Para avaliar a capacidade da toxina ExoU de P. aeruginosa de induzir a expressão do fator tissular (FT) por células epiteliais respiratórias da linhagem BEAS-2B, células infectadas pela cepa PA103, produtora da toxina, foram comparadas com outras infectadas por cepa mutante obtida por deleção do gene exoU e com células controles não infectadas quanto a i) expressão do mRNA do FT, por RT-PCR; ii) expressão da proteína FT em lisados celulares, por ensaio imunoenzimático (ELISA), e na superfície celular, por citometria de fluxo; iii) atividade pró-coagulante das células, pela determinação da capacidade de indução de coagulação de plasma humano normal e do lisado celular, através de ensaio colorimétrico; iv) presença de FT solúvel no sobrenadante das culturas, por ELISA; v) liberação de micropartículas expressando FT e fosfatidilserina (FS), por citometria de fluxo. Nossos resultados mostraram que ExoU foi responsável pelo aumento da expressão do mRNA e da concentração da glicoproteína FT tanto nos lisados quanto na superfície celular. Esse aumento foi revertido quando as bactérias foram tratadas com uma droga inibidora de PLA2 (MAFP), comprovando-se a dependência da atividade fosfolipásica A2 de ExoU para a modulação da expressão do FT. Células infectadas pela cepa PA103 induziram uma diminuição no tempo de coagulação do plasma humano normal e o aumento da hidrólise do substrato sintético utilizado no teste colorimétrico em comparação com as células infectadas com a cepa mutante, mostrando que o FT expresso era funcionalmente ativo. Foi também detectado um aumento na concentração de FT solúvel presente nos sobrenadantes de culturas infectadas por PA103 e no número de micropartículas expressando, simultaneamente, FT e FS em relação à cultura infectada pela cepa PA103∆exoU. Os resultados obtidos nos testes in vitro foram validados pela demonstração de que a concentração de FT no parênquima pulmonar de camundongos infectados, por via intratraqueal, com a cepa selvagem foi significativamente superior à detectada nos animais infectados com a cepa mutante. / To evaluate the capacity of the P. aeruginosa toxin ExoU to induce the expression of tissue factor (TF) by epithelial respiratory cells from the BEAS-2B cell line, cells infected with the ExoU-producing PA103 bacterial strain were compared with cells infected with a mutant obtained by deletion of the exoU gene and with control non-infected cells in their i) expression of the TF mRNA, by RT-PCR; ii) expression of the protein TF in cell lisates and surfaces, by enzyme immunoassay (ELISA) and flow cytometry, respectively; iii) procoagulant activity by determining the ability of intact cells to induce the coagulation of normal human plasma and the ability of cell lysates to cleave the synthetic substrate of a chromogenic assay; iv) presence of soluble TF in cell culture supernatants, by ELISA and v) release of microparticles simultaneously expressing TF and phosphatidylserine, by flow cytometry. Cells infected with the wild type bacteria exhibited increased expression of TF mRNA 1 hour after infection and a positive modulation of TF expression in both cell lysates and cell surfaces. The enhancement of TF expression was inhibited when cells were infected with bacteria previously treated with a PLA2 inhibitor (MAFP), confirming that the ability of ExoU to modulate TF expression depended on its phospholipase A2 activity. Newly expressed TF was shown to be functionally active, by both the decrease in the clotting time of human plasma and the enhancement of the hydrolysis of the chromogenic assay substrate. Cells infected with the ExoU-producing bacteria exhibited also higher concentrations of soluble TF and of TF and PS bearing microparticles in the cell culture supernatants. These in vitro results were validated by our finding of increase TF concentrations in the lung parenchyma of mice infected intratracheally with the ExoU producing-bacteria at 24 h post-infection.

Pseudomonas aeruginosa est un pathogène opportuniste à Gram-négatif, responsable d’infections nosocomiales chez des patients immunodéprimés et principale cause de morbidité et de mortalité chez les patients atteints de mucoviscidose. Les traitements utilisés contre P. aeruginosa peuvent être mis en échec en raison des nombreux mécanismes de résistance développés par la bactérie tels que les systèmes d’efflux RND, capables d’exporter les antibiotiques à l’extérieur de la cellule. Parmi ces systèmes, MexEF-OprN est très peu produit dans les souches sauvages mais il est surproduit chez les mutants appelés nfxC et conduit à une résistance aux fluoroquinolones, au chloramphénicol et au triméthoprime. Ces mutants ont également la particularité de résister de façon concomitante aux carbapénèmes et d’être peu virulents. Notons enfin que la pompe MexEF-OprN est codée par un opéron à trois gènes, mexEF-oprN, dont la transcription est activée par MexT, un régulateur appartenant à la famille LysR.Les mutants nfxC étant peu décrits dans le contexte clinique, nous avons évalué leur prévalence et caractérisé les événements génétiques conduisant à la surexpression de mexEF-oprN. A partir d’une collection de 221 souches cliniques isolées au CHRU de Besançon, et sélectionnées en raison de leur sensibilité diminuée à la ciprofloxacine et à l’imipénème, 19.5% surexprimaient mexEF-oprN. Nous avons par la suite caractérisé 22 souches non-redondantes et montré que seulement 13.6% d’entre elles possédaient des mutations inactivatrices dans le gène mexS alors que 40.9% avaient des mutations conduisant à la substitution d’un seul