Thesis PlanA (M.S.)--University of Wisconsin--Stout, 2006. / Includes bibliographical references.

Submitted by ISAMERY AUXILIADORA MACHADO DE SARMIENTO null (isamerymachado@yahoo.com) on 2016-08-24T00:16:43Z No. of bitstreams: 1 Archivo combinado tese completa con link Isa.pdf: 3685365 bytes, checksum: 2df7162dfd0eb21c6e675c7966fce592 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-08-25T20:40:51Z (GMT) No. of bitstreams: 1 machadodesarmiento_ia_dr_bot.pdf: 3685365 bytes, checksum: 2df7162dfd0eb21c6e675c7966fce592 (MD5) / Made available in DSpace on 2016-08-25T20:40:51Z (GMT). No. of bitstreams: 1 machadodesarmiento_ia_dr_bot.pdf: 3685365 bytes, checksum: 2df7162dfd0eb21c6e675c7966fce592 (MD5) Previous issue date: 2016-06-30 / As doenças de transmissão alimentar (DTA) por bactérias constituem um problema de saúde pública no mundo. O objetivo do trabalho foi identificar por métodos microbiológicos e moleculares a presença de Campylobacter spp., Salmonella spp. e Escherichia coli em frangos de Botucatu-SP, Brasil. Sessenta (60) amostras de frangos resfriados de diferentes marcas foram coletadas aleatoriamente em diferentes estabelecimentos localizados tanto na periferia, quanto no centro da cidade de Botucatu, SP, no período de julho a outubro de 2015. Posteriormente, Campylobacter spp, Salmonella spp e E. coli foram isolados através de métodos microbiológicos convencionais. A confirmação das bactérias isoladas se realizou por provas bioquímicas e PCR. Além disso, as provas para determinar a resistência antimicrobiana e a existência de gene integron classe 1 foram realizadas. Os resultados demostraram a presença de três das principais bactérias que causam doenças de origem alimentar em carcaças de frango provenientes de supermercados e casas de carne de Botucatu. A prevalência de Campylobacter, Salmonella, e E. coli foi 38,3%, 13,3% e 60%, respectivamente. A resistência antimicrobiana dos isolados foi elevada e presença do gene íntegron classe 1 foi identificada em alguns agentes patogénicos. / The transmission of Foodborne Diseases (FBD) by bacteria constitutes a public health problem in the world. The objective of this study was to identify by microbiological and molecular methods the presence of Campylobacter spp., Salmonella spp. and Escherichia coli in broiler chickens at Botucatu, SP, Brazil. Sixty samples of chilled chickens of different brands were randomly collected from supermarkets and meat houses located in both the periphery and the center of the city, in the period from July to October 2015. Later, Campylobacter spp., Salmonella spp., and E. coli were isolated by conventional microbiological methods. Confirmation of the isolated bacteria was performed by biochemical and PCR tests. In addition, proofs to determine antimicrobial resistance and the existence of class 1 integron gene were carried out. Results confirmed the presence of the three assessed bacteria in poultry carcasses from selected establishments. The prevalence was 38.3%, 13.3% and 60% to Campylobacter, Salmonella and E. coli, respectively. Antimicrobial resistance of the isolates was high and the presence of integron class 1 gene has been identified in some pathogens.

