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Carbon-infiltrated carbon nanotube (CICNT) forests are carbon nanotube (CNT) forests infiltrated with pyrolytic carbon to increase durability by becoming a solid material. This material can be tuned to maintain the nanotube geometry of a CNT forest and can also be fabricated on a variety of materials and geometries. Additionally, the present work has indicated that CICNT forests may resist bacterial proliferation and biofilm formation. This phenomenon is not due to the CICNT chemistry; it is presumably due to the CICNT nanostructure morphology. Thus, both silicon and stainless steel substrates were used to investigate CICNT's structural resistance to Methicillin-resistant Staphylococcus aureus (MRSA) biofilm. From in vitro experimental testing, CICNT on both these substrates resisted MRSA cell attachment and biofilm proliferation. The discovery of this non-pharmaceutical biofilm resistance expands the potential applications of CICNT to include medical devices that are prone to infection and/or devices that contribute to infection. Two representative applications were investigated: external fixator pins and scalpel blades. CICNT-coated versions of these applications underwent additional MRSA biofilm resistance testing as well as mechanical testing. In particular, external fixator pins were identified as a high potential application of CICNT surface coating technology. Previous work on both CNT and CICNT forests has largely been performed on planar structures. However, any potential medical device applications involve curved substrates. In particular, concave curvatures are challenging due to the potential for stress-related CICNT forest defects. Thus, the present work also included a study of the incidence rates and determining factors of these defects. SEM images of the cross-sections revealed different types of microscale forest defects while the top surface showed morphologies that are largely consistent with flat substrates. CICNT forest height and substrate curvature were identified as contributing factors to CICNT forest defect incidence rates. Thus, the present work advances the understanding of bacterial resistance and microstructure-related properties of CICNT surface coatings, with applications in medical devices.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Poultry production is a very important economic activity in Brazil once the country is among the highest world avian producers. The knowledge of the pathogens epidemiology is essential to the control of infectious diseases and such control is very strict in chickens and turkeys on the avian industry. However, the avian population of the country shows a big diversity of domestic and wild birds and the chicken backyard population is out of this control. To investigate the presence of antibodies against specific viruses in the backyard chicken population, blood was collected of 867 non-vaccinated birds, from 60 farms and 22 counties from the Rio Grande do Sul State, Brazil. Neutralizing antibodies against infectious bronchitis virus (IBV) were detected in 65% (564/867) of the individuals, against avian reovirus (ARV) in 21.6% (187/867) and, against infectious bursal disease virus (IBDV) in 80.2% (695/867). The results presented on the first chapter indicated that the tested viruses are circulating among this population. Among the wild species there is a group of Galliformes, classified at the Cracidae family and commonly known as guans, chachalacas and curassows which deserved a special attention in the present study. To determine the microbiota, the bacterial resistance and the presence of antibodies against specific viruses in these birds, fifty one serum and cloacal swab samples were collected from 10 different cracid species captive in the Rio Grande do Sul State during 2007. Serum samples were submitted to serum-neutralization test and specific antibodies were detected against IBV in 5.9% (3/51) of the cracids, against ARV in 15.7% (8/51) and, against IBDV in 35.3% (18/51). All the samples were found to be negative to fowlpox virus by the AGID test. Bacterial isolation and identification were performed from the cloacal swabs. After that, the isolates were tested for antimicrobial susceptibility. Ninety three bacterial isolates were obtained from 10 different genera. Escherichia spp., Staphylococcus spp. and Streptococcus spp. are among the most prevalent genera. Antimicrobial resistance was observed in several isolates, with Serratia marcescens presenting the highest level of resistance to multi drugs followed by Streptococcus spp., Staphylococcus aureus and Escherichia coli, among others. The results from the second chapter of this dissertation allowed us to conclude that bacterial resistance is spread in the captive cracid microbiota and, most importantly, these species are susceptible to the infection by IBV, IBDV and ARV. / A avicultura é uma das principais atividades econômicas do Brasil, que ocupa posição de destaque entre os exportadores de frango e subprodutos. O conhecimento da epidemiologia de patógenos que podem gerar prejuízos a essa atividade é essencial para o controle das enfermidades infecciosas. Este controle é realizado em larga escala em galinhas e perus criados no sistema industrial. Entretanto a população avícola do país consiste de uma grande diversidade de aves domésticas e selvagens, sendo o grupo conhecido como