One hundred and eighteen (118) Campylobacter strains were studied by DNA homology experiments and characterized phenotypically. These strains formed eleven (11) distinct DNA homology groups (species) corresponding to C. fetus, C. "hyointestinalis", C. jejuni, C. coli, C. laridis, C. nitrofigilis, C. sputorum, C. mucosalis, C. concisus, and two unnamed groups currently referred to as the aerotolerant campylobacters and the "catalase-negative or weak" (CNW) strains. For practical reasons, we propose retaining the subspecies fetus and venerealis designations for C. fetus. In addition, we propose that the subspecies sputorum and bubulus designations for C. sputorum be dropped and replaced with biovars sputorum, bubulus and fecalis, the latter biovar including the catalase-positive strains formerly known as C. “fecalis". Biotyping schemes are also presented for C. jejuni and C. coli. Growth at 25 and 42°C, sensitivity to nalidixic acid and cephalothin, growth in semisolid medium containing 1% glycine, 1% oxgall or 3.5% NaCl, growth in a semisolid minimal medium (MM), anaerobic growth in 0.1% trimethylamine-N-oxide (TMAO), H₂S production in Sulfide-Indole-Motility (SIM) medium, or on triple sugar iron (TSI) agar slants, hippurate hydrolysis, aerobic growth on agar plates, a requirement for H₂ or formate for microaerophilic growth or H₂ or formate and fumarate for anaerobic growth, alkaline phosphatase activity, and deoxyribonuclease (DNase) activity proved to be the most useful phenotypic characteristics for identifying these strains at the species, subspecies and biovar levels. / Ph. D.

Atualmente, a campilobacteriose representa uma importante zoonose tanto em países desenvolvidos quanto em países em desenvolvimento. No Brasil, vários estudos relatam a alta frequência de suínos eliminando o agente nas fezes, porém, a contaminação da carne suína comercializada tem sido pouco avaliada, principalmente no que diz respeito à presença de Campylobacter spp. A incidência deste agente em cortes de carne de aves é mais descrita, porém ainda faltam estudos que esclareçam a epidemiologia da doença. Os objetivos principais do presente estudo foram avaliar a presença de Campylobacter spp. em cortes de carne de frangos e suínos vendidos em mercados municipais, açougues e mercados de pequeno porte distribuídos nas cinco regiões do município de São Paulo. Das 115 amostras de origem suína avaliadas sete se mostraram positivas ao isolamento de Campylobacter coli e, das 105 amostras de carne de frango, 31 estavam contaminadas por Campylobacter jejuni ou Campylobacter coli. Dentre as 38 amostras de carne de frango e suíno positivas foram selecionadas 60 estirpes, as quais foram caracterizadas quanto à espécie, utilizando a reação em cadeia pela polimerase e a espectrometria de massa MALDI-TOF, foram ainda avaliadas quanto ao perfil de resistência a antimicrobianos e foram submetidas a genotipagem pelo polimorfismo de comprimento de fragmentos amplificados (AFLP). A partir dos resultados obtidos seis estirpes foram selecionadas para realização do sequenciamento do genoma completo e a partir da análise dos genomas foram identificados os STs, os genes de resistência e genes de virulência. / Currently, Campylobacteriosis represents an important zoonosis in both developed and developing countries. In Brazil, several studies report a high frequency of pigs excreting the agent in the feces, but the contamination of marketed pork has been insufficiently evaluated, especially with regard to the presence of Campylobacter spp. The incidence of this agent in cuts of poultry meat is more detailed; however, there are still studies lacking that clarify the epidemiology of the disease. The main aims of the present study were to evaluate the presence of Campylobacter spp. in chicken and pork cuts sold in municipal markets, butchers and small markets distributed in the five regions of the city of São Paulo. Of the 115 pork samples evaluated, seven were Campylobacter coli isolation positive and 31 of the 105 chicken samples were contaminated with Campylobacter jejuni or Campylobacter coli. Of the 38 chicken and pork positive samples, 60 strains were selected, which were characterized by species using polymerase chain reaction and MALDI-TOF mass spectrometry. They were also assessed for antimicrobial resistance profile and were genotyped by amplified fragment length polymorphism (AFLP). From the results obtained six strains were selected to carry out the complete genome sequencing and from the genome analysis the STs, the resistance genes and the virulence genes were identified.