acide-aminé. Il est apparu que ces dernières mutations avaient des effets modérés sur les profils de résistance et de virulence alors que les mutations inactivatrices donnaient des hauts niveaux de résistance mais aucune virulence. Enfin, nous n’avons pas pu identifier de mutations génétiques pouvant expliquer la surexpression de mexEF-oprN des 45.5% de souches restantes, suggérant l’existence des mécanismes de régulation encore inconnus de cet opéron.Nous avons donc étudié des mutants résistants au chloramphénicol, sélectionnés in vitro à partir de la souche de référence PA14. Leur caractérisation nous a permis de découvrir un nouveau type de mutants surproducteurs de MexEF-OprN que nous avons appelé nfxC2. Tous possédaient des mutations gain-de-fonction sur le gène PA14_38040 (nommé cmrA) codant pour un régulateur de la famille AraC, jamais étudié auparavant. Chez les mutants nfxC2, l’expression de cmrA est augmentée, ainsi que celle de l’opéron mexEF-oprN et ceci, d’une façon MexS- et MexT-dépendante. De façon intéressante, ces mutations dans cmrA font apparaître un phénotype résistant sans toutefois altérer la virulence de la souche. Une analyse transcriptomique a montré que CmrA pouvait activer l’expression de 11 gènes parmi lesquels PA14_38020 apparaît comme étant nécessaire pour l’activation indirecte de mexEF-oprN. Ce gène code pour une quinol monooxygenase partageant des domaines conservés avec YgiN, une enzyme d’Escherichia coli qui participe à la réponse contre les électrophiles. D’ailleurs, l’exposition de la souche PA14 à des concentrations sub-inhibitrices d’électrophiles toxiques (glyoxal, méthylglyoxal et cinnamaldéhyde) active suffisamment la pompe MexEF-OprN pour générer un phénotype de résistance et ce, de façon CmrA-dépendante. Enfin, cette même exposition aux électrophiles active également deux autres pompes RND, à savoir MexAB-OprM et MexXY/OprM. Les voies de régulation conduisant à l’activation de ces deux opérons d’efflux seront étudiées prochainement au laboratoire. / Pseudomonas aeruginosa is a Gram negative opportunistic pathogen, responsible for several nosocomial infections in immunocompromised patients, and the main cause of mortality and morbidity of patients suffering from cystic fibrosis. Treatment of P. aeruginosa infections turns to be difficult due to its natural resistance to antibiotics, increased in part by the overproduction of RND efflux pumps capable to export antibiotics out of the cell. Amongst these systems, MexEF-OprN exports several antibiotics such as fluoroquinolones, chloramphenicol and trimethoprim. This efflux pump is quiescent in wild-type strains but it is highly produced in nfxC mutants, making them resistant to MexEF-OprN substrates. In addition, these mutants are characterized by their concomitant resistance to carbapenems and their low-virulence profile. MexEF-OprN is encoded by a three-gene operon, mexEF-oprN, whose transcription is activated by MexT, a member of the LysR family of transcriptional regulators. In the clinical context, nfxC mutants being poorly described, we evaluated their prevalence and characterized the genetic events responsible for mexEF-oprN overexpression. A collection of 221 clinical isolates from the University Hospital of Besançon exhibiting a reduced susceptibility to ciprofloxacin and imipenem was screened. We found that 19.5% of these strains overexpressed mexEF-oprN and further characterization of the 22 non-redundant mutants showed that only 13.6% of these mutants harbored a disrupted mexS gene. Moreover, 40.9% of nfxC clinical strains harbored missense mutations in mexS conducing to the substitution of a single amino-acid residue in the encoding protein. Interestingly, these mutations were associated to moderate effects on resistance and virulence factor production while disruptive mutations produced highly resistant but completely non-virulent strains. For the 45.5% of remaining strains, we failed to identify genetic mutations, which could explain mexEF-oprN overexpression; this indirectly suggested that there might be additional regulatory loci controlling the expression of this operon.We thus studied chloramphenicol resistant mutants selected in vitro derived from reference strain PA14 and found a new class of MexEF-OprN overproducers, which we called nfxC2, harboring gain-of-function mutations in a so-far uncharacterized gene, PA14_38040 (hereafter called cmrA) coding for an AraC transcriptional regulator. In nfxC2 mutants, the mutated CmrA increases its proper gene expression and upregulates the expression of mexEF-oprN through MexS and MexT, resulting in a multi-drug resistant phenotype without altering virulence factor production. Transcriptomic experiments showed that CmrA positively regulates the expression of 11 genes, including PA14_38020, which is required for the MexS/MexT-dependent activation of mexEF-oprN. Gene PA14_38020 is predicted to code a quinol monooxygenase sharing conserved domains with YgiN of Escherichia coli, which was reported to be involved in the response of the bacterium to electrophiles. Interestingly, exposure of strain PA14 to sub-inhibitory concentrations of toxic electrophiles (glyoxal, methylglyoxal or cinnamaldehyde) strongly activates the CmrA-pathway and upregulates mexEF-oprN sufficiently to provoke the resistance to the pump substrates. Finally, we found that the same exposure to electrophiles is capable to activate two other RND pumps, MexAB-OprM and MexXY/OprM. The regulatory pathways conducing to activation of these two efflux operons will be elucidated at the laboratory.

