Дисертації з теми "Antibiotic resistance transmission"
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Bellinger, Christina G. "Commercial Soils as a Potential Vehicle for Antibiotic Resistance Transmission." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503298572132004.
Повний текст джерелаGast, Richard K. "The effects of antibiotic administration on the proliferation and interspecies transmission of drug-resistant Salmonella /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487327695620759.
Повний текст джерелаOlofsson, Sara K. "Relation Between Drug Exposure and Selection of Antibiotic Resistant Bacteria." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis Univ.-bibl. [distributör], 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7197.
Повний текст джерелаKaarme, Johan. "A world inside : Gastrointestinal microbiota in healthy Swedish children at day care centers and aspects on antibiotic resistance, enteric pathogens and transmission." Doctoral thesis, Uppsala universitet, Institutionen för kvinnors och barns hälsa, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-310335.
Повний текст джерелаPesapane, Risa Raelene. "Tracking Pathogen Transmission at the Human-Wildlife Interface: Banded Mongoose (Mungos mungo) and Escherichia coli as a Model System in Chobe, Botswana." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/76930.
Повний текст джерелаMaster of Science
Stoesser, Nicole Elinor. "Applications of whole genome sequencing to understanding the mechanisms, evolution and transmission of antibiotic resistance in Escherichia coli and Klebsiella pneumonia." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:10ed1097-b2a1-4e3e-a4b3-58318d325f89.
Повний текст джерелаLópez, Causapé Carla. "Clonal epidemiology and antimicrobial resistance in Pseudomonas aeruginosa chronic respiratory infections: interpatient transmission and resistome evolution of an international cystic fibrosis clone." Doctoral thesis, Universitat de les Illes Balears, 2018. http://hdl.handle.net/10803/666251.
Повний текст джерела[spa] La infección respiratoria crónica por P. aeruginosa es la principal causa de morbilidad y mortalidad en pacientes con fibrosis quística (FQ). Durante la progresión desde la infección temprana a la colonización crónica, P. aeruginosa experimenta un complejo proceso adaptativo y de diversificación que resulta en una población heterogénea y persistente en la que la aparición de resistencias a los antibióticos comprometen la selección de terapias apropiadas. En este trabajo se investigó la interacción entre tres aspectos microbiológicos clave de estas infecciones: la presencia de cepas transmisibles y persistentes, la aparición de variantes con tasas de mutación incrementadas y la evolución de la resistencia a los antibióticos. La epidemiología clonal, los perfiles de sensibilidad antibiótica, la contribución de los mecanismos clásicos de resistencia de P. aeruginosa y el papel de las variantes hipermutadoras se estudiaron en dos grandes colecciones de aislados procedentes de pacientes con fibrosis quística de las Islas Baleares y España. Asimismo, mediante secuenciación de genoma completo, se determinó la filogenia, diseminación interpaciente, evolución intrapaciente, genotipo hipermutador y resistoma de una colección de aislados clonales pertenecientes al complejo clonal 274 (CC274), proviniendo dichos aislados de dos países muy distantes, Australia y España, y cubriendo un período de 18 años. Finalmente, dada la relevancia de los aminoglucósidos en el manejo de estos pacientes, se estudió la dinámica del desarrollo de resistencia a aminoglucósidos in vitro mediante secuenciación de genoma completo. A pesar de encontrarse discrepancias entre los métodos de genotipado molecular, se documentó un alto grado de diversidad genética en las colecciones de las Islas Baleares y España, siendo escasa la representación de cepas epidémicas. No obstante, por primera vez en España, se documentó un caso de sobreinfección con el clon epidémico multirresistente de Liverpool. Además, en 5 pacientes de Baleares, crónicamente colonizados y sin aparente relación epidemiológica, se detectó el CC274. Puesto que este complejo clonal también ha sido detectado en pacientes de países como Austria, Australia y Francia, éste debería incluirse en la creciente lista de cepas epidémicas. El análisis posterior de las secuencias de genoma completo de los