Food safety is a critical issue for beef harvest operations. There are multiple interventions available for treating carcasses; however, this project was designed to evaluate an intervention capable of reducing bacterial counts on the hide prior to opening in order to minimize carcass contamination. In Trial I, fresh beef hides (n = 12) were cut into sections and assigned to serve as either clipped (hair trimmed) or non-clipped sections. Sections were inoculated with a bovine fecal slurry and sampled following a water wash. Treatments (distilled water, isopropyl alcohol, 3% hydrogen peroxide, 2% L-lactic acid, 1% cetylpyridinium chloride (CPC), and 10% Povidone-iodine) then were applied to each section and sampled for aerobic plate counts (APCs), coliform, and Escherichia coli counts. Within clipped samples, 1% CPC and 3% hydrogen peroxide caused the greatest reductions in aerobic plate counts, and 1% CPC, 2% L-lactic acid, and 3% hydrogen peroxide showed among the greatest reductions in coliform counts. In Trial II, beef carcasses with hides on were sampled initially and clipped, and then antimicrobials (2% L-lactic acid, 3% hydrogen peroxide, and 1% CPC) were applied before sampling again for APC, coliform, and E. coli counts. This procedure was replicated in Trial II utilizing a non-pathogenic E. coli Type I indicator strain transformed to produce a green fluorescing protein (GFP). In Trial II, though few differences existed between antimicrobial treatments, all three (1% CPC, 2% L-lactic acid, and 3% hydrogen peroxide) resulted in approximately a 2-log10 CFU/100-cm2GFP reduction when applied to clipped hide surfaces in the brisket region of the carcass. In Trial III, 1% CPC produced the greatest reduction on the hide surface for APCs. In Trial IV clipped beef hide sections were sampled initially and then antimicrobials (2% L-lactic acid, 3% hydrogen peroxide, and 1% CPC) were applied before sampling again to determine reduction. Trial IV also involved the use of the E. coli GFP indicator strain. In Trial IV, non-clipped samples had a mean reduction of 2.8 log10 CFU/100 cm2, and clipped samples had a mean reduction of 2.2 log10 CFU/100 cm2. Within the antimicrobials tested, 1% CPC and 3% hydrogen peroxide produced the greatest reductions.

Effects of a 10% xylitol solution (X) on adhesion of Escherichia coli O157:H7 and Salmonella serotype Typhimurium to meat surfaces were examined utilizing three approaches. In Experiment 1, rifampicin-resistant strains of E. coli O157:H7 and S. Typhimurium were dispersed in xylitol or a peptone solution (containing approximately 8.9 mean log per ml of each pathogen) and used to inoculate beef outside round meat surfaces. Samples were then rinsed with water or not rinsed in a 2X2 factorial arrangement. No interaction existed between inoculum type and post-inoculation treatments (P > 0.84). Incubation of pathogens in peptone or xylitol had minimal impact on pathogen adhesion (P > 0.76). Rinsing reduced counts by approximately 0.5 log CFU/cm2 (P < 0.01). Experiment 2 meat samples received a pretreatment of a water rinse, xylitol, or no rinse, followed by inoculation with pathogens dispersed in peptone solution (containing approximately 8.6 log mean log per ml of each pathogen). Samples received a post-inoculation treatment of a water rinse, xylitol rinse or no rinse in a 3X3 factorial arrangement. No interactions between pre- and post-inoculation factors were observed for surface pathogen load (P > 0.50). Post-inoculation rinsing reduced counts by approximately 0.5 log CFU/cm2 (P < 0.01) with no difference between water and xylitol (P > 0.64). Experiment 3 carcass surfaces were inoculated with pathogens at an initial level of 5.5 log CFU/cm2 and received a hot (35°C) water wash, 2.5% L-lactic acid spray, 10% xylitol spray, lactic acid + xylitol or hot water + xylitol. Pathogen counts were taken at 0 and 24 h post treatment. Lactic acid treatments reduced Salmonella by 3.3 log CFU/cm2 at 0 h (P < 0.01) and by 2.6 log CFU/cm2 after 24 h (P < 0.02). Hot water treatments reduced Salmonella by 1.5 log CFU/cm2 at 0 h (P < 0.07). Xylitol did not minimize pathogens (P > 0.62) nor did it increase effectiveness of other treatments. These data indicate that xylitol is ineffective at preventing E. coli O157:H7 and S. Typhimurium adhesion to meat surfaces.

Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2017-06-09T19:43:53Z No. of bitstreams: 2 Dissertação - Bruno Ferreira Carneiro - 2016.pdf: 5993509 bytes, checksum: 6618dde69432c91af4865caf6369cd9a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-06-12T12:23:07Z (GMT) No. of bitstreams: 2 Dissertação - Bruno Ferreira Carneiro - 2016.pdf: 5993509 bytes, checksum: 6618dde69432c91af4865caf6369cd9a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-06-12T12:23:07Z (GMT). No. of bitstreams: 2 Dissertação - Bruno Ferreira Carneiro - 2016.pdf: 5993509 bytes, checksum: 6618dde69432c91af4865caf6369cd9a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-04-04 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The Arrau river turtle is the best known species of the genus Podocnemis and most testudines of freshwater in South America. In the North and Central West regions of the country is common to commercial production of the species P. expansa, but there are still parameters for to improve the production process and ensure the microbiological quality of meat produced. This study aimed to determine the presence of Salmonella sp. and Campylobacter spp. in skeletal striated muscle samples from the fillet region and forelimb and hindlimb, as well as the realization of cloacal swab. Skeletal muscle tissue of 20 males were picked with sterilized surgical instruments, packed in sterile vials and analyzed in the Laboratory of Microbiology and Food Technology Research Centre in Food UFG/EVZ and Bacteriological tests Laboratory and Anatomopathological of Birds of UFG/EVZ for evaluation according to the industry protocol. In the survey by Salmonella sp., Two samples (2/240) 0.83%, were positive for the bacterium gender researched and compared the search for microorganisms of the genus Campylobacter spp., were not detected microorganisms in the samples. To evaluate the results related to microbiology, we performed the Fisher Exact Test (p <0.05). The statistical test showed no statistical difference in relation to the treatment (p = 0.4737) and (p = 0.4979), relating the area of harvest, also not statistically significant. The data were important for improving the quality of carcasses slaughtered the species. / A tartaruga-da-amazônia é a espécie mais conhecida do gênero Podocnemis e o maior testudíneo de água-doce da América do Sul. Nas regiões Norte e Centro Oeste do país é comum a produção comercial da espécie P. expansa, mas ainda faltam parâmetros para melhorar o processo de produção e garantir a qualidade microbiológica da carne produzida. O presente estudo teve como objetivo determinar a presença de Salmonella sp. e Campylobacter spp. em amostras de musculatura estriada esquelética da região de filé e membros anteriores e posteriores, bem como a realização de swab cloacal. Os tecidos musculares esqueléticos dos 20 machos foram colhidos com instrumental cirúrgico esterelizado, acondicionados em frascos estéreis e analisados no Laboratório de Microbiologia e Tecnologia de Alimentos do Centro de Pesquisa em Alimentos da UFG/EVZ e Laboratório de Exames Bacteriológicos e Anatomopatológicos de Aves da UFG/EVZ para avaliação segundo o protocolo do setor. Na pesquisa por Salmonella sp., duas amostras (2/240) 0,83%, foram positivas para o gênero de bactéria pesquisado, sendo idenficado o microrganismo Salmonella enterica subsp. enterica. Em relação a pesquisa por microrganismos do gênero Campylobacter spp., não foram detectados microrganismos nas amostras analisadas. Para avaliação dos resultados referentes à microbiologia, foi utilizado o Teste Exato de Fischer (p < 0,05). O teste estatístico empregado demonstrou não haver diferença estatística em relação ao tratamento empregado (p = 0,4737) e (p = 0,4979), relacionando a área de colheita, também não apresentou significância estatística. Os dados obtidos foram importantes para melhoria de qualidade das carcaças abatidas da espécie.