L'objectif de ce travail a consisté à (i) déterminer l'occurrence et (ii) à étudier le comportement de différents micro-organismes pathogènes pour l'Homme reconnus comme responsables d'épidémies d'origine hydrique dans des ressources (eaux de surface et eaux de nappes) et des eaux traitées de plusieurs collectivités situées le long de la Moselle. Trois agents microbiologiques aux propriétés morphologiques et intrinsèques très différentes ont été étudiés: des bactéries (C. jejuni et C. coli), des virus entériques (adénovirus humains dont les adénovirus entériques), des parasites (C. parvum, C. hominis, C. meleagridis). Après avoir mis en place différentes méthodologies permettant leur détection, leur quantification et la révélation de leur viabilité et/ou leur infectiosité, nous avons montré que l'eau de la Moselle était largement contaminée par ces pathogènes à des concentrations variables selon la période de l'année. Ainsi par exemple, il a été retrouvé des bactéries C. jejuni plus fréquemment en été que pendant la période hivernale alors que l'inverse a été observé pour les adénovirus humains. Les résultats d'occurrence au niveau des nappes alluviales étudiées ont montré que malgré une protection liée à la filtration naturelle de l'eau, elles pouvaient être contaminées par des campylobacters viables et des adénovirus entériques. Concernant les eaux traitées, plusieurs signatures génomiques liées à ces deux derniers agents (bactérien et viral) ont été révélées par des outils de biologie moléculaire sans qu'un risque en lien avec la viabilité et l'infectiosité puisse être établi. Dans ces eaux, les expérimentations d'inactivation ont clairement montré la grande sensibilité de ces deux agents au traitement chloré mais pas celle des parasites Cryptosporidium qui s'avèrent être les pathogènes les plus résistants quel que soit le milieu ou la température d'incubation / The aim of this study was (i) to determine the occurrence and (ii) to study the behavior of different microorganisms known to cause human waterborne outbreaks in raw waters (surface water and groundwater) and treated water of several reservoirs along the Moselle river. Three pathogens were studied: bacteria (C. jejuni and C. coli), enteric viruses (human adenoviruses which enteric adenoviruses), parasites (C. parvum, C. hominis, C. meleagridis). Because of these micro-organisms have different properties such as size, various methodologies were used for their detection, quantification and viability and/or infectivity. In the study of occurrence we showed that the Moselle river was heavily contaminated by these pathogens in varying concentrations depending on time of the year. For example it was found bacteria C. jejuni more frequently in summer than during winter while the reverse was observed for human adenoviruses. The results obtained in groundwater showed that despite a protection linked to the natural filtration of water, they could be contaminated with viable campylobacters and enteric adenoviruses. In the treated water, several genomic signatures associated with these two agents (bacterial and viral) were revealed by molecular biology tools without any risk related to the viability and infectivity can be established. In these waters, the inactivation experiments clearly showed the high sensitivity of these two agents to chlorination but not the parasite Cryptosporidium, which known to be the most resistant pathogens, whatever the type of water or incubation temperature

