Tesis sobre el tema "Arcobacter"
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Levican, Asenjo Arturo. "Sanitary importance of arcobacter". Doctoral thesis, Universitat Rovira i Virgili, 2013. http://hdl.handle.net/10803/125666.
Texto completoEl género Arcobacter incluye especies consideradas patógenos emergentes, ya que se han asociado con patologías gastrointestinales y bacteriemia en humanos y con diarrea, mastitis y abortos en animales. Sin embargo, aún no se ha definido completamente las rutas de transmisión, los factores de virulencia presentes en cepas patogénicas no se han determinado y los métodos de aislamiento e identificación aún son deficientes. Todo esto genera una subestimación de la importancia sanitaria de Arcobacter. En esta tesis doctoral se demostró la existencia de 5 nuevas especies de este género. Para su diferenciación se utilizó herramientas nuevas, tales como el Matrix Assisted Laser desorption Ionization Time of Flight (MALDI TOF) y un Multilocus Phylogenetic Analysis (MLPA) con 5 genes concatenados (rpoB, gyrB, hsp60, atpA y gyrA). Considerando el número de especies incluidas actualmente en el género (n=17), se evaluó si 5 de los métodos moleculares de identificación son todavía útiles para la identificación de las especies para las que se habían definido o si se generan confusiones, demostrrando que todos ellos generan algún error que osciló entre el 16,8% y 67,4% de las cepas estudiadas. En este sentido, la ampliación del método 16S rRNA-RFLP para poder identificar todas las especies resultó ser de gran utilidad. Por otra parte, en esta tesis se observó una gran diversidad de especies de este género en muestras de mariscos y aguas residuales. Ambas matrices han sido poco estudiados a pesar de su importancia epidemiológica. Más aún, se demostró que el uso en paralelo del cultivo por siembra directa y post enriquecimiento, además de incubación en aerobiosis y microaerofilia, favorece la recuperación de una mayor diversidad. Por otra parte, también se demostró que la mayoría de las especies de este género, en especial algunas cepas A. butzleri, A. cryaerophilus, A. skirrowii, A. trophiarum y A. defluvii, son potenciales enteropatógenos para el hombre, ya que presentaron factores de virulencia y fueron capaces de adherir e invadir células intestinales humanas (Caco-2). Por último, se demostró que Arcobacter puede ser confundido con Campylobacter sp., lo que puede contribuir aún más a subestimar su importancia sanitaria.
Sloane, Julia Yvette. "Molecular epidemiology of Arcobacter in cattle". Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533924.
Texto completoStoeva, Kalina. "Arcobacter butzleri-genome organisation and pathogenicity". Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/14489.
Texto completoCollado, González Luis Roberto. "Taxonomy and epidemiology of the genus arcobacter". Doctoral thesis, Universitat Rovira i Virgili, 2010. http://hdl.handle.net/10803/8744.
Texto completoThe genus Arcobacter includes species associated with human and animal diseases. However, its prevalence in water is unknown and so far do not exist methods able to differentiate the nine accepted species. In this thesis we have developed a molecular identification method (16S rDNA-RFLP) that enables the differentiation of most of species. In addition, we have demonstrated that the presence of Arcobacter in environmental waters correlates with high level of faecal pollution. Theses microorganisms showed a high prevalence in the Llobregat River and a high genetic diversity. However, these microorganisms were never detected from drinking water, which demonstrate that the treatment of the river water is effective for its elimination. Additionally, have been demonstrated the high prevalence of Arcobacter in several types of meat and shellfish. Finally, 4 new species have been discovered and described: Arcobacter mytili, Arcobacter valdiviensis, Arcobacter defluvii y Arcobacter molluscorum.
Pérez, Cataluña Alba. "Epidemiology and taxogenomics of the genus arcobacter". Doctoral thesis, Universitat Rovira i Virgili, 2018. http://hdl.handle.net/10803/663660.
Texto completoEl género Arcobacter pertenece a la familia Campylobacteraceae e incluye especies consideradas patógenos emergentes ya que producen infecciones en humanos y animales. Las bacterias de este género presentan una amplia distribución a nivel mundial y se cree que se transmiten por el consumo de aguas o alimentos contaminados. Existen diversas herramientas para el estudio epidemiológico que nos ayudarían a esclarecer estas rutas de contagio. Sin embargo, los mecanismos de acción de estas bacterias son todavía poco conocidos y no existe tratamiento estandarizado. El número de especies del género ha aumentado considerablemente en los últimos años y el uso de nuevas técnicas de aislamiento ha provocado el hallazgo de otras especies nuevas. En esta tesis, se ha demostrado que el uso de la técnica de Multilocus Sequence Typing (MLST) para el estudio epidemiológico es poco precisa. Además, se evidenció la elevada resistencia a determinados antibióticos que sugieren la necesidad de introducir un cambio en el uso de las terapias utilizadas hasta ahora en las infecciones ptoducidas por Arcobacter. También se describieron un total de 4 nuevas especies utilizando técnicas como el análisis fenotípico, el Multilocus Phylogenetic Analysis (MLPA) mediante la concatenación de 5 genes (atpA, gyrA, gyrB, hsp60 y rpoB) y la información extraída de los genomas secuenciados de dichas especies y de las especies filogenéticamente cercanas. El uso de los genomas, su comparación y el análisis filogenético evidenció además que la especie A. cryaerophilus está formada por 4 genomovares, que representan especies genómicas pero que no se pudieron diferenciar fenotípicamente. Finalmente, el análisis filogenético de los genomas de todas las especies del género, junto con el cálculo de diferentes índices genómicos (ANI, isDDH, AAI, POCP y RSCU) permitió descubrir que el género Arcobacter está en realidad formado por al menos 7 géneros, diferenciables genéticamente y mediante combinación de pruebas fenotípicas.
The genus Arcobacter belongs to the family Campylobacteraceae and includes species considered emergent pathogens because they can produce infections in humans and animals. The species of the genus are widely distributed worldwide and the consumption of contaminated food or water is considered the source of the infection. There are several tools for the epidemiological characterization of the strains that could help to clarify the routes of infection. However, the mechanisms of action of these bacteria are still poorly understood and there is no standardized treatment. The number of species of the genus has increased considerably in recent years and the use of new isolation techniques has led to the discovery of other new species. In this thesis, it was demonstrated that the epidemiological analysis using the Multilocus Sequence Typing (MLST) technique is not precise. In addition, the high resistance to certain antibiotics suggested the need for introducing changes in the treatments used in Arcobacter infections. A total of 4 new species were described using phenotypic characterization, Multilocus Phylogenetic Analysis (MLPA) of 5 genes (atpA, gyrA, gyrB, hsp60 and rpoB) and information extracted from the sequenced genomes of these species and the phylogenetically close ones. The use of genomes and their comparison and phylogenetic analysis also showed that the species A. cryaerophilus is composed by 4 genomovars, which represent genomic species that could not be phenotypically differentiated. Finally, the phylogenetic analysis of the genomes of all the species of the genus, together with the calculation of different genomic indexes (ANI, isDDH, AAI, POCP and RSCU) allowed us to discover that the genus Arcobacter is actually formed by at least 7 genera, differentiable genetically and with a combination of phenotypic tests.
Abu-Halaweh, Marwan y n/a. "Molecular Methods for Campylobacter and Arcobacter Detection". Griffith University. School of Biomolecular and Biomedical Science, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20060223.084457.
Texto completoAbu-Halaweh, Marwan. "Molecular Methods for Campylobacter and Arcobacter Detection". Thesis, Griffith University, 2005. http://hdl.handle.net/10072/367268.
Texto completoThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Biomedical Sciences
Full Text
Teschke, Miriam. "Prävalenz von Arcobacter spp. in Puten- und Schweinefleisch aus dem Berliner Einzelhandel und Vergleich von drei kulturellen Arcobacter-Nachweisverfahren /". Berlin : Mbv, 2008. http://d-nb.info/990056414/04.
Texto completoEtonsi, Majde Ali. "Studies on Arcobacter species, their isolation and pathogenicity". Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2692.
Texto completoAbdelbaqi, Khalil. "Le genre Arcobacter : étude taxonomique, diagnostique et pathogénique". Bordeaux 1, 2007. http://www.theses.fr/2007BOR13532.