P. aeruginosa est un pathogène opportuniste capable d'infecter un large spectre d'hôtes. Elle possède un vaste arsenal de facteurs de virulence. Le système de sécrétion de type III (SSTT) est un facteur de virulence majeur dont la régulation est complexe pour permettre une adaptation la plus précise possible de la bactérie au cours de l'infection. Nous nous sommes intéressés à déterminer le rôle potentiel de nouveaux acteurs de l'adaptation de P.aeruginosa au cours de l'infection. La porine OprF qui représente la protéine la plus abondante de la membrane externe de P. aeruginosa lui permettrait d'évaluer l'état d'activation du système immunitaire de son hôte afin d'adapter sa virulence. Chez P. aeruginosa, le tryptophane est le précurseur des kynurenines qui sont également produites par l'hôte à partir du tryptophane et qui, dans ce dernier contexte, sont des immunomodulateurs. Peu ou pas d'études ont été réalisées pour mettre en œuvre un éventuel rôle d'immunomodulation ou dans la virulence des kynurénines bactériennes. Dans un premier temps, nous nous sommes intéressés à un signal anciennement découvert au laboratoire et qui réprime l'expression du SSTT à haute densité bactérienne. Nous avons montré que ce signal exerce une régulation post-transcriptionnelle en plus d'une inhibition de la transcription des gènes du SSTT. Le métabolisme du tryptophane et de l'anthranilate semble être au cœur de ce processus de régulation. En inactivant des voies du catabolisme du tryptophane, nous avons montré que la production de ce signal dépend partiellement de la voie des kynurénines mais ne dépend pas ni des voies classiques du quorum sensing ni de l'opéron phnAB, impliqué dans la synthèse de l'anthranilate. Cependant, la voie des phénazines pourrait être impliquée dans la production de ce signal. Par CLHP couplée à la spectrométrie de masse, nous avons pu séparer des espèces moléculaires réprimant le SSTT et qui sont contenues dans ce signal, mais l'identification précise nécessite plus d'investigations. Dans un second temps, nous nous sommes intéressés aux kynurénines produites par la bactérie. Nous avons confirmé que P. aeruginosa produit des kynurénines et le gène kynA est le gène clé de la voie de synthèse de ces métabolites. En utilisant des fusions transcriptionnnelles, nous avons montré que le tryptophane et la kynurénine régulent positivement la production des kynurénines en agissant sur l'expression des gènes clés. D'autres parts, nous avons remarqué que la bactérie module l'activité de la voie métabolique des kynurénines issue du tryptophane en fonction de son état de croissance. Nous avons montré qu'au cours du dialogue interrègne bactérie/hôte, la voie des kynurénines de P. aeruginosa est stimulée par certains composants du système immunitaire. Grâce à un modèle d'infection pulmonaire aiguë, nous avons prouvé que les kynurénines produites par la bactérie sont importantes pour sa virulence. Selon notre hypothèse les kynurénines pourraient avoir une action sur la réponse immune, mais cela reste à déterminer. Dans un troisième temps, nous nous somme focalisés sur la porine OprF. Nous avons montré que la mutation ∆oprF est à l'origine d'une altération de la production mais vraisemblablement pas de la sécrétion des exotoxines du SSTT. Un ligand connu d'OprF, l'interféron gamma, module la voie des kynurénines. OprF pourrait donc avoir un rôle central dans les différents aspects de la régulation de la virulence. Nous avons donc produit des anticorps monoclonaux anti-OprF. Ces derniers se sont révélés capables de reconnaître spécifiquement la protéine OprF. Afin de vérifier l'efficacité de ces anticorps, des expériences de neutralisation de la bactérie in vitro puis in vivo seront réalisées. Mots clés : Pseudomonas aeruginosa, Système de Sécrétion de Type III, régulation, catabolisme du tryptophane, kynurénines, OprF. / P. aeruginosa is an opportunistic pathogen capable of infecting a wide host range. It possesses a large arsenal of virulence factors. The type III secretion system (TTSS) is a major virulence factor whose regulation is complex to allow the most accurate adaptation of the bacteria during infection. We were interested to determine the potential role of new actors in the adaptation of P. aeruginosa during infection. OprF represents the most abundant protein of the outer membrane of P. aeruginosa. This protein allows bacteria to assess the activation status of the host's immune system to adapt its virulence. In P. aeruginosa, tryptophan is the precursor of kynurenines that are also produced by the host from tryptophan and in the latter context, are immunomodulators. Little or no studies have been done to determine a possible role of bacterial kynurenines in immune modulation or virulence. Initially, we were interested in a signal previously discovered in the laboratory and which suppresses the expression of TTSS at high bacterial density. We have shown that this signal exerts a post-transcriptional regulation in addition to inhibition of TTSS genes transcription. The metabolism of tryptophan and anthranilate appears to be at the heart of this regulatory process. By inactivating pathways of tryptophan catabolism, we showed that production of this signal depends partly on the kynurenines pathway but does not depend neither classical ways of quorum sensing or phnAB operon involved in the synthesis of anthranilate. However, the phenazines pathway could be involved in the production of this signal. By HPLC coupled with mass spectrometry, we were able to separate molecular species suppressing the TTSS and which are contained in this signal, but accurate identification requires further investigation. In a second time, we were interested to kynurenines produced by the bacterium. We confirmed that P. aeruginosa produces kynurenines and KynA is the key gene in the synthesis of these metabolites. We showed that tryptophan and kynurenine upregulate the production of kynurenines by acting on the expression of key genes. Other shares, we found that the bacterium modulates the activity of the kynurenines pathway depending on its state of growth. We showed that during the dialogue bacteria / host, the pathway of kynurenines in P. aeruginosa is stimulated by certain immune system components. With an acute lung infection model, we proved that kynurenines produced by the bacterium are important to its virulence. We hypothesized that the kynurenines could have an effect on the immune response, but this remains to be determined. In a third time, we focused on the protein OprF. We showed that mutation ΔoprF is causing an alteration in production but probably not the secretion of TTSS exotoxins. One known ligand of OprF is the gamma interferon. It modulates the pathway of kynurenines. OprF could therefore have a central role in various aspects of the regulation of virulence. So, we produced monoclonal anti-OprF which recognizes specifically the protein OprF. To verify the effectiveness of these antibodies, neutralization experiments of the bacteria in vitro and in vivo will be realized.