O uso de antimicrobianos de forma terapêutica, preventiva e promotora de crescimento trouxe inúmeras vantagens para a avicultura mundial, entretanto a utilização excessiva dos antimicrobianos e de maneira indevida tem estimulado um aumento no número de micro-organismos resistentes. Entre eles, destaca-se o Campylobacter jejuni, bactéria frequentemente associada a enterites em humanos, sendo o frango a principal reservatório e fonte de transmissão deste patógeno para o homem. A transmissão de bactérias resistentes entre animais e seres humanos pode resultar em infecções multirresistentes e insucesso no tratamento terapêutico, sendo a exposição continua destes micro-organismos a esses medicamentos o fator mais importante na origem da resistência. Diante desse cenário, objetivou-se nesse trabalho investigar e caracterizar, através de métodos fenotípico e genotípico, a susceptibilidade antimicrobiana de 54 isolados de C. jejuni coletados em diferentes etapas do processamento da carne de frango de matadouro-frigoríficos da região do Rio Grande do Sul. Para a determinação do MIC, os isolados foram testados frente aos seguintes antimicrobianos: ácido nalidíxico, ciprofloxacina, cloranfenicol, eritromicina, gentamicina e tetraciclina. Dos 54 isolados de C. jejuni, 94,4% foram resistentes a ciprofloxacina, 83,3% ao ácido nalidíxico, 51,8% a tetraciclina e 48% a eritromicina. Todos os isolados foram sensíveis a gentamicina e ao cloranfenicol. Doze isolados foram resistentes a três classes diferentes de antibióticos, sendo assim considerados multi-resistentes. Para verificar a presença da mutação gênica da Região Determinante de Resistência à Quinolona (RDRQ) no gene gyrA, foi realizado sequenciamento gênico de 31 isolados considerados resistentes por métodos fenotípicos. Todos os isolados possuíam a mutação Tre-86-Ile na RDRQ do gene gyrA, que confere resistência às fluoroquinolonas, confirmando a predominância dessa mutação em Campylobacter spp. resistentes a esses antimicrobianos. A ocorrência do gene de resistência à tetraciclina foi verificada por PCR. Dos 28 isolados considerados resistentes por métodos fenotípicos, 42,8% possuíam o gene tet(O), que confere resistência as tetraciclinas. Os resultados mostram um alto nível de resistência antimicrobiana em C. jejuni evidenciando a necessidade da implementação de políticas de uso prudente de antimicrobianos na medicina veterinária. / The use of antimicrobials in a therapeutic, preventive and growth promoting way has brought numerous advantages to the world poultry industry; however, the excessive and undue use of antimicrobials has stimulated an increase in the number of resistant microorganisms. Among them, we highlight Campylobacter jejuni, a bacterium frequently associated with enteritis in humans, with chicken being the main reservoir and source of transmission of this pathogen to man. The transmission of resistant bacteria between animals and humans can result in multi resistant infections and failure in therapeutic treatment, and the continued exposure of these microorganisms to these drugs is the most important factor in the source of resistance. Therefore, the aim of this study was to investigate and characterize, through phenotypic and genotypic methods, the antimicrobial susceptibility of 54 C. jejuni isolates collected at different stages of the processing of chicken meat from slaughterhouse in Rio Grande do Sul. For MIC determination, strains were tested against the following antimicrobials: nalidixic acid, ciprofloxacin, chloramphenicol, erythromycin, gentamicin and tetracycline. Of the 54 isolates of C. jejuni, 94.4% were resistant to ciprofloxacin, 83.3% to nalidixic acid, 51.8% to tetracycline and 48% to erythromycin. All isolates were sensitive to gentamicin and chloramphenicol. Twelve strains were resistant to three different classes of antibiotics, thus being considered multi resistant. To verify the presence of the gene mutation of the Quinolone Resistance Determinant Region (QRDR) in the gene gyrA, gene sequencing of 31 strains considered resistant by phenotypic methods was performed. All strains had the Tre-86-Ile mutation in the QRDR of the gyrA gene, which confers resistance to fluoroquinolones, confirming the predominance of this mutation in Campylobacter spp. resistant to these antimicrobials. The occurrence of tetracycline resistance gene was verified by PCR. Of the 28 strains considered resistant by phenotypic methods, 42.8% had the tet(O) gene. The results show a high level of antimicrobial resistance in C. jejuni that evidences the need for implementation of policies in the prudent use of antimicrobials in veterinary medicine.