Texto completoTeschke, Miriam [Verfasser]. "Prävalenz von Arcobacter spp. in Puten- und Schweinefleisch aus dem Berliner Einzelhandel und Vergleich von drei kulturellen Arcobacter-Nachweisverfahren / Miriam Teschke". Berlin : Freie Universität Berlin, 2008. http://d-nb.info/1023097095/34.
Texto completoBrückner, Vanessa [Verfasser]. "Arcobacter: pathogenes Potential und Bedeutung als Zoonoseerreger / Vanessa Brückner". Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2020. http://d-nb.info/1223927369/34.
Texto completoMilesi, S. "EMERGING PATHOGEN ARCOBACTER SPP. IN FOOD OF ANIMAL ORIGIN". Doctoral thesis, Università degli Studi di Milano, 2011. http://hdl.handle.net/2434/157298.
Texto completoGobbi, Débora Dirani Sena de. "Isolamento e caracterização de amostras de Arcobacter spp em sistemas intensivos de produção de suinos e abatedouros". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/10/10134/tde-19012011-143610/.
Texto completoThe species of Arcobacter spp. genus have been classified until 1990 as species belonging to the genus Campylobacter. Nowadays, three of five species of this genus are consider as potencially zoonotic, and can be transmitted from food of animal origin. The present study goal was to isolate and characterize genetically strains of Arcobacter spp. isolated from 120 carcasses, 120 faeces and 24 swine muscle sampled in two swine slaughterhouses located in São Paulo State. Isolates were submitted to multiplex-PCR to identify species of the genus and analyzed by pulsed field gel electrophoresis. The agent was isolated from 71,6% of carcasses, 4,16% of faeces and 8,3% of muscles samples. A. butzleri and A. cryaerophilus were the most prevalent species. The analysis of data obtained in PFGE showed 51 distinct profiles, the discriminatory index of 0,98 and it demonstrated large genotipic diversity among the strains. The main isolation site were the carcasses and the PFGE was a good tool to characterize and discriminate Arcobacter spp. strains.
Oliveira, Maria Gabriela Xavier de. "Caracterização genotípica de Arcobacter spp. isolados de carnes de aves comercializadas no Município de São Paulo - SP". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/10/10133/tde-23032016-105513/.
Texto completoArcobacter spp. is a Gram negative microorganism that causes watery diarrhea and septicemia in humans. A. butzleri, A. cryaerophilus and A. skirrowii are pathogenic for humans. The aim of this study was to detect the presence of Arcobacter spp. in poultry meat from butcher shops in the city of São Paulo, checking the virulence genes and profile genotypic. A total of 300 chicken cuts were used for cultivation and isolation in broth and JM agar, under aerobic conditions, at 30 °C for 72 hours. Arcobacter colonies were selected and submitted to molecular detection by polymerase chain reaction (PCR), in order to determine species and virulence genes. Results show the presence of Arcobacter spp. in 18.3% (55/300) of poultry meat samples, identified as A. butzleri 63.6% (35/55) and A. cryaerophilus 36.3% (20/55) in chicken isolates. The virulence genes on Arcobacter spp. researched demonstrated positive these 100% (55/55) for ciaB and mviN, followed by cj134998,1% (54/55), pldA 94,4% (52/55), cadF 72.7% (40/55), tlyA 92,7% (51/55), hecA 49% (27/55), irgA 47,2% (26/55) and hecB 34,5% (19/55). These strains were submitted to AFLP generating two dendogramas. Nineteen profiles genotypins were obtained for A. butzleri and seventeen for A. cryaerophilus. The results of this research point to the presence of Arcobacter butzleri and A. cryaerophilus in the final stage of distribution of poultry meat to butcher shops. The lack of safety of food of animal origin, as well as the presence of virulent strains pose risks to Public Health, with special focus on cross contamination risks generated by uncooked food and utensils
Zhang, Xiaochen [Verfasser]. "Prevalence and cold shock response of Arcobacter spp. / Xiaochen Zhang". Berlin : Freie Universität Berlin, 2021. http://d-nb.info/1231276061/34.
Texto completoCarter, Eddye Rachelle. "Enteropathogenicity of Arcobacter butzleri in rabbit and pig ileal loops". Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-11182008-063126/.
Texto completoMcElwain, Robert Darrell. "Survival and recovery characteristics of Arcobacter butzleri in groundwater microcosms". Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2586.
Texto completoTitle from document title page. Document formatted into pages; contains viii, 71 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 65-70).
Karadas, Gül [Verfasser]. "Characterization of the virulence potential of Arcobacter butzleri / Gül Karadas". Berlin : Freie Universität Berlin, 2016. http://d-nb.info/1114138096/34.
Texto completoAtabay, Halil Ibrahim. "The ecology of campylobacters and related organisms in food animals". Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262846.
Texto completoVandenberg, Olivier. "Clinical, laboratory and epidemiological investigations of Arcobacter and Dientamoeba Fragilis infections". Doctoral thesis, Universite Libre de Bruxelles, 2006. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210829.
Texto completoDaucher, James Andrew. "Occurrence of pyruvate:ferredoxin oxidoreductase in Campylobacter, Wolinella, Helicobacter and Arcobacter species". Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09052009-040436/.
Texto completoGobbi, Débora Dirani Sena de. "Caracterização fenotípica e genotípica de isolados de Arcobacter spp. provenientes de suínos". Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/10/10134/tde-08092014-150431/.
Texto completoAmong the known species of the genus Arcobacter, the species A. butzleri, A. cryaerophilus and A. skirrowii are considered potentially zoonotic and can be transmitted by food of animal origin. This study aimed to isolate and characterize phenotypically and genotypically strains of Arcobacter spp from swine carcasses and slaughterhouse environment samples located in the State of São Paulo. The isolated strains were subjected to polymerase chain reaction for identification and detection of a group of putative virulence genes. The minimum inhibitory concentration was determined against nine antimicrobials indicated for the control of infection by the agent and the strains were analyzed by PFGE and by AFLP. Among the 30 carcasses evaluated, 25 were positive for the agent and 70 strains were selected and identified as Arcobacter spp. The isolated species were A. butzleri (n = 61), A. cryaerophilus (n = 7) and A. skirrowii (n = 2). The frequency of virulence genes found ranged from 71.4 % to 100 % for genes tlyA , pldA , cj1349 , ciaB , cadF and mviN . The genes hecA, hecB and irgA were not detected. The virulence profile ciaB/ cj1349/ mviN/ cadF/ pldA/ tlyA was the most frequent and detected in 66 % of the strains. All strains were susceptible to gentamicin and tetracycline and 77.1% were multirresistant, among these the most common profile of resistance was azithromycin/ florfenicol/ nalidixic acid/ telithromycin/ clindamycin There were large genotypic diversity among strains by PFGE and AFLP and both techniques showed the same discriminatory power in the analysis of the isolated strains.
Knighton, Matthew Charles. "Comparison of Arcobacter butzleri ED-1 and Arcobacter L anode biofilm formation and a proteomic comparison of A. butzleri ED-1 at the anode of a half microbial fuel cell". Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8004.
Texto completoRidsdale, James Andrew. "Characterisation of the intestinal microflora of the commercially reared duck with respect to the carriage of salmonellas and campylobacters". Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297819.
Texto completoScullion, R. "Arcobacter Spp. in raw products of animal origin in Northern Ireland : detection and characterisation". Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419429.
Texto completoSchönknecht, Antje [Verfasser]. "Prävalenz und Quantifizierung von Arcobacter spp. im Gastrointestinaltrakt von Masthähnchen am Geflügelschlachthof / Antje Schönknecht". Berlin : Freie Universität Berlin, 2021. http://d-nb.info/1240230389/34.
Texto completoAsif, Muhammad. "Acanthamoeba and the bacterial pathogen interactions". Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/20427.
Texto completoStiny, Sascha. "Vergleich von PCR- und kulturellen Nachweisverfahren zum Vorkommen von Arcobacter spp. in Geflügelfleisch und Geflügelfleischerzeugnissen". kostenfrei, 2009. http://edoc.ub.uni-muenchen.de/10828/.
Texto completoStiny, Sascha. "Vergleich von PCR- und kulturellen Nachweisverfahren zum Vorkommen von Arcobacter spp. in Geflügelfleisch und Geflügelfleischerzeugnissen". Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-108288.