Salmonella species is the etiologic agent of salmonellosis, which is a zoonotic infection that is characterized by diarrhea and systemic infection. Contaminated foods are usually the vehicles of Salmonella transmission along the food supply chain. Asymptomatic food production animals and effluents also contribute to contamination of meat. Antimicrobials have contributed significantly to treatment of salmonellosis. However, uncontrolled antimicrobial use is among the causes of antibiotic resistance, which results in treatment failure. The aim of this research study was to determine the extent of Salmonella spp contamination during the cattle slaughtering process in South African rural abattoirs (n = 23), water and cattle feaces. In addition, the aim was to determine antimicrobial resistance profiles of the Salmonella spp isolates. The specific objectives were: i) to establish the occurrence and distribution of Salmonella spp on cattle carcasses, hides, and intestinal contents and environmental samples using classical microbiology and molecular techniques; ii) to determine the Salmonella serovars using serotyping; and iii) to determine antimicrobial resistance patterns and multidrug resistance among the Salmonella isolates using the Kirby-Bauer disc diffusion method. Materials and Classical microbiology techniques were used to analyze cattle faeces (n = 400), hides (n = 67), intestinal contents (n = 62), carcass sponges (n = 100), and water from the abattoirs (n = 75) for the presence of Salmonella spp. Further confirmation of the Salmonella isolates was done using Polymerase Chain Reaction whereby the invA gene was targeted. A total of 92 Salmonella spp isolates were recuperated. The 92 Salmonella were serotyped as described in the White-Kauffmann-Le Minor scheme. The 92 Salmonella spp isolates were further subjected to antimicrobial susceptibility examination towards the following antimicrobials: ampicillin (10μg), cefotaxine (30μg), kanamycin (30μg), oxytetracycline (30μg), and enrofloxacin (5μg) by using the Kirby-Bauer disk diffusion procedure. All the isolates carried the invA genes. The average Salmonella spp occurrence on carcasses, hides, and intestinal contents was 35.37% (n = 81). Eleven of the faecal samples (2.75%) tested positive for Salmonella spp. The Salmonella serovar that occurred more frequently was S. Enteritidis. Different serovars that were recognized on carcasses were not automatically found on the hides and intestinal contents. The incompatible frequency of the different Salmonella serovars on carcasses, intestinal contents and hides means that in addition to carriage on hides and in intestinal contents, new external causes that did not form part of this study also play a vital role concerning carcass contamination. Most Salmonella spp (n = 66; 71.7%) isolates were resistant to a minimum of one antimicrobial with main resistance detected towards oxytetracycline (51.90%). This emphasizes on the call for wise antimicrobial use at some stage in animal production and strict sanitation for the duration of slaughtering. Briefly, cattle slaughtered in South African rural abattoirs harboured different types of Salmonella serovars that were resistant to antimicrobials, which could be a public health risk and danger. The outcome should support policymakers with determining the effectiveness of existing sanitary measures during cattle slaughtering in rural abattoirs, which is vital from socio-economic, public health, and epidemiological perspectives. / College of Agriculture and Environmental Sciences

A presença de Salmonella no conteúdo intestinal do suíno ao abate é a principal fonte de contaminação da carcaça. O processo de abate embora capaz de controlar a contaminação de carcaças pode não ser capaz de garantir baixa frequência de carcaças positivas para Salmonella em lotes que apresentam elevado número de suínos excretores. O objetivo deste estudo exploratório foi acompanhar lotes suínos abatidos em um matadouro-frigorífico em relação à presença de excretores de Salmonella no conteúdo intestinal e à frequência de carcaças positivas para Salmonella no pré-resfriamento. O estudo foi conduzido em dez dias de abate; em cada dia, cinco suínos foram amostrados, totalizando 50 animais, destes foram coletados: sangue, conteúdo intestinal, suabes de superfície