No description available.

No description available.

Dentre os bacilos Gram-negativos não fermentadores (BGNNF), Acinetobacter baumannii, complexo Burkholderia cepacia, Pseudomonas aeruginosa e Stenotrophomonas maltophilia se destacam devido à ampla capacidade de adaptação, as quais podem habitar uma grande variedade de ambientes e adquirir resistência a uma grande variedade de antimicrobianos. A resistência aos ?-lactâmicos ocorre principalmente pela produção de enzimas do tipo ?-lactamases, as quais são capazes de clivar o anel ?-lactâmico. O objetivo do presente estudo foi isolar bactérias pertencentes a esses gêneros, determinar o perfil de resistência aos antimicrobianos através dos métodos de disco difusão e da concentração inibitória mínima (CIM) e investigar a presença de genes codificadores de ?-lactamases. Foram isolados 60 BGNNF, sendo 24 pertencentes ao complexo B. cepacia, 13 P. aeruginosa, 13 S. maltophilia e 10 A. baumannii obtidos de diferentes amostras de solo provenientes de diferentes estados e cidades das cinco regiões do Brasil. Dentre os isolados, 50 (83,3%) foram não suscetíveis a pelo menos um ?-lactâmico e altas CIMs para as cefalosporinas de amplo espectro foram detectadas. Diferentes genes codificadores ?-lactamases de importância clínica foram pesquisados, e um total de 70 foram detectados, como blaSHV, blaGES, blaOXA-1-like, blaPER, blaVEB, blaCTX-M-Gp1, blaCTX-M-Gp9, blaKPC, blaVIM e blaNDM, sendo que, a maior prevalência foi do blaSHV (46%). Este é o primeiro relato no mundo de uma bactéria isolada do solo com o gene blaKPC e o primeiro relato no Brasil e o segundo no mundo de uma bactéria isolada do solo portadora do gene blaNDM-1. O grande número de genes codificadores de ?-lactamases encontrados indica uma grande disseminação destas enzimas em bactérias isoladas do solo. / Among the nonfermenting Gram-negative bacilli (NFGNB), Acinetobacter baumannii, Burkholderia cepacia complex, Pseudomonas aeruginosa and Stenotrophomonas maltophilia stand out due to the large adaptation capacity, which can inhabit a wide variety of environments and acquire resistance to a wide variety of antibiotics. Resistance to ?-lactam antibiotics occurs mainly by the production of ?-lactamase, which are capable of cleaving the ?-lactam ring. The aim of the present study was to isolate bacteria belonging to these genera, to determine the antimicrobial resistance profile through disc diffusion and minimum inhibitory concentration (MIC) methods and to investigate the presence of ?-lactamase encoding genes. Sixty NFGNB were obtained, being 24 belonging to the B. cepacia complex, 13 P. aeruginosa, 13 S. maltophilia and 10 A. baumannii from different soil samples from different states and cities of the five Brazilian regions. Among the isolates, 50 (83.3%) were not susceptible to at least one ?-lactam antibiotics and high MICs for the extended-spectrum cephalosporins were detected. Different ?-lactamase encoding genes of clinical importance were investigated, and 70 were detected, such as blaSHV, blaGES, blaOXA-1-like, blaPER, blaVEB, blaCTX-M-Gp1, blaCTX-M-Gp9, blaKPC, blaVIM and blaNDM, with the highest prevalence being blaSHV (46%). This is the first report in the world of blaKPC gene in bacteria isolated from soil and the first report in Brazil and the second in the world of blaNDM-1 gene in bacterium isolated from soil. A large number of ?-lactamase encoding genes found indicates a large spread of these enzymes in bacteria isolated from soil.

