Orientador: Mary Luci de Souza Queiroz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-03T06:49:33Z (GMT). No. of bitstreams: 1 Pereira_AnaClaudiaNeves_M.pdf: 9613520 bytes, checksum: 0b95edc09c18a68e5d4f71f703e32217 (MD5) Previous issue date: 2001 / Resumo: Neste trabalho tivemos como objetivo a investigação dos efeitos do extrato hidroalcoólico da Acanthospermum hispidum (ERAA.hispidum) sobre o crescimento e diferenciação das células progenitoras hematopoiéticas para a série granulócitos-macrófagos (CFU-GM) da medula óssea e do baço, em animais infectados comListeria monocytogenes. Para a realização dos experimentos camundongos Balb/c foram tratados oralmente por cinco dias com ERA A.hispidum nas doses de 100, 500 ou 1000mg/kg/dia. Ao final do tratamento, os animais foram infectados intraperitonealmente com uma dose subletal de Listeria monocytogenes (lx105/animal) e sacrificados 48 e 72 horas após a infecção. Os animais somente infectados apresentaram uma diminuição no número de colônias de precursores hematopoiéticos (CFU-GM) na medula nas 48 (I-48h) e 72 (I-72h) horas após a infecção. A administração das 3 diferentes doses de ERA A.hispidum aos animais normais conduziu a uma diminuição dosedependente do CFU-GM da medula em relação ao grupo controle. Os animais tratados/infectados com as três diferentes doses de ERA A.mspidum nas 48 (TI-48h) e 72 (TI-72h) horas após a infecção, mantiveram a diminuição provocada pela infecção no número de CFU-GM da medula óssea da infecção, sendo que esta diminuição foi mais acentuada no período de 72 horas após a infecção. Com relação à hematopoiese esplênica, a inoculação de uma dose subletal de Listeria monocytogenes levou a um aumento no número de CFU-GM no baço nas 48 e 72 horas após a infecção. Os animais normais tratados com as 3 diferentes doses de ERAA.hispidum tiveram um aumento no número de CFU-GM do baço em relação ao grupo controle. Os animais tratados/infectados (TI-48h) com as três diferentes doses de ERA A.hispidum mantiveram o número de CFU-GM do baço quando comparado ao grupo infectado (I-48h). Após 72 horas, os grupos tratados/infectados (TI-72h) com as doses de 100 e 50Orng/kg de ERA A.hispidum apresentaram uma diminuição no número de CFU-GM em relação ao infectado (I-72h), enquanto que o grupo tratado com a dose de 1000 mg!kg de EHA A.hispidum, neste mesmo período de, infecção apresentou aumento significativo no número de CFU-GM em relação a todos os demais grupos. o peso do baço dos animais tratados com as doses de 500 e 1000mg!kg de EHA A.hispidum aumentou em relação ao grupo controle. A infecção produziu aumento no peso do baço nas 48 e 72 horas em relação ao controle, sendo que os animais infectados (I-48h) tiveram aumento superior aos dos infectados (I-72h). Valores normais foram observados nos animais tratados/infectados (TI-48h) com 100,500 e 1000mglkg de EHAA.hispidum. Porém, nos animais tratados/infectados (TI-72h) com as 3 doses o peso do baço não variou em relação ao grupo infectado (I-72h). Com o objetivo de verificar a resistência à infecção dos animais previamente tratados com as 3 diferentes doses do extrato hidroalcoólico de Acanthospermum hispidum realizamos uma curva de sobrevida com camundongos Balb/c infectados com uma dose letal de L .monocytogenes. Após 30 dias de observação, 30% dos animais tratados com a dose de 100mglkg, e 60% dos animais tratados com 500 e 1000 mg!kg sobreviveram a dose letal da L .monocytogenes, enquanto que 100% dos animais do grupo controle infectado morreram em seis dias. Nossos resultados sugerem que o EHA A.hispidum aumenta a resistência dos camundongos Balb/c infectados com a L. monocytogenes através de mobilização dos precursores hematopoiéticos medulares que se alojam no baço / Abstract: The objective of this work was to investigate the effects of A.hispidum hidroalcoholic extract (A. hispidum HAE) on the growth and differentiation of granulocyte-macrophage hematopoietic progenitor cells (CFU-GM) ITomthe bone marrow and spleen of mice infected with L. monocytogenes. In this study, groups of Balb/c mice were treated orally for 5 days with 100, 500 or 1000mg/kgl day of A. hispidum HAE. At the end of the treatment, mice were infected intraperitoneaIly with a subletal dose of L. monocytogenes (lxl05 bacteria/animaI) and sacrificed 48 or 72 hours after infection. The administration of the 3 different