da carcaça nas etapas de pós-sangria e pré-resfriamento. O soro foi submetido ao teste ELISA-Typhimurium; Salmonella foi enumerada no conteúdo intestinal pela técnica do Numero Mais Provável (NMP); e nos suabes de carcaça foi realizada pesquisa de Salmonella e enumeração de Mesófilos aeróbios totais (MAT) e Enterobactérias. Todos os suínos foram positivos na pesquisa de IgG anti-Salmonella, em 64% destes Salmonella foi detectada no conteúdo intestinal em médias estimadas entre 2,7 e >1.400 NMP/g de conteúdo intestinal. A superfície das carcaças apresentou média de 3,28 log UFC/cm2 de MAT, quando amostradas na pós-sangria. As mesmas carcaças, na etapa de pré-resfriamento, apresentaram médias entre 1,43 e 2,48 log UFC/cm2, observando-se uma redução logarítmica média de 0,64 a 2,35 UFC/cm2 entre as etapas de coleta. A enumeração de Enterobactérias apresentou maior variação entre os dias e entre as etapas de abate. Na etapa de pós-sangria as médias variaram de 0,27 a 2,64 log UFC/cm2. Já no pré-resfriamento as médias variaram de -0,71 até 0,46 log UFC/cm2. Em relação ao isolamento de Salmonella, houve uma frequência de 16% (8/50) de carcaças positivas na etapa de pós-sangria e 8% (4/50) no pré-resfriamento. Os sorovares Typhimurium, Derby, Infantis e O:4,5 foram encontrados nas carcaças. As quatro carcaças positivas no pré-resfriamento foram originadas de suínos que apresentaram Salmonella no conteúdo intestinal; duas delas provenientes de um mesmo dia de abate, no qual todos os suínos apresentavam elevado número de Salmonella no conteúdo intestinal (130 até > 1.400 NMP/g-1). Os resultados obtidos indicam que lotes de abate com suínos apresentando alta contagem de Salmonella no conteúdo intestinal podem apresentar maior frequência de carcaças positivas no pré-resfriamento, mesmo em processos de abate de acordo com os padrões higiênico-sanitários. / The presence of Salmonella in the intestinal contents of slaughter pigs is considered the main source for carcass contamination. The slaughter process can control the contamination of carcasses, but may not be able to ensure a low frequency of Salmonella-positive carcasses in slaughter batches that have a high number of shedders. The objective of this exploratory study was to follow slaughter pig batches for the presence of Salmonella in intestinal content and to determine the frequency of Salmonella-positive pre-chill carcasses. The study was conducted in ten slaughter; in each day five pigs were sampled for: blood, intestinal contents; carcass surface swabs taken at the post-bleeding and pre-chill steps. The serum was subjected to the ELISA- Typhimurium test; Salmonella was enumerated in the intestinal contents by the Most Probable Number (MPN) protocol; and carcass swabs were subjected to Salmonella detection and enumeration of Total aerobic mesophilic (MAT) and Enterobacteriaceae. All pigs were positive in the anti-Salmonella IgG testing, in 64% of them Salmonella was detected in the intestinal contents. The estimated Salmonella mean ranged from 2.7 to > 1,400 MPN/g-1 of intestinal content. In the carcass surface an averaged of 3.28 log CFU/cm2 of MAT was found at the post-bleeding step. The same carcasses presented averages between 1.43 and 2.48 log CFU/cm2 in the pre-cooling stage, corresponding to a mean log reduction from 0.64 to 2.35 log CFU/cm2 between steps. Enumeration of Enterobacteriaceae showed a greater variation between days and slaughtering stages. In the post-bleeding step averages ranged from 0.27 to 2.64 log CFU/cm2. In the pre-cooling the average ranged from -0.71 to 0.46 log CFU/cm2. Regarding the isolation of Salmonella, the frequency was 16% (8/50) of positive carcasses at the post-bleeding step and 8% (4/50) at the pre-chilling. The serovar Typhimurium, Derby, Infantis and O:4,5 were found in the carcasses. The four positive carcasses in the pre-cooling step originated from pigs that had Salmonella in intestinal contents, two of them were slaughter on a same day, in which all pigs had a high number of Salmonella in intestinal contents (130 to > 1,400 MPN/g-1). The results indicate that slaughter pig batches presenting high counts of Salmonella in intestinal contents may have higher frequency of positive carcasses in the pre-chilling, even in slaughtering processes complying to hygienic-sanitary standards.