Texto completoHilton, Claire L. "The physiology and toxicity of the newly emerging food-borne pathogen Arcobacter butzleri NCTC 12481". Thesis, Nottingham Trent University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396375.
Texto completoSalas, Massó Núria. "Epidemiology of arcobacter-related spp. In shellfish exposed to marine and brackish water with different levels of fecal pollution". Doctoral thesis, Universitat Rovira i Virgili, 2019. http://hdl.handle.net/10803/668373.
Texto completoEl género Arcobacter, que ha sido recientemente dividió en 7 nuevos géneros, comprende especies zoonoticas y patógenas. Estos géneros han sido detectados, con un alto porcentaje de positividad en marisco y junto con el hecho de que estos alimentos son consumidos poco cocinados, suponen un riesgo para el consumidor. En esta tesis, se ha estudiado la relación entre estas bacterias y bivalvos expuestos a aguas con diferentes niveles de contaminación fecal. El desarrollo de una nueva metodología, consistente en el suplemento del caldo Arcobacter-CAT con 2.5%NaCl y su posterior cultivo en agar marino, ha mejorado el aislamiento de especies relacionadas con Arcobacter de ambientes salobres y marinos. Una correlación positiva entre los niveles de Escherichia coli y Arcobacter fue observada en bivalvos y su agua circundante. Sin embargo, cuando los bivalvos son cultivados en agua con temperaturas superiores a 26.2ºC, E. coli no predice la presencia de estos patógenos. La evaluación de la distribución de Arcobacter en los tejidos de mejillones y ostrones, mostró que el líquido intervalval es el compartimento con mayor prevalencia de Arcobacter. La depuración de E. coli, A. butzleri y M. molluscorum en mejillón y ostrón bajo distintas condiciones de carga bacteriana y en dos estaciones distintas (verano e invierno) fue analizada. Se observó que este proceso no elimina del todo Arcobacter de los bivalvos, y que es dependiente de la temperatura. También se desarrolló una v-qPCR para la detección de células viables de Arcobacter spp. en diferentes bivalvos. Este método consiguió una inhibición de la amplificación del ADN procedente de células muertas en el 85% de las especies de Arcobacter examinadas. Como resultado de todos estos experimentos, junto con el uso en paralelo la metodología enriquecida y no enriquecida con NaCl, se han aislado y descrito siete nuevas especies pertenecientes a cuatro nuevos géneros.
The genus Arcobacter, which recently has been divided into 7 new genera, comprises species that have been considered zoonotic agents and emergent pathogens. Arcobacter-related species have been recovered with a high positivity from seafood, posing a risk for the consumer as they are consumed raw or slightly cooked. In this thesis, the relationship between these bacteria and shellfish exposed to water with different levels of fecal pollution has been studied. A new approach, for improving the recovery of Arcobacter-related genera from marine and brackish environments was developed and consisted on the supplementation of Arcobacter-CAT broth with 2.5% NaCl and posterior culture in marine agar. The correlation between the levels of Escherichia coli and Arcobacter was also examined in shellfish and their surrounding water, showing positive results. However, when shellfish were harvested from water with a temperature above 26.2ºC, E. coli would fail to predict the presence of these pathogens. The distribution of Arcobacter-related genera within the tissues of mussels and oysters showed that the intervalval liquid was the compartment with higher prevalence of Arcobacter. Depuration of E. coli, A. butzleri and M. molluscorum in mussels and oysters under different bacterial loads and in two seasons (summer and winter) was analyzed. The efficacy of the conventional depuration process may not fully eliminate Arcobacter from shellfish and, probably, it is a temperature dependent process. A viable qPCR method for the detection of viable Arcobacter spp. cells in different shellfish matrixes was developed with a satisfactory inhibition of DNA amplification from dead cells in 85% of the Arcobacter species tested. As results of all these experiments, together with the use in parallel of the NaCl.enriched and non-enriched approaches, the isolation and description of seven new species belonging to four new different genera was performed.
Zur, Brügge Jennifer [Verfasser]. "Studies on pathogen-host interaction: Impact of the emerging zoonotic pathogen Arcobacter butzleri on human macrophages / Jennifer zur Brügge". Berlin : Freie Universität Berlin, 2015. http://d-nb.info/1077478356/34.
Texto completoHoosain, Nisreen. "Molecular detection and study of Campylobacter and related microorganisms". Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_9449_1342787170.
Texto completoSpecies of Campylobacter, Arcobacter and Helicobacter have been associated with various diseases in humans and animals
and chickens have been identified as a reservoir of these microorganisms. Two published techniques and a new technique, developed in this dissertation, were evaluated to test its efficiency in removing PCR inhibitors from chicken samples. All of the techniques were based on agarose/DNA slants and were evaluated using multiplex PCR and an Internal Amplification Control. The new technique was found to be most effective and consequently used further in the study. A novel study was done to evaluate the survival of Campylobacter, Arcobacter and Helicobacter strains in chicken blood at -20, 4, 37 and 42º
C as well as at ambient room temperature (±
22º
C). It was found that all strains could survive at all temperatures, albeit at different duration times. Most notably, an A. butzleri strain was able to survive at 4oC for up to 297 days.
Bayas, Morejón Isidro Favián. "Aportaciones a la epidemiología de Arcobacter y Helicobacter spp.: Aplicación de métodos moleculares a su detección e identificación en alimentos". Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/75087.
Texto completoLas bacterias del género Arcobacter son microorganismos pertenecientes a la familia Campylobacteraceae. Actualmente, el género Arcobacter comprende 23 especies, aisladas de una gran diversidad de hospedadores y nichos ecológicos. Las aguas de mar son consideradas el hábitat natural para muchas de ellas, aunque la mayor parte de las especies patógenas son de origen fecal. La transmisión al hombre parece estar asociada al consumo de alimentos crudos o poco cocidos. Sin embargo, la presencia de especies patógenas de Arcobacter en alimentos de origen marino y vegetales ha sido muy poco estudiada. Cuando la detección e identificación de Arcobacter, se establece exclusivamente en función de métodos convencionales de cultivo, el proceso resulta lento, tedioso y poco efectivo en muchas ocasiones, originando frecuentes falsos negativos. Los métodos de detección molecular basados en el análisis de ácidos nucleicos, como la Reacción en Cadena de la Polimerasa (PCR), pueden suponer una alternativa más rápida, sensible y fiable. Por todo ello, en este trabajo se ha realizado la detección de Arcobacter spp. mediante aislamiento por cultivo en placa y PCR, a partir de 100 muestras de moluscos y 100 de verduras. Los resultados obtenidos por ambos métodos confirman la existencia de Arcobacter en las muestras. La PCR, realizada tras un periodo de enriquecimiento, ha resultado ser más sensible que el cultivo para la detección del microorganismo en las muestras. En este trabajo se ha detectado contaminación por Arcobacter en el 71 % de las muestras de moluscos y el 20 % de las muestras de verduras. Los aislados de Arcobacter obtenidos han sido identificados a nivel de especie mediante un análisis PCR-RFLP del gen 16 ARNr. Esta técnica ha permitido identificar las especies A. butzleri, A. cryaerophilus y A. defluvii de los aislados de moluscos, siendo la primera vez que es identificada A. defluvii de muestras de almejas. También es la primera vez que se detecta Arcobacter spp. en berberechos. En el caso de las verduras, se han aislado A. butzleri y A. cryaerophilus. Esta última especie ha sido identificada por primera vez en este tipo de muestras. También se ha estudiado la sensibilidad de los aislados obtenidos a ciprofloxacino y levofloxacino. El porcentaje de muestras contaminadas con cepas resistentes fue del 2 % en moluscos y del 1 % en verduras. Tres aislados procedentes de moluscos y 2 de verduras, identificados previamente como A. butzleri, han mostrado resistencia a ambas fluoroquinolonas. En todos ellos se ha detectado la existencia de una mutación en la posición 254 (C normal por T mutante) en la Región Determinante de Resistencia a Quinolonas (QRDR) del gen gyrA. Nuestros resultados sobre la presencia del patógeno en ambos tipos de muestras son lo suficientemente relevantes como para considerar que el consumo de estos alimentos contaminados con Arcobacter, especialmente A. butzleri, podría suponer un riesgo para la salud humana. Adicionalmente, en este trabajo se ha realizado un análisis de detección de Helicobacter spp. y H. pylori mediante PCR convencional y PCR a tiempo real. El género Helicobacter comprende un gran número de especies consideradas patógenas. La especie más estudiada es H. pylori, uno de los patógenos más comunes en humanos, responsable del 90 % de las úlceras pépticas y relacionado estrechamente con el desarrollo de cáncer gástrico. Aunque parece claro que H. pylori se transmite por la vía fecal-oral a través del agua, su presencia en los alimentos es poco conocida. Por lo tanto, en este estudio se tomó como objetivo estudiar la presencia de estos microorganismos en las muestras de moluscos y verduras. El análisis mediante PCR convencional no mostró resultados positivos para la detección de Helicobacter spp. ni H. pylori. La técnica PCR a tiempo real, sin embargo, ha permitido la detección de H. pylori en una muestra procedente de verduras (lechuga).