Orientador: Fernando Antônio de Ávila / Banca: José Moacir Marim / Banca: Patricia Amoroso / Banca: Simone Barone Salgado Marques / Banca: Tammy Priscilla Chioda Delfino / Resumo: Foram estudadas 180 amostras de água de 45 consultórios odontológicos da cidade de Barretos-SP, com o objetivo de isolar, identificar, determinar a contagem de isolados de Pseudomonas aeruginosa UFC/mL, determinar o perfil clonal e avaliar a diversidade genômica dos isolados e a suscetibilidade das mesmas frente a diferentes antibióticos. As amostras de água foram filtradas em filtro Millipore® e a membrana colocada sobre o centro de uma placa de Petri contendo agar cetrimida, As colônias típicas de bactérias do gênero Pseudomonas foram identificadas pelo método de Gram, inoculação em TSI agar (Triple Sugar Iron), crescimento a 42ºC, produção de pigmento, produção de alginato, oxidase, motilidade e alcalinização da acetamida. O teste utilizado para análise genômica foi o ERIC-PCR. Dos 76 (42,2%) isolados de Pseudomonas aeruginosa, 15 eram provenientes das amostras de torneira de lavagem das mãos, 18 de reservatório de garrafa pet, 23 de seringa tríplice e 20 do motor de alta rotação. Todos os isolados de Pseudomonas aeruginosa foram submetidos ao teste de suscetibilidade segundo a técnica de Kirby- Bauer. Dos antibióticos testados o que apresentou melhor resultado quanto à sensibilidade (65,8%) foi a ciprofloxacina. Quanto à similaridade genética dos isolados dos diferentes pontos analisados, foram encontrados nove "clusters" de 100% de similaridade. / Abstract: The biofilm found in water supplies and lines of hospitals and dental units is extremely important because it presents a large number of bacteria, leading to risk of infection in immunocompromised patients vulnerable to opportunistic pathogens such as the Pseudomonas aeruginosa. One hundred eighty water samples from dental units of the city of Barretos-SP were evaluated. The water samples filtered in Millipore® filter were incubated in plates containing Cetrimide ágar. The bacteria colonies were identified through the gram-staining test, inoculation in agar T.S.I (triple sugar Iron), growth at 42 ° C, pigment production, production of alginate, oxidase acetamide alkalization and motility observation. All Pseudomonas aeruginosa bacteria were submitted to the susceptibility test according to the Kirby-Bauer technique. The test used for genomic analysis was the ERIC-PCR. From the total microorganisms studied, 76 (42,2%) were positive for Pseudomonas aeruginosa, isolates from 180 water samples, where 15 strains were from hand washing incoming local water supplies, 18 from PET bottled water, 23 from 3-in-1 syringes and 20 from the high speed handpiece. In relation to the antibiotics tested, the one presenting the best result with regard to sensibility was ciprofloxacin with 65.8%. The genetic similarity of isolates from different points analyzed, there were nine clusters of 100% similarity. / Doutor

Les biopiles microbiennes sont des sources d’énergies renouvelables utilisant des bactéries qui convertissent une énergie chimique en électricité. Pour cela, l’anode doit collecter les électrons issus des microorganismes. La sélection d’un matériau d’anode possédant de grandes performances est d’une importance cruciale dans la construction d’une biopile microbienne. Le graphène est considéré comme un matériau prometteur avec de grandes possibilités d’application dans de nombreux domaines tels que les batteries Li-ion, les cellules photovoltaïques et les super condensateurs électrochimiques en raison de sa structure nanométrique. Ainsi, la modification de surface par de l’oxyde de graphène réduit a été appliquée à la construction d’anodes pour biopiles microbiennes. La cathode abiotique a aussi été étudiée puisqu’elle présente souvent une limitation cinétique vis-à-vis de la réduction de l’oxygène. Les potentialités des complexes organométalliques, et en particulier les phthalocyanines de nickel, ont été étudiés et appliquées à la construction d’une cathode pour biopile. Ainsi, une biopile hybride à deux compartiments a été construite en combinant une bioanode en mousse d’acier inoxydable modifiée par de l’oxyde de graphène réduite et une cathode en feutre de carbone modifiée avec de la phthalocyanine de nickel. La biopile microbienne ainsi construite utilise du lixiviat de terreau, comme source de microorganismes, pour le développement d’un biofilm électroactif à l’anode et présente une bonne stabilité dans le temps. Le graphène a permis d’obtenir une densité de puissance stable pendant une période 40 jours (24.8 mW/m² en présence d’oxygène pur). La cathode présentée dans ce travail a permis d’obtenir une densité de puissance supérieure à une cathode de platine (7.5 fois supérieur). Par ailleurs, un nouveau design de biopile à deux compartiments a été construit, afin de produire de l’électricité à partir d’une souche pure : Pseudomonas aeruginosa qui est connu pour la formation de biofilm électroactive. Un nouveau design a été proposé, permettant de travailler à alimentation constante et non plus en batch comme cela se fait de manière classique. Cette configuration permet de ne plus avoir de diminution de courant liée à un manque d’apport en carburant. Différents paramètres ont ainsi été explorés tel que le débit d’alimentation, la consommation en glucose dans le compartiment anodique, la variation de pH au cours du temps ainsi que l’évolution de la biomasse. Une première approche d’étude de corrélation de ces différents paramètres est proposée. / Microbial fuel cell (MFC) has been considered as a renewable energy source which uses bacteria to convert chemical energy into electricity. Since the anode, as the electron acceptor for the electroactive bacteria, directly interacts with microorganisms, the selection of high performance anode materials is of crucial importance in the design of a MFC. Recently, graphene has been considered as the intriguing material, attracting strong scientific and technological interest with great application potentials in various fields, such as lithium ion batteries, solar cells and electrochemical super-capacitors, for its unique nanostructure and extraordinary properties. Therefore, surface modification using reduced graphene oxide has been investigated for the construction of anodes. An abiotic cathode has also been investigated since it often has a kinetic limitation regarding the oxygen reduction reaction. The potential of the use of organometallics complexes, and more particularly nickel phthalocyanines (poly-NiTSPc), has been studied and applied to the fabrication of cathodes for biofuel cells applications. Thereby, a dual chamber hybrid MFC has been constructed combining a reduced graphene oxide modified bioanode with a chemical poly-NiTSPc modified carbon felt. This MFC uses compost garden leachate, as source of microorganisms, for the growth of an electroactive biofilm onto the anode and presents an excellent lifetime. Indeed, graphene allowed to obtain a power density stable for 40 fays (24.8 mW/m² with pure oxygen). When the modified carbon felt was used as cathode, the power densities obtained were 7.5 higher than the use of platinum cathode. Furthermore, a new design of a dual chamber MFC has been built up in order to work with a constant flow, to supply continuously substrates to the biofilm formed onto the anode from a pure strain, Pseudomonas aeruginosa, and to avoid to work in a batch as it is usually done. The interest of this configuration is to prevent any current loss due to a lack in supply of substrates. Using this bioreactor as a MFC, different parameters have been explored such as the feed rate and the glucose consumption in the anodic compartment, the evolution of the pH as well as the biomass between the entrance and the exit of the chamber. A first study of the correlation between all these parameters has been proposed.