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Master of Science / Food Science Institute, Animal Science and Industry / Daniel Y.C. Fung / Within the United States, it has been estimated that 60 deaths and 73,000 illnesses are caused by Escherichia coli O157:H7 infection annually (Gavin et al., 2004). Multiple effects have been known to occur with the onset of infection from E. coli O157:H7 in which some of these can become life-threatening. Escherichia coli O157:H7 is defined as a Shiga-toxin-producing E. coli strain (STEC). This microbial pathogen is a gram-negative bacillus organism that is motile, non-sorbitol fermenting, and β-glucuronidase negative. The infectious dose of E. coli O157:H7 can be as low as ten cells (Food and Drug Administration, 2009). Consumption of contaminated food, mainly undercooked ground beef and non or incorrectly pasteurized milk, are the primary sources of E. coli O157:H7 infection in human. Cattle, in particular, are considered chief asymptomatic reservoirs for this pathogen. Carried in their gut, feces, and milk, cattle carry this Shiga toxin-producing E. coli in ranges from 10[superscript]2 to 10[superscript]5 CFU/g. Although colonized with E. coli O157:H7, cattle and other ruminants show no adverse side effects from the pathogenic bacteria. There is also a difference in the prevalence of this pathogen between human and cattle. There has been a low incidence of illness caused by E. coli O157:H7 in humans when compared to the high prevalence of E. coli 057:H7 found in cattle and their environment. It has been discovered, through population genetic analysis, that E. coli O157:H7 and other O157:H- isolates make up a clone complex. In spite of the clonal nature of E. coli O157:H7 and other O157:H[superscript]- isolates, there are significant characteristics showing variability between the clone complex. These variability aspects can possibly account for the rapid divergence of E. coli strains including the recently discovered divergence of E. coli O157:H7 in to two separate lineages. Other possible reasons for a non-linear relationship between cattle prevalence and human infection include diversity of the Shiga Toxin-Encoding bacteriophage and receptors in cattle verses human, and finally the difference between the production of Locus of Enterocyte Effacement (LEE) in both human and cattle lineages.

Pas de résumé / Recently targeted therapies appeared as attractive alternatives to classical antitumoral treatments. The approach, developed on the concept of targeting drug to cancer cells, aims to spear normal tissues and decrease the side effects. This doctoral dissertation focuses on developing new anticancer targeted treatments in the field of chemotherapy and cancer immunotherapy by exploiting an original targeting moiety, the B subunit of Shiga toxin (STxB). Its specific properties, such as, recognition with its receptor Gb3 overexpressed in cancer cells or in antigen-presenting cells, its unconventional intracellular trafficking, guided the choice of this protein as targeting carrier. This project is based in the use of copper-free Huisgen [3+2] cycloaddition as a coupling method, which led to successful preparation of various conjugates for their respective applications. The concept was first validated by STxB-biotin conjugate. The high yield of the reaction and the compatibility between the targeting carrier and the chemical ligation promoted the design of conjugates for chemotherapy and immunotherapy. Two therapeutical optimizations of previously developed strategy in STxB drug targeting delivery were investigated: synthesis of multivalent drug-conjugates and synthesis of conjugates containing a highly potent anticancer agent. Both approaches exploited three anticancer agents: SN38, Doxorubicin and Monomethyl auristatin F. The disulfide spacer, combined with various self-immolative systems, insured drug release. Two cytotoxic conjugates STxB–doxorubicin (STxB-Doxo) and STxB-monomethyl auristatin F (STxB-MMAF) were obtained in very high yield and demonstrated strong tumor inhibition activity in the nanomolar range on Gb3-positive cells. Based on the results the STxB-MMAF conjugate was investigated on a mouse model. The project aimed also to develop STxB bioconjugates for vaccine applications. Previous studies used B subunit as a targeting carrier coupled to an antigenic protein in order to induce a more potent immune response against cancer. The conjugates were prepared using a commercial linker, requiring modifying the antigen at first place, or by oxime ligation, where slightly acidic conditions promoted the coupling. Thus, the work presented herein proposed an alternative ligation via copper-free click chemistry especially for more sensitive antigenic proteins. Various types of conjugates were synthesised and investigated for their immune stimulation properties. The STxB targeting strategy was also applied to the development of a new vaccine based on coupling the targeting carrier to alpha-GalCer, one of the most potent immune stimulating agents known. The work focused on the synthesis of functionalised alpha-Galcer with an azide handle.