Submitted by Natalia Vieira (natalia.vieira@famerp.br) on 2016-05-30T18:51:03Z No. of bitstreams: 1 julianatiemitakahashi_dissert.pdf: 1874616 bytes, checksum: 4b57c05bf0ee3402a9384302e26ebd23 (MD5) / Made available in DSpace on 2016-05-30T18:51:03Z (GMT). No. of bitstreams: 1 julianatiemitakahashi_dissert.pdf: 1874616 bytes, checksum: 4b57c05bf0ee3402a9384302e26ebd23 (MD5) Previous issue date: 2015-11-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Introduction: Bacterial resistance to antimicrobials is an important public health problem, which results in increased treatment period, increase in mortality and in health care costs. This phenomenon is considered a result of the indiscriminate use of antimicrobials in human and veterinary medicine, and along the food chain. In recent years, it has been observed the frequent isolation of resistant bacteria from animal production and food of animal origin. In this context, have been highlighted the resistance to beta-lactâmicos and to quinolones, the first, due to extended-spectrum beta-lactamase (ESBL) production and the second, resultant from the acquisition of qnr genes encoding proteins that interfere in quinolone action on DNA gyrase and topoisomerase IV. Several bacterial species with antimicrobial resistance have been isolated from farm animals. Objective: This study evaluated the antimicrobial susceptibility profile and the presence of resistance genes blaCTX-M, blaSHV, blaTEM, qnrA, qnrB, qnrS and oqxAB in Enterobacteriaceae isolated from meat market in the municipality of São José do Rio Preto- SP, acquired between November 2010 and August 2012. Material and Methods: The antimicrobial susceptibility was determined by disk diffusion according to CLSI. Strains resistant to beta-lactams and quinolones were submitted to PCR using specific primers for detection and sequencing of these genes for identification. Results: A total of 75 isolates were resistant to beta-lactam and 125 to quinolones. Among these, 6.6% blaCTX-M, 6.6% blaTEM, 16% blaSHV, 21.6% had qnr variants and 13.6% oqxAB. In a strain of Aeromonas sobria was detected the coexistence of qnrA and qnrS genes; the qnrB gene was detected in five strains of E. coli, five K.pneumoniae, two Salmonella spp. and 12 Citrobacter spp. The qnrB19 gene was detected in two K. pneumoniae, duas E. coli and one Citrobacter braakii. qnrB2 was detected in three K. pneumoniae. The qnrS1 gene was detected in a strain of K. pneumoniae. The sequencing blaCTX-M revealed blaCTX-M-2, all of which were derived from chicken meat samples. Conclusion: These data demonstrate there nay be association between excessive use of antimicrobials in animal production and isolation of bacteria resistant to these antimicrobials. The presence of bacteria resistant to antimicrobials in meat intended for human consumption consists in a public health problem and can affect commercials relationships of the country, since it the Brazil is one of the world's largest meat exporters. / Introdução: A resistência bacteriana aos antimicrobianos é um importante problema de saúde pública, que prolonga o período de tratamento, aumenta as taxas de mortalidade e custos da assistência à saúde. Este fenômeno pode ter considerado consequência do uso indiscriminado de antimicrobianos na medicina humana e veterinária, e ao longo da cadeia produtiva de alimentos. Nos últimos anos tem sido observado o frequente isolamento de bactérias resistentes a partir de animais de produção e alimentos de origem animal. Neste contexto, têm-se destacado a resistência aos beta-lactâmicos, devido à produção de beta-lactamase de espectro estendido (ESBL) e às quinolonas pela aquisição de genes qnr que codificam proteínas que interferem na ação das quinolonas sobre a DNA-girase e a topoisomerase IV. Diversas espécies bacterianas apresentando resistência aos antimicrobianos têm sido isoladas a partir de animais de produção. Objetivo: Este estudo teve como objetivo isolar enterobactérias resistentes aos beta-lactâmicos e quinolonas e detectar os genes blaCTX-M, blaSHV, blaTEM, qnrA, qnrB, qnrS e oqxAB em Enterobacteriaceae resistentes isoladas de carnes resfriadas de frango, suína e bovina comercializadas no município de São José do Rio Preto-SP, adquiridas entre novembro de 2010 e agosto de 2012. Material e Métodos: A