doses of A. hispidum HAE to normal mice led to a dose-dependent decrease in the number ofCFU-GM in the bone marrow in relation to controI. A decrease in the number of CFU-GM in the bone marrow of infected mice at 48 (I-48h) and 72 (I-72h) hours after infection was observed, when compared with controI. The effect observed in bone marrow CFU-GM number of infected mice was mantainned when mice were pre-treated with the 3 different doses of A. hispidum HAE, however the decrease was more accentuated at 72 hours after infection. Treatment with these 3 doses of A. hispidum HAE enhanced the number of CFU-GM in the spleen of normal mice, in relations to controls. A significant increase of splenic CFU-GM was also observed in infected mice. At 48 hours after the infection, the animais previously treated with the 3 different doses of A. hispidum HAE kept the number of CFU-GM at the infected (I-48h) leveI. At 72 hours, the groups treated/infected mice with the doses of 100 and 500mg/kg after infection had a decrease in the number of CFU-GM in relation to infected group (I-72h), while, infected mice pre-treated with 1000mg/kg showed an increase in the number of splenic CFU-Gmover the leves of infection. Spleen weight also increased in the groups of 500 and 1000mglkg of A. hispidum HAE in relation to controI. The infection also increased the spleen weight at both periods after infection. A decrease was observed in groups with the 3 doses of A. hispidum HAE at 48 hours after infection, whereas at 72 hours, no changes were produced in the spleen weight of infected mice when mice were pre-treated with the 3 doses. We ana1yzed the mice resistance previously treated with the 3 different doses of A. hispidum HAE and infected with a lethal dose of L. monocytogenes (3xl05 bacteriaJanimal) and observed during 30 days after infection. Thirty percent of the 1O0mglkgtreated mice and 60% of 500mglkg and 1000 mglkg treated mice survived , while 100% of control mice died into 6 days. Based on these findings, we suggest that A. hispidum HAE may induce mobilization of hematopoietic precursors .ITomthe bon~ marrow to the spleen, thus increasing the resistance of L. monocytogenes infected mice / Mestrado / Mestre em Farmacologia

Listeria monocytogenes is a bacterial pathogen that is typically transmitted to humans through consumption of contaminated foods. Infection with this organism can lead to a severe and life-threatening illness referred to as listeriosis. The goal of this study was to develop monoclonal antibodies (MAbs) with high specificity and affinity to proteins found on the surface of all strains of L. monocytogenes while not cross-reacting with non-pathogenic Listeria spp. or other major bacterial pathogens commonly found in foods. A literature search was conducted to identify ten candidate surface proteins involved or putatively involved in the virulence of L. monocytogenes. Bioinformatics analyses using BLAST on the NCBI website showed that five of the ten candidate proteins were potentially present in L. monocytogenes strains but absent from strains of other Listeria spp. Genes encoding for these five proteins, ActA, InlA, InlC2, InlJ and LapB, were cloned and expressed in Escherichia coli. MAbs were raised against recombinant LapB, InlJ and InlC2 proteins using hybridoma technology. A total of 48 anti-LapB, 33 anti-InlJ and 37 anti-InlC2 MAbs were developed. Based on the comparison of IFM signal of each MAb against L. monocytogenes cells, seven anti-LapB MAbs and six anti-InlC2 MAbs were selected for further characterization. All of the anti-InlJ MAbs showed weak IFM signals and negative reactivity in ELISA against L. monocytogenes cells. The selected anti-LapB and anti-InlC2 MAbs were further characterized by assessing their ability to bind to cells of 51 strains representing 11 L. monocytogenes serotypes using ELISA. Six anti-LapB MAbs (M3484, M3495, M3500, M3509, M3517, M3519) reacted strongly with 44 of 51 strains representing 9 of the 11 L. monocytogenes serotypes tested. Five anti-InlC2 MAbs (M3607, M3618, M3630, M3633, M3636) reacted strongly with 47 strains representing 10 of the 11 L. monocytogenes serotypes tested. These results indicate that anti-LapB and anti-InlC2 MAbs could potentially be used as diagnostic reagents for isolation and detection of almost all L. monocytogenes strains in contaminated foods.