Orientador: Noeme Sousa Rocha / Resumo: As doenças de transmissão alimentar (DTA) por bactérias constituem um problema de saúde pública no mundo. O objetivo do trabalho foi identificar por métodos microbiológicos e moleculares a presença de Campylobacter spp., Salmonella spp. e Escherichia coli em frangos de Botucatu-SP, Brasil. Sessenta (60) amostras de frangos resfriados de diferentes marcas foram coletadas aleatoriamente em diferentes estabelecimentos localizados tanto na periferia, quanto no centro da cidade de Botucatu, SP, no período de julho a outubro de 2015. Posteriormente, Campylobacter spp, Salmonella spp e E. coli foram isolados através de métodos microbiológicos convencionais. A confirmação das bactérias isoladas se realizou por provas bioquímicas e PCR. Além disso, as provas para determinar a resistência antimicrobiana e a existência de gene integron classe 1 foram realizadas. Os resultados demostraram a presença de três das principais bactérias que causam doenças de origem alimentar em carcaças de frango provenientes de supermercados e casas de carne de Botucatu. A prevalência de Campylobacter, Salmonella, e E. coli foi 38,3%, 13,3% e 60%, respectivamente. A resistência antimicrobiana dos isolados foi elevada e presença do gene íntegron classe 1 foi identificada em alguns agentes patogénicos. / Abstract: The transmission of Foodborne Diseases (FBD) by bacteria constitutes a public health problem in the world. The objective of this study was to identify by microbiological and molecular methods the presence of Campylobacter spp., Salmonella spp. and Escherichia coli in broiler chickens at Botucatu, SP, Brazil. Sixty samples of chilled chickens of different brands were randomly collected from supermarkets and meat houses located in both the periphery and the center of the city, in the period from July to October 2015. Later, Campylobacter spp., Salmonella spp., and E. coli were isolated by conventional microbiological methods. Confirmation of the isolated bacteria was performed by biochemical and PCR tests. In addition, proofs to determine antimicrobial resistance and the existence of class 1 integron gene were carried out. Results confirmed the presence of the three assessed bacteria in poultry carcasses from selected establishments. The prevalence was 38.3%, 13.3% and 60% to Campylobacter, Salmonella and E. coli, respectively. Antimicrobial resistance of the isolates was high and the presence of integron class 1 gene has been identified in some pathogens. / Doutor

Water and food borne Escherichia coli O157:H7 could be one of the pathogens posing high health risk to patients suffering from Acquired Immunodeficiency Syndrome (AIDS) because of its incrimination in diarrhoea cases in AIDS patients. The present study, which was conducted between March 2005 and August 2006, investigated the prevalence of E. coli O157:H7 in water, meat and meat products and vegetables and its impact on diarrhoeic conditions of confirmed and non-confirmed HIV/AIDS patients in the Amathole District in the Eastern Cape Province of South Africa. The water samples used in the study were obtained from stand pipes supplying treated drinking water to communities residing in Fort Beaufort, Alice, Dimbaza and Mdantsane whereas borehole waters were sampled from Ngwenya and Kwasaki. The meat and meat products and vegetable samples were purchased from shops, butcheries, supermarkets and open air markets in Fort Beaufort, Alice and Mdantsane. The stool swabs used in the study were obtained from HIV/AIDS and outpatient clinics at Frere Hospital in East London. A total of 180 each of water, meat and meat products and vegetable samples and another 360 stool samples were analyzed for E. coli O157:H7. Presumptive E. coli O157 was isolated from the samples by culture-based methods and confirmed using Polymerase Chain Reaction techniques. Anti-biogram as well as risk assessment were also carried out using standard methods. The viable counts of presumptive E. coli O157 