aislados del CC274 evidenció la diseminación interpaciente de un sublinaje hipermutador, denotando además el potencial de estas variantes para la inesperada evolución a corto plazo del secuenciotipo y la rápida diseminación de resistencias. Además, los estudios epidemiológicos demostraron la coexistencia de dos linajes divergentes, no evidenciándose barrera geográfica. Asimismo se documentó una tendencia generalizada a la acumulación de resistencias a los antibióticos en el tiempo, acompañada de hipersensibilidad a ciertos antibióticos como aztreonam, lo cual se puede explicar en términos de sensibilidad colateral. La correlación entre los fenotipos y genotipos determinados mediante secuenciación del genoma completo de los aislados pertenecientes al CC274 nos permitió definir el resistoma mutacional de P. aeruginosa en la FQ, el cual se extiende más allá de los mecanismos mutacionales clásicos. Entre los nuevos determinantes de resistencia cromosómica encontrados caben destacar tanto las mutaciones en la proteína fijadora de penicilina PBP3, que confieren resistencia a betalactámicos, como las mutaciones en fusA1, que codifica para el factor de elongación G, y que junto con la hiperexpresión de MexXY contribuyen a la resistencia de alto nivel a aminoglucósidos. Paradójicamente, encontramos que la hiperexpresión de MexXY es prescindible para el desarrollo de resistencia in vitro a aminoglucósidos, lo que sugiere que dicha hiperexpresión confiere una ventaja evolutiva in vivo. En conjunto, este trabajo demuestra que, en la FQ, la epidemiología clonal y la evolución de la resistencia a los antibióticos son el resultado de una compleja interacción entre los mecanismos de resistencia mutacionales, la diversificación de la población infectante y la transmisión interpaciente de cepas epidémicas.
[cat] La infecció respiratòria crònica per P. aeruginosa és la principal causa de morbiditat i mortalitat en els pacients amb fibrosi quística (FQ). Durant la progressió des de la infecció primerenca a la colonització crònica, P. aeruginosa experimenta un complexe procés adaptatiu i de diversificació que resulta en una població heterogènia i persistent en la qual l'aparició de variants resistents a múltiples antibiòtics comprometen la selecció de teràpies antibiòtiques apropiades. En aquest treball es va investigar la interacció entre tres aspectes microbiològics clau: la presència de soques transmissibles i persistents, l'aparició de variants amb taxes de mutació incrementades i l'evolució de la resistència als antibiòtics. L'epidemiologia clonal, els perfils de sensibilitat antibiòtica, la contribució dels mecanismes clàssics de resistència i el paper de les variants hipermutadores es van estudiar en dos grans col·leccions d'aïllats procedents de pacients amb FQ de les Illes Balears i Espanya. Així mateix, mitjançant seqüenciació del genoma complet, es va determinar la filogènia, disseminació interpacient, evolució intrapacient, genotip hipermutador i resistoma d'una col·lecció d'aïllats pertanyents al complexe clonal 274 (CC274), provenint de dos països molt distants, Austràlia i Espanya, i cobrint un període de 18 anys. Finalment, donada la rellevància dels aminoglicòsids en el maneig d’aquests pacients, es va estudiar la dinàmica del desenvolupament de resistència a aminoglicòsids in vitro mitjançant seqüenciació de genoma complet. Tot i trobar discrepàncies entre els mètodes de genotipat molecular, es va documentar un alt grau de diversitat genètica en les col·leccions de les Illes Balears i Espanya, sent escassa la representació de soques epidèmiques. No obstant això, per primera vegada a Espanya, es va documentar un cas de sobreinfecció amb el clon epidèmic multiresistent de Liverpool. A més, en 5 pacients de les Illes Balears, crònicament colonitzats i sense aparent relació epidemiològica, es va detectar el CC274. Ja que aquest complexe clonal també ha estat detectat en països com Àustria, Austràlia i França, aquest clon hauria d'incloure a la creixent llista de soques epidèmiques. L'anàlisi posterior de les seqüències de genoma complet dels aïllats pertanyents al CC274, va evidenciar la disseminació interpaciente d'un subllinatge hipermutador, denotant a més el potencial d'aquestes variants per a la inesperada evolució a curt termini del sequenciotip i per a la ràpida disseminació de la resistència antibiòtica. A més, els estudis epidemiològics van