suscetibilidade aos antimicrobianos foi determinada por disco-difusão de acordo com as normas do CLSI. As cepas resistentes aos beta-lactâmicos e às quinolonas foram submetidas à PCR com primers específicos para a detecção destes genes e ao sequenciamento para a identificação dos mesmos. Resultados: Um total de 75 isolados apresentou resistência aos beta-lactâmicos e 125 às quinolonas. Entre estes, 6,6% blaCTX-M, 6,6% blaTEM, 16% blaSHV, 21,6% apresentaram variantes de qnr e 13,6% oqxAB. Em uma cepa de Aeromonas sobria foi detectada a coexistência dos genes qnrA e qnrS; o gene qnrB foi detectado em cinco cepas de E. coli, cinco K.pneumoniae, duas Salmonella spp. e 12 Citrobacter spp. O gene qnrB19 foi detectado em duas K. pneumoniae, duas E. coli e uma Citrobacter braakii. qnrB2 foi detectado em três K. pneumoniae. O gene qnrS1 foi detectado em uma cepa de K. pneumoniae. O sequenciamento de blaCTX-M revelou blaCTX-M-2, sendo que todas foram provenientes de amostras de carne de frango. Conclusão: Esses dados revelam que pode haver associação entre o excessivo uso de antimicrobianos em animais de produção e o isolamento de bactérias resistentes aos mesmos. A presença de bactérias resistentes aos antimicrobianos em carnes destinadas ao consumo humano consiste em um problema de saúde pública e pode afetar as relações comerciais do país, já que o Brasil é um dos maiores exportadores de carne do mundo.

Les béta-lactamines sont les antibiotiques préférentiellement utilisés contre les bactéries Gram négatif responsables d’infections. La dissémination mondiale d’organismes produisant des béta-lactamases à spectre élargi (BLSE) ou des carbapénémases est une préoccupation générale ainsi qu’une menace économique.Parmi ces organismes, les Entérobactéries jouent un rôle important dans les infections nosocomiales (ainsi que les infections communautaires pour E. coli). L’émergence et la dissémination d’Entérobactéries productrices de BLSE (E-BLSE), exprimant principalement des béta-lactamases de la famille des CTX-Ms, et dans une mesure plus inquiétante de carbapénémases (EPC), principalement les enzymes NDM, KPC, IMP, VIM et OXA-48, sont sans le moindre doute un problème de santé publique majeur.Les CTX-Ms hydrolysent les céphalosporines à large spectre et sont les BLSEs principalement rencontrées chez les Entérobactéries lors d’infections urinaires communautaires, mais aussi les bactériémies à E. coli qui peuvent en découler. Ces infections sévères sont traitées avec des carbapénèmes, considérés comme les antibiotiques de dernier recours. Malheureusement, leur utilisation croissante à soumis les entérobactéries à une pression de sélection conduisant à de plus en plus de souches montrant une sensibilité réduite aux carbapénèmes pouvant aboutir à un échec thérapeutique.Si l’on considère les possibilités de traitement limitées pour les E-BLSEs, que les EPCs sont souvent résistantes à plusieurs si ce n’est toutes les classes d’antibiotiques, et que pour certaines peu ou pas de traitements antibiotiques sont disponibles, leur rapide détection et identification sont essentielles. Des tests fiables sont nécessaires pour aider les cliniciens à, rapidement mettre en place des mesures de contrôle de ces infections, adapter les traitements antibiotiques et optimiser les stratégies de soins et leur issue favorable.Lors de la détection des E-BLSEs et des EPCs, il est aussi crucial d’identifier la béta-lactamase impliquée pour la mise en place d’une thérapie adaptée. Les méthodes basées sur la spécificité des anticorps sont sans aucun doute parmi les plus appropriées pour atteindre cet objectif.Pour répondre aux besoins actuels, les méthodes de détection des résistances ont antibiotiques doivent être peu coûteuses (coûts réduits des consommables et des équipements) et facile à mettre en place (technicité faible) pour l’utilisateur. C’est pourquoi nous avons décidé de développer des tests immunochromatographiques qui répondent parfaitement à ce cahier des charges. Pour atteindre cet objectif, nous avons produit des anticorps monoclonaux dirigés contre les CTX-Ms, et les familles de carbapénémases NDM, KPC, et OXA-48. Les tests immuno-chromatographiques correspondants ont été développés et validés. Nos tests sont robustes, facilement transférables dans une version commerciale et