Persistence of Listeria monocytogenes in food processing plants is a huge health and economic burden. Biofilms are considered to be one of the major mechanisms by which this pathogen persists within these environments. Studies so far have mostly used optimal growth conditions in their investigations which may not provide a realistic understanding of the biofilm forming abilities of L. monocytogenes in food processing plants. Therefore the aim of this study was to 1) establish a model (12 ºC, Beef Broth) that closely relates to the food processing environment 2) screen 66 isolates of L. monocytogenes from food and clinical sources and determine their biofilm forming phenotypes (non-, weak, moderate and strong formers) and 3) analyze the correlation between biofilm formation phenotypes and biofilm associated genes detected using polymerase chain reaction (PCR) and Basic Local Alignment Search Tool (BLAST) for whole genome sequences. Biofilm formation established at 12 ºC in Beef Broth was the most consistent and quantifiable at day 9 of incubation. Subsequently, 66 isolates were screened using this model, resulting in 60 isolates being identified as strong biofilm formers, 5 isolates as moderate biofilm formers and 1 isolate as a weak biofilm former. Twenty biofilm associated genes were analyzed using PCR in 27 representative isolates. Out of the 20 genes, at least 17 of them were detected in all the tested isolates. Out of the 106 biofilm associated genes analyzed using BLAST, all the isolates were found to show the presence of at least 92 genes. In conclusion, there was no obvious correlation between the presence/absence of the genes selected for analysis and the ability to form biofilms using approaches performed in this study. However, the model established in the study will be useful in further analysis (transcription and translation studies) of genetic markers responsible for biofilm formation of L. monocytogenes under food processing conditions.

Mutations in the Leucine-rich repeat kinase 2 (Lrrk2) gene are associated with familial and sporadic cases of Parkinson’s disease but are also found in inflammatory-related disorders such as Crohn’s disease, systemic lupus erythematosus, tuberculosis and leprosy. There is also evidence that LRRK2 is highly expressed in immune cells, particularly in macrophages, and has been functionally linked to pathways pertinent to immune cell function such as modulating the course of infections, cytokine release, autophagy and phagocytosis. Indeed, G2019S mutation in Lrrk2 is the most common mutation in Parkinson’s disease. Accordingly, we hypothesized that G2019S mutation in Lrrk2 might enhance the activation of the innate immune system. We tested our hypothesis by performing challenge experiments in a mouse model of Listeria monocytogenes, and by measuring the activation of bone marrow derived macrophages (BMDMs) following in vitro infection with the bacterium. We found that Lrrk2G2019S mutant mice controlled L. monocytogenes better than WT mice. The mechanism behind the better control of L. monocytogenes by the G2019S mutation of Lrrk2 was investigated in BMDMs following in vitro infection with L. monocytogenes. Interestingly, we found that Lrrk2G2019S mutation enhances the production of TNF-α, IL-1β and IL-10 by infected BMDMs. The impact on TNF-α and IL-1β was specifically due to the G2019S mutation of Lrrk2 since there was no impact on the expression of these cytokines in Lrrk2 knockout macrophages. Western blotting experiments revealed that the G2019S mutation of Lrrk2 enhances MAPK signaling (TAK1, p38 and ERK). Modulation of the expression of the pro-inflammatory cytokines, TNF-α and IL-1β by G2019S mutation of Lrrk2 occurred via p38 MAPK activation. The impact on IL-10 expression occurred through increased ERK activation by the G2019S mutation of Lrrk2. We did not observe any impact of G2019S mutation of Lrrk2 on the activation of NF-κB and JNK MAPK pathways. Increased expression of IL-1β by G2019S mutation of Lrrk2 revealed increased inflammasome signaling. Inflammasome signaling in response to L. monocytogenes was mainly mediated by the AIM2- and partly by NLRP3- inflammasome and was dependent on activation of caspase-1. We found that Lrrk2G2019S mutation enhanced the expression of NLRP3 and caspase-1. Finally, we found that the expression of reactive oxygen species (ROS) following infection with L. monocytogenes was augmented by G2019S mutation of Lrrk2, and this can be an important mechanism that promotes the enhanced clearance of the bacterium in vivo. Overall, these results present new insights into the signaling mechanisms through which the G2019S mutation of Lrrk2 augments innate immune response which leads to better control of infection.