demostrar la coexistència de dos llinatges divergents, no existint barrera geogràfica. Així mateix es va evidenciar una tendència generalitzada a l'acumulació de resistències en el temps, acompanyada d'hipersensibilitat a certs antibiòtics com l’aztreonam, la qual cosa es pot explicar en termes de sensibilitat col·lateral. La correlació entre els fenotips i genotips determinats mitjançant seqüenciació del genoma complet dels aïllats pertanyents al CC274 ens va permetre definir el resistoma mutacional de P. aeruginosa en la FQ, el qual s'estén més enllà dels mecanismes de resistència mutacionals clàssics. Entre els nous determinants de resistència cromosòmica trobats cal destacar tant les mutacions en la proteïna fixadora de penicil·lina PBP3, que confereixen resistència a betalactàmics, així com les mutacions en fusA1, que codifica per al factor d'elongació G, i que juntament amb la hiperexpressió de MexXY contribueixen a la resistència d'alt nivell a aminoglucòsids. Paradoxalment, vam trobar a més que la hiperexpressió de MexXY és prescindible per al desenvolupament de resistència in vitro a aminoglucòsids, el que suggereix que aquesta hiperexpressió suposa un avantatge evolutiu in vivo. En conjunt, aquest treball demostra que l'epidemiologia clonal i l'evolució de la resistència als antibiòtics en el context de la FQ són el resultat d'una complexa interacció entre els mecanismes de resistència mutacionals, la diversificació de la població infectant i la transmissió interpaciente de ceps epidèmiques.
Herindrainy, Perlinot. "Epidémiologie et transmission mère-enfant des entérobactéries productrices de bêta-lactamases à spectre étendu (E-BLSE) à Madagascar." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLV074/document.
Повний текст джерелаThe emergence and spread of antibiotic-resistant bacteria is a concern. Infection caused by multidrug-resistant bacteria (MDR) worsens the prognosis of infected patients and increases the costs associated with their management. Among the MDRs, Gram-negative bacteria (GNB), especially extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) are the most frequently isolated. Antibiotic resistance may have an impact on morbidity and mortality in low- and middle-income countries (LMICs) because of the potential for emergence and spread of antibiotic-resistant bacteria, and the burden of bacterial infections in these countries. However, data on bacterial resistance are scarce or came from the hospital, for the great majority, in LMICs. In these settings, severe neonatal bacterial infections (sepsis, pneumoniae and meningitis) still represent the leading causes of death in newborns. Enterobacteriaceaeare responsible for a great part of these neonatal infections. Thus, investigating the transmission of ESBL-PE in newborns would make it possible to propose prevention strategies. This work was based on the BIRDY program (Bacterial Infections and Antibiotic Resistant Diseases among Young Children in Low-Income Countries). The first objective was to estimate the prevalence of colonization by ESBL-PE in pregnant women in Madagascar as well as the risk factors of this colonization. The results showed an overall colonization prevalence of 18.5% [95% CI 14.5-22.6]. Factors reflecting a higher socioeconomic level such as private access to drinking water and having a house are associated with colonization. The second objective of this work was to study the incidence of ESBL-PE colonization in community-based infants and to identify acquisition risk factors. The results reveal an overall incidence of ESBL-PE acquisition of 10.4 per 1000 newborn-days [95% CI: 8.0; 13.4]. In addition, we found that low birth weight adjusted HR 2.7 [95% CI 1.2; 5.9], cesarean section delivery adjusted HR 3.4 [95% CI 1.7; 7.1], maternal intake of antibiotic at delivery adjusted HR 2.2 [95% CI 1.1; 4.5] were risk factors for the acquisition of ESBL-PE. The third objective was to document neonatal infections. We found an incidence of neonatal infections of 30.6 cases per 1000 live births [95% CI: 23.4; 40.1]. Our results suggest that public health measures should focus on the improvement of pregnancy follow-up and early diagnosis of neonatal infections
Benavides, Julio. "Dynamique des maladies dans les systèmes sociaux complexes : émergence des maladies infectieuses chez les primates." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20163/document.