Els bacteris del gènere Arcobacter són microorganismes pertanyents a la família Campylobacteraceae. Actualment, el gènere Arcobacter comprèn 23 espècies, aïllades d'una gran diversitat d'hostes i nínxols ecològics. Les aigües de la mar són considerades l'hàbitat natural per a moltes d'aquestes espècies, encara que la major part de les patògenes són d'origen fecal. La transmissió a l'home sembla estar associada al consum d'aliments crus o poc cuits. No obstant això, la presència d'espècies patògenes d'Arcobacter en aliments d'origen marí i vegetals ha sigut molt poc estudiada. Quan la detecció i identificació d'Arcobacter s'estableix exclusivament en funció de mètodes convencionals de cultiu, el procés resulta lent, tediós i sovint poc efectiu, i origina amb freqüència falsos negatius. Els mètodes de detecció molecular basats en l'anàlisi d'àcids nucleics, com la reacció en cadena de la polimerasa (PCR), poden suposar una alternativa més ràpida, sensible i fiable. Per tot això, en aquest treball s'ha realitzat la detecció d'Arcobacter spp. mitjançant aïllament per cultiu en placa i PCR, a partir de 100 mostres de mol·luscos i 100 de verdures. Els resultats obtinguts pels dos mètodes confirmen l'existència d'Arcobacter en les mostres. La PCR, després d'un període d'enriquiment, ha resultat ser més sensible que el cultiu per a la detecció del microorganisme en mostres de mol·luscos. En aquest treball, s'ha detectat contaminació per Arcobacter en el 71 % de les mostres de mol·luscos i el 20 % de les mostres de verdures. Els aïllats d'Arcobacter obtinguts han sigut identificats a nivell d'espècie mitjançant una anàlisi PCR-RFLP del gen 16 ARNr. Aquesta tècnica ha permès identificar les espècies A. butzleri, A. cryaerophilus i A. defluvii en els aïllats de mol·luscos. Aquesta és la primera vegada que A. defluvii és identificada en mostres de cloïsses. També és la primera vegada que es detecta Arcobacter spp. en catxels. En el cas de les verdures, s'han aïllat A. butzleri i A. cryaerophilus. Aquesta última espècie ha sigut identificada per primera vegada en aquest tipus de mostres. També s'ha estudiat la sensibilitat dels aïllats obtinguts a la ciprofloxacina i la levofloxacina. El percentatge de mostres contaminades amb soques resistents va ser del 2 % en mol·luscos i de l'1 % en verdures. 3 aïllats procedents de mol·luscos i 2 de verdures, identificats prèviament com A. butzleri, han mostrat resistència a ambdues fluoroquinolones. En tots aquests s'ha detectat l'existència d'una mutació en la posició 254 (C normal per T mutant) en la regió determinant de resistència a quinolones (QRDR) del gen gyrA. Els nostres resultats sobre la presència del patogen en els dos tipus de mostres són prou rellevants per a considerar que el consum d'aquests aliments contaminats amb Arcobacter, especialment A. butzleri, podria suposar un risc per a la salut humana. Addicionalment, en aquest treball s'ha fet una anàlisi de detecció d'Helicobacter spp. i H. pylori mitjançant PCR convencional i PCR a temps real. El gènere Helicobacter comprèn un gran nombre d'espècies considerades patògenes. L'espècie més estudiada és H. pylori, un dels patògens més comuns en humans, responsable del 90% de les úlceres pèptiques i relacionada estretament amb el desenvolupament de càncer gàstric. Encara que sembla clar que H. pylori es transmet per la via fecal-oral a través de l'aigua, la presència d'aquest bacteri en els aliments és poc coneguda. Per tant, en aquest estudi es va definir com a objectiu estudiar la presència d'aquests microorganismes en les mostres de mol·luscos i verdures. L'anàlisi mitjançant PCR convencional no va mostrar resultats positius per a la detecció d'Helicobacter spp. ni d'H. pylori. La tècnica PCR a temps real, en canvi, ha permès la detecció d'H. pylori en una mostra procedent de verdures (encisam).
Bayas Morejón, IF. (2016). Aportaciones a la epidemiología de Arcobacter y Helicobacter spp.: Aplicación de métodos moleculares a su detección e identificación en alimentos [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/75087
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Stubbe, Angela [Verfasser]. "Einsatz von kulturellem Nachweis nach Johnson & Murano und Multiplex-PCR nach Harmon & Wesley zur Ermittlung des Vorkommens von Arcobacter spp. bei Frischgeflügel und Rinderhack im Berliner Einzelhandel / Angela Stubbe, geb. Rohder". Berlin : Freie Universität Berlin, 2011. http://d-nb.info/1026265908/34.
Texto completoNoguerola, Solà Imma. "Diversity, dynamics and activity of Epsilonproteobacteria in a stratified karstic lake. Implications in carbon and sulfur cycles". Doctoral thesis, Universitat de Girona, 2016. http://hdl.handle.net/10803/403813.
Texto completoEn aquesta tesi doctoral s’ha estudiat l’abundància, diversitat, dinàmica estacional i activitat dels Epsilonproteobacteria en una cubeta meromíctica de l’Estany de Banyoles durant tres cicles anuals. L’estudi combina diferents tècniques moleculars per resoldre la identitat i funció ecològica d’aquests microorganismes al sistema, amb especial atenció a la seva contribució als cicles del C i del S. Els resultats van mostrar una clara estacionalitat en l’abundància d’Epsilonproteobacteria amb màxims hivernals a la redoxclina i al monimolimnion, i van revelar un predomini de seqüències afiliades al gènere Arcobacter. A més, els resultats van demostrar que els Epsilonproteobacteria assimilen activament CO2 en la foscor, essent els responsables de les elevades taxes de fixació fosca de C mesurades a la redoxclina a l’hivern. Anàlisis moleculars complementàries van resoldre que el membre predominant de la comunitat estudiada és un microorganisme quimiolitotròfic i oxidador de sofre del gènere Arcobacter, filogenèticament emparentat amb l’espècie marina Candidatus A.sulfidicus.
Rea, Christopher L. "Fate and Transport of Avian-Associated Pathogens in Western Lake Erie Beaches". The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1385999641.
Texto completoBonifácio, Marina Alexandra Carriço. "Transformação Natural em Arcobacter butzleri". Master's thesis, 2018. http://hdl.handle.net/10362/56679.
Texto completoSousa, Vanessa Cristina Gouveia. "The role of phytochemicals in Arcobacter butzleri resistance". Master's thesis, 2017. http://hdl.handle.net/10400.6/6392.