Les stratégies thérapeutiques mises en place contre le cancer ont de nos jours besoin de nouveaux médicaments, à la fois plus actifs que ceux déjà existants et induisant moins d’effets secondaires. Ces nouvelles stratégies visent à cibler spécifiquement les cellules cancéreuses. Parmi ces stratégies, ces travaux de thèse concernent la vectorisation active, à l’aide d’un vecteur protéique dérivé de la toxine de Shiga, STxB. STxB reconnait spécifiquement son récepteur biologique Gb3, surexprimé à la surface des cellules cancéreuses humaines. Ce projet de recherche porte sur la conception et la synthèse de conjugués, combinant STxB et un agent cytotoxique. Le linker chimique, qui relie ces deux espèces, a été soigneusement conçu pour respecter les deux critères suivants : être suffisamment stable et néanmoins pouvoir être clivé pour libérer l’agent cytotoxique une fois les cellules cancéreuses atteintes. Un premier linker a été construit autour du motif mercaptoethanol, lié au vecteur STxB par une liaison disulfure. La libération de l’agent cytotoxique peut donc être initiée par un réducteur biologique comme le glutathion, puis par une étape d’auto-immolation. Ce linker a été appliqué à deux composés cytotoxiques très puissants, dérivés de l’auristatine, et a conduit à des résultats prometteurs in vitro. La labilité de la liaison ester à pH acide a également été mise à profit dans l’élaboration de deux linkers, conçus autour de motifs glutamate et thréoninate. L’utilisation d’un agent cytotoxique modérément puissant a été l’occasion de développer une stratégie de multivalence, consistant à augmenter la charge d’agents cytotoxiques sur STxB. Une autre option a été de considérer les nano-batônnets d’or comme une plate-forme nanométrique multimodale, capable de lier plusieurs milliers d’agents cytotoxiques et STxB. Enfin l’incorporation d’une séquence peptidique, connue pour être substrat d’une protéase, a donné lieu à une troisième étude, reposant sur un linker clivable plus sélectivement. Plusieurs linkers ont été étudiées, selon qu’ils libèrent l’agent cytotoxique sous sa forme native ou non. / We need new therapeutic strategies to treat cancerous patients by the discovery of new drugs that would be more active than those existing and especially assigning fewer side effects. These new therapies aim to specifically target cancer cells. Among the strategies for cancer targeting, we investigated drug-targeted strategies using a proteic carrier, STxB, derived from Shiga toxin. This protein recognizes specifically its biological receptor Gb3, which is over-expressed on human cancer cells. This work consisted in the design and synthesis of conjugates combining STxB and a cytotoxic drug. The chemical linker binding these two moieties was carefully designed in order to fit requirements of both stability and ability to trigger a drug-delivery. A first linker was designed around a mercaptoethanol core, able to be conjugated to STxB by a disulfide bond. This constitutes a drug-delivery trigger, activated by a biological reducing agent such as glutathion, and followed by a self-immolative step. Two highly potent conjugates of auristatin derivatives were obtained and showed promising results in vitro. The ester bonds lability in acidic pH was exploited for the design of two amino acid based linker. With the aim of increasing the ratio of drug on STxB, we investigated several multivalent linkers. Another option was to consider gold nanorods as a nanometric platform, able to carry thousands of drugs and STxB. The incorporation of a protease substrate to produce an enzyme-cleavable linker was investigated. Several spacers, which induced release of the drug under native form or under prodrug form, were designed and tested.