Повний текст джерелаUnderstanding the emergence and spread of infectious disease in wild animal populations has become an important priority for both public health and animal conservation. Combining the collection of empirical data with the development of epidemiological models, this thesis focuses on understanding two key issues of wildlife epidemiology: (i) how heterogeneity at the individual, group, population and landscape level affects parasite spread (ii) investigating whether transmission of antibiotic resistant bacteria from humans to wildlife is occurring within three protected areas of Africa (Tsaobis NP-Namibia, Lope NP-Gabon and Dzanga-Ndoki NP-Central African Republic). The main findings of this work indicated that: (1) multiple-scale factors including temperature, rainfall, home range use, sex, age and body condition influence gastro-intestinal parasite richness among wild baboons; (2) animal contacts around ‘habitat hotspots' can substantially influence the spatio-temporal dynamics of a disease; (3) antibiotic resistant enterobacteria seem to be spreading from humans/livestock to wildlife when the territory overlap between these two populations is expected to be high; (4) gradients in gorilla density created by bushmeat hunting can reverse the expected pattern of decreasing parasite prevalence with distance to human-spillover. The conclusions of this work open new possibilities for studying the mechanisms explaining the spread of emerging infectious diseases among wild animals
Schages, Laura [Verfasser], Dirk [Gutachter] Bockmühl, Rainer [Gutachter] Kalscheuer, and Peter [Gutachter] Proksch. "Ways of transmission of antibiotic resistant organisms in the environment and households / Laura Schages ; Gutachter: Dirk Bockmühl, Rainer Kalscheuer, Peter Proksch." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2021. http://d-nb.info/1229691707/34.
Повний текст джерелаVALLONE, ALESSANDRA. "INVESTIGATION OF NOVEL THERAPEUTIC TOOLS AGAINST INFECTIOUS DISEASES Part 1. Medicinal Chemistry Investigation of MMV019918 Derivatives as Dual Schizonticide And Gametocytocidal Agents Against Plasmodium falciparum Part 2. Investigation of 5-Aryl-Heterocycles As Potential Inhibitors of Metallo beta-Lactamase Enzymes." Doctoral thesis, Università di Siena, 2017. http://hdl.handle.net/11365/1004943.
Повний текст джерелаSilva, Pedro Guilherme Braz Pinto. "Dynamics of companion animal to human transmission of antimicrobial resistance, during skin and soft tissue companion animal infection." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2021. http://hdl.handle.net/10400.5/21490.
Повний текст джерелаABSTRACT - Objective: This study aims to characterize the dynamics of antibiotic resistance gene transmission in dogs with skin and soft tissue infections (SSTI) and human beings co habiting with them. We also aim to evaluate the gut colonization of these individuals for the presence of extended spectrum beta-lactamases (ESBL’s) in Enterobacteriaceae and to assess the effect of antibiotherapy on the selection of MDR bacteria from human and canine gut microbiota. Methods: Two types of biological samples were gathered in a teaching veterinary hospital in Portugal, at the dermatology department, from twelve dogs diagnosed with SSTI and their household members. Collections included a swab from the infection site (ISS) and a faecal sample (FS). Gathering of samples was performed at two different times. The ISS were cultured and an AST was performed. The FS was also cultured, and the bacteria isolated subjected to molecular analysis. Antibiotic resistance patterns were obtained by disk diffusion antimicrobial susceptibility’s testing and Enterobactereaceae ESBL’s production was confirmed by amplification of the specific gene by PCR and sequencing. Results: High levels of Methicillin resistant Staphylococcus pseudintermedius (MRSP) were isolated, and high levels of other multidrug resistant bacteria (MDR) as well. One family was suspected of carrying the same E. coli clone, shared by two humans and one dog of the same household, with a blaCTX-M-15 gene. All of the isolated Enterobactereaceae displayed susceptibility to carbapenems. The most common ESBL genes found were from the blaCTX-M group, followed by blaOXA-1 and then blaTEM, no gene from the blaSHV gene was found. Conclusions: There is a high prevalence of ESBL-producing E. coli. Interspecies transmission of antimicrobial resistance is real. This issue should be addressed with introduction of antimicrobial stewardship strategies on a wider scale and better use of antimicrobials like chlorohexidine, especially in SSTI.