galinhas de terreiro formado por indivíduos desta espécie criados fora do sistema industrial. Com o objetivo de investigar a presença de anticorpos contra alguns vírus específicos na população de galinhas de terreiro, foram coletadas amostras de sangue de 867 galinhas não vacinadas, em 60 propriedades de 22 municípios do Estado do Rio Grande do Sul, Brasil, que foram testadas pela técnica de soroneutralização. Anticorpos contra o vírus da bronquite infecciosa das galinhas (IBV) foram detectados em 65% (564/867) destas aves, contra o reovírus aviário (ARV) em 21,6% (187/867) e contra o vírus da doença infecciosa da bolsa (IBDV) em 80,2% (695/867). Os descritos no primeiro capítulo desta dissertação permitiram demostrar a circulação dos vírus testados na população descrita. No segundo capítulo trabalhou-se com aves da ordem Galliformes, pertencentes à família Cracidae e conhecidos popularmente como jacus, jacutingas, araquãs e mutuns, com o intuito de conhecer a microbiota, resistência bacteriana e a presença de anticorpos contra vírus de aves, 51 amostras de soro e swab cloacal de 10 diferentes espécies de cracídeos cativos do Estado do Rio Grande do Sul foram coletadas durante o ano de 2007. As amostras de soro foram utilizadas para a detecção de anticorpos neutralizantes contra o IBV, ARV e IBDV, onde obteve os seguintes resultados: contra o IBV em 5,9% (3/51) das amostras positivas, contra o ARV em 15,7% (8/51) e contra o IBDV em 35,3% (18/51). Através do teste de imunodifusão em gel de ágar (IDGA) determinou-se que todas as amostras de soro eram negativas para o vírus da bouba aviária. Para o isolamento e identificação bacteriana foram realizados dos swabs cloacais e, posteriormente, foi testada a susceptibilidade antimicrobiana. Foram obtidos 93 isolados bacterianos, divididos em 10 diferentes gêneros. Entre os gêneros bacterianos mais prevalentes estavam Escherichia spp., Staphylococcus spp. e Streptococcus spp. Foi observada em grande número de isolados resistência à antimicrobianos, sendo que a bactéria Serratia marcescens apresentou o maior índice de resistência múltipla antimicrobiana. Os altos índices de resistência também foram detectados para Streptococcus spp., Staphylococcus aureus e Escherichia coli. Os resultados apresentados permitem concluir que a resistência bacteriana está disseminada na microbiota de cracídeos cativos e que indivíduos destas espécies são suscetíveis à infecção pelo IBV, IBDV e ARV, assim como as galinhas de terreiro.

L’organisation mondiale de la santé estime que le choléra entraîne 100, 000 décès par an pour environ 4 millions de cas recensés, plaçant ainsi cette maladie comme un enjeu de santé publique majeur. Cette infection est causée par Vibrio cholerae, une bactérie à Gram négatif vivant en milieu aquatique. Face à cette agression, l’épithélium intestinal et les bactéries du microbiote agissent comme une barrière, en exprimant notamment des peptides antimicrobiens (PAM). V. cholerae, comme de nombreux pathogènes, montre une résistance accrue aux PAM. Malgré une avancée constante sur la compréhension des mécanismes de résistances bactériens aux PAM, de nombreuses inconnues demeurent, principalement en raison des techniques de mutagénèse aléatoire utilisées pour leur identification. L’objectif de cette étude est d’identifier de nouveaux mécanismes de résistance impliqués dans la résistance de V. cholerae aux PAM. Grâce à des expériences de séquençage par spectrométrie masse suivi d’études bio-informatiques, nous avons identifié les protéines OmpV et Lap comme des candidates intéressantes pour être impliquées dans la résistance de V. cholerae. Alors que la souche V. cholerae A1552 délétée du gène ompV (DompV) ne semble pas présenter de défaut de croissance ou de perméabilité, nos résultats ont montré une diminution des concentrations minimales inhibitrices en différents PAM tels que LL-37. Les tests fonctionnels semblent suggérer l’implication des vésicules de sécrétion dans le mécanisme de d’OmpV face à LL-37 chez V. cholerae. / According to the World Health Organization, cholera remains a significant health problem, causing 100,000 death per 4 millions infections per year. V. cholerae, the etiologic agent of cholera and a Gram-negative bacterium, is generally transmitted via contaminated food or water. During infection, the microbiota and intestinal epithelium acts as a barrier by producing antimicrobial peptides (AMP). Resistance to AMP has emerged as a virulence factor in pathogens and specifically in V. cholerae. As AMP are considered as novel molecular therapeutic agents, it is truly important to better understand strategies of resistance of V. cholerae. The aim of this study is to identify unknown mechanisms involved in V. cholerae resistance to AMP. For this purpose, after protein sequencing by mass spectrometry (MS-MS) and bioinformatics, we identified the OmpV porin, member of the outer membrane protein family and the Lap protease as new protein candidates for strategies of resistance. We characterized the V. cholerae A1552 strain deleted for ompV (DompV). We confirmed OmpV implication in AMP resistance by minimum inhibitory concentration and did not observed any differences in growth or permeability in the presence of AMP between the wild-type (wt) and the (DompV) strains. The work presented here suggest an implication of outer membrane vesicules in V. cholerae resistance mechanisms to some AMP as LL-37.