Center for Disease Control and Food and Drug Administration reports indicate that cantaloupe is one of the five most likely fruits and vegetables to cause a foodborne disease outbreak. Cantaloupe is a potential hazardous food based on the FDA food code since it is capable of supporting pathogen growth due to its low acidity and high moisture content. The objectives of this study were to determine the effect of strain and temperature on growth and biofilm formation of L. monocytogenes and Salmonella spp. in cantaloupe flesh and peel extracts on different food-contact processing surfaces. Growth of L. monocytogenes and Salmonella strains was greater in high cantaloupe flesh and peel extract concentration at 22°C and 10°C. In 50 mg/ml of cantaloupe flesh or peel extract, the cell numbers of L. monocytogenes and Salmonella increased by 5.0-5.5 log CFU/ml in 40 h at 22°C and 1-3.5 log CFU/ml in 72 h at 10°C. In 2 mg/ml of cantaloupe flesh or peel extract, the cell numbers of L. monocytogenes and Salmonella increased by 4.0-4.5 log CFU/ml in 72 h at 22°C but no change in log CFU/ml in 72 h at 10°C. There were no differences (P ˃ 0.05) among L. monocytogenes orSalmonella strains for biofilm formation in cantaloupe extracts, but biofilm formation was greater (P < 0.05) at high temperature and high cantaloupe flesh or peel extract concentration. In 50 mg/ml cantaloupe flesh or peel extract, L. monocytogenes and Salmonella produced biofilms of 7 log CFU/coupon in 4 days at 22°C and 4-5 log CFU/coupon in 7 days at 10°C. In 2 mg/ml cantaloupe flesh or peel extract, L. monocytogenes and Salmonella produced biofilms of 5-6 log CFU/coupon in 4 days at 22°C and 3-4 log CFU/coupon in 7 days at 10°C. L. monocytogenes and Salmonella spp. formed less biofilms (P < 0.05) on buna-n rubber when compared to stainless steel, polyethylene and polyurethane surfaces. These findings indicate that a very low concentration of nutrients that are leaked from cantaloupe flesh or peel can induce growth and biofilm formation in L. monocytogenes and Salmonella spp. on different food-contact surfaces.

Infectious disease remains one of the leading causes of morbidity and mortality worldwide. Many bacteria that cause disease have the capacity to enter into eukaryotic cells such as epithelial cells and tissue macrophages. Gaining access into the intracellular environment is one of the most critical steps in their survival and/or in pathogenesis. The entry mechanisms employed by these organisms vary considerably, but most mechanisms involve sabotaging and manipulating host cell functions. Invasion of epithelial cells involves triggering host signal transduction mechanisms to induce cytoskeleton rearrangement, thereby facilitating bacterial uptake. My work focuses on understanding the molecular mechanisms employed by bacterial pathogen Listeria monocytogenes and Chlamydia trachomatis to gain access into the host cells in order to cause the disease. In first part of my thesis I investigated the mechanism of Listeria monocytogenes entry. Listeria, a facultative intracellular organism, is responsible for causing meningitis, septicemia, gastroenteritis and abortions. Critical for Listeria virulence is its ability to get internalized, replicates and spread into adjacent host cells. One of the pathways of Listeria internalization into mammalian cells is promoted by binding of its surface protein Internalin B (InlB) to host receptor MET. Studies done in the past demonstrated a critical role of host type IA Phosphoinositide (PI) 3-kinase in controlling cytoskeleton rearrangement and entry of Listeria downstream of MET. An important unresolved question was how activation of PI3K results in cytoskeleton rearrangements that promote Listeria entry. In this work, we identified 9 host signaling molecules, that iv includes Rab 5c, SWAP 70, GIT1, PDK1, mTor, ARAP2, ARNO, DAPP1 & PKC-δ, acting downstream of type IA Phosphoinositide (PI) 3-kinase to regulate changes in host cytoskeleton to cause Listeria entry. Second part of my thesis involved studying the functions of chlamydial effector protein Tarp in its invasion. Infection caused by Chlamydia Trachomatis is the most common sexually transmitted disease resulting in uro-genital diseases, LGV, ectopic pregnancy and infertility. It is also responsible for causing trachoma, the leading cause of preventable blindness in third world countries. Being an obligate intracellular pathogen, gaining access into intracellular environment is the most critical step in lifecycle and pathogenesis of Chlamydia. Previous studies demonstrate the role of both chlamydial