stables pour 24 mois sans réfrigération. Ils sont conviviaux, performants en termes de spécificité et sensibilité, et peu couteux, de 7€ (pour un mono-test) à moins de 15€ (pour un multiplex). De plus les résultats sont obtenus dans un court délai sans la nécessité d’un équipement particulier pour la lecture. Nous avons validé un mono-test pour la détection des CTX-Ms du groupe 1, et évalué la détection des groupes 1, 2, 8 et 9 directement dans des échantillons cliniques comme les hémocultures ou l’urine. Des mono-tests pour la détection des NDMs, KPCs et des OXA-48 et un multiplex pour la détection simultanée des cinq principales carbapénémases ont également été validés. Pour ce faire, nous avons utilisés 180 souches isolées sur boites, provenant du Centre National de Référence pour la résistance aux carbapénémases chez les Entérobactéries, dont le contenu en béta-lactamase est caractérisé. / Beta-lactams are antibiotics preferentially used against gram-negative bacilli infections. The worldwide spread of extended spectrum beta-lactamases (ESBL) or carbapenemase-producing organisms is a global concern and also an economic threat.Within those organisms, Enterobacteriaceae have a major role as causes of nosocomial infections (and, for E. coli, also of community-acquired infections). The emergence and dissemination of ESBL-producing Enterobacteriaceae (ESBL-E), mainly expressing beta-lactamases from the CTX-M family, and in a worrier aspect of carbapenemase-producing Enterobacteriaceae (CPE), mainly NDM, KPC, IMP, VIM and OXA-48 like enzymes, are undoubtedly a matter of great public health concern.CTX-Ms hydrolyze broad-spectrum cephalosporins and are the most encountered BLSE in Enterobacteriaceae, and CTX-Ms producers have been reported as the most prevalent ESBL producers in community-onset urinary tract infections (UTIs). Moreover, CTX-M-producing E.coli are a major cause of bloodstream infections that are often secondary to UTIs. These severe infections are treated with carbapenems, considered as last resort antibiotics. Unfortunately, their increasing use put a selective pressure on Enterobacteriaceae, leading to more and more strains showing decreased susceptibility to carbapenems and potentially leading to therapeutic failure.Considering the limited treatment options for ESBL-E and that CPE are often resistant to several if not all classes of antibiotics, and for which very few (or no) antibiotic options remain available, their rapid detection and identification are essential. Reliable tests are needed to help physicians, to quickly provide appropriate infection control measures, to adapt rapidly antibiotic treatment and optimize care strategies and outcomes.While detecting ESBL-Es or EPCs, it is also crucial to identify the implicated beta-lactamase for accurate therapy implementation. To do so, the antibody-specificity based methods are undoubtedly appropriate. To respond to the current needs, antimicrobial drug resistance detection methods must be cheap (reduced costs of consumables and equipment) and easy to use (reduced technical complexity) for the end user, and LFIAs respond to this requirements. Our objective was to develop such tests, and this led us to produce monoclonal antibodies against CTX-Ms, NDM, KPC, IMP, VIM and OXA-48 carbapenemase families and to develop and validate the corresponding LFIAs. Our tests are robust assays, easily transferable in a commercialized version, stable for more than 24 months without refrigeration, user-friendly (no requirement of trained staff), high performance (sensitive and specific), low cost, from 7€ (monotest) to less than 15€ (multiplex). Moreover, the detection results are obtained in short delay without the need for highly technical equipment for the readout.Here, we validated a LFIA for the detection of CTX-Ms (from group 1) and to a wider extent evaluated the direct detection of CTX-Ms from groups 1, 2, 8 and 9 in clinical samples such as blood culture and urine. Mono-tests to detect NDMs and OXA-48-like, and a multiplex for the simultaneous detection of the five main carbapenemases were also validated. These validations were conducted using 180 well characterized isolates in terms of their -lactamase content from the French National Reference Centre for carbapenem-resistant Enterobacteriaceae.