Os procedimentos de limpeza e desinfecção usados na produção frangos de corte são fundamentais para a manutenção do alto nível de saúde do plantel, reduzindo o risco de ocorrência de enfermidades e melhorando o desempenho produtivo das aves. Existe a possibilidade de contaminação dos produtos desde a chegada das aves às instalações até o abate. Campylobacter é uma bactéria constantemente encontrada no trato gastrointestinal das aves e merece destaque na produção avícola devido a sua capacidade de provocar enfermidades em humanos. Para evitar a ocorrência de surtos de doenças transmitidas por alimentos como a campilobacteriose, para manutenção da saúde de plantéis avícolas e o aumento da produtividade de lotes de frangos de corte é necessário a realização das práticas preventivas como a limpeza e desinfecção. Desta maneira, o presente estudo teve como objetivos avaliar: o desempenho produtivo em lotes de frangos de corte desafiados com Campylobacter jejuni, a redução da pressão de infecção em instalações submetidas a diferentes protocolos de limpeza e desinfecção, e sua viabilidade econômico-financeira. Foi conduzido protocolo experimental no Laboratório de Pesquisa em Aves do departamento de Nutrição e Produção Animal, da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, Campus Pirassununga. Foram realizados dois alojamentos cada um com 960 pintos de um dia de idade. No primeiro alojamento, todas as aves foram inoculadas com uma cepa conhecida de Campylobacter jejuni (atcc 33560) a fim de contaminar o ambiente criando desafio sanitário. No segundo alojamento foram realizados dois protocolos de limpeza e desinfecção, constituindo os dois tratamentos experimentais (Comum e Proposto). Neste lote, para avaliação da produtividade, foram mensurados os parâmetros: viabilidade, mortalidade, conversão alimentar, ganho de peso e consumo de ração. Para avaliação microbiológica do ambiente e das carcaças foi realizada a contagem total de microrganismos para ambiente e a identificação de Campylobacter spp.. As amostras positivas foram submetidas a um ensaio de PCR multiplex para identificação de espécies de Campylobacter spp. Para avaliação econômica financeira dos lotes de frangos de corte foram utilizados e adaptados os dados de custos de produção elaborados pela Embrapa Suínos e Aves às condições de criação e resultados obtidos no presente estudo. O tratamento Proposto demonstrou influências positivas no desempenho das aves, na redução da contagem total de microrganismos, na eliminação de Campylobacter spp. e viabilidade econômico-financeira / The procedures of cleaning and disinfection used in broiler production are necessary to maintaining a high standard of birds health, decreasing the risk of diseases, optimizing the animal performance, as well as to ensure sanitary quality of meat. There is possibility of contamination in all farming steps, since chicks arrival until the end of slaughter. Campylobacter is a bacteria constantly found at gastrointestinal tract of the birds, and so, a special concern must be given since it can cause human diseases. In order to avoid foodborne illness outbreaks such as campylobacteriosis, to ensure poultry flocks health maintenance and to improve broilers productivity, adopting preventive practices such as cleaning and disinfection is required. Thus, this study aimed to evaluate: the animal performance of broilers challenged with Campylobacter jejuni; the reduction of infection pressure in housing plants subjected to different cleaning protocols and disinfection, and its economic and financial viability. Experimental protocol was conducted at the Research Laboratory of Poultry of Nutrition and Animal Production Department, College of Veterinary Medicine and Animal Science, University of São Paulo, Campus Pirassununga. Two housings each with 960 day-old chicks of age were performed. In the first housing, all birds were inoculated with a known strain of Campylobacter jejuni (ATCC 33560) to contaminate the environment in order to create health challenge. In the second housing were performed two cleaning and disinfection protocols, featuring two experimental treatments (Common and Proposed). In this lot, to evaluate animal performance, the parameters were measured: feasibility, mortality, feed conversion, weight gain and feed intake. For microbiological evaluation of environment and of carcasses, was performed a total count of microorganisms for environmental and identification of Campylobacter spp. The positive samples were subjected to a multiplex PCR assay identification of species of Campylobacter spp. For economic and financial evaluation of batches, the data of husbandry costs elaborated by Embrapa Swine and Poultry were adapted to conditions and rsults obtained in this study. Based on results, the Proposed treatment has shown positive influences on bird performance, reduction of total count of microorganisms, on elimination of Campylobacter spp. and on economic and financial viability