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Pseudomonas aeruginosa and Acinetobacter spp. are non-fermenting Gram negative bacilli (NF-BGN), unable to use carbohydrates as an energy source through fermentation, are considered opportunistic and have great clinical importance in Related to Health Care Infections (HAIs). The high resistance to antimicrobials that these species present is attributed to a number of factors such as selective pressure of antimicrobials, inadequate empirical antimicrobial therapy, long periods of hospitalization and patient-related factors. A total of 102 isolates from the University Hospital of Santa Maria (HUSM) were studied with 63 Pseudomonas aerugionosa and 39 Acinetobacter spp.. The assessment of their sensitivity profile was performed using the standard disc diffusion method. Comparing the two genus, in this study, P. aeruginosa showed higher sensitivity than Acinetobacter spp. the antimicrobials tested. P. aeruginosa showed 85,7% sensitivity to polymyxin B and Acinetobacter spp. 41,0% to tetracycline.The mechanism of chromosome AmpC searched by the phenotypic test for beta-lactamase induction in Group 1 was only detected in P. aeruginosa (68,2%). None of the samples showed beta-lactamase extended spectrum (ESBL) evaluated the test of synergism or bringing the disks. Among P. aeruginosa, 57,1% were simultaneously sensitive to imipenem and meropenem, with these carbapenem-resistant strains were 100% sensitive to polymyxin B and tobramycin 61,5%. In the genus Acinetobacter only 15,4% were susceptible to imipenem and 17,9% to meropenem, but resistant to this class samples showed 100% sensitivity to polymyxin B and 59,4% to tetracycline. Multidrug resistance to antimicrobials detected this nosocomio mainly isolates of Acinetobacter spp. shows the importance of monitoring the sensitivity profile for the promotion of patient safety with the introduction of effective empiric treatment, and to constitute an attempt to minimize bacterial resistance. / Pseudomonas aeruginosa e Acinetobacter spp. são bacilos Gram negativos não fermentadores (BGN-NF), incapazes de utilizar carboidratos como fonte de energia através da fermentação, são considerados oportunistas e possuem grande importância clínica nas Infecções Relacionadas à Assistência à Saúde (IRAS). A elevada resistência aos antimicrobianos que estas espécies apresentam atribui-se a uma série de fatores como pressão seletiva dos antimicrobianos, terapia antimicrobiana empírica inadequada, longos períodos de hospitalização e fatores relacionados ao paciente. Um total de 102 isolados do Hospital Universitário de Santa Maria (HUSM) foram estudados sendo 63 Pseudomonas aerugionosa e 39 Acinetobacter spp.. A avaliação do seu perfil de sensibilidade foi realizada utilizando o método convencional de difusão do disco. Comparando os dois gêneros, neste estudo, P. aeruginosa apresentou maior sensibilidade que Acinetobacter spp., frente aos antimicrobianos testados. P. aeruginosa mostrou 85,7% de sensibilidade à polimixina B e Acinetobacter spp. 41,0% à tetraciclina. O mecanismo de AmpC cromossômica, pesquisado através do teste fenotípico de indução de beta-lactamase do Grupo 1, somente foi detectado em P. aeruginosa (68,2%). Nenhuma das amostras apresentou beta-lactamase de espectro estendido (ESBL) avaliado pelo teste do sinergismo ou da aproximação dos discos. Entre as P. aeruginosa, 57,1% apresentaram sensibilidade simultânea ao imipenem e meropenem, sendo que as cepas resistentes a estes carbapenêmicos foram 100% sensíveis à polimixina B e 61,5% à tobramicina. No gênero Acinetobacter somente 15,4% foram sensíveis ao imipenem e 17,9% ao meropenem, mas as amostras resistentes a esta classe apresentaram 100% de sensibilidade à polimixina B e 59,4% à tetraciclina. A multirresistência aos antimicrobianos detectada neste nosocômio, principalmente dos isolados de Acinetobacter spp. mostra a importância do monitoramento do perfil de sensibilidade para a promoção da segurança do paciente com a instituição do tratamento empírico efetivo, além de constituir-se numa tentativa de minimização da resistência bacteriana.

Made available in DSpace on 2014-12-17T15:01:54Z (GMT). No. of bitstreams: 1 MarcioSB_TESE.pdf: 2488710 bytes, checksum: a89cb34af4b96bdd59b8b2051a8431f1 (MD5) Previous issue date: 2012-06-11 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / This study evaluates the biosurfactants production from cassava wastewater, an agro industrial residue, to be used as carbon source. Using a factorial design 24-1 (half fraction), 10 tests were performed using Pseudomonas aeruginosa AP029/GVII-A in submerged batch cultivation in rotating incubator (shaker). The influence of factors (temperature, agitation, aeration ratio and concentration of cultivation medium) at two different levels for the synthesis of the biosurfactant. Samples were collected throughout the cultivation by 132 hours of fermentation were completed. The best outcome was intended by following production through substrate consumption, dry matter, reduction of surface tension (ring method) and emulsification index. The kinetics of microorganism was assessed for the carbon source used. The results showed that the cassava wastewater is a well assimilable substrate for the production of biotensoactive, reaching 91 % of consumption by the micro-organism under study. The growth temperature was found to be one of the leading factors in the synthesis of the metabolite, followed by aeration and also due to the agitation. The best results showed a 30 % reduction in surface tension (% RTS) for the environment, reaching values of 30 mN/m; 3.0 g /L of biomass and emulsifying index greater than 65 %. The metabolite synthesized still remained stable for different salt concentrations (1, 5 and 10 % w/ v) and alkaline pH (8-10). / O presente trabalho avalia a produ??o de biossurfactantes a partir de manipueira, um res?duo agroindustrial a ser utilizado como fonte de carbono. Empregando um planejamento fatorial 24-1 (fra??o meia), 10 ensaios foram realizados utilizando Pseudomonas aeruginosa AP029-GVIIA em cultivo descont?nuo submerso em incubador rotat?rio (shaker). Foi analisada a influ?ncia dos fatores (temperatura, agita??o, raz?o de aera??o e concentra??o do substrato) em dois diferentes n?veis para a s?ntese do biossurfactante. Amostras foram coletadas em intervalos regulares durante o cultivo at? 132 horas de fermenta??o. Buscou-se o melhor resultado acompanhando a produ??o atrav?s do consumo de substrato, massa seca, redu??o da tens?o superficial (m?todo do anel) e ?ndice de emulsifica??o. O comportamento cin?tico do micro-organismo foi avaliado para a fonte de carbono utilizada. Os resultados mostraram que a manipueira ? bastante assimil?vel e potencial substrato na produ??o do biotensoativo, onde se observou 91% de consumo pelo micro-organismo em estudo. A temperatura de cultivo revelou ser um dos fatores preponderantes na s?ntese do metab?lito, acompanhada pela raz?o de aera??o e agita??o. Os melhores resultados mostraram redu??o de 30% da tens?o superficial (%RTS) em rela??o ao meio inicial, alcan?ando valores de 31 mN/m; 3,0 g/L de biomassa e ?ndice de emulsifica??o superior a 65%. O metab?lito sintetizado ainda se mostrou est?vel para diferentes concentra??es salinas (1, 5 e 10% m/v) e pH alcalino (8-10).