As Enfermidades Transmitidas por Alimentos representam um crescente e relevante problema de saúde pública. Além do prejuízo social, a contaminação de alimentos com microrganismos patogênicos gera um enorme prejuízo econômico. Técnicas de Análise de Risco permitem mensurar de forma mais adequada o impacto dos microrganismos contaminantes de alimentos na saúde da população. Uma Análise de Riscos, associada a uma combinação patógeno-alimento, envolve três passos: avaliação do risco, gestão do risco e comunicação do risco. Uma das etapas da avaliação do risco é a avaliação da exposição, baseada em dados sobre freqüência e nível de contaminação dos alimentos pelo patógeno avaliado no alimento em questão, o nível atingido pelo patógeno no momento do consumo e os padrões de consumo. Os produtos cárneos são os principais alimentos responsáveis pela veiculação de patógenos ao homem e os microrganismos de maior relevância nestes produtos são Listeria monocytogenes, Salmonella spp., Campylobacter spp. e Escherichia coli produtora de toxina de Shiga. O objetivo do presente estudo foi levantar informações qualitativas e quantitativas desses quatro patógenos em produtos cárneos (salsicha bovina, lingüiça suína, carne bovina moída e coxa de frango) comercializados no município de São Paulo, de forma a contribuir com dados para futuras avaliações de risco em relação a estes microrganismos nestes produtos. Das 552 amostras de produtos cárneos analisadas, L. monocytogenes foi o patógeno isolado com maior freqüência, sendo detectado em 48,7% das amostras, seguido por Campylobacter spp. em 6,0% e Salmonella spp. em 5,8%. E. coli produtora de toxina de Shiga não foi detectada em nenhuma das amostras estudadas. Listeria monocytogenes foi detectada em todos os tipos de produtos cárneos estudados, com freqüências mais elevadas nas amostras de carne bovina moída (59,4%), seguido de coxa de frango (58,0%), lingüiça suína (39,8%) e salsicha bovina (37,7%). Na maioria das amostras (94,4%), as contagens de L. monocytogenes foram inferiores a 102 UFC/g. As cepas de L. monocytogenes apresentaram ampla distribuição, sendo detectados os quatro grupos de sorotipos: 28,7% pertenceram ao Grupo 1 (sorotipos 1/2a e 3a), 21,0% ao Grupo 2 (sorotipos 1/2c e 3c), 17,0% ao Grupo 3 (sorotipos 1/2b, 3b e 7) e 13,8% ao Grupo 4 (sorotipos 4b, 4d e 4e). Salmonella spp. foi detectada em 32 amostras, sendo 20 (14,5%) de lingüiça e 12 (10,6%) de coxa de frango. As contagens foram baixas, variando de 3,0 a 9,3x10 NMP/g e os sorovares mais freqüentemente isolados foram S. Typhimurium (28,1%), S. Enteritidis (12,5%), S. Derby (12,5%) e S. I 4,[5],12:i:- (12,5%). Campylobacter spp. foi detectado em 33 amostras (6,0%), sendo 27 de coxa de frango (19,6%) e seis amostras de carne moída (4,3%). A presença de L. monocytogenes, Salmonella spp. e Campylobacter spp. nos produtos cárneos analisados representa um risco à saúde da população. O consumo destes produtos quando submetidos à cocção inadequada e/ou a contaminação cruzada com outros alimentos pode levar a ocorrência de Enfermidades Transmitidas por Alimentos. / Foodborne Diseases represent an increasingly important public health problem. Besides the social losses, contamination of food with pathogenic microorganisms generates an enormous economic damage. A more accurate measurement of the impact of microorganisms in food health can be achieved using Risk Analysis techniques. A risk analysis is composed by three elements: risk assessment, risk management and risk communication. One of the four steps of a risk assessment is the exposure assessment, based on data on frequency and level of contamination of a food by the pathogen under evaluation, levels of the pathogen in the food at the time of consumption and consumption patterns. Meat products are the main vehicles of pathogens to humans, where Listeria monocytogenes, Salmonella spp., Campylobacter spp. and Shiga toxin-producing Escherichia coli are the most relevant pathogens. The aim of this study was to obtain qualitative and quantitative information on these four pathogens in four types of meat products (beef sausage, pork sausage, ground beef and chicken leg) marketed in the city of Sao Paulo in order to contribute with data for future risk assessments for these microorganisms in these products. L. monocytogenes is the most frequent pathogen in the 552 samples of meat products analyzed, being detected in 48.7% of the samples, followed by Campylobacter spp. 6.0% and Salmonella spp. 5.8%. Shiga toxin-producing E. coli was not detected in any sample. L. monocytogenes was detected in all types of meat products, with highest frequency in ground beef (59.4%), followed by chicken leg (58.0%), pork sausage (39.8%) and beef sausage (37.7%). In most samples (94.4%), the counts of L. monocytogenes were below 102 CFU/g. L. monocytogenes strains were widely distributed in the four groups of serotypes: 28.7% belonged to Group 1 (serotypes 1/2a and 3a), 21% to Group 2 (serotypes 1/2c and 3c), 17% to Group 3 (serotypes 1/2b, 3b and 7) and 13.8% to Group 4 (serotypes 4b, 4d and 4e). Salmonella spp. was detected in 32 samples, being 20 (14.5%) of pork sausage and 12 (10.6%) of chicken leg. The counts were low, ranging from 3.0 to 9.3 x 10 MPN/g and the most frequent serovars were S. Typhimurium (28.1%), S. Enteritidis (12.5%), S. Derby (12.5%) and S. I 4, [5], 12: i: - (12.5%). Campylobacter spp. was detected in 33 samples (6.0%), being 27 of chicken leg (19.6%) and six samples of ground beef (4.3%). The presence of L. monocytogenes, Salmonella spp. and Campylobacter spp. in the tested meat products represent a risk to health. The consumption of inadequately cooked products and/or subjected to cross-contamination with other foods may lead to occurrence of foodborne diseases.