A presença de Salmonella no conteúdo intestinal do suíno ao abate é a principal fonte de contaminação da carcaça. O processo de abate embora capaz de controlar a contaminação de carcaças pode não ser capaz de garantir baixa frequência de carcaças positivas para Salmonella em lotes que apresentam elevado número de suínos excretores. O objetivo deste estudo exploratório foi acompanhar lotes suínos abatidos em um matadouro-frigorífico em relação à presença de excretores de Salmonella no conteúdo intestinal e à frequência de carcaças positivas para Salmonella no pré-resfriamento. O estudo foi conduzido em dez dias de abate; em cada dia, cinco suínos foram amostrados, totalizando 50 animais, destes foram coletados: sangue, conteúdo intestinal, suabes de superfície da carcaça nas etapas de pós-sangria e pré-resfriamento. O soro foi submetido ao teste ELISA-Typhimurium; Salmonella foi enumerada no conteúdo intestinal pela técnica do Numero Mais Provável (NMP); e nos suabes de carcaça foi realizada pesquisa de Salmonella e enumeração de Mesófilos aeróbios totais (MAT) e Enterobactérias. Todos os suínos foram positivos na pesquisa de IgG anti-Salmonella, em 64% destes Salmonella foi detectada no conteúdo intestinal em médias estimadas entre 2,7 e >1.400 NMP/g de conteúdo intestinal. A superfície das carcaças apresentou média de 3,28 log UFC/cm2 de MAT, quando amostradas na pós-sangria. As mesmas carcaças, na etapa de pré-resfriamento, apresentaram médias entre 1,43 e 2,48 log UFC/cm2, observando-se uma redução logarítmica média de 0,64 a 2,35 UFC/cm2 entre as etapas de coleta. A enumeração de Enterobactérias apresentou maior variação entre os dias e entre as etapas de abate. Na etapa de pós-sangria as médias variaram de 0,27 a 2,64 log UFC/cm2. Já no pré-resfriamento as médias variaram de -0,71 até 0,46 log UFC/cm2. Em relação ao isolamento de Salmonella, houve uma frequência de 16% (8/50) de carcaças positivas na etapa de pós-sangria e 8% (4/50) no pré-resfriamento. Os sorovares Typhimurium, Derby, Infantis e O:4,5 foram encontrados nas carcaças. As quatro carcaças positivas no pré-resfriamento foram originadas de suínos que apresentaram Salmonella no conteúdo intestinal; duas delas provenientes de um mesmo dia de abate, no qual todos os suínos apresentavam elevado número de Salmonella no conteúdo intestinal (130 até > 1.400 NMP/g-1). Os resultados obtidos indicam que lotes de abate com suínos apresentando alta contagem de Salmonella no conteúdo intestinal podem apresentar maior frequência de carcaças positivas no pré-resfriamento, mesmo em processos de abate de acordo com os padrões higiênico-sanitários. / The presence of Salmonella in the intestinal contents of slaughter pigs is considered the main source for carcass contamination. The slaughter process can control the contamination of carcasses, but may not be able to ensure a low frequency of Salmonella-positive carcasses in slaughter batches that have a high number of shedders. The objective of this exploratory study was to follow slaughter pig batches for the presence of Salmonella in intestinal content and to determine the frequency of Salmonella-positive pre-chill carcasses. The study was conducted in ten slaughter; in each day five pigs were sampled for: blood, intestinal contents; carcass surface swabs taken at the post-bleeding and pre-chill steps. The serum was subjected to the ELISA- Typhimurium test; Salmonella was enumerated in the intestinal contents by the Most Probable Number (MPN) protocol; and carcass swabs were subjected to Salmonella detection and enumeration of Total aerobic mesophilic (MAT) and Enterobacteriaceae. All pigs were positive in the anti-Salmonella IgG testing, in 64% of them Salmonella was detected in the intestinal contents. The estimated Salmonella mean ranged from 2.7 to > 1,400 MPN/g-1 of intestinal content. In the carcass surface an averaged of 3.28 log CFU/cm2 of MAT was found at the post-bleeding step. The same carcasses presented averages between 1.43 and 2.48 log CFU/cm2 in the pre-cooling stage, corresponding to a mean log reduction from 0.64 to 2.35 log CFU/cm2 between steps. Enumeration of Enterobacteriaceae showed a greater variation between days and slaughtering stages. In the post-bleeding step averages ranged from 0.27 to 2.64 log CFU/cm2. In the pre-cooling the average ranged from -0.71 to 0.46 log CFU/cm2. Regarding the isolation of Salmonella, the frequency was 16% (8/50) of positive carcasses at the post-bleeding step and 8% (4/50) at the pre-chilling. The serovar Typhimurium, Derby, Infantis and O:4,5 were found in the carcasses. The four positive carcasses in the pre-cooling step originated from pigs that had Salmonella in intestinal contents, two of them were slaughter on a same day, in which all pigs had a high number of Salmonella in intestinal contents (130 to > 1,400 MPN/g-1). The results indicate that slaughter pig batches presenting high counts of Salmonella in intestinal contents may have higher frequency of positive carcasses in the pre-chilling, even in slaughtering processes complying to hygienic-sanitary standards.