Texto completoArcobacter butzleri é um patogéneo emergente normalmente associado a doenças gastrointestinais em humanos e animais, e a problemas reprodutores, nomeadamente abortos, em animais. Como muitos agentes patogénicos, A. butzleri tem vindo a desenvolver resistência e multirresistências a vários antibióticos. Considerando que as bombas de efluxo são um importante mecanismo de resistência antimicrobiana, sendo essenciais para o desenvolvimento de multirresistências, a estratégia de usar inibidores de bombas de efluxo para restaurar a suscetibilidade desta bactéria a antibióticos comuns é deveras promissora. Tendo em conta que as plantas estão constantemente expostas a stresses bióticos e abióticos e, apesar de alguns fitoquímicos apresentarem fraca atividade antimicrobiana contra bactérias Gram-negativas, as plantas conseguem combater infeções bacterianas com sucesso através do sinergismo entre compostos, surgindo assim como uma potencial fonte de compostos a explorar. O objetivo deste trabalho foi avaliar a capacidade de 14 fitoquímicos em inibir as bombas de efluxo de A. butzleri, e avaliar o seu potencial na melhoria da atividade de vários antibióticos contra esta bactéria. Para alcançar este objetivo, o perfil antimicrobiano dos fitoquímicos e de vários antibióticos foi avaliado através da determinação da concentração mínima inibitória. Ensaios de acumulação de brometo de etídio foram realizados para determinar a possível inibição das bombas de efluxo pelos compostos em estudo. A concentração mínima inibitória dos fitoquímicos na presença de inibidores de bombas de efluxo conhecidos foi definida, a fim de investigar se as bombas de efluxo são o principal mecanismo de resistência da bactéria aos fitoquímicos. Também foram realizados ensaios de checkerboard para avaliar o potencial sinergismo entre os fitoquímicos e antibióticos e por fim também foram realizados ensaios de inibição do quorum sensing. A determinação da concentração mínima inibitória dos fitoquímicos e dos antibióticos revelou que todos os fitoquímicos têm uma concentração mínima inibitória superior a 1024 µg/mL, exceto o resveratrol, o pterostilbeno e o pinosilvino, cujos valores variam entre 64 e 512 µg/mL, para as estirpes em estudo. Os resultados obtidos relativos aos ensaios de acumulação de brometo de etídio mostraram que alguns fitoquímicos, nomeadamente (+)-catequina, (-)-epicatequina, rutina, ácidos cafeico e clorogénico, resveratrol, pterostilbeno e pinosilvino levam a um aumento de fluorescência superior ao aumento de fluorescência verificado para os controlos dos solventes. Isto é, eles levam a uma acumulação de brometo de etídio dentro das células superior aos controlos, o que sugere que estes compostos podem estar a inibir as bombas de efluxo. Porém, somente os estilbenos registaram um aumento de fluorescência superior ao verificado para o inibidor de bombas de efluxo usado como controlo. Estes compostos são também os únicos que apresentam um perfil típico de um inibidor de bombas de efluxo. A fim de determinar se as bombas de efluxo são um mecanismo relevante de resistência aos fitoquímicos, a concentração mínima inibitória dos fitoquímicos foi determinada na presença de concentrações sub-inibitórias de inibidores de bombas de efluxo para as estirpes de A. butzleri mais suscetível (DQ46M1) e mais resistente (CR50-2), de entre as estudadas. Verificou-se que a importância das bombas de efluxo na resistência da bactéria aos fitoquímicos é dependente da estirpe, sendo a mais resistente mais dependente das bombas de efluxo do que a mais suscetível. Com base nos resultados do ensaio da acumulação de brometo de etídio, vários fitoquímicos foram selecionados para testes de checkerboard. Os resultados mostraram que várias combinações fitoquímico/antibiótico apresentaram um efeito aditivo, não se observando interação antagonista para nenhuma das combinações avaliadas. Os estilbenos, mais uma vez, foi a classe de fitoquímicos que apresentou os melhores resultados. Por fim, ensaios de inibição do quorum sensing foram realizados a fim de determinar se os fitoquímicos têm a capacidade de inibir estes mecanismos de comunicação celular. Os ensaios mostraram que o resveratrol e o pinosilvino conseguem inibir estes sistemas. Assim, uma vez que o quorum sensing é fundamental para a regulação de diversos fatores de virulência como é o caso da formação de biofilmes, estes compostos bioativos podem ter o potencial de contribuir para o controlo de A. butzleri ao atuar sobre a formação de biofilmes, inibindo-os. Concluindo, apesar do reduzido potencial antimicrobiano da maioria dos fitoquímicos testados, alguns destes compostos apresentaram potencial no aumento de atividade de antibióticos, como foi o caso do resveratrol, pinosilvino e ácido gálico, os quais mostraram ter uma interação aditiva com os antibióticos. De acordo com o ensaio da acumulação de brometo de etídio, o efeito aditivo apresentado pelo resveratrol e pelo pinosilvino pode estar associado à inibição das bombas de efluxo. Estes dois estilbenos também demostraram a capacidade de inibir o quorum sensing, o que sugere que podem ter a capacidade de inibir fatores de virulência associados a A. butzleri.
Ferreira, Susana Margarida Paraíso. "Study of molecular and cellular pathogenicity mechanisms of Arcobacter species". Doctoral thesis, 2014. http://hdl.handle.net/10400.6/4404.
Texto completoO género Arcobacter foi proposto em 1991 e faz parte da família Campylobacteraceae juntamente com os géneros Campylobacter e Sulfurospirillum, compreendendo atualmente 18 espécies. Entre as espécies reconhecidas, Arcobacter butzleri, Arcobacter cryaerophilus e Arcobacter skirrowii têm sido associados a doença em humanos e animais. O género Arcobacter está amplamente distribuído, tendo sido isoladas espécies em alimentos, água, instalações de processamento e manipulação de alimentos, diversas amostras ambientais, animais e amostras humanas. Em produtos de origem animal, este microrganismo, tem sido isolado com maior prevalência em frangos, seguido de porco e vaca. O consumo de alimentos ou água contaminados com Arcobacter é considerado como a via de transmissão mais provável. Assim, o conhecimento sobre a distribuição de Arcobacter em alimentos ou ambiente de processamento alimentar, juntamente com a avaliação da variabilidade genética e outras características fenotípicas e genotípicas associadas ao seu potencial de virulência, pode ajudar na compreensão do mecanismo de persistência de Arcobacter na cadeia alimentar e contribuir para o seu controlo. Devido à ausência de estudos prévios sobre a prevalência de Arcobacter em Portugal para humanos ou relativos ao sector alimentar, procedeu-se neste trabalho ao seu isolamento a partir de amostras recolhidas de três bandos de frangos e de superfícies da linha de processamento do matadouro. A. butzleri foi isolado e identificado em todas as amostras recolhidas, com exceção das amostras correspondentes ao conteúdo cecal. Quarenta e três isolados de A. butzleri foram caracterizados por eletroforese em gel de campo pulsado, utilizando as enzimas de restrição Smal e Sacll, revelando uma elevada diversidade genética, com os 43 isolados pertencendo a 32 padrões distintos. No entanto, foram identificados genótipos comuns entre diferentes amostras, indicando a possibilidade de ocorrência de contaminação cruzada durante o processo de abate. Verificou-se ainda neste estudo que os isolados de A. butzleri apresentaram elevados níveis de resistência aos antibióticos em estudo, com todos os isolados a serem resistentes a pelo menos três antibióticos dos nove testados. Enquanto os 43 isolados demonstraram ser suscetíveis à gentamicina e 2,3 % resistentes ao cloranfenicol, 55,8 % das estirpes foram resistentes à ciprofloxacina. Genotipicamente a resistência à ciprofloxacina foi associada a uma transição de citosina para timina na região determinante de resistência às quinolonas do gene gyrA, como previamente descrito. Entre 36 isolados selecionados, 72,2 % apresentaram capacidade de formação de biofilme, o que poderá em parte estar associado à sobrevivência de A. butzleri em ambiente de matadouro, provavelmente por favorecer a dispersão e contaminação cruzada ao longo da linha de processamento. A deteção de genes putativos de virulência por PCR demonstrou a presença dos genes cadF, ciaB, cj1349, mviN, pldA e tlyA em todos os isolados, com uma deteção variável dos genes hecA (75 %), hecB (89 %) e irgA (42 %). Como neste estudo se encontrou uma elevada prevalência de A. butzleri nas amostras estudadas, pressupõe-se que o frango possa ser considerado uma via de transmissão importante para humanos. Este facto associado a diversos fatores de virulência, como elevada resistência a antimicrobianos, capacidade de formação de biofilmes e presença de possíveis genes de virulência, tornam este microrganismo como um patogéneo potencialmente relevante a nível alimentar. A potencial transmissão de Arcobacter através de alimentos contaminados, a elevada prevalência encontrada para A. butzleri e o facto de A. cryaerophilus ser a segunda espécie mais comum associada com alimentos, para além da resistência a antimicrobianos comuns e da sua capacidade de sobreviver a tratamentos físicos e químicos, torna relevante encontrar