RESUMO - Esta dissertação enquadra-se nos objetivos de um projeto muito maior e ainda mais ambicioso, chamado PetRisk. Pretende-se analisar o impacto e as interações dos genes de resistência aos antibióticos, percebendo de que forma as barreiras interespécie podem ser ultrapassadas. Assim sendo, o estudante integrou o núcleo desse mesmo empreendimento em Portugal, o Laboratório de Resistência aos Antibióticos da FMV-UL, liderado pela Professora Doutora Constança Pomba. Objetivo: Este estudo teve como objetivo principal compreender a dinâmica de transmissão de genes de resistência aos antibióticos, entre cães com infeção de pele e tecidos moles e as pessoas com quem vivem em regime de co-habitação. Pretendeu-se avaliar a colonização do tubo digestivo desses mesmos indivíduos quanto à presença de Enterobactereacea produtoras de beta-lactamases de largo expectro e verificar o efeito da antibioterapia na seleção de estirpes multiresistentes da microbiota intestinal canina e humana. Outro obejtivo da realização deste trabalho é o de aumentar os recursos biológicos – com isto subentende-se, bactérias de diferentes agregados familiares e o seu perfil de resistência aos antimicrobianos – para o projeto mãe, o PetRisk. Métodos: Para tal, recolheram-se dois tipos de amostras biológicas no departamento de dermatologia do hospital veterinário escolar da FMV-ULisboa. A amostra inclui doze cães com infeções de pele e tecidos moles, assim como os restantes membros do seu agregado familiar. Os materiais recolhidos foram zaragatoas do local de infeção (ZLI) e amostras fecais (AF). As colheitas decorreram em dois tempos diferentes. Às ZLI após cultura microbiológica realizaram-se testes de suscetibilidade aos antibióticos de rotina. Os isolados provenientes das AF foram sujeitos a cultura microbiológica e análise molecular. Os padrões de resistência aos antibióticos foram obtidos pelo método de difusão de discos e a confirmação da produção das beta-lactamases de largo expectro pelas Enterobactereaceae por amplificação do respetivo gene por PCR e sequenciação. Resultados: Foram encontrados elevados níveis de Staphylococcus resistentes à meticilina, assim como a resistência a multiplos antibióticos. Também as nas Escherichia coli provenientes das AF foram encontrados elevados nívreis de resistência a múltiplos antibióticos. Uma familia foi suspeita de partilhar o mesmo clone de E.coli (duas pessoas e um cão) com o mesmo filogrupo e o gene blaCTX-M-15. Todas as Enterobactereaceae isoladas demonstraram suscetibilidade aos carbapenemos. Os genes de beta-lactamases de largo expectro detetados foram (da maior para a menor frequência): blaCTX-M , blaOXA-1 e blaTEM, com nenhum registo de blaSHV. Conclusões: Existe uma elevada prevalência de E. Coli produtoras de beta-lactamases de largo expetro. A transmissão de informação genética inter-espécies é uma realidade. A prática clínica beneficiaria de uma administração mais prudente e integrada de antibióticos, com uma equipa a trabalhar apenas para a gestão destes recursos num hospital, assim como maior atenção ao uso de antisséticos como a clorohexidina, especialmente em infeções de pele e tecidos moles onde os produtos disponivéis são de fácil aplicação.
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Lamba, Manisha. "Study on antibiotic resistance transmission and proliferation in Delhi and development of possible mitigation strategy." Thesis, 2017. http://localhost:8080/xmlui/handle/12345678/7386.
Повний текст джерелаScaccia, Nazareno. "Evaluation of possible risks of antibiotic resistance transmission to humans by wastewater-irrigated crops." Doctoral thesis, 2020. http://hdl.handle.net/10400.14/32153.