and host actin nucleators, Tarp and Arp2/3 complex respectively, in mediating Chlamydial entry into non-phagocytic cells. But the molecular details of these processes were not well understood. In this study, we demonstrate novel function of Tarp protein to form actin bundles by its ability to bind filamentous actin through newly identified FAB domains. And we also provide bio-chemical evidence that Tarp and Arp2/3 complex works in conjunction to cause changes in host cytoskeleton that effectively culminate into bacterial uptake by host cells. Overall, this research was a significant step in enhancing our understanding, at a molecular level, to pathogenesis of infections caused by Listeria monocytogenes and Chlamydia trachomatis

Raw produce has frequently been identified as the source of bacterial pathogens that can cause human illnesses, including listeriosis and salmonellosis. Microbial pathogens may attach and form biofilms on raw fruit surfaces and can be difficult to remove. A cavitation process (formation of bubbles in water) was studied for its effectiveness for removal and inactivation of Listeria monocytogenes and Salmonella Newport from the surfaces of fresh Roma tomatoes and cantaloupes. Individual fruit were separately inoculated with each pathogen, then submerged in a water tank and treated with a bubble flow through an air stone using one airflow rate (0 – 14 liters/min.) for up to 60 sec. As air flow increased, pathogen reduction increased up to 1.2 log CFU/fruit greater than with water alone (no bubbles). Additional pathogen reduction in the tank water (organisms detached from the fruit) was observed with the bubble treatments. Therefore, these bubble streams can be used to enhance the detachment of bacteria from fruit surfaces and to inactivate a proportion of these detached microorganisms. Additionally, recoveries of Salmonella from inoculated Roma tomatoes and cantaloupe were determined for treatment water that contained 50 or 150 ppm sodium hypochlorite. The combination of cavitation and chlorine resulted in greater efficacy of inactivating the pathogen in treatment water, but not in removing this organism from the fruit surfaces. The physical force of a bubble stream on raw produce can effectively reduce and inactivate surface bacteria, and has the potential to reduce antimicrobial chemical and water use in post-harvest packing operations. / Master of Science in Life Sciences

A exportação de carne bovina possui lugar de destaque na economia brasileira, e, com o intuito de aumentar a disputa por novos mercados, tem-se buscado a produção de alimentos de qualidade e seguros. Dentro dessa concepção, a presença de Listeria monocytogenes constitui uma preocupação, devido à gravidade das infecções, veiculadas por alimentos, em humanos. O objetivo deste estudo foi avaliar a presença de Listeria sp. e microrganismos mesófilos totais em carcaças bovinas, em três pontos da linha de abate, verificando os perfis de resistência aos antimicrobianos das Listeria monocytogenes isoladas. Também objetivou-se avaliar a presença de Listeria sp. no ambiente de produção onde as carcaças foram processadas. Para tanto, suabes de superfície foram utilizados para coletar as amostras no ambiente de produção e nas carcaças bovinas, sendo as amostras ambientais inoculadas em placas Petrifilm para Listeria e as amostras de carcaça avaliadas segundo métodos preconizados pela norma ISO 11290. Das 110 carcaças analisadas, 12 foram positivas para Listeria sp., as quais: 7 L. innocua , 4 L. monocytogenes ,uma Listeria sp.Todas essas amostras foram isoladas do ponto 1, onde os animais ainda estavam com couro. Das 200 amostras ambientais, 25 foram positivas para Listeria sp, sendo uma L. monocytogenes e 24 L. innocua. Os isolados de L. monocytogenes foram susceptíveis a todos os antimicrobianos testados. As contagens médias de microrganismos mesófilos totais foram de 6,3 x 102; 4,9 x102 e 3,8 x102 UFC/100cm2 nos pontos 1, 2 e 3, respectivamente. Observou-se que no dia em que as contagens totais foram mais elevadas nas carcaças, houve maior número de isolamentos de L. innocua no ambiente, sugerindo contaminação cruzada. / The beff export ocupies a prominent place in the Brazilian economy, and, with the aim of increasing competition for new markets, have sought the production of quality food and insurance. Within this concept, the presence of Listeria monocytogenes , the product is a concern, mainly due to the severity of infections transmitted by food in humans. The objective of this study was to evaluate the presence of Listeria sp. And mesophilic