estratégias alternativas para o seu controlo. Assim sendo, o objetivo seguinte foi centrado na avaliação das propriedades antimicrobianas do resveratrol contra A. butzleri e A. cryaerophilus. O resveratrol exibiu atividade bactericida, levando a uma redução igual ou superior a 3 log10 UFC/mL do inóculo inicial, para células em fase exponencial de crescimento de A. butzleri após 6 horas de incubação com uma concentração de resveratrol de 100 Xg/mL, ou de 200 Xg/mL após 24 horas de incubação com células em fase estacionária. Para as células de A. cryaerophilus em fase exponencial de crescimento, o efeito bactericida foi observado após 24 horas com 100 Xg/mL, enquanto para as células em fase estacionária, a atividade bactericida foi apenas detetada com 200 Xg/mL. Com o objetivo de elucidar o potencial mecanismo de ação deste composto sobre Arcobacter, começou por se avaliar o conteúdo intracelular de ADN e atividade metabólica por citometria de fluxo. Após incubação com resveratrol verificou-se uma diminuição em ambos os parâmetros avaliados. Este composto levou também a um aumento na acumulação de brometo de etídio nas células, demonstrando que o resveratrol pode agir como inibidor de bombas de efluxo, e a uma redução da concentração mínima inibitória de resveratrol pelo inibidor de bombas de efluxo fenilalanina-arginina Z-naftilamida. Para avaliar a ação do resveratrol sobre a morfologia e integridade celular de Arcobacter usou-se a técnica de microscopia eletrónica de varrimento. Com esta técnica verificou-se que o resveratrol provocou desintegração das células de A. butzleri tratadas com concentração mínima inibitória de resveratrol durante 6 horas, enquanto nenhuma alteração morfológica foi observada para as células de A. cryaerophilus. Deste estudo concluiu-se que o resveratrol mostrou elevada atividade anti-Arcobacter e os resultados obtidos sugerem que esta atividade antibacteriana pode resultar da ação do mesmo sobre diferentes alvos celulares, o que pode por sua vez levar à indução de morte celular, em consequência de danos nas funções celulares. Assim, neste estudo foram realçadas as potencialidades antimicrobianas do resveratrol sobre um patogéneo de origem alimentar, Arcobacter. Este aspeto associado ao facto de o resveratrol ser naturalmente sintetizado por plantas em respostas a diversas agressões, e de adicionalmente exibir diversas propriedades descritas como benéficas para a saúde humana e ser um reconhecido antioxidante, encoraja a utilização do resveratrol como um potencial conservante alimentar. O género Arcobacter compreende algumas espécies que têm sido relacionadas maioritariamente com doença gastrointestinal em humanos, no entanto, apesar de algumas serem consideradas patogéneos emergentes, não têm sido vistas como microrganismo de elevada preocupação para a saúde pública. Diversos estudos de prevalência têm apresentado A. butzleri como a quarta espécie mais comum em fezes humanas de indivíduos com gastroenterite, de entre os organismos denominados Campylobacter-like organisms. Assim, foi realizado um estudo de prevalência em 298 amostras de fezes de pacientes com diarreia, recolhidas de 22 hospitais portugueses, entre setembro e novembro de 2012. As amostras foram analisadas quanto à prevalência e diversidade de espécies de Arcobacter e Campylobacter, usando técnicas de deteção molecular. Relativamente às espécies de Arcobacter, 1,3 % das amostras foram positivas para A. butzleri e 0,3% para A. cryaerophilus. Foram encontradas espécies de Campylobacter em 31,9 % das amostras de fezes diarreicas, com C. jejuni e C. concisus sendo as espécies predominantes deste género (13,7 % e 8,0 % , respetivamente). Neste grupo de amostras, A. butzleri foi a quarta espécie mais frequente. Estes resultados evidenciam a importância das espécies de Arcobacter e Campylobacter como agentes etiológicos de gastroenterite aguda entre os pacientes portugueses, afetando particularmente a faixa etária pediátrica. Dado que não existe nenhum trabalho prévio relativo à prevalência e distribuição de Arcobacter em Portugal, este trabalho contribui para um conhecimento da epidemiologia local de Arcobacter, tal como de espécies de Campylobacter. Embora A. butzleri tenha sido implicado em algumas doenças em humanos como diarreia e bacteriémia, ainda são necessários mais estudos para clarificar a patogénese associada a este microrganismo. Assim, o potencial de virulência de A. butzleri foi avaliado através da caracterização genotípica e de propriedades patogénicas de três isolados humanos e três não- humanos. Os isolados mostraram suscetibilidade às tetraciclinas e aminoglicosídeos testados, porém exibindo alta resistência às quinolonas. A. butzleri demonstrou uma atividade hemolítica fraca e capacidade de formar biofilmes em superfícies de poliestireno. Foram demonstrados níveis de adesão semelhantes aos de Salmonella Typhimurium para A. butzleri em células Caco-2, sendo que a inflamação pré-existente das células mostrou não ter efeito significativo sobre a capacidade de adesão dos isolados, no entanto, a capacidade de invasão aumentou significativamente para dois dos isolados humanos. A. butzleri demonstrou capacidade de sobrevivência intracelular em células Caco-2 e de indução significativa da secreção de interleucina-8, assim como demonstrou capacidade de induzir perturbação da estrutura celular. Não foi encontrada correlação entre a presença de genes putativos de virulência e os diferentes fenótipos de patogenicidade. Estes resultados forneceram novas perspetivas acerca da virulência e potencial patogénico de A. butzleri. Em conclusão, este trabalho avaliou a prevalência de espécies Arcobacter tanto em amostras humanas como alimentares o que vem contribuir para um melhor conhecimento acerca da epidemiologia deste microrganismo em Portugal. A sobrevivência e a persistência deste organismo no ambiente foi evidenciada devido à sua capacidade de formação de biofilmes, tal como a sua importância como patogéneo humano foi salientada pela resistência aos antimicrobianos, presença de vários genes de virulência, capacidade de adesão, invasão, sobrevivência intracelular e indução da secreção de citoquinas pró-inflamatórias em células de epitélio intestinal. Para controlar este microrganismo foi ainda testada uma abordagem baseada no resveratrol, um composto de origem natural com o potencial para atuar como conservante na indústria alimentar. Este trabalho permitiu assim ampliar o conhecimento acerca da epidemiologia e patogenicidade de Arcobacter, bem como contribuir para o desenvolvimento de novas estratégias de controlo.
Martins, Ana Sofia Vicente. "Prevalência, diversidade genética e resistência a antibióticos de Arcobacter spp". Master's thesis, 2016. http://hdl.handle.net/10400.6/6980.
Texto completoThe genus Arcobacter currently includes 23 recognized species, and has been isolated from a wide range of hosts and environments such as food and food processing surfaces, water, or human clinical samples. It is considered a foodborne emerging pathogen with ability to cause disease among humans and animals. The wide distribution and high prevalence of Arcobacter in food is a significant concern, since consumption of contaminated food and water is considered the most probable route of transmission of Arcobacter spp. to humans. High level of resistance to several antibiotics has been demonstrated, which may threaten the effective treatment of infections caused by this genus. Considering that there are still few studies analysing the distribution of Arcobacter spp. in food and also the resistance of these bacteria to antibiotics, the objectives of this work were to evaluate the prevalence of Arcobacter spp. in different food products, to characterize the genetic diversity among the isolates and to assess the resistance to 9 antibiotics commonly used to treat infections by this microrganism. Therefore, food samples were collected in retail shops at Covilhã and Fundão during one year, which were then tested for the presence and prevalence of Arcobacter spp.. After isolation and molecular identification of the isolates, these were genotyped using Enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR), followed by an assessment of their resistance to different antibiotics. The results demonstrated a high contamination of food by Arcobacter spp., being observed a discrepancy between the prevailing values when the molecular detection was applied to enrichment broth (72.2 %) versus when the isolation methodology was performed (47.0 %). Regarding isolation, prevalence values of 28.6% for packaged vegetables, 68.0 % for poultry meat, 37.5 % for pork, 43.8 % for beef, 56 % fish samples, and 100 % for a single sample constituted by two different types of meat were obtained. A large genetic heterogeneity among the isolates was also observed, revealing 103 different genetic profiles among isolates from 54 samples. Nonetheless, genotyping of the isolates showed a possible cross-contamination between food samples. Concerning to antibiotic resistance, multiresistance was observed for 94 of the 106 analyzed strains. In conclusion, the Arcobacter genus was widely distributed among the collected food samples, showing a high genetic heterogeneity and high resistance to several antibiotics.