Les toxines Shiga (Stx) sont produites par Shigella dysenteriae et certaines espèces d’E. coli transmisent aux humains par la consommation d'aliments contaminés et causant des maladies graves. La toxine Stx est libérée par les bactéries dans l'intestin et par la suite, traverse les vaisseaux sanguins en aval pour atteindre leurs principaux organes cibles, notamment les reins. Les dommages causés aux reins peuvent entraîner des complications graves notamment Le syndrome hémolytique urémique (SHU). A ce jour, il n’existe aucun traitement disponible contre le SHU. Les toxines Stx usent du transport rétrograde intracellulaire pour infester les cellules endothéliales rénales et atteindre leur cible cytosolique, l'ARN ribosomal 28S. Via un screening à haut débit, il a été démontré que le composé Rétro-2 bloque le trafic rétrograde de Stx à l'interface Endosome-TGN, sans affecter la morphologie des organites cellulaires et le trafic des protéines endogènes. Au cours de cette thèse, une analyse des relations structure fonction du composé Retro-2 nous a permis d’identifier les régions de l'inhibiteur qui sont critiques pour l'activité de protection. Nous avons identifié un dérivé dihydroquinazolinone nommé Rétro-2.1 qui est à ce jour l'inhibiteur le plus puissant contre les toxines Stx. Afin d’identifier la cible moléculaire de Retro-2.1, nous avons développé des sondes photo-activables bio-actives. En outre, les données de diffraction des rayons X ont révélé que de l'activité antitoxine réside principalement dans l’énantiomère S. (S) -Retro-2.1 est 500 fois plus puissant contre Stx (50 nM) que la molécule initiale. Cette étude peut donner lieu à un nouveau concept thérapeutique ciblant la voie de transport rétrograde de la toxine à l'intérieur de la cellule hôte. Une telle stratégie thérapeutique pourrait donc être étendue à d'autres agents pathogènes qui usent également du trafic rétrograde pour une intoxication des cellules hôtes. Ce nouveau concept thérapeutique qui permet de cibler les cellules hôtes et non l'agent pathogène représente une véritable percée dans la découverte de médicaments à large spectre et réduit le risque de développement d’une résistance chez l’agent pathogène. / Shiga toxins (Stx) are produced by Shigella dysenteriae and certain species of E. coli that can be transmitted to humans primarily through consumption of contaminated foods and may cause severe disease. Stx is released by the bacteria in the intestine and subsequently, could cross the downstream blood vessels to reach their main target organs such as kidney. Damage to the kidney can result in serious life-threatening complication hemolytic uremic syndrome, for which there is no proven safe treatment available other than supportive care. Stx invades renal endothelial cells in a retrograde manner from cell surface to the endoplasmic reticulum in order to gain access to its cytosolic target, 28S rRNA. By using HTS, it was previously demonstrated that the compound Retro-2 blocks retrograde trafficking of Stx at the early endosome-TGN interface, without affecting the morphology of cellular organelles and trafficking of other endogenous proteins. In this work, different regions of the lead inhibitor Retro-2 that are critical for the protective activity have been determined by systematic structure-activity relationship studies. It allowed us to identify a dihydroquinazolinone derivative, named Retro-2.1 that is the most potent inhibitor of Stx to date and also to develop bio-active photo-activatable probes with the aim of identifying the molecular target of Retro-2 derivatives. Further, crystal X-ray diffraction data revealed that the antitoxin activity resides mainly in the S-enantiomer. (S)-Retro-2.1 has displayed 500 fold more potency (50 nM) than parent molecule against Stx cytotoxicity. This study may result in a new therapeutic concept - targeting the retrograde transport route of toxin inside host cell - for the treatment of Stx-producing E. coli infections and could therefore be extended to other pathogens that also traffic via the retrograde transport. Such a new therapeutic concept that target the host cells and not the pathogen itself would represent a real breakthrough in drug discovery leading to broad spectrum drugs.