for water samples ranged between 3.3 × 104 and 1.71 × 105 CFU/ml, and between 1.8 × 104 and 5.04 × 106 CFU/g for meat and meat products, whereas those for vegetables ranged between 1.3 × 103 and 1.6 × 106 CFU/g. The counts of presumptive E. coli O157 for the water and vegetable samples were not significantly different whereas those for meat and meat products were found to be significantly different (P ≤ 0.05). The prevalence rates of presumptive E coli O157 in meat and meat products was 35.55 percent (64/180), and 25.55 percent (46/180) and 21.66 percent (39/180) for water and vegetables respectively. Prevalence of presumptive E. coli O157 in the stool samples of HIV/AIDS patients was 36.39 percent (131/360), of which 56.5 percent (74/131) and 43.5 percent (57/131) were from stools of confirmed and non-confirmed HIV/AIDS patients, respectively. Molecular analysis of representative presumptive E. coli O157 indicated that 10.29 percent (4/39) of vegetables; 14.81 percent (4/27) of water and 38.46 percent (5/13) of meat and meat products carried E. coli O157:H7. Also 36 percent (9/25) and 17.24 percent (5/29) of the stool samples were positive for E. coli O157:H7. Antimicrobial susceptibility profile revealed that all of the E. coli O157:H7 isolated from water, meat and meat products and vegetables as well as those isolated from stools of confirmed and non-confirmed HIV/AIDS patients were resistant (R) to gentamycin and erythromycin. However, 75 percent (20/27) of these isolates were resistant (R) to ampicillin and tetracycline whereas approximately 25 percent (6/27) were resistant (R) to nalidixic acid, ceftriaxone, and chloramphenicol. All the isolates (27/27) were susceptible (S) to amikacin. Probability of risk of E. coli O157:H7 infection was high for confirmed HIV/AIDS patients than for the non-confirmed HIV/AIDS patients. Estimated probability of risk of E. coli O157:H7 due to ingestion of water was 1.00 for 100 confirmed and non-confirmed HIV/AIDS patients. Risk due to meat and meat products was estimated at 0.27 and 0.20 and for vegetables at 0.21 and 0.15 per 100 confirmed and non-confirmed HIV/AIDS patients. The findings of this study predicted a possible link between E. coli O157:H7 isolated from drinking water, meat and meat products and vegetables and diarrhoeic conditions in both confirmed and non-confirmed HIV/AIDS patients, and concludes that confirmed HIV/AIDS patients can be at higher risk of contracting water and food borne E. coli O157:H7 than nonconfirmed HIV/AIDS patients. It is thus recommended that proper water treatment and food handling, maximum food and water safety and sanitation as well as personal body hygiene should be maintained, in order to prevent E. coli O157:H7 infections. Education initiatives and active surveillance of E. coli O157:H7 should be taken by all the stake-holders working directly or indirectly towards ensuring enduring sound public health.

Community-acquired Clostridium difficile infections have recently been increasing in incidence and severity. Several studies have isolated C. difficile spores from livestock and retail meats, suggesting that food may play a role in transmission. No research has been done, however, on what food conditions might allow for the survival and/or growth of the bacterium. We therefore modelled the minimum thresholds for C. difficile growth under low pH, water activity (aw), and temperature. We also sampled retail ground meats, cheese, and milk for the presence of C. difficile spores and subtyped food isolates for comparison with clinical strains. We found that C. difficile growth could be prevented by refrigeration temperatures. C. difficile spores were also detected for the first time in Canada in ground lamb, ground turkey, ground chicken, cheese and milk. The majority of these food isolates were genetically similar to epidemic strain NAP7/078, suggesting that food may not be a direct vector for C. difficile transmission, but could still be clinically relevant.