Les antibiotiques, et plus particulièrement les β-lactamines, furent pendant longtemps considérés comme l’arme absolue pour le traitement des infections bactériennes, du fait de leur efficacité, leur bonne tolérance et de leur faible coût. Cependant, les bactéries ont développé des mécanismes de résistance, y compris vis-à-vis des β-lactamines possédant le spectre d’activité le plus large, les carbapénèmes. Ces derniers sont considérés comme les antibiotiques de derniers recours pour le traitement des infections sévères à bacilles à Gram négatif en milieu hospitalier. Chez les entérobactéries, cette résistance émergente aux carbapénèmes est principalement due à l’expression d’enzymes appelées les carbapénèmases capables d’inactiver les carbapénèmes. L’émergence exponentielle à l’échelle mondiale de ces entérobactéries productrices de carbapénèmases (EPC) constitue un problème majeur de santé publique. Actuellement, les carbapénémases les plus répandues dans le monde sont les KPC (Klebsiella pneumoniae carbapenemase), NDM-1 (New Delhi metallo- β- lactamase) et OXA-48 (Oxacillinase). La première KPC a été identifiée en 1996 aux Etats- Unis, NDM-1 en 2009 en Suède chez une patiente en provenance d’Inde et OXA-48 en 2003 en Turquie. En France, les carbapénèmases de type OXA-48 sont largement majoritaires et représentent près de 70% des EPC. Ainsi, le retentissement de leur dissémination et le besoin de développer de nouveaux inhibiteurs capables d’inactiver les carbapénèmases se fait de plus en plus pressante.Cette thèse a pour objectif de mieux comprendre le mode d’ action de ces 3 carbapénèmases d’un point de vue moléculaire et biochimique, afin d’ identifier les éléments structuraux nécessaires à leur fonctionnement, mais aussi de poser les bases du développement de « pan-inhibiteurs » et de nouveaux outils de diagnostics. Pour cela, la caractérisation biochimique des carbapénèmases de type KPC, NDM et OXA-48, de leurs variants naturels et de mutants générés in vitro a été entreprise. Il a pu être mis en exergue l’implication de résidus spécifiques et d’éléments structuraux nécessaires à l’ hydrolyse des carbapénèmes. L ’ étude cristallographique et RMN ainsi que l’étude in silico (modélisation) de ces enzymes et de leurs mutants respectifs, nous a permis de mieux comprendre le mode d’ interaction enzyme- substrat. Nous avons ainsi pu comprendre les bases de la capacité impressionnante de ces carbapénèmases à s’adapter et à évoluer en fonction des pressions de sélections exercées.En collaborations avec différentes équipes de chimistes nous avons développés différentes séries de molécules « pan-inhibiteurs » capables d’inhiber les 3 classes de carbapénèmases. Ainsi nous avons montré un effet inhibiteur de certains composés de la famille des flavonoïdes dont la myrécétine, molécule la plus active. Nous avons également identifié une série de composés, les imidazolines, possédant un effet pan-inhibiteur avec des valeurs de CI50 sub-micromolaires et donc compatible avec une utilisation in vivo.Enfin, nous avons participé au développement (en collaboration avec le CEA) d’ un outil de diagnostic rapide basé sur l’immunochromatographie, permettant détection des EPC en moins de 15 minutes. / Antibiotics, and particularly ß- lactams, have long been considered the ultimate weapon for the treatment of bacterial infections, because of their effectiveness, good tolerance and low cost. However, bacteria have developed mechanisms of resistance, including against β- lactams with the broadest spectrum of activity, carbapenems. The latter are considered as last resort antibiotics for the treatment of severe infections due to Gram negative bacilli in hospital. This emerging resistance to carbapenems in Enterobacteriaceae is mainly due to the expression of enzymes called carbapenemases capable of inactivating carbapenems. The worldwide exponential spread of these carbapenemase-producing enterobacteria (CPE) represents a major public health issue. Currently, the most common carbapenemases