Para avaliar a capacidade da toxina ExoU de P. aeruginosa de induzir a expressão do fator tissular (FT) por células epiteliais respiratórias da linhagem BEAS-2B, células infectadas pela cepa PA103, produtora da toxina, foram comparadas com outras infectadas por cepa mutante obtida por deleção do gene exoU e com células controles não infectadas quanto a i) expressão do mRNA do FT, por RT-PCR; ii) expressão da proteína FT em lisados celulares, por ensaio imunoenzimático (ELISA), e na superfície celular, por citometria de fluxo; iii) atividade pró-coagulante das células, pela determinação da capacidade de indução de coagulação de plasma humano normal e do lisado celular, através de ensaio colorimétrico; iv) presença de FT solúvel no sobrenadante das culturas, por ELISA; v) liberação de micropartículas expressando FT e fosfatidilserina (FS), por citometria de fluxo. Nossos resultados mostraram que ExoU foi responsável pelo aumento da expressão do mRNA e da concentração da glicoproteína FT tanto nos lisados quanto na superfície celular. Esse aumento foi revertido quando as bactérias foram tratadas com uma droga inibidora de PLA2 (MAFP), comprovando-se a dependência da atividade fosfolipásica A2 de ExoU para a modulação da expressão do FT. Células infectadas pela cepa PA103 induziram uma diminuição no tempo de coagulação do plasma humano normal e o aumento da hidrólise do substrato sintético utilizado no teste colorimétrico em comparação com as células infectadas com a cepa mutante, mostrando que o FT expresso era funcionalmente ativo. Foi também detectado um aumento na concentração de FT solúvel presente nos sobrenadantes de culturas infectadas por PA103 e no número de micropartículas expressando, simultaneamente, FT e FS em relação à cultura infectada pela cepa PA103∆exoU. Os resultados obtidos nos testes in vitro foram validados pela demonstração de que a concentração de FT no parênquima pulmonar de camundongos infectados, por via intratraqueal, com a cepa selvagem foi significativamente superior à detectada nos animais infectados com a cepa mutante. / To evaluate the capacity of the P. aeruginosa toxin ExoU to induce the expression of tissue factor (TF) by epithelial respiratory cells from the BEAS-2B cell line, cells infected with the ExoU-producing PA103 bacterial strain were compared with cells infected with a mutant obtained by deletion of the exoU gene and with control non-infected cells in their i) expression of the TF mRNA, by RT-PCR; ii) expression of the protein TF in cell lisates and surfaces, by enzyme immunoassay (ELISA) and flow cytometry, respectively; iii) procoagulant activity by determining the ability of intact cells to induce the coagulation of normal human plasma and the ability of cell lysates to cleave the synthetic substrate of a chromogenic assay; iv) presence of soluble TF in cell culture supernatants, by ELISA and v) release of microparticles simultaneously expressing TF and phosphatidylserine, by flow cytometry. Cells infected with the wild type bacteria exhibited increased expression of TF mRNA 1 hour after infection and a positive modulation of TF expression in both cell lysates and cell surfaces. The enhancement of TF expression was inhibited when cells were infected with bacteria previously treated with a PLA2 inhibitor (MAFP), confirming that the ability of ExoU to modulate TF expression depended on its phospholipase A2 activity. Newly expressed TF was shown to be functionally active, by both the decrease in the clotting time of human plasma and the enhancement of the hydrolysis of the chromogenic assay substrate. Cells infected with the ExoU-producing bacteria exhibited also higher concentrations of soluble TF and of TF and PS bearing microparticles in the cell culture supernatants. These in vitro results were validated by our finding of increase TF concentrations in the lung parenchyma of mice infected intratracheally with the ExoU producing-bacteria at 24 h post-infection.

A maioria das bactérias não cresce como células individuais, mas em comunidades estruturadas como organismos pseudomulticelulares, ou biofilmes, estando presentes em praticamente todos os ecossistemas naturais e patogênicos. A adesão bacteriana à superfície e subsequente formação de biofilme promove mudanças metabólicas, fenotípicas e genotípicas que faz com que a sua erradicação seja extremamente difícil. Desta maneira, microrganismos que apresentam susceptibilidade a determinados antimicrobianos em testes laboratoriais convencionais, são na verdade altamente resistentes aos mesmos quando na forma de biofilmes. Bactérias na forma de biofilmes estão associadas com aproximadamente 80% das infecções médicas, ganhando destaque naquelas relacionadas a implantes médicos. Com o aumento da expectativa de vida humana, maior é a necessidade de substituição e reparo de funções biológicas e, portanto é estimado um aumento no número de pessoas hospitalizadas e que irão receber implantes biomédicos. Esses materiais, independente do seu nível de sofisticação, estão suscetíveis ao risco de colonização microbiana e infecção. O presente trabalho, conduzido de forma multidisclinar, utilizou microrganismos patogênicos e superfícies modelo, para demonstrar provas de conceito com relação a duas estratégias para o combate da formação de biofilmes de bactérias: (i) a busca por fitocompostos com atividade antiformação de biofilmes, guiado por relatos etnofarmacológicos, e o posterior recobrimento de superfície polimérica com estes compostos e, (ii) a modificação de propriedades de superfícies, através da técnica de plasma iônico, para a obtenção de superfícies antiadesivas. Assim, 45 extratos aquosos foram obtidos de 24 plantas utilizadas na medicina tradicional do bioma Caatinga. O rastreamento de atividade antibiofime e antibacteriana (nas concentrações de 0,4 e 4,0 mg/mL) evidenciou o alto potencial antibiofilme de extratos contra Staphylococcus epidermidis ATCC 35984 e indicou três plantas com atividade antimicrobiana para Pseudomonas aeruginosa ATCC 27853. Subsequentemente, o estudo foi focado na purificação dos compostos bioativos de quatro plantas: Pityrocarpa moniliformis, ativa contra S. epidermidis e, Anadenanthera colubrina, Commiphora leptophloeos e Myracrodruon urundeuva, ativas contra P. aeruginosa. O fracionamento bioguiado e a caracterização química das frações por MALDI MS MS demonstraram que os compostos ativos nos quatros casos pertencem à classe dos taninos. Estruturas complexas de proantocianidinas (composta principalmente por profisetinidina para A. colubrina e por prorobinetinidina para