Práticas nutricionais saudáveis e a globalização cultural popularizaram o consumo de pratos à base de peixe cru, anteriormente restritos aos países orientais. Estimativas mostram que doenças de origem alimentar causam aproximadamente 76 milhões de casos, 325 mil hospitalizações e 5 mil mortes a cada ano, somente nos Estados Unidos. Casos com etiologia desconhecida somam 62 milhões, com 265 mil hospitalizações e 3.200 mortes. O objetivo deste estudo foi investigar a presença de Escherichia coli, Salmonella spp. e Staphylococcus aureus e cepas potencialmente patogênicas de Aeromonas spp. e Vibrio spp. em peixes comercializados em feiras livres da cidade de São Paulo, Brasil. Vinte amostras de peixes, de diferentes espécies, foram adquiridas em feiras livres e analisadas utilizando metodologia convencional para investigação de patógenos em alimentos. Altos níveis de contaminação fecal foram detectados em 25% das amostras. Staphylococcus aureus foi isolado em 10% das amostras, entretanto em valores abaixo do permitido pela legislação brasileira. Todas as amostras estavam negativas para Salmonella spp. V. parahaemolyticus não foi isolado, 30% das amostras foram positivas para outras espécies de Vibrio, inclusive Vibrio cholerae não-O1/não-O139. Aeromonas spp. , incluindo A. hydrophila foi isolada em 50% das amostras de peixe. O isolamento de Vibrio cholerae não-O1/não-O139 e Aeromonas hydrophila, assim como Staphylococcus aureus e Escherichia coli, sugere que peixes comercializados em feiras livres da cidade de São Paulo podem representar um risco para os consumidores e ser um importante veículo de transmissão de espécies enteropatogênicas. / Healthier nutritional lifestyles and cultural globalization have popularized the consumption of raw fish dishes that were previously restricted to oriental countries. Estimates indicate that food-borne diseases cause approximately 76 million illnesses, 325,000 hospitalizations and 5,000 deaths each year in the United States alone. Cases with unknown etiology account for 62 million illnesses, 265,000 hospitalizations and 3,200 deaths. The purpose of this study was to investigate the presence of Escherichia coli, Salmonella spp., Staphylococcus aureus and potentially pathogenic strains of Aeromonas spp. and Vibrio spp. in fish commercialized at the retail level in the markets of São Paulo City, Brazil. Twenty fish of different species were analysed for foodborne pathogens using conventional methodologies. High levels of faecal contamination were detected in 25% of fish samples. Staphylococcus aureus was isolated from 10% of samples; however, in each case this was below the limits established by Brazilian legislation. All samples were negative for Salmonella and 30% tested positive for others Vibrio spp., including Vibrio cholerae non-O1/non-O139. Vibrio parahaemolyticus was not found in this study. Aeromonas spp., including A. hydrophila, were isolated in 50% of fish samples. The isolation of Vibrio cholerae non-O1/non-O139 and Aeromonas hydrophila as well as Staphylococcus aureus and Escherichia coli suggests that fish commercialized in São Paulo City may represent a health risk to consumers and be an important vehicle for transmission of these enteropathogenic species.

Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-10-17T18:41:11Z No. of bitstreams: 2 Dissertação - Thatyana Lacerda de Almeida - 2014.pdf: 1047552 bytes, checksum: 19f6c0b581be0e42b2884ae3ecdddbcc (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2014-10-17T20:28:41Z (GMT) No. of bitstreams: 2 Dissertação - Thatyana Lacerda de Almeida - 2014.pdf: 1047552 bytes, checksum: 19f6c0b581be0e42b2884ae3ecdddbcc (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-10-17T20:28:41Z (GMT). No. of bitstreams: 2 Dissertação - Thatyana Lacerda de Almeida - 2014.pdf: 1047552 bytes, checksum: 19f6c0b581be0e42b2884ae3ecdddbcc (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-02-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Studies conducted in Brazil showed the presence of pathogenic bacteria in foods whose consumption can cause diseases and food-borne disorders. In general, consumers have expectations about consuming safe food and foodborne diseases are highly unpleasant, generating distrust in the quality of food products on the market. Listeria monocytogenes is an important pathogen transmitted by food, whose accurate identification is important for the correct risk determination associated with the ingestion of various kinds of food. Considering the importance of this pathogen to the consumer, the present study aimed to isolate and identify Listeria monocytogenes in frescal type of sausages, butchers sold in the city of Aparecida de Goiânia Goiás. 