Infecções associadas a cepas da Escherichia coli enterohemorrágica (EHEC), podem causar manifestações clínicas sendo a Síndrome Hemolítica Urêmica (SHU), a complicação mais severa. SHU está relacionada a presença da toxina de Shiga do tipo 2 (Stx2) e até o momento não se dispõe de uma vacina ou tratamentos efetivos para uso em humanos. Assim, este trabalho teve por objetivo desenvolver uma vacina baseada no derivado atóxico contendo a subunidade B e a porção A2 da subunidade A denominado Stx2ΔAB. Após expressão em linhagens de E.coli e tentativas iniciais de purificação, resultaram na formação de agregados proteicos. Ajustes nas condições de cultivo e purificação permitiram obter a proteína na forma de monômero da subunidade B, mas sem a presença da porção A2. O antígeno foi incorporado a lipossomas multilamelares (MLVs), combinados ao lipídio A e administrados por via subcutânea a camundongos. Animais imunizados desenvolveram anticorpos sistêmicos específicos contra Stx2 capazes de neutralizar a toxina in vitro e conferir proteção parcial a animais desafiados com dose letal da toxina. Em conclusão, o trabalho confirmou o potencial vacinal do antígeno e validou a estratégia baseada na incorporação do antígeno às MLVs como estratégia de imunização. / Infections associated with strains of enterohaemorrhagic Escherichia coli (EHEC), can cause clinical manifestations are the hemolytic uremic syndrome (HUS), the most severe complication. HUS is related to the presence of Shiga toxin type 2 (Stx2) and yet do not have a vaccine or effective treatments for use in humans. This work aimed to develop a vaccine based on non-toxic derivative containing the B subunit and the A2 portion of the subunit called Stx2ΔAB. After expression in E. coli strains and initial purification attempts resulted in the formation of protein aggregates. Adjustments in the cultivation and purification conditions have enabled the protein as the monomer subunit B but without the presence of the A2 portion. The antigen was incorporated into multilamellar liposomes (MLVs), the combined lipid A and administered subcutaneously to mice. immunized animals develop systemic antibodies specific against Stx2 able to neutralize toxin in vitro and to confer partial protection when challenged with a lethal dose of toxin. In conclusion, the study confirmed the potential vaccine antigen and validated strategy based on antigen incorporation into MLVs as immunization strategy.

Thesis (Ph. D.)--University of Virginia, 2008. / Title from title page. Includes bibliographical references. Also available online through Digital Dissertations.

Thesis (Ph. D.)--University of Virginia, 2008. / Title from title page. Includes bibliographical references. Also available online as viewed 8/06/2009 through Digital Dissertations.

As Enfermidades Transmitidas por Alimentos representam um crescente e relevante problema de saúde pública. Além do prejuízo social, a contaminação de alimentos com microrganismos patogênicos gera um enorme prejuízo econômico. Técnicas de Análise de Risco permitem mensurar de forma mais adequada o impacto dos microrganismos contaminantes de alimentos na saúde da população. Uma Análise de Riscos, associada a uma combinação patógeno-alimento, envolve três passos: avaliação do risco, gestão do risco e comunicação do risco. Uma das etapas da avaliação do risco é a avaliação da exposição, baseada em dados sobre freqüência e nível de contaminação dos alimentos pelo patógeno avaliado no alimento em questão, o nível atingido pelo patógeno no momento do consumo e os padrões de consumo. Os produtos cárneos são os principais alimentos responsáveis pela veiculação de patógenos ao homem e os microrganismos de maior relevância nestes produtos são Listeria monocytogenes, Salmonella spp., Campylobacter spp. e Escherichia coli produtora de toxina de Shiga. O objetivo do presente estudo foi levantar informações qualitativas e quantitativas desses quatro patógenos em produtos cárneos (salsicha bovina, lingüiça suína, carne bovina moída e coxa de frango) comercializados no município de São Paulo, de forma a contribuir com dados para futuras avaliações de risco em relação a estes microrganismos nestes produtos. Das 552 amostras de produtos cárneos analisadas, L. monocytogenes foi o patógeno isolado