Batista, Carolina Carvalho. "Sobrevivência de Arcobacter butzleri quando sujeito a condições de stress". Master's thesis, 2020. http://hdl.handle.net/10400.6/10541.
Texto completoIn the last decade, an intensification of studies regarding Arcobacter spp. has occurred, in order to fulfil the lack of knowledge that still exists about subjects as pathogenicity levels, resistance and survival of this microorganism. Some of the species among the genus Arcobacter are seen as a concern to public health, as well as to food safety, due to its association to illness in humans and in animals, and also due to its high distribution in food, food processing environments or water for human consumption. Among the 30 species of the Arcobacter genus, Arcobacter butzleri was included in the list of microorganisms that are considered serious hazard to human health by the International Commission on Microbiological Specifications for Foods. In the meantime, a limited knowledge about its survival capacity and persistence in foods still exists, such as the survival of the A. butzleri in conditions of stress associated with food processing and hygienization conditions. Therefore, the aim of this work was to evaluate the survival capacity of the A. butzleri in the presence and absence of food matrixes (chicken and lettuce), when submitted to stress conditions (temperature of 55 ºC, vinegar and AMUKINA). When the survival ability of the A. butzleri was evaluated in the absence of food matrixes, in a general manner, it was observable a high decline of the number of cells for all the stress conditions evaluated in this study. As to what concerns the other stress conditions, for the thermal treatment a reduction in the survival of the A. butzleri was noticeable, and in the group submitted to vinegar and AMUKINA an elimination of the A. butzleri was verified. However, in the presence of food matrixes the survival reduction was not as accentuated as in the absence of food matrixes, that is, these treatments stopped being effective for some strains of this bacterial group, being therefore evidenced a decrease in the effectiveness of the temperature, vinegar and AMUKINA in the elimination of the A. butzleri. In sum, despite the effectiveness of the temperature, vinegar and AMUKINA in the elimination of A. butzleri in the absence of food matrixes, the food matrixes influenced the course of food processing and hygienization, pointing towards a hazard for the consumer’s heath.
Silva, Ana Luísa Cota Mateiro da. "A Contribuição de Bombas de Efluxo para a Resistência em Arcobacter butzleri". Master's thesis, 2017. http://hdl.handle.net/10400.6/6631.
Texto completoThe genus Arcobacter consists of 26 species recognized so far, among them Arcobacter butzleri, A. cryaerophilus and A. skirrowii are considered as emergent pathogens associated with human enteritis and bacteremia. A. butzleri is the most frequently found on human, environmental and food samples, and it pertains to the list of microorganisms considered to be a serious hazard to human health by the International Commission on Microbiological Specifications for Foods (ICMSF). Simultaneously, the high resistance rates in A. butzleri have been increasing, which may jeopardize the treatment of serious infections or even lead to the spread of resistance. Regarding this, and considering that the research on the resistance mechanisms of this bacterium is scarce but relevant, the focus of this investigation was to evaluate the efflux pumps role on the resistance mechanisms of A. butzleri against antimicrobials, and study the relevance of a putative efflux system of the RND superfamily. To evaluate the efflux pump role on the resistance mechanism of A. butzleri, it was first assessed the effect of the efflux pump inhibitors on antimicrobial resistance, through determination of the minimum inhibitory concentration of antibiotics, bile salts and a disinfectant in the presence and absence of EPIs in five strains of A. butzleri. Subsequently, in silico analysis was used to characterize the putative efflux pump CmeABC, belonging to the superfamily RND. Aiming to understand its role on the resistance mechanism of A. butzleri, a mutant strain was created containing an inactivated cmeB gene from the efflux pump CmeABC. The mutant was constructed by natural transformation through insertional mutagenesis, inserting transforming DNA containing a kanamycin resistance cassette flanked by upstream and downstream regions of cmeB gene from the native strain. After confirmation of the mutation, the minimum inhibitory concentration of antimicrobials of the native and respective mutant strains were compared, as well as changes on the accumulation of EtBr. Considering the obtained results, it was observed a multidrug resistance profile of some strains, with all strains being resistant to cefotaxime. On the other hand, none of the strains were resistant to gentamicin. The use of EPIs is effective, lowering the minimum inhibitory concentration values to some compounds. The PAßN, which is an inhibitor of RND efflux systems, demonstrated to be the most effective inhibitor. These results suggest that the RND efflux pumps could play an important role on the resistance of A. butzleri against antimicrobials such as erythromycin, Irgasan, and in some cases bile salts. The in silico analysis shows the existence of a putative efflux pump CmeABC in A. butzleri, which presents a high identity with other RND systems. By comparing the minimum inhibitory concentration of the parent strains to their respective mutant strains, it was possible to confirm that the efflux pump CmeABC has a role on the A. butzleri resistance against ciprofloxacin, ß-lactams and erythromycin. Indeed, EtBr accumulation assays confirmed a correlation between the inactivation of the cmeB gene and increase in EtBr accumulation, showing that the cmeB gene, and consequently the efflux pump CmeABC, has a role on the efflux of compounds. In sum, this work demonstrates that the efflux pumps play a global role on the resistance against antibiotics, bile salts and disinfectant, and demonstrates the existence of an efflux pump CmeABC with a functional role on the resistance mechanisms of A. butzleri against some antimicrobials.
Venâncio, Igor Miguel Antunes. "Avaliação de águas superficiais como reservatório de Campylobacter e Arcobacter sensu lato". Master's thesis, 2020. http://hdl.handle.net/10400.6/11491.
Texto completoThe bacteria of the genera Campylobacter and Arcobacter sensu lato group are Gram-negative bacilli, belonging to the Campylobacteraceae family. Until now, 35 species have been recognized for the genus Campylobacter, and 31 species for Arcobacter sensu lato. Amongst the species of both groups, Campylobacter jejuni, Campylobacter coli, Aliarcobacter butzleri, Aliarcobacter cryaerophilus and Aliarcobacter skirrowii are the most frequently associated with infections in humans and animals. Although requiring a host, bacteria of the genus Campylobacter are commonly isolated from samples of natural waters, such as spring waters, rivers and lakes. Likewise, more than half of the Arcobacter sensu lato species have been isolated from aquatic environments. In fact, water is considered a relevant contamination source and an important threat to public health due to their consumption and direct contact with humans. This concern is increased by the association of outbreaks with the consumption of water contaminated with these bacteria, pointing to their consumption as an important route of transmission. Thus, this study focused on assessing the distribution of Campylobacter spp. and Arcobacter sensu lato in different water samples, such as river water, water from affluents and untreated spring water, collected in the municipality of Covilhã, and evaluation of their resistance to seven antibiotics commonly used in the treatment of infections by these microorganisms. Through the analysis of the results, of the 150 samples evaluated by two distinct detection methodologies, PCR and culture, 56 (37.3 %) samples were positive for Campylobacter spp. when using direct detection on the enrichment broth, and 22 (14.6%) were positive by culture; in total, 60 samples were positive by both methods. The distribution by species was as follows: eight of 22 samples (36.4%) were positive for C. jejuni, seven (31.4 %) for C. coli, four (18.2 %) for C. lari, one sample (4.5 %) was positive for C. upsaliensis, and for two of the samples it was not possible to obtain an identification at the species level. Regarding Arcobacter sensu lato, some variability was also found when using these two methodologies, where 72 out of 150 samples (48%) were positive for the genus when using direct PCR detection in the enrichment medium. Through culture it was possible the isolation of bacteria from this group from 89 (59.3%) samples; and in total 99 samples were positive by both methods. Concerning Arcobacter sensu lato, the distribution of the species was as follows: 74 of the 89 samples (83.1%) were positive for A. butzleri, 20 (22.5%) for A. cryaerophilus and 28 samples were contaminated with other species of Arcobacter. Through the evaluation of the genetic diversity by enterobacterial intergenic consensus-PCR polymerase chain reaction technique (ERIC-PCR), a large genetic heterogeneity was observed among isolates of both genera. Among isolates from 22 Campylobacter spp. positive samples by culture, 37 different genetic profiles were found. Similarly, 255 unique profiles of a total of 291 Arcobacter sensu lato isolates were observed. When the antibiotic susceptibility profile was evaluated, divergences between the resistance of both groups were noted. Thus, in addition to pontual resistances, a low multidrug resistance was observed for the genus Campylobacter, only two among the 25 isolates studied. Higher values were obtained for Arcobacter sensu lato, where from a total of 238 isolates, 194 showed a multidrug resistance profile, of which some presented transversal resistance to six of the seven antibiotics tested. In sum, the results of this study demonstrate a high prevalence of both bacterial groups in water samples accessible to humans, worsen by the high resistance found in those samples, presenting not only high risk for the population and animals of the region, but also for possible food contamination.