88 samples were analyzed, been 44 frescal type of pork sausage and 44 of chicken meat from the butchers of Aparecida de Goiânia, registered in the Comércio Varejista de Carnes Frescas in Goiás. Was followed the methodology of sampling and analytical recommended by the American Public Health Association, and the analyzes were performed at the Laboratório de Controle Higiênico Sanitário de Alimentos da Faculdade de utrição da Universidade Federal de Goiás. Of the total samples, six were considered suspicious and inteneded with biochemical evidence, none were considered positive for the target bacteria. The results obtained in this research found a quality sausages for the target bacteria, but must be reinforced the need for legal support to facilitate recognition of research actions broader control and disease severity dissemination, especially in pregnant women, newborn born, immunocompromised and elderly who are the most vulnerable population. / Estudos conduzidos no Brasil demonstram a presença de bactérias patogênicas nos alimentos, cujo consumo pode causar doenças e transtornos de origem alimentar. Em geral, os consumidores têm expectativas em consumir alimentos seguros e as doenças transmitidas por alimentos são altamente desagradáveis, gerando desconfianças na qualidade dos produtos alimentícios no mercado. Listeria monocytogenes é um patógeno relevante transmitido por alimentos, cuja identificação precisa é importante para a correta determinação do risco associado à ingestão de diversos tipos de alimentos. Considerando a importância desse patógeno para o consumidor, o presente estudo pretendeu isolar e identificar Listeria monocytogenes de linguiças do tipo frescal, comercializadas em açougues do Município de Aparecida de Goiânia, Goiás. Foram analisadas 88 amostras, sendo 44 de linguiça tipo frescal de carne suína e 44 de carne de frango, provenientes dos açougues de Aparecida de Goiânia, cadastrados no Sindicato do Comércio Varejista de Carnes Frescas no Estado de Goiás. Seguiu-se a metodologia de coleta de amostras e analítica preconizada pela American Public Health Association e, realizaram-se as análises no Laboratório de Controle Higiênico Sanitário de Alimentos da Faculdade de Nutrição da Universidade Federal de Goiás. Do total de amostras, seis foram consideradas suspeitas e destinadas às provas bioquímicas. Dessas, nenhuma foi considerada positiva para a bactéria alvo. Os resultados obtidos nesta pesquisa constatam uma qualidade nas linguiças para a bactéria alvo, porém deve ser reforçada a necessidade de um amparo legal, para facilitar reconhecimento das pesquisas, ações de controle mais amplas e na divulgação da gravidade da doença, principalmente em gestantes, recém-nascidos, imunodeprimidos e idosos que constituem a população mais vulnerável.

Práticas nutricionais saudáveis e a globalização cultural popularizaram o consumo de pratos à base de peixe cru, anteriormente restritos aos países orientais. Estimativas mostram que doenças de origem alimentar causam aproximadamente 76 milhões de casos, 325 mil hospitalizações e 5 mil mortes a cada ano, somente nos Estados Unidos. Casos com etiologia desconhecida somam 62 milhões, com 265 mil hospitalizações e 3.200 mortes. O objetivo deste estudo foi investigar a presença de Escherichia coli, Salmonella spp. e Staphylococcus aureus e cepas potencialmente patogênicas de Aeromonas spp. e Vibrio spp. em peixes comercializados em feiras livres da cidade de São Paulo, Brasil. Vinte amostras de peixes, de diferentes espécies, foram adquiridas em feiras livres e analisadas utilizando metodologia convencional para investigação de patógenos em alimentos. Altos níveis de contaminação fecal foram detectados em 25% das amostras. Staphylococcus aureus foi isolado em 10% das amostras, entretanto em valores abaixo do permitido pela legislação brasileira. Todas as amostras estavam negativas para Salmonella spp. V. parahaemolyticus não