the first time in a laboratory setting, I test how varying the rate of fluctuation in the antibiotics present in a heterogeneous antibiotic environment impacts the rate of evolution of resistance. Unexpectedly, I find the rate of evolution of resistance increases with increasing levels of antibiotic heterogeneity.
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Eldek, Ahmed. "Antibiotic-Regulated Plasmid Copy Number Variation: A Driver of Antibiotic Resistance?" Thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388523.
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Plasmids are small circular DNA molecules within bacterial cells that are separated from the bacterial chromosome and replicate independently. Also, they play a crucial role in the dissemination of antibiotic resistance genes among bacteria through horizontal gene transfer. They can be present in many copies within host cell, which is known as plasmid copy number. Plasmids can regulate their own copy number by different mechanisms. Additionally, the selective pressure can also play a pivotal role in determining plasmid copy number. The presence of antibiotics in the surrounding environment can drive variations of plasmid copy number. In this study, we examined plasmid copy number variations of multidrug resistance plasmids in presence of antibiotics by using EvaGreen® - based multiplexed digital droplet PCR. We could observe that cultures of Klebsiella pneumoniae and Escherichia coli harboring multidrug resistance plasmids grown in presence of sub-MIC concentrations of the antibiotics did not show high variations in plasmid copy numbers. On the other hand, mutants of K. pneumoniae selected for increased antibiotic resistance showed high increases in copy number of a multidrug-resistance plasmid.
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Harris, Ryan A. "Identification Of Genes Involved In The Production Of Novel Antimicrobial Products Capable Of Inhibiting Multi-Drug Resistant Pathogens." Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1562068774992706.
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Macvanin, Mirjana. "The Physiological Cost of Antibiotic Resistance." Doctoral thesis, Uppsala University, Department of Cell and Molecular Biology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3761.
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Becoming antibiotic resistant is often associated with fitness costs for the resistant bacteria. This is seen as a loss of competitiveness against the antibiotic-sensitive wild-type in an antibiotic-free environment. In this study, the physiological alterations associated with fitness cost of antibiotic resistance in vitro (in the laboratory medium), and in vivo (in a mouse infection model), are identified in the model system of fusidic acid resistant (FusR) Salmonella enterica serovar Typhimurium.
FusR mutants have mutations in fusA, the gene that encodes translation elongation factor G (EF-G). FusR EF-G has a slow rate of regeneration of active EF-G·GTP off the ribosome, resulting in a slow rate of protein synthesis. The low fitness of FusR mutants in vitro, and in vivo, can be explained in part by a slow rate of protein synthesis and resulting slow growth. However, some FusR mutants with normal rates of protein synthesis still suffer from reduced fitness in vivo. We observed that FusR mutants have perturbed levels of the global regulatory molecule ppGpp. One consequence of this is an inefficient induction of RpoS, a regulator of general stress reponse and an important virulence factor for Salmonella. In addition, we found that FusR mutants have reduced amounts of heme, a co-factor of catalases and cytochromes. As a consequence of the heme defect, FusR mutants have a reduced ability to withstand oxidative stress and a low rate of aerobic respiration.
The pleiotropic phenotypes of FusR mutants suggest that antibiotic resistance can be associated with broad changes in bacterial physiology. Knowledge of physiological alterations that reduce the fitness of antibiotic-resistant mutants can be useful in identifying novel targets for antimicrobial agents. Drugs that alter the levels of global transcriptional regulators such as ppGpp or RpoS deserve attention as potential antimicrobial agents. Finally, the observation that FusR mutants have increased sensitivity to several unrelated classes of antibiotics suggests that the identification of physiological cost of resistance can help in optimizing treatment of resistant bacterial populations.
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Sjölund, Maria. "Development and Stability of Antibiotic Resistance." Doctoral thesis, Uppsala University, Clinical Bacteriology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4523.
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Antibiotic resistance is of current concern. Bacteria have become increasingly resistant to commonly used antibiotics and we are facing a growing resistance problem. The present thesis was aimed at studying the impact of antibiotic treatment on pathogenic bacteria as well as on the normal human microbiota, with focus on resistance development.
Among the factors that affect the appearance of acquired antibiotic resistance, the mutation frequency and biological cost of resistance are of special importance. Our work shows that the mutation frequency in clinical isolates of Helicobacter pylori was generally higher than for other studied bacteria such as Enterobacteriaceae; ¼ of the isolates displayed a mutation frequency higher than Enterobacteriaceae defective mismatch repair mutants and could be regarded as mutator strains.
In H. pylori, clarithromycin resistance confers a biological cost, as measured by decreased competitive ability of the resistant mutants in mice. In clinical isolates, this cost could be reduced, consistent with compensatory evolution stabilizing the presence of the resistant phenotype in the population. Thus, compensation is a clinically relevant phenomenon that can occur in vivo.
Furthermore, our results show that clinical use of antibiotics selects for stable resistance in the human microbiota. This is important for several reasons. First, many commensals occasionally can cause severe disease, even though they are part of the normal microbiota. Therefore, stably resistant populations increase the risk of unsuccessful treatment of such infections. Second, resistance in the normal microbiota might contribute to increased resistance development among pathogens by interspecies transfer of resistant determinants.