Повний текст джерелаThe reuse of treated wastewater has been encouraged worldwide, in particular for agricultural irrigation, because it can be a reliable and important water source, mainly in countries under water stress. The recycling of wastewater poses still not evaluated risks concerning, among other, the dissemination of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) across distinct One-Health compartments. One of the main concerns associated with such dissemination is the contamination of the human food-chain through crops irrigation with treated wastewater. Currently, the knowledge about the transmission of ARB and ARGs to humans through environmental sources is sparse. However, wastewater reuse emerges as a potential source for direct or indirect transmission, mainly through the human food-chain. This project addressed these issues, through literature- and experiment-based investigation about potential risks of antibiotic resistance transmission to humans emerging from treated wastewater reuse. The study was planned aiming to infer if bacteria surviving in wastewater would be able to colonize plants and if wastewater ARB and the respective ARGs would be able to persist in the presence of the autochthonous fecal microbiota of a healthy human. The research hypotheses of this work were: 1) ARB and ARGs present in treated wastewater are capable of colonizing plants, and establish as endophytes; 2) ARB and ARGs are able to persist in the presence of the autochthonous human gut microbiota. The rationale behind these two hypotheses was that if ingested through vegetables, ARB and ARGs could be able to persist in the human gut. To test the study hypotheses were used three major approaches: a) it was made a literature search seeking to investigate the diversity of endophytic bacteria that belong to groups that can also be found in wastewater and in the human microbiota as well as in edible crops, normally consumed raw - this approach offered a predictor of the likelihood of a crop behave as a possible mode of transmission of ARB to humans; b) it was analysed the presence of potential ARB and ARGs in isolates from ready-to-eat watercress and strawberry; and c) it was assessed the persistence of ARGs harboured by wastewater ARB in the presence of fecal microbiota of a healthy child. The literature-based investigation aimed to explore the diversity of endophytic bacteria associated with different habitats (plant, wastewater, and human microbiota), and infer the probability that ARB and ARGs might be transferred from wastewater to plants and then to humans (Chapter 3). This literature survey permitted to shortlist of more than 20 phyla of Abstract ii endophytic bacteria distributed over more than 45 crop varieties. Because the major focus was on potential links of transmission to humans, the array of crops found in the literature was narrowed to plants that can be consumed raw, such as lettuce, carrot, radish, cucumber and tomato. In order to assess the likelihood that these plants uptake bacteria that might be antibiotic resistance vectors, the bacterial groups identified as endophytes were also investigated as potential wastewater and human microbiome member communities. Finally, for bacterial groups, whose occurrence was reported in the three types of environments, the previous description of antibiotic resistance and virulence genes was surveyed from public databases and literature. The search revealed that members of genera such as Enterobacter, Acinetobacter, Pseudomonas, and Staphylococcus, with known taxonomic proximity to human opportunistic pathogens and harbour of acquired antibiotic resistance may be found as endophytes in edible crops as well as in wastewater or the human microbiota. These results support the hypothesis that bacteria transported by wastewater, with physiological and ecological properties similar to endophytes, may be uptake by edible crops and being ingested may eventually colonize the human body. It is suggested that wastewater irrigation may raise the risks of transmission of clinically relevant bacteria from the environment to humans, via the food-chain. Plant associated bacteria were also searched on ready-to-eat watercress and strawberry, based on culture-dependent methods (Chapter 4). Ready-to-eat watercress were purchased at local supermarkets and strawberries samples were collected along a fruit processing chain of a company that produces fruits preparations for the food industry. Bacteria adsorbed onto watercress leaves as well as strawberry-associated bacteria (epiphytic and endophytic community) were isolated and analysed. The antibiotic resistance phenotype of watercress (n=68) and strawberry (n=52) isolates was characterized. Isolates exhibiting resistance to at least three antibiotics classes were selected for identification based on the 16S rRNA gene sequence analysis, and the presence of class 1 integron integrase gene intl1, the ARGs sul1, blaTEM, blaCTX-M, blaOXA-A and blaSHV and the plasmid incompatibility groups FIA, FIB, FIC, HI1, HI2, I1-Iγ, L/M, N, P, W, T, A/C, K, B/O, X, Y, F, and FIIA by conventional Polymerase Chain Reaction (PCR) were screened. Some isolates were also tested for the capacity to acquire ARGs by transformation assay. Ready-to-eat watercress presented