com maior freqüência, sendo detectado em 48,7% das amostras, seguido por Campylobacter spp. em 6,0% e Salmonella spp. em 5,8%. E. coli produtora de toxina de Shiga não foi detectada em nenhuma das amostras estudadas. Listeria monocytogenes foi detectada em todos os tipos de produtos cárneos estudados, com freqüências mais elevadas nas amostras de carne bovina moída (59,4%), seguido de coxa de frango (58,0%), lingüiça suína (39,8%) e salsicha bovina (37,7%). Na maioria das amostras (94,4%), as contagens de L. monocytogenes foram inferiores a 102 UFC/g. As cepas de L. monocytogenes apresentaram ampla distribuição, sendo detectados os quatro grupos de sorotipos: 28,7% pertenceram ao Grupo 1 (sorotipos 1/2a e 3a), 21,0% ao Grupo 2 (sorotipos 1/2c e 3c), 17,0% ao Grupo 3 (sorotipos 1/2b, 3b e 7) e 13,8% ao Grupo 4 (sorotipos 4b, 4d e 4e). Salmonella spp. foi detectada em 32 amostras, sendo 20 (14,5%) de lingüiça e 12 (10,6%) de coxa de frango. As contagens foram baixas, variando de 3,0 a 9,3x10 NMP/g e os sorovares mais freqüentemente isolados foram S. Typhimurium (28,1%), S. Enteritidis (12,5%), S. Derby (12,5%) e S. I 4,[5],12:i:- (12,5%). Campylobacter spp. foi detectado em 33 amostras (6,0%), sendo 27 de coxa de frango (19,6%) e seis amostras de carne moída (4,3%). A presença de L. monocytogenes, Salmonella spp. e Campylobacter spp. nos produtos cárneos analisados representa um risco à saúde da população. O consumo destes produtos quando submetidos à cocção inadequada e/ou a contaminação cruzada com outros alimentos pode levar a ocorrência de Enfermidades Transmitidas por Alimentos. / Foodborne Diseases represent an increasingly important public health problem. Besides the social losses, contamination of food with pathogenic microorganisms generates an enormous economic damage. A more accurate measurement of the impact of microorganisms in food health can be achieved using Risk Analysis techniques. A risk analysis is composed by three elements: risk assessment, risk management and risk communication. One of the four steps of a risk assessment is the exposure assessment, based on data on frequency and level of contamination of a food by the pathogen under evaluation, levels of the pathogen in the food at the time of consumption and consumption patterns. Meat products are the main vehicles of pathogens to humans, where Listeria monocytogenes, Salmonella spp., Campylobacter spp. and Shiga toxin-producing Escherichia coli are the most relevant pathogens. The aim of this study was to obtain qualitative and quantitative information on these four pathogens in four types of meat products (beef sausage, pork sausage, ground beef and chicken leg) marketed in the city of Sao Paulo in order to contribute with data for future risk assessments for these microorganisms in these products. L. monocytogenes is the most frequent pathogen in the 552 samples of meat products analyzed, being detected in 48.7% of the samples, followed by Campylobacter spp. 6.0% and Salmonella spp. 5.8%. Shiga toxin-producing E. coli was not detected in any sample. L. monocytogenes was detected in all types of meat products, with highest frequency in ground beef (59.4%), followed by chicken leg (58.0%), pork sausage (39.8%) and beef sausage (37.7%). In most samples (94.4%), the counts of L. monocytogenes were below 102 CFU/g. L. monocytogenes strains were widely distributed in the four groups of serotypes: 28.7% belonged to Group 1 (serotypes 1/2a and 3a), 21% to Group 2 (serotypes 1/2c and 3c), 17% to Group 3 (serotypes 1/2b, 3b and 7) and 13.8% to Group 4 (serotypes 4b, 4d and 4e). Salmonella spp. was detected in 32 samples, being 20 (14.5%) of pork sausage and 12 (10.6%) of chicken leg. The counts were low, ranging from 3.0 to 9.3 x 10 MPN/g and the most frequent serovars were S. Typhimurium (28.1%), S. Enteritidis (12.5%), S. Derby (12.5%) and S. I 4, [5], 12: i: - (12.5%). Campylobacter spp. was detected in 33 samples (6.0%), being 27 of chicken leg (19.6%) and six samples of ground beef (4.3%). The presence of L. monocytogenes, Salmonella spp. and Campylobacter spp. in the tested meat products represent a risk to health. The consumption of inadequately cooked products and/or subjected to cross-contamination with other foods may lead to occurrence of foodborne diseases.