A presença de Salmonella no conteúdo intestinal do suíno ao abate é a principal fonte de contaminação da carcaça. O processo de abate embora capaz de controlar a contaminação de carcaças pode não ser capaz de garantir baixa frequência de carcaças positivas para Salmonella em lotes que apresentam elevado número de suínos excretores. O objetivo deste estudo exploratório foi acompanhar lotes suínos abatidos em um matadouro-frigorífico em relação à presença de excretores de Salmonella no conteúdo intestinal e à frequência de carcaças positivas para Salmonella no pré-resfriamento. O estudo foi conduzido em dez dias de abate; em cada dia, cinco suínos foram amostrados, totalizando 50 animais, destes foram coletados: sangue, conteúdo intestinal, suabes de superfície da carcaça nas etapas de pós-sangria e pré-resfriamento. O soro foi submetido ao teste ELISA-Typhimurium; Salmonella foi enumerada no conteúdo intestinal pela técnica do Numero Mais Provável (NMP); e nos suabes de carcaça foi realizada pesquisa de Salmonella e enumeração de Mesófilos aeróbios totais (MAT) e Enterobactérias. Todos os suínos foram positivos na pesquisa de IgG anti-Salmonella, em 64% destes Salmonella foi detectada no conteúdo intestinal em médias estimadas entre 2,7 e >1.400 NMP/g de conteúdo intestinal. A superfície das carcaças apresentou média de 3,28 log UFC/cm2 de MAT, quando amostradas na pós-sangria. As mesmas carcaças, na etapa de pré-resfriamento, apresentaram médias entre 1,43 e 2,48 log UFC/cm2, observando-se uma redução logarítmica média de 0,64 a 2,35 UFC/cm2 entre as etapas de coleta. A enumeração de Enterobactérias apresentou maior variação entre os dias e entre as etapas de abate. Na etapa de pós-sangria as médias variaram de 0,27 a 2,64 log UFC/cm2. Já no pré-resfriamento as médias variaram de -0,71 até 0,46 log UFC/cm2. Em relação ao isolamento de Salmonella, houve uma frequência de 16% (8/50) de carcaças positivas na etapa de pós-sangria e 8% (4/50) no pré-resfriamento. Os sorovares Typhimurium, Derby, Infantis e O:4,5 foram encontrados nas carcaças. As quatro carcaças positivas no pré-resfriamento foram originadas de suínos que apresentaram Salmonella no conteúdo intestinal; duas delas provenientes de um mesmo dia de abate, no qual todos os suínos apresentavam elevado número de Salmonella no conteúdo intestinal (130 até > 1.400 NMP/g-1). Os resultados obtidos indicam que lotes de abate com suínos apresentando alta contagem de Salmonella no conteúdo intestinal podem apresentar maior frequência de carcaças positivas no pré-resfriamento, mesmo em processos de abate de acordo com os padrões higiênico-sanitários. / The presence of Salmonella in the intestinal contents of slaughter pigs is considered the main source for carcass contamination. The slaughter process can control the contamination of carcasses, but may not be able to ensure a low frequency of Salmonella-positive carcasses in slaughter batches that have a high number of shedders. The objective of this exploratory study was to follow slaughter pig batches for the presence of Salmonella in intestinal content and to determine the frequency of Salmonella-positive pre-chill carcasses. The study was conducted in ten slaughter; in each day five pigs were sampled for: blood, intestinal contents; carcass surface swabs taken at the post-bleeding and pre-chill steps. The serum was subjected to the ELISA- Typhimurium test; Salmonella was enumerated in the intestinal contents by the Most Probable Number (MPN) protocol; and carcass swabs were subjected to Salmonella detection and enumeration of Total aerobic mesophilic (MAT) and Enterobacteriaceae. All pigs were positive in the anti-Salmonella IgG testing, in 64% of them Salmonella was detected in the intestinal contents. The estimated Salmonella mean ranged from 2.7 to > 1,400 MPN/g-1 of intestinal content. In the carcass surface an averaged of 3.28 log CFU/cm2 of MAT was found at the post-bleeding step. The same carcasses presented averages between 1.43 and 2.48 log CFU/cm2 in