Alves, Ana Catarina Natividade. "Avaliação da atividade anti-Arcobacter de complexos de inclusão com resveratrol e ciclodextrinas". Master's thesis, 2014. http://hdl.handle.net/10400.6/4810.
Texto completoCurrently, the genus Arcobacter has 18 described species, with the most relevant being A. butzleri since it is now considered an emerging zoonotic enteropathogenic agent for both animals and humans. This microorganism is usually detected in food products and water environments and also presents a high antimicrobial resistance to antimicrobials and disinfectants which has led, in recent years, to the need to develop new techniques and to search new compounds for the control and, even, eradication of this bacterium. Resveratrol, the main compound of the phytoalexins family, has innumerous bioactive properties, including antimicrobial activity against fungi and Gram-positive and Gram-negative bacteria, and recently its inhibition over Arcobacter species was demonstrated. In order to promote the use of this compound in various applications, its low stability and water solubility have been overcome by its complexation and inclusion in various polymers such as cyclodextrins, bile salts and polymeric microspheres. In fact, resveratrol complexation with modified cyclodextrins showed a considerable increase in the aqueous solubility and photostability of this compound. Thus, the main goal of this work was the evaluation of resveratrol antimicrobial activity, inclusion complexes with modified cyclodextrin hydroxypropyl-gamma-cyclodextrin (HP-?-CD) against an A. butzleri reference strain (LMG 10828), two animal origin (AB 17/11 and AB 36/11) and two clinical origin (INSA 593 and INSA 776) isolates. The first step of the study was the determination of the virulence factors where both clinical isolates presented the cadF, tlyA, cj1349, hecA, pldA, ciaB and mviN genes, the strain AB 36/11 presented one more gene, hecB while the strains LMG 10828 and AB 17/11 presented in their genome the gen irgA besides the eight ones already described for the other strains. The antimicrobial resistance profile to 9 common antibiotics was also evaluated and the results showed that both the reference strain and the clinical isolates were resistant to ampicillin, amoxicillin, vancomycin, cefoperazone, piperacillin and trimethoprim. Besides being resistant to all antibiotics previously mentioned, the strain AB 36/11 also presented resistance to ciprofloxacin. The strain AB 17/11 was the one that exhibited the highest susceptibility since its resistance profile only included vancomycin, ciprofloxacin and trimethoprim. This microrganism’s susceptibility to the inclusion complexes (ICs) was determined by the microdilution method where minimum inhibitory concentrations (MIC) of resveratrol contained in the IC of 256 µg/mL for strains LMG 10828 and INSA 776 and 64 µg/mL for AB 36/11, AB 17/11 and INSA 593 were obtained. At this stage, the susceptibility of all strains to free RV was also assessed, obtaining a MIC of 100 µg/mL for the five strains studied. In order to determine the bacteriostatic or bactericidal action of ICs, time-kill curves were performed for a clinical (INSA 776) and an animal origin (AB 36/11) isolates, which showed that the observed bactericidal activity of the ICs was dependent on both incubation time and antimicrobial agent concentration. For IC concentrations corresponding to 2x and 4x MIC, cell viability is similar for both isolates, with the clinical origin isolate exhibiting a higher susceptibility when exposed to concentrations equal to MIC values. For free RV, the bactericidal effect occurs more quickly for 1x, 2x e 4xMIC in both isolates. The ICs mechanism of action was evaluated by flow cytometry for these two isolates, using SYTO® 40 fluorochrome for total cell staining and bis-(1,3-dibutylbarbituric acid)trimethine oxonol (BOX) and 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) for the evaluation of cell membrane potential and metabolic activity, respectively. Flow cytometry results showed that increasing IC concentration led to increased reduction of the metabolic activity of cells which, in turn, resulted in increased cell membrane depolarization. A microorganism’s ability to form biofilms is commonly associated with its increased virulence, colonization and resistance to antibiotics, thus being of extreme relevance to monitor these biofilms’ formation while studying new ways to prevent or inhibit their development. Given this, this work also evidenced ICs and free RV action on biofilm formation as well as dispersion of pre-formed biofilms showing a high reduction in the biofilm’s biomass for concentrations of 1x, 2x and 4x CMI. Overall, the results obtained in this work showed that the ICs exhibited antimicrobial activity over A. butzleri reference strain and isolates both in planktonic cells and biofilms, suggesting the application of these natural-origin formulations in the food industry to prevent Arcobacter spp. development.
D'Sa, Elaine M. "Fate of Arcobacter spp. upon exposure to environmental stresses and predictive model development". 2002. http://purl.galileo.usg.edu/uga%5Fetd/dsa%5Felaine%5Fm%5F200205%5Fphd.
Texto completoKessen, Volker [Verfasser]. "Qualitativer und quantitativer Nachweis von Arcobacter spp. in der Putenschlachtung / vorgelegt von Volker Kessen". 2009. http://d-nb.info/996028501/34.
Texto completoAlves, Ana Rita Martins. "Contribuição de mutações genéticas no gene gyrA para a resistência a fluoroquinolonas por Arcobacter butzleri". Master's thesis, 2018. http://hdl.handle.net/10400.6/9993.
Texto completoArcobacter butzleri is the fourth Campylobacter-like organism found in human diarrhoeal disease samples. The first line treatment for severe infections by Arcobacter spp. is based in the use of fluoroquinolones. The high frequency of resistance to this class of antibiotics found in A. butzleri strains could raise a significant public health concern. Thus, this work aimed to evaluate the mechanisms of resistance to fluoroquinolone in A. butzleri, with focus in the contribution of spontaneous mutations and their diversity, also in the contribution of efflux pumps. Firstly, the minimal inhibitory concentration (MIC) of the susceptible strains to three fluoroquinolones (ciprofloxacin, levofloxacin, and moxifloxacin) was determined. The spontaneous mutation rate was then calculated by a fluctuation assay procedure, where all the tested A. butzleri strains had an average rate of around 2.34x10-9 ± 1.72x10-9. After, the MIC for A. butzleri mutants derived from this assay was determined, followed by the analysis of target mutations in the quinolone resistance determining region (QRDR) of gyrA and gyrB through amplification and sequencing of these regions. The mutants were confirmed to be fluoroquinolone-resistant, where three different single point mutations were identified in QRDR of gyrA, one previously described to A. butzleri the mutation Thr85Ile (C254T), and two new mutations correlated with the fluoroquinolone resistance in A. butzleri Asp89Asn and Asp89Gli (G265A and A266G respectively); however with no direct correlation with the MIC value was found. The influence of gyrB in fluoroquinolone-resistance in A. butzleri was not confirmed. Nonetheless, for the cases where no point mutation was found in the gyrA gene, the obtained results suggest an influence of efflux pumps to fluoroquinolone-resistance. The role of C254T point mutation in gyrA QRDR was validated by transformation of a susceptible strain. The presence of this mutation, either arising spontaneously or by transformation, does not seem to have a cost to the fitness of A. butzleri. In sum, the results propose the mutations found in codons 85 and 89 of QRDR of gyrA, as well as, the action of efflux pumps as mechanisms behind the fluoroquinolone resistance in A. butzleri strains.
Son, Insook. "Prevalence, genetic diversity, and antimicrobial resistance patterns of arcobacter and campylobacter on broiler carcasses during processing". 2005. http://purl.galileo.usg.edu/uga%5Fetd/son%5Finsook%5F200512%5Fphd.
Texto completoDirected by Mark A. Harrison. Includes articles submitted to International journal of food microbiology, Journal of food protection and International journal of antimicrobial agents. Includes bibliographical references.