counts of total heterotrophs in the order of 3.5 x 107 ± 4.9 x 107 and 5.4 x 105 ± 6.2 x 104 CFU/mL of watercress washing solution for supermarket A and B, respectively, whilst processed strawberry presented counts of total heterotrophs in the order of 9.1 x 105 ± 1.8 x 105 CFU/g of strawberry dry weight, with some isolates exhibiting antibiotic resistance phenotypes. The Abstract iii bacteria identified belong to the genera Pseudomonas, Stenotrophomonas, Erwinia, Rahnella, Methylobacterium, and Chryseobacterium. These bacterial taxa were previously identified as endophytes and some, such as members of the genera Pseudomonas and Stenotrophomonas are closely related to human opportunistic pathogens that can harbor acquired ARGs. The screening of ARGs, int1 and plasmid incompatibility groups revealed that these genetic elements were present within a minority group (2 isolates) of the examined plant-associated bacterial isolates. Additionally, preliminary results suggested that watercress and strawberry isolates could be susceptible to acquire antibiotic resistance and thus be involved in the dissemination of antibiotic resistance. The third study was designed based on the arguments that wastewater bacteria as well as their harboured ARGs would be rapidly lost in the complex community of fecal microbiota. This study was performed using fecal microcosm assays (FMAs) inoculated with wastewater ARB isolates harbouring known ARGs (Chapter 5). The inoculated wastewater isolates were Escherichia coli (strain A2FCC14) and Enterococcus faecium (strain H1EV10), harbouring the ARGs blaTEM, blaCTX, blaOXA-A and vanA, respectively. The effect of variables such as the presence or absence of oxygen or sub-inhibitory dose of the antibiotic cefotaxime or vancomycin on the feces microbial community composition and on the persistence of the exogenous ARGs were investigated. FMAs were monitored at time 0, 1, 3 and 7 days of incubation based on cultivation methods, quantitative PCR (qPCR) and 16S rRNA gene sequence amplicon community analyses. The fecal bacterial community was characterized by the predominance of members of the phyla Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, and Verrucomicrobia. The presence of oxygen was associated with an increase in the relative abundance of Proteobacteria, while antibiotics did not lead to consistent microbial community composition variations. The ARGs harboured by the inoculated ARB persisted over the 7 days incubation period in all the assays and could still be quantified at least for one month, under both aerobic and anaerobic conditions. Sub-inhibitory concentrations of antibiotics were not correlated with significant variations on the persistence of the tested ARB or ARGs, when compared with antibiotic-free microcosms. This microcosm-based investigation suggested that wastewater ARB can persist at least for a week in the complex fecal microbiota and, even when these ARB are below the culture detection limit, their ARGs were quantifiable by qPCR. These results support the hypothesis that, if wastewater bacteria by chance can reach the human Abstract iv gut, a successful colonization cannot be disregarded, a topic that deserves further investigation. Overall, the investigation conducted in this thesis suggests that bacteria with potential clinical relevance that may occur in treated wastewater used for irrigation, may establish stable association with edible crops, as endophytes. If, as consequence of this fact, these bacteria reach the human gut, they may be capable of persisting there. Although this investigation put in evidence the complexity of this issue, showing that further studies are required, the thesis presented is that the wastewater, edible crops and humans may be part of the same transmission link chain of ARB and ARGs.
Martineau, Annie. "Isolement et caractérisation de bactériophages comme moyen de lutte naturel contre les infections nosocomiales." Thèse, 2009. http://hdl.handle.net/1866/4705.
Повний текст джерелаNosocomial infections are directly related to opportunistic germs, which are often resistant to antibiotics and persistent on surfaces, representing a high infectious risk in hospitals. In this context, the isolation and characterization of bacteriophages specifically targeting nosocomial bacteria such as resistant Staphylococcus aureus (MRSA), resistant Enterococcus (VRE), Pseudomonas aeruginosa and Acinetobacter baumanii, could provide a natural bactericidal alternative against the transmission of these infections. Phages, isolated from waste water, were selected according to their capacity of amplification, their genomic profile and lytic potential towards various bacterial clinical strains. The best ones were characterized in detail to primarily ensure their specificity, safety, stability and effectiveness, before studying their in vivo usage. Seven phages against MRSA and three against Acinetobacter baumanii were characterized. Four MRSA phages proved to be good potential candidates and could be tested in hospitals as disinfectant agents with the aim of fighting nosocomial infections.
SOUMAROVÁ, Michaela. "Analýza výskytu vybraných zoonóz v Jihočeském kraji." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-188181.
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