C. leptophloeos), e de taninos hidrolisáveis (constituído por unidades de ácido gálico em M. urundeuva) foram identificadas. Estes taninos inibiram a formação de biofilme de P. aeruginosa através da ação bacteriostática, causando danos de membrana e excesso na proliferação de vacúolos bacterianos, embora a membrana de eritrócitos tenha sido preservada. Com relação à P. moniliformis, proantocianidinas ricas em prodelfinidina (0.125 mg/mL) foram os compostos responsáveis pela completa inibição da formação de biofilme de S. epidermidis, sem afetar a viabilidade do microrganismo. Como demonstrado por diversas técnicas, os resultados indicam que tanto a superfície bacteriana (S. epidermidis) quanto a superfície dos materiais testados (vidro e poliestireno) são espontaneamente recobertos pelas proantocianidinas, tornando-as superfícies hidrofílicas. Através da técnica de “spin coating”, a superfície polimérica foi recoberta com estas proantocianidinas, convertendo-se em uma superfície fortemente hidrofílica. A habilidade de prevenir a adesão de S. epidermidis foi mantida e o material se mostrou compatível com as células epiteliais de mamíferos, indicando o grande potencial destes produtos naturais como agentes funcionais de recobrimento de superfícies. No outro enfoque deste estudo, a modificação de propriedades de superfícies via descarga de plasma dos gases N2/H2 produziu, de maneira rápida e bastante efetiva, superfícies de poliestireno capazes de impedir a adesão de bactérias altamente resistentes aos antimicrobianos. Através de espectroscopia de raio X, verificou-se que uma concentração de nitrogênio de 8,8% e a componente polar da energia de superfície superior a 15 mJ/m2, são necessários para reduzir a adesão de bactérias que apresentam superfície hidrofílica (como enterobactérias produtoras de carbapenemase e MRSA), enquanto que cepas hidrofóbicas (exemplificadas pelo S. epidermidis) mantiveram a capacidade de aderir e formar biofilmes. As interações respulsivas explicam os efeitos antiadesivos obtidos, tanto no recobrimento de superfícies por proantocianidinas quanto no tratamento por plasma iônico. / Most bacteria do not grow as individual cells, but in communities structured as pseudomulticelulares organisms, or biofilms, being present in virtually all natural ecosystems and pathogens. The bacterial adhesion to surfaces and subsequent biofilm formation promotes metabolic, phenotypic and genotypic changes, which makes their eradication extremely difficult. Thereby, microorganisms that exhibit susceptibility to antimicrobials during conventional laboratory tests are in fact highly resistant to them when in the form of biofilms. Bacteria living as biofilms are associated with approximately 80% of all medical infections, mainly those related to indewelling devices. With increasing life expectancy, greater is the need for replacement and repair biological functions and, therefore, it is estimated an increasing number of hospitalized people and who will receive biomedical implants. However, regardless of the level of material sophistication, all of them are susceptible to the risk of microbial colonization and infection. This study, conducted in a multidisclinar way, employed pathogenic microorganisms and surface models to demonstrate proofs of concept regarding two strategies to combat bacterial biofilm formation: (i) the search for phytocompounds having antibiofilm formation activity, guided by ethnopharmacological reports, and further the polymer surface coating with these compounds, and (ii) the modification of surface properties, by the ionic plasma discharge technique to obtain anti-adhesive surfaces. Thus, 45 aqueous extracts were obtained from 24 plants used in the tradicinal medicine of the Caatinga biome. The screening of antibiofim and antibacterial activities (at concentrations 0.4 and 4.0 mg/mL) showed the high antibiofilm potential of the extracts against Staphylococcus epidermidis ATCC 35984 and indicated three plants with antimicrobial activity against Pseudomonas aeruginosa ATCC 27853. Subsequently, the study was focused on the purification of bioactive compounds from four plants: Pityrocarpa moniliformis, active against S. epidermidis and, Anadenanthera colubrina, Commiphora leptophloeos and Myracrodruon urundeuva, active against P. aeruginosa. The bioguided fractionation and the chemical characterization of the fractions by MALDI MS MS showed that the active compounds in the four cases belong to the class of tannins. Complex structures of proanthocyanidins (mainly composed profisetinidin for A. colubrina and prorobinetinidin for C. leptophloeos), and hydrolysable tannins (consisting of gallic acid units in M. urundeuva) were identified. These tannins inhibited biofilm formation of P. aeruginosa through bacteriostatic action, causing membrane damage and excess on the proliferation of bacterial vacuoles while the erythrocyte membrane was preserved. With respect to P. moniliformis, proanthocyanidins riched in prodelphinidin (0.125 mg/mL) were the compounds responsible for the complete inhibition of S. epidermidis biofilm formation, without affecting the viability of the microorganism. As demonstrated by various techniques, the results indicated that both surfaces, of the bacterium (S. epidermidis) and of the tested materials (glass and polystyrene), were spontaneously covered by proanthocyanidins, becoming hydrophilic surfaces. Using spin coating technique, the surface was coated with these proanthocyanidins, making the surface highly hydrophilic. The ability to prevent adherence of S. epidermidis was maintained and the material proved to be compatible with mammalian epithelial cells, indicating the potential usefulness of these natural products as functional agents for coating surfaces. In another approach of this study, the modification of surface properties via plasma discharge using N2/H2 gases mixtures produced, by a quickly and effectively way, polystyrene surfaces able to prevent the adhesion of bacteria highly resistant to antibiotics. Through X-ray spectroscopy, it was found that a nitrogen concentration of 8.8% and the polar component of surface energy greater than 15 mJ/m2 are needed to reduced adhesion by bacteria exhibiting hydrophilic surface (such as Enterobacteriaceae carbapenemase-producing and the MRSA), while hydrophobic strains (exemplified by S. epidermidis) had the capacity to adhere and to form biofilms. The respulsive interactions could explain the anti-adhesive effects obtained in the coating of surfaces by proanthocyanidins as well as in the ionic plasma treatments.