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2014-08-26T13:42:44Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertacao Agna Miranda Castro.pdf: 723885 bytes, checksum: 7fb4bb6ea94888ba4e3c34d11346c85f (MD5) / Made available in DSpace on 2014-08-26T13:42:44Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertacao Agna Miranda Castro.pdf: 723885 bytes, checksum: 7fb4bb6ea94888ba4e3c34d11346c85f (MD5) Previous issue date: 2012-03-29 / The Campylobacteriosis is a zoonosis of worldwide distribution, being Campylobacter jejuni the principal agent etiologic of gastroenteritis cases in humans. The presente study was check for the presence of Campylobacter spp. in carcasses and giblets of poultry, evisceration and depenadeira of three agribusiness located in Goiás State, subject to state inspection service (SIE). 160 samples were analysed from broiler slaughterhouses (A, B, and C), between the months of March and June 2011.Used the technique of conventional bacterial isolation. The positivity was found in 12.5% C. lari e C. jejuni) for liver, 12.5%(C. jejuni) for heart and 4.17% (C. lari) for gizzards. In analyses of the evisceration,broiler carcasses and depenadeira not detectedany samples positive. Through this study noted high exposure to the pathogen, since among the 160 samples analysed 7 (4.37%) contained the bacteria, giblets of poultry larger related edible risk exposure of the consumer population of this class of food. / A campilobacteriose é uma zoonose de distribuição mundial, sendo Campylobacter jejuni o principal agente etiológico de gastroenterites em humanos nos últimos anos.Objetivou-se com este estudo verificar a presença de Campylobacter spp. em carcaças e miúdos de frango, calha de evisceração e depenadeira de três agroindústrias localizadas no estado de Goiás. Foram analisadas 160 amostras provenientes de abatedouros de frangos (A, B e C), entre os meses de março e junho de 2011. Utilizou-se a técnica de isolamento convencional bacteriano. A positividade encontrada foi de 12,5% para fígado (C. jejuni e C. lari) , 12,5% para moela (C. lari) e 4,17%(C. jejuni) para coração. Nas análises de calha de evisceração, depenadeira e carcaças de frango não detectou-se nenhuma amostra positiva. Por meio deste estudo verificou-se exposição ao patógeno, uma vez que dentre as 160 amostras analisadas 7 (4,37%) continham a bactéria, sendo os miúdos de frango associados à maior exposição ao risco da população consumidora desta classe de alimentos.

Broiler flocks become frequently asymptomatically contaminated by the enteric bacteria Salmonella sp. and Campylobacter sp. which are human pathogens. Among the strategies developed at farm level to reduce the incidence of these pathogens, some lactic acid bacteria have been shown to be interesting because of their antimicrobial activity and their stimulatory properties on the immune system of poultry. The aim of this thesis was to select bacteria with antagonistic activity against Salmonella or Campylobacter, and to improve their inhibitory effect by the combination with enzymes of polysaccharidase type. The first step of the thesis was an epidemiological study carried out in the Walloon region in order to determine the contamination way of broilers by Campylobacter in free range production. Results showed that the major way of contamination is the open-air range to which the animals have access during the rearing period. A preventive treatment of the open-air range and the straw litter with an antagonistic strain in combination with an enzyme seems thus to be suitable in this case. The second step of the work aimed at the selection of a xylanase for using as a dietary additive in combination with an antagonistic bacterial strain against Salmonella. Four xylanases were studied in vivo for their effect on growth performances of broiler chickens. Diet supplementation with enzyme led to an increased final body weight and daily weight gain (P < 0.05), without difference according to the bacterial or fungal origin of the xylanase. The Belfeed B1100MP xylanase, which is commercialized in he Walloon region, was selected in order to develop a probiotic-xylanase feed additive. The purpose of the third part was to select a bacterial strain with antagonistic activity against Campylobacter for applying on open-air range and broiler litter. An in vitro screening of 12 lactic acid bacteria was realised using a co-culture assay with a growth medium based on straw and dehydrated poultry excreta, supplemented with different cellulase concentrations. Lactobacillus pentosus and Enterococcus faecium showed inhibitory effect against Campylobacter without enzyme which was intensified by cellulose from 200 ppm. Finally, the effect of dietary supplementation with a L. plantarum strain combined with the Belfeed B1100MP (PE treatment) on growth performance, microflora, and faecal Salmonella Typhimurium concentrations, was studied with experimentally infected broiler chickens. The PE diet allowed to partially overcome the negative effects associated with the infection on growth performance and microflora, and to significantly reduce faecal Salmonella concentration.