microrganism in carcasses of cattle in three points of the slaughter line, checking the profiles of antimicrobial resistance of Listeria monocytogenes isolated. It also aimed to assess the presence of Listeria sp. in the production abbatoir environment industrial. For both, surfaces swabs were used to collect samples in the production environmental cattle carcass, environmental samples were inoculated in Petri film’s plate for Listeria and the samples carcass was evaluated according to the methods suggested by ISO 11290. Of the 110 carcasses, 12 were positives for Listeria spp., which were identified as L. innocua (7), L. monocytogenes (4), Listeria sp. (1). All samples were isolated from a point where the animals were still with leather. Of the 200 environmental samples, 25 were positive for Listeria sp, being one L. monocytogenes and 24 L. innocua. Isolates of L. monocytogenes were susceptible to all antimicrobials. The average counts of mesophilic microrganism were 6,3 x 102; 4,9 x102 e 3,8 x102UFC/100cm2 in the points 1, 2 e 3, respectively. We could see that on the total counts were higher in the carcasses higher number of L. innocua in the environment, suggesting the possibility of cross contamination.

A exportação de carne bovina possui lugar de destaque na economia brasileira, e, com o intuito de aumentar a disputa por novos mercados, tem-se buscado a produção de alimentos de qualidade e seguros. Dentro dessa concepção, a presença de Listeria monocytogenes constitui uma preocupação, devido à gravidade das infecções, veiculadas por alimentos, em humanos. O objetivo deste estudo foi avaliar a presença de Listeria sp. e microrganismos mesófilos totais em carcaças bovinas, em três pontos da linha de abate, verificando os perfis de resistência aos antimicrobianos das Listeria monocytogenes isoladas. Também objetivou-se avaliar a presença de Listeria sp. no ambiente de produção onde as carcaças foram processadas. Para tanto, suabes de superfície foram utilizados para coletar as amostras no ambiente de produção e nas carcaças bovinas, sendo as amostras ambientais inoculadas em placas Petrifilm para Listeria e as amostras de carcaça avaliadas segundo métodos preconizados pela norma ISO 11290. Das 110 carcaças analisadas, 12 foram positivas para Listeria sp., as quais: 7 L. innocua , 4 L. monocytogenes ,uma Listeria sp.Todas essas amostras foram isoladas do ponto 1, onde os animais ainda estavam com couro. Das 200 amostras ambientais, 25 foram positivas para Listeria sp, sendo uma L. monocytogenes e 24 L. innocua. Os isolados de L. monocytogenes foram susceptíveis a todos os antimicrobianos testados. As contagens médias de microrganismos mesófilos totais foram de 6,3 x 102; 4,9 x102 e 3,8 x102 UFC/100cm2 nos pontos 1, 2 e 3, respectivamente. Observou-se que no dia em que as contagens totais foram mais elevadas nas carcaças, houve maior número de isolamentos de L. innocua no ambiente, sugerindo contaminação cruzada. / The beff export ocupies a prominent place in the Brazilian economy, and, with the aim of increasing competition for new markets, have sought the production of quality food and insurance. Within this concept, the presence of Listeria monocytogenes , the product is a concern, mainly due to the severity of infections transmitted by food in humans. The objective of this study was to evaluate the presence of Listeria sp. And mesophilic microrganism in carcasses of cattle in three points of the slaughter line, checking the profiles of antimicrobial resistance of Listeria monocytogenes isolated. It also aimed to assess the presence of Listeria sp. in the production abbatoir environment industrial. For both, surfaces swabs were used to collect samples in the production environmental cattle carcass, environmental samples were inoculated in Petri film’s plate for Listeria and the samples carcass was evaluated according to the methods suggested by ISO 11290. Of the 110 carcasses, 12 were positives for Listeria spp., which were identified as L. innocua (7), L. monocytogenes (4), Listeria sp. (1). All samples were isolated from a point where the animals were still with leather. Of the 200 environmental samples, 25 were positive for Listeria sp, being one L. monocytogenes and 24 L. innocua. Isolates of L. monocytogenes were susceptible to all antimicrobials. The average counts of mesophilic microrganism were 6,3 x 102; 4,9 x102 e 3,8 x102UFC/100cm2 in the points 1, 2 e 3, respectively. We could see that on the total counts were higher in the carcasses higher number of L. innocua in the environment, suggesting the possibility of cross contamination.