in the world are KPC (Klebsiella pneumoniae carbapenemase), NDM-1 (New Delhi metallo-β-lactamase) and OXA-48 (Oxacillinase). The first KPC was identified in 1996 in the United States, NDM-1 in 2009 in Sweden in a patient from India and OXA-48 in 2003 in Turkey. In France, OXA-48- type are the most abundant carbapenemases with nearly 70% of the EPCs. Thus, the repercussion of their dissemination and the development of new inhibitors capable of inactivating carbapenemases is becoming more and more urgent.The aims of this thesis were to better understand the mode of action of the 3 main carbapenemases from a molecular and biochemical point of view, in order to identify the structural elements necessary for their functioning, but also to lay the basis for the development of "pan-inhibitors" and noveldiagnostic tools. For this purpose, the biochemical characterization of carbapenemases of the KPC, NDM and OXA-48 type, their natural variants and mutants generated in vitro has been undertaken.We could highlight the involvement of specific residues and structural elements necessary for the hydrolysis of carbapenems. The crystallographic and NMR study as well as the in silico (modeling) studies of these enzymes and their respective mutants, allowed us to better understand the enzyme-substrate interaction mode. We could thus understand the basis of the impressive capacity of these carbapenemases to adapt and therefore to evolve according to the selection pressures exerted.In collaboration with several chemists we participated in the development of different series of "pan-inhibitors" that were able to inhibit the 3 classes of carbapenemases. Thus we could show the inhibitory properties of some compounds of the family of flavonoids including myricetin, the most active molecule. We have also been able to identify a series of compounds, imidazolines, possessing a pan- inhibitory effect with sub-micromolar IC50 values and therefore compatible with in vivo use. Finally, we participated in the development (in collaboration with the CEA) of a rapid diagnostic tool based on theimmunochromatographic, allowing the detection of EPCs in less than 15 minutes.

This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department (rlmlill@iu.edu).

No description available.

Introduction: In this decade, the CTX-M family of enzymes are considered to be the most common type of extended-spectrum β-lactamases (ESBLs). The production of these Class A β-lactamases are noted to be most prevalent in the Enterobacteriaceaeae family. Many global reports indicated that CTX-M-15, of the CTX-M-1 group, is a growing concern, causing resistance to different classes of antibiotics. Worrisome trends of the spread of this enzyme have been indicated in nosocomial and community settings worldwide. Moreover, the same predicament is faced along the Middle East area, especially in the absence of restricted antibiotic usage policies. Many reports from Kuwait indicated the spread of a multi-drug resistant (MDR) blaCTX-M-15 gene in different hospitals. blaCTX-M-15 genes are often known to be carried on large transferable plasmids. Usually, the mobilization of these plasmid-encoded enzymes is carried out by insertion sequence like ISEcp1. Aims: This work aims to investigate the distribution of blaCTX-M genes in five major hospitals in Kuwait and to study and analyse the genetic environment of the described blaCTX-M genes. Materials and methods: One hundred and seven isolates of E. coli (84) (78.50%) and K. pneumoniae (23) (21.49%) were collected between 2006 and 2010 from five distantly located hospitals in Kuwait. All of the collected isolates were identified as ESBL-producers using Vitek 2 system. The production of cefotaximases was detected using disc diffusion with cefotaxime and clavulanic acid according to Clinical and Laboratory Standards Institute (CLSI) criteria. Conformation of CTX-M production was maintained by PCR amplification and further sequencing. The minimum inhibitory concentrations (MICs) of the collected isolates were determined by the double dilutions agar method described by the CLSI. Four different classes of antibiotics were used (aminoglycosides, different generations of cephalosporins, fluoroquinolones, and 3 different carbapenems). The genotypic relatedness of the collected strains was assessed by the use of an enhanced Pulsedfield gel electrophoresis (PFGE) method. Further amplifications with primer walking and simplex PCR were done to seek the genetic context of the MDR strains. S1 nuclease was used to size plasmids carrying the described blaCTX-M genes and conjugation studies were implemented to detect the transferability of the plasmids carrying the reported blaCTX-M genes. Results: All of the collected strains showed to be ESBL-producers and in particular cefotaximases-producers. Upon amplification, CTX-M-1 group was the only CTX-Mgroup present in the collected strains. When sequenced, blaCTX-M-15 was found to be the most prevalent. In addition, strains carrying the blaCTX-M-3 gene were identified, these have previously been found in the Middle East; however, this thesis has the first descriptions of blaCTX-M-28, blaCTX-M-55, and blaCTX-M-117 in this region. After the determination of the MICs of the collected strains, 94 (87.85%) were resistant to cefepime, 107 (100%) to cefotaxime, 48 (44.85%) to cefoxitin, 78 (72.89%) ciprofloxacin, and 71 (66.35%) to gentamicin. All of the strains were susceptible to carbapenems. Twenty-eight strains (26.2%) showed MDR pattern. With the enhanced PFGE method, only 22 isolates exhibited banding patterns that allowed grouping them into 10 distinct PFGE clusters. Notably, strains sharing ≥85% were from the same hospitals (isolates 1 with 2, 21 with 22, and 91 with 92 from the maternity hospital (M), 52 with 53 from Kuwait Oil Company hospital (KOC), 78 with 79 and 83 with 84 from Infectious Diseases Hospital (IDH), 97 with 98 and 95 with 96 from Al-Amiri hospital(A) ). Primer walking and simplex PCR experiments used for the genetic environment studies yielded 7 different genetic constructions for the described blaCTX-M genes. All of the described blaCTX-M genes were carried on plasmids ranging in size from 60 – 271 kb. Only 3 of the selected strains were of IncFII and the rest wereindeterminate. Possibly, two blaCTX-M-15 genes are likely to be carried on the chromosome. All of the described blaCTX-M genes are considered to be transferable except for blaCTX-M-28. The sizes of the conjugative plasmids and incompatibility groups are the same as their parental plasmids. Conclusion: In conclusion, blaCTX-M-15 is the most common ESBL gene found in Kuwaiti hospitals. It is also causing a MDR pattern with resistance to 3 different generations of cephalosporins and to two other classes (aminoglycosides and gentamicin), but sensitive to carbapenems. This led to restricting the treatment option into carbapenems. Antibiotic selective pressure could have played a major role in the development of blaCTX-M-15 derivatives such as blaCTX-M-28, blaCTX-M-55, and blaCTX-M-117. The probable explanation of the spread of blaCTX-M-15 is horizontal gene transfer carried by ISEcp1 and the conjugative properties of the plasmids carrying blaCTX-M-15. Variability of the genetic environments obtained explains the nonconditional existence of ISEcp1 to the ‘’W’’ region. Absence of the ISEcp1 in one of the reported structures of blaCTX-M-15 genetic contexts is noted. Therefore, the existence of blaCTX-M-15 could be due to the presence of another insertion sequences downstream or as a part of a larger gene cassette.

Thesis (Ph. D.)--School of Pharmacy and Dept. of Chemistry. University of Missouri--Kansas City, 2005. / "A dissertation in pharmaceutical sciences and chemistry." Advisor: Steven H. Neau and Thomas P. Johnston. Typescript. Vita. Description based on contents viewed Mar. 12, 2007; title from "catalog record" of the print edition. Includes bibliographical references (leaves 97-108). Online version of the print edition.