This thesis reports the development of Comparative Genomic Fingerprinting (CGF), a rapid genotyping method for Campylobacter jejuni that assesses the conservation status of 20 genes previously described as having high intraspecies variability based on comparative genomics studies. This novel method for genotyping C. jejuni, CGF was validated two-fold. First, by comparison to flaA restriction fragment length polymorphism analysis, and second a subset of isolates was validated using two higher resolution CGF assays assessing 35 and 119 genes. CGF was then tested in a molecular epidemiological study of C. jejuni isolated from environmental, animal and human clinical samples from southern Alberta. Reservoirs of infection, subtypes associated with higher incidence of human infection, and the persistence of prevalent subtypes in animal/environmental reservoirs were identified. This thesis demonstrates that CGF analysis is robust and can be used to rapidly assess genetic similarity of C. jejuni isolates and to detect epidemiologically relevant clonal groups. / xii, 184 leaves : ill. ; 29 cm

Campylobacter spp., especially C. jejuni and C. coli, are the leading cause of bacterial gastroenteritis in Europe. There is a recognised need to develop detection tools which can be performed on farms to facilitate reducing the presence of Campylobacter in poultry. A similar application could be beneficial for detection of C. fetus, a veterinary pathogen which causes significant economic loss in the cattle industry. Campylobacter species perform protein N-linked glycosylation and in C. jejuni at least 150 proteins, many of which are surface-exposed, may be modified. Therefore, the first portion of this thesis investigated the feasibility of using N-linked glycans as targets for antibody-based detection of Campylobacter species. To do this, a His-tagged N-glycoprotein was expressed and purified from C. fetus and used as immunogen to raise an antiserum termed CfNgp. The Campylobacter N-glycan reactivity of this antiserum was characterised and it was shown to react with N-glycoproteins and cells of C. fetus and other emerging Campylobacter species such as C. concisus. Immunoblotting techniques and flow cytometry were used to characterise an antiserum (CjNgp) raised against a C. jejuni N-linked glycoprotein and demonstrated that it can specifically detect cells of C. jejuni, C. coli and other emerging Campylobacter species found in poulty. This thesis also describes the investigation of the relatively uncharacterised C. fetus N-linked glycosylation system. Functional analysis of C. fetus predicted glycosyltransferases was acheived by developing glycocompetent E. coli containing a hybrid C. jejuni/C. fetus pgl system. The N-glycan structures biosynthesised were analysed using mass spectrometry and this novel approach discovered the activity of two C. fetus glycosyltransferase enzymes. Finally, this work used a bioinformatics pipeline to produce a C. fetus predicted N-linked glycoproteome and experimentally verified a newly identified N-linked glycoprotein. This pipeline was also applied to investigate the putative conservation of N-linked glycoproteins throughout the Campylobacter genus and highlighted ‘core’ N-linked glycoproteins which are key targets for experimental investigation. Overall, this work demonstrates that Campylobacter N-linked glycans are attractive targets for antibody-based detection, expands our knowledge of C. fetus N-linked glycosylation and contributes to the broader understanding of this intriguing aspect of Campylobacter biology.