A exportação de carne bovina possui lugar de destaque na economia brasileira, e, com o intuito de aumentar a disputa por novos mercados, tem-se buscado a produção de alimentos de qualidade e seguros. Dentro dessa concepção, a presença de Listeria monocytogenes constitui uma preocupação, devido à gravidade das infecções, veiculadas por alimentos, em humanos. O objetivo deste estudo foi avaliar a presença de Listeria sp. e microrganismos mesófilos totais em carcaças bovinas, em três pontos da linha de abate, verificando os perfis de resistência aos antimicrobianos das Listeria monocytogenes isoladas. Também objetivou-se avaliar a presença de Listeria sp. no ambiente de produção onde as carcaças foram processadas. Para tanto, suabes de superfície foram utilizados para coletar as amostras no ambiente de produção e nas carcaças bovinas, sendo as amostras ambientais inoculadas em placas Petrifilm para Listeria e as amostras de carcaça avaliadas segundo métodos preconizados pela norma ISO 11290. Das 110 carcaças analisadas, 12 foram positivas para Listeria sp., as quais: 7 L. innocua , 4 L. monocytogenes ,uma Listeria sp.Todas essas amostras foram isoladas do ponto 1, onde os animais ainda estavam com couro. Das 200 amostras ambientais, 25 foram positivas para Listeria sp, sendo uma L. monocytogenes e 24 L. innocua. Os isolados de L. monocytogenes foram susceptíveis a todos os antimicrobianos testados. As contagens médias de microrganismos mesófilos totais foram de 6,3 x 102; 4,9 x102 e 3,8 x102 UFC/100cm2 nos pontos 1, 2 e 3, respectivamente. Observou-se que no dia em que as contagens totais foram mais elevadas nas carcaças, houve maior número de isolamentos de L. innocua no ambiente, sugerindo contaminação cruzada. / The beff export ocupies a prominent place in the Brazilian economy, and, with the aim of increasing competition for new markets, have sought the production of quality food and insurance. Within this concept, the presence of Listeria monocytogenes , the product is a concern, mainly due to the severity of infections transmitted by food in humans. The objective of this study was to evaluate the presence of Listeria sp. And mesophilic microrganism in carcasses of cattle in three points of the slaughter line, checking the profiles of antimicrobial resistance of Listeria monocytogenes isolated. It also aimed to assess the presence of Listeria sp. in the production abbatoir environment industrial. For both, surfaces swabs were used to collect samples in the production environmental cattle carcass, environmental samples were inoculated in Petri film’s plate for Listeria and the samples carcass was evaluated according to the methods suggested by ISO 11290. Of the 110 carcasses, 12 were positives for Listeria spp., which were identified as L. innocua (7), L. monocytogenes (4), Listeria sp. (1). All samples were isolated from a point where the animals were still with leather. Of the 200 environmental samples, 25 were positive for Listeria sp, being one L. monocytogenes and 24 L. innocua. Isolates of L. monocytogenes were susceptible to all antimicrobials. The average counts of mesophilic microrganism were 6,3 x 102; 4,9 x102 e 3,8 x102UFC/100cm2 in the points 1, 2 e 3, respectively. We could see that on the total counts were higher in the carcasses higher number of L. innocua in the environment, suggesting the possibility of cross contamination.