foi isolado, 30% das amostras foram positivas para outras espécies de Vibrio, inclusive Vibrio cholerae não-O1/não-O139. Aeromonas spp. , incluindo A. hydrophila foi isolada em 50% das amostras de peixe. O isolamento de Vibrio cholerae não-O1/não-O139 e Aeromonas hydrophila, assim como Staphylococcus aureus e Escherichia coli, sugere que peixes comercializados em feiras livres da cidade de São Paulo podem representar um risco para os consumidores e ser um importante veículo de transmissão de espécies enteropatogênicas. / Healthier nutritional lifestyles and cultural globalization have popularized the consumption of raw fish dishes that were previously restricted to oriental countries. Estimates indicate that food-borne diseases cause approximately 76 million illnesses, 325,000 hospitalizations and 5,000 deaths each year in the United States alone. Cases with unknown etiology account for 62 million illnesses, 265,000 hospitalizations and 3,200 deaths. The purpose of this study was to investigate the presence of Escherichia coli, Salmonella spp., Staphylococcus aureus and potentially pathogenic strains of Aeromonas spp. and Vibrio spp. in fish commercialized at the retail level in the markets of São Paulo City, Brazil. Twenty fish of different species were analysed for foodborne pathogens using conventional methodologies. High levels of faecal contamination were detected in 25% of fish samples. Staphylococcus aureus was isolated from 10% of samples; however, in each case this was below the limits established by Brazilian legislation. All samples were negative for Salmonella and 30% tested positive for others Vibrio spp., including Vibrio cholerae non-O1/non-O139. Vibrio parahaemolyticus was not found in this study. Aeromonas spp., including A. hydrophila, were isolated in 50% of fish samples. The isolation of Vibrio cholerae non-O1/non-O139 and Aeromonas hydrophila as well as Staphylococcus aureus and Escherichia coli suggests that fish commercialized in São Paulo City may represent a health risk to consumers and be an important vehicle for transmission of these enteropathogenic species.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on March 23, 2010). Thesis advisor: Dr. Mengshi Lin. Includes bibliographical references.

Submitted by Gabriel Augusto Marques Rossi null (gabrielrossiveterinario@hotmail.com) on 2018-01-10T19:18:16Z No. of bitstreams: 1 Tese_Gabriel_Augusto_Marques_Rossi.pdf: 3246904 bytes, checksum: 2ed62292bd3bfa8f9ec88fe41c5bbaa2 (MD5) / Approved for entry into archive by Alexandra Maria Donadon Lusser Segali null (alexmar@fcav.unesp.br) on 2018-01-11T10:23:42Z (GMT) No. of bitstreams: 1 rossi_gam_dr_jabo.pdf: 3246904 bytes, checksum: 2ed62292bd3bfa8f9ec88fe41c5bbaa2 (MD5) / Made available in DSpace on 2018-01-11T10:23:42Z (GMT). No. of bitstreams: 1 rossi_gam_dr_jabo.pdf: 3246904 bytes, checksum: 2ed62292bd3bfa8f9ec88fe41c5bbaa2 (MD5) Previous issue date: 2017-12-06 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / As bactérias pertencentes ao grupo do Bacillus cereus são importantes para indústrias processadoras de leite e produtos lácteos devido à capacidade de sobrevivência aos tratamentos térmicos utilizados durante os processamentos, e consequente deterioração dos produtos e risco à saúde pública. Assim, inicialmente, objetivou-se compreender a estrutura populacional de isolados pertencentes ao grupo do B. cereus na cadeia produtiva do leite e produtos lácteos. Por meio da utilização de amostragem estruturada e técnicas genômicas comparativas, investigou-se quais linhagens específicas e genes estão significativamente associados a estágios de produção específicos e produtos. Os genomas de 69 isolados obtidos de equipamentos, leite cru e produtos lácteos foram comparados com outros 193 disponíveis de diversas origens. A estrutura populacional incluiu os conhecidos grupos filogenéticos II, III, IV, V e VI, e quase todos os isolados dos produtos lácteos pertenceram ao grupo III. A investigação de genes específicos revelou um grande número de isolados carreando aqueles relacionados à produção de toxinas, como o cytK (53,62%), hblA (59,42%), hblC (44,93%), hblD (53,62%), nheA (84,06%), nheB (89,86%), nheC (84,06%), cesA (2,90%) e cesB (2,90%). Os isolados pertencentes aos grupos IV e V possuíram uma prevalência significativamente maior dos genes