O uso de antimicrobianos de forma terapêutica, preventiva e promotora de crescimento trouxe inúmeras vantagens para a avicultura mundial, entretanto a utilização excessiva dos antimicrobianos e de maneira indevida tem estimulado um aumento no número de micro-organismos resistentes. Entre eles, destaca-se o Campylobacter jejuni, bactéria frequentemente associada a enterites em humanos, sendo o frango a principal reservatório e fonte de transmissão deste patógeno para o homem. A transmissão de bactérias resistentes entre animais e seres humanos pode resultar em infecções multirresistentes e insucesso no tratamento terapêutico, sendo a exposição continua destes micro-organismos a esses medicamentos o fator mais importante na origem da resistência. Diante desse cenário, objetivou-se nesse trabalho investigar e caracterizar, através de métodos fenotípico e genotípico, a susceptibilidade antimicrobiana de 54 isolados de C. jejuni coletados em diferentes etapas do processamento da carne de frango de matadouro-frigoríficos da região do Rio Grande do Sul. Para a determinação do MIC, os isolados foram testados frente aos seguintes antimicrobianos: ácido nalidíxico, ciprofloxacina, cloranfenicol, eritromicina, gentamicina e tetraciclina. Dos 54 isolados de C. jejuni, 94,4% foram resistentes a ciprofloxacina, 83,3% ao ácido nalidíxico, 51,8% a tetraciclina e 48% a eritromicina. Todos os isolados foram sensíveis a gentamicina e ao cloranfenicol. Doze isolados foram resistentes a três classes diferentes de antibióticos, sendo assim considerados multi-resistentes. Para verificar a presença da mutação gênica da Região Determinante de Resistência à Quinolona (RDRQ) no gene gyrA, foi realizado sequenciamento gênico de 31 isolados considerados resistentes por métodos fenotípicos. Todos os isolados possuíam a mutação Tre-86-Ile na RDRQ do gene gyrA, que confere resistência às fluoroquinolonas, confirmando a predominância dessa mutação em Campylobacter spp. resistentes a esses antimicrobianos. A ocorrência do gene de resistência à tetraciclina foi verificada por PCR. Dos 28 isolados considerados resistentes por métodos fenotípicos, 42,8% possuíam o gene tet(O), que confere resistência as tetraciclinas. Os resultados mostram um alto nível de resistência antimicrobiana em C. jejuni evidenciando a necessidade da implementação de políticas de uso prudente de antimicrobianos na medicina veterinária. / The use of antimicrobials in a therapeutic, preventive and growth promoting way has brought numerous advantages to the world poultry industry; however, the excessive and undue use of antimicrobials has stimulated an increase in the number of resistant microorganisms. Among them, we highlight Campylobacter jejuni, a bacterium frequently associated with enteritis in humans, with chicken being the main reservoir and source of transmission of this pathogen to man. The transmission of resistant bacteria between animals and humans can result in multi resistant infections and failure in therapeutic treatment, and the continued exposure of these microorganisms to these drugs is the most important factor in the source of resistance. Therefore, the aim of this study was to investigate and characterize, through phenotypic and genotypic methods, the antimicrobial susceptibility of 54 C. jejuni isolates collected at different stages of the processing of chicken meat from slaughterhouse in Rio Grande do Sul. For MIC determination, strains were tested against the following antimicrobials: nalidixic acid, ciprofloxacin, chloramphenicol, erythromycin, gentamicin and tetracycline. Of the 54 isolates of C. jejuni, 94.4% were resistant to ciprofloxacin, 83.3% to nalidixic acid, 51.8% to tetracycline and 48% to erythromycin. All isolates were sensitive to gentamicin and chloramphenicol. Twelve strains were resistant to three different classes of antibiotics, thus being considered multi resistant. To verify the presence of the gene mutation of the Quinolone Resistance Determinant Region (QRDR) in the gene gyrA, gene sequencing of 31 strains considered resistant by phenotypic methods was performed. All strains had the Tre-86-Ile mutation in the QRDR of the gyrA gene, which confers resistance to fluoroquinolones, confirming the predominance of this mutation in Campylobacter spp. resistant to these antimicrobials. The occurrence of tetracycline resistance gene was verified by PCR. Of the 28 strains considered resistant by phenotypic methods, 42.8% had the tet(O) gene. The results show a high level of antimicrobial resistance in C. jejuni that evidences the need for implementation of policies in the prudent use of antimicrobials in veterinary medicine.