Os sistemas de sinalização de dois componentes são sistemas prevalentes em bactérias, permitindo a adaptação a diferentes condições ambientais. O sistema de dois componentes classicamente possui uma proteína histidina quinase, o primeiro componente, capaz de reconhecer o estímulo ambiental e fosforilar o regulador de resposta, o segundo componente. Pseudomonas aeruginosa é uma proteobactéria ubíqua, capaz de infectar hospedeiros filogeneticamente distintos. Esse patógeno oportunista apresenta um dos maiores conjuntos de sistemas de dois componentes em bactérias, que permite que ela sobreviva numa grande gama de ambientes, incluindo humanos. P. aeruginosa UCBPP-PA14 apresenta pelo menos 64 histidina quinases e 76 reguladores de resposta codificados em seu genoma. Diversos sistemas de dois componentes já foram correlacionados com a virulência, sendo o sistema GacSA o exemplo melhor caracterizado. Há poucos estudos sistemáticos sobre o envolvimendo dos reguladores de resposta na virulência de P. aeruginosa e os sinais que induzem a ativação dos reguladores de resposta precisam ser encontrados. Para identificar novos reguladores de resposta envolvidos na patogenicidade, infecções in vitro em macrófagos e in vivo em Drosophila melanogaster foram realizadas neste trabalho. Os macrófagos foram infectados com cada mutante dos reguladores de resposta ou com a linhagem selvagem, e a produção da citocina pró-inflamatória TNF-α e o clearance bacteriano foram determinados. Alternativamente, as moscas foram infectadas utilizando-se a estratégia de feeding e a sobrevivência foi verificada. Utilizando-se essas abordagens, a identificação de diversos reguladores de resposta com papel na virulência foi alcançada, além de se corfirmar o papel de reguladores de resposta já estudados. Um dos novos genes envolvidos em virulência, PA14_26570 (nomeado neste trabalho de atvR), codifica um regulador de resposta atípico com substituição no aspartato fosforilável para glutamato, o que usualmente induz um estado sempre ativo. Um mutante não polar em atvR foi construído e macrófagos infectados com a linhagem ΔatvR confirmaram um maior clearance bacteriano e maior produção de TNF-α em comparação aos macrófagos infectados com a linhagem selvagem. Para comprovar a participação de AtvR durante a patogênese, um modelo de pneumonia aguda em camundongos foi utilizado. Camundongos infectados com a linhagem ΔatvR apresentaram uma maior sobrevivência em comparação aos camundongos infectados com a linhagem selvagem. Além disso, os camundongos infectados com ΔatvR apresentaram menor carga bacteriana, aumento no recrutamento de neutrófilos ativados e aumento na produção de citocinas pró-inflamatórias (TNF-α e IFN-γ). Utilizando-se uma abordagem transcritômica (RNA-Seq), foi determindo diversos genes são regulados positivamente na linhagem superexpressando AtvR em relação à linhagem controle. Dentre esses, os clusters de respiração anaeróbia nar, nir, nor e nos estão incluídos. Esse resultado foi confirmado por qRT-PCR e análises fenotípicas, em que a linhagem ΔatvR apresentou menor crescimento e expressão da nitrato redutase durante condições de hipóxia em comparação à linhagem selvagem. Em suma, neste trabalho foi demonstrado que diversos reguladores de resposta são importantes para a virulência de P. aeruginosa em macrófagos in vitro e in vivo em Drosophila, além de caracterizar o regulador de resposta atípico AtvR, que regula a respiração anaeróbica por desnitrificação, permitindo que P. aeruginosa possa infectar e colonizar o hospedeiro com maior eficiência. / Two-component systems are widespread in bacteria, allowing the adaptation to environmental changes. A two-component system is classically composed by a sensor kinase that phosphorylates a cognate response regulator. Pseudomonas aeruginosa is a ubiquitous proteobacterium able to cause disease in several hosts. This opportunistic pathogen presents one of the largest sets of two-component systems known in bacteria, which certainly contributes to its ability to thrive in a wide range of environmental settings, including humans. P. aeruginosa UCBPP-PA14 genome codes for at least 64 sensor kinases and 76 response regulators. Some response regulators are already known to be related to virulence, with the GacSA system as the best characterized. There are no systematic studies about the involvement of P. aeruginosa response regulators in virulence. Moreover, the input signal that triggers the response regulator activation is yet to be uncovered for most systems. To find new response regulators involved in virulence, in vitro infections werecarried out using macrophages. Briefly, the macrophages were infected with each response regulator mutant or the wild-type strain, the pro-inflammatory cytokine production (TNF-α) and the bacterial clearance were evaluated. Using this approach, we identified several response regulators involved in virulence, and we also confirmed the involvement of known response regulators in this process. One of the novel virulence-related response regulators, PA14_26570 (named here as AtvR), is an atypical response regulator with a substitution in the phosphorylable aspartate to glutamate, that usually leads to an always-on state. A non-polar mutant was constructed, and macrophage infection with ΔatvR confirmed an increased bacterial clearance as well as a higher TNF-α production as compared to the wild-type strain. To ascertain the role of AtvR during the pathogenic process, an acute pneumonia model was used. Mice infected with ΔatvR showed an increased survival as compared to mice infected with the wildtype strain. In addition, ΔatvR infected mice showed reduced bacterial burden, increased neutrophil recruitment and activation, as well as increased pro-inflammatory cytokine production (TNF-α and IFN-γ). Also, using a transcriptomic approach (RNASeq), we showed that several genes were upregulated in the strain overexpressing AtvR. These genes include the anaerobic respiration clusters nar, nir, nor and nos. This result was confirmed by qRT-PCR and phenotypic analysis, in which ΔatvR showed reduced growth and nitrate reductase expression during hypoxic conditions as compared to the wild-type strain. In conclusion, we have demonstrated that several response regulators are important for P. aeruginosa virulence in vitro. In addition, we further characterized the atypical response regulator AtvR, which regulates anaerobic respiration via denitrification, allowing this bacterium to infect and colonize the host more efficiently.