hblACD e o grupo IV do gene cytK. Os isolados obtidos de produtos lácteos tiveram uma prevalência significativamente menor dos genes cytK e hblACD comparados aos de equipamentos e leite cru/tanques de refrigeração. A análise genômica populacional demonstrou a diversidade dos isolados e a variedade de funções dentro do grupo do B. cereus da cadeia produtiva leiteira, com grande número de isolados potencialmente capazes de causar doenças alimentares. Posteriormente, objetivou-se avaliar a viabilidade do processo de tindalização de leite cru refrigerado e determinar se o processo de pasteurização do leite influencia na expressão dos genes relacionados à produção das toxinas diarreicas pelo B. cereus s.s. em leite experimentalmente contaminado. Para isso, realizou-se um processo de tindalização de leite cru refrigerado e então foi realizada a contaminação com um isolado potencialmente toxigênico, e, posteriormente, o mesmo foi pasteurizado, envasado e mantido em refrigeração durante 10 dias. Em momentos determinados, foram coletadas amostras do produto afim de avaliar a expressão de genes codificadores de toxinas (hblACD, nheABC e cytK). O protocolo de tindalização utilizado permitiu redução logarítmica da população de bactérias do grupo do B. cereus e foi possível detectar a expressão do gene hblA em amostras de leite 5 e 10 dias após a pasteurização. Conclui-se que o modelo proposto foi adequado e que a expressão do gene hblA não foi inibida após a realização da pasteurização do leite, demonstrando o potencial risco aos consumidores decorrentes do consumo de leite pasteurizado contaminado. / The bacteria belonging to Bacillus cereus group are important to dairy industries due their ability to survive to thermal treatments used during processing, and consequently cause food spoilage and risk to public health. Thus, firstly, this study aimed to better understand the population structure of B. cereus group isolates in dairy production chain. Using structured sampling of B. cereus in dairy production chain and comparative genomics techniques, we investigated if specific lineages and genes are significantly overrepresented in particular production stages. The genomes of 69 isolates obtained from equipments, raw milk and dairy products were compared with others 193 avaiable from several origins. The populational structure included the known phylogenetic groups II, III, IV, V and V, and almost all isolates from dairy products belonged to group III. The genes investigation showed a high number of isolates carrying genes related to toxins production, such as cytK (53.62%), hblA (59.42%), hblC (44.93%), hblD (53.62%), nheA (84.06%), nheB (89.86%), nheC (84.06%), cesA (2.90%) and cesB (2.90%). The isolates belonging to groups IV and V had a significant higher prevalence of genes hblACD an group VI of cytK. The isolates obtained from dairy products had a significant lower prevalence of genes cytK and hblACD compared to those from equipments and raw milk/bulk tanks. The populational genomic analyses showed the diversity of isolates and variability of functions in B. cereus group in dairy production chain, with a high number of isolates potentially able to cause foodborne disease. Posteriorly, this study aimed to evaluate the viability of tyndallizating raw milk and to establish if milk’s pasteurization influences on the expression of genes related to the production of diarrheal toxins by B. cereus s.s. using a milk contamined experimentally. For this purpose, the tyndallization of raw milk was performed and later it was contaminated with a potentially toxigenic isolate, and, posteriorly, it was pasteurized, packaged and kept under refrigeration during 10 days. In established periods, samples of this product were collected in order to evaluate the expression of genes related to toxins production (hblACD, nheABC and cytK). The protocol used for tyndallization allowed a logarithmic reduction of population of B. cereus group and the expression of hblA gene was detected in samples from milk after 5 and 10 days after pasteurization. It was concluded that the proposed model was appropriate and the expression of hblA gene was not inihibited after milk pasteurization, highlighting the potential risk for consumers through consumption of contamined pasteurized milk. / 2016/19214-9 / 2014/13104-1