the pre-cooling stage, corresponding to a mean log reduction from 0.64 to 2.35 log CFU/cm2 between steps. Enumeration of Enterobacteriaceae showed a greater variation between days and slaughtering stages. In the post-bleeding step averages ranged from 0.27 to 2.64 log CFU/cm2. In the pre-cooling the average ranged from -0.71 to 0.46 log CFU/cm2. Regarding the isolation of Salmonella, the frequency was 16% (8/50) of positive carcasses at the post-bleeding step and 8% (4/50) at the pre-chilling. The serovar Typhimurium, Derby, Infantis and O:4,5 were found in the carcasses. The four positive carcasses in the pre-cooling step originated from pigs that had Salmonella in intestinal contents, two of them were slaughter on a same day, in which all pigs had a high number of Salmonella in intestinal contents (130 to > 1,400 MPN/g-1). The results indicate that slaughter pig batches presenting high counts of Salmonella in intestinal contents may have higher frequency of positive carcasses in the pre-chilling, even in slaughtering processes complying to hygienic-sanitary standards.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Tiruvoor G. Nagaraja / Escherichia coli O157 is a major foodborne pathogen. The bovine gut is the primary reservoir and the organism is shed in the feces, which serves as the major source of contamination. The objectives of our research on E. coli O157 were to 1) determine prevalence and characterize presence in the rectoanal mucosa of cattle, 2) rationalize preferential prevalence in the hindgut, 3) evaluate fecal prevalence and concentration in relation to carcass contamination 4) determine the efficacy of preharvest intervention strategies to reduce fecal prevalence and/or concentration in cattle. We determined that E. coli O157 isolated from the rectoanal mucosa were similar to fecal isolates. We evaluated methods of enumeration in cattle feces to identify fecal samples with > 10[superscript3] and 10[superscript4] CFU of E. coli O157/g. We observed that prevalence of E. coli O157 on carcasses was correlated with high-shedders. We identified gluconic acid as a substrate which stimulates growth of E. coli O157 in fermentations with ruminal microbial or fecal microbial inocula from cattle. This may explain the preference to persist or colonize the hindgut because gluconic acid is a component of colonic mucin. Additionally, we evaluated the effects of cattle diets (two grain types and two grain processing methods), which present different amounts of fermentable starch to the hindgut, on prevalence of E. coli O157. Dry-rolled grain-based diets reduced prevalence of E. coli O157, possibly because of increased flow of starch to the hindgut. Competitive exclusion cultures of E. coli in in vitro fermentations reduced E. coli O157 in ruminal microbial inoculum, but in fecal microbial inoculum cultures were only efficacious when gluconic acid also was added. Lastly, we evaluated a vaccine which targeted the siderophore receptor/porin proteins of E. coli O157. The vaccine reduced prevalence, the total number of days cattle tested positive, and the total number of days cattle were identified as high-shedders of E. coli O157. In summary, our research adds further knowledge to the literature about E. coli O157 in the hindgut, provides methods to identify high-shedding animals, demonstrates the importance of high-shedding animals, and offers information about potential preharvest interventions.

<p>U radu je ispitan i razvijen novi pristup tretmanu kože goveda prirodnom smolom &scaron;elak, koja je dozvoljena za kori&scaron;ćenje u hrani, u cilju redukcije unakrsne mikrobiolo&scaron;ke kontaminacije sa kože na goveđe meso. Mehanizam ovog tretmana je baziran na imobilizaciji mikroorganizama na dlaci tretirane kože i prevenciji njihovog fizičkog prenosa sa dlake na meso trupova tokom procesa obrade zaklanih goveda.<br />U in vitro uslovima, tretman uzoraka vizuelno čiste i suve kože 23% rastvorom &scaron;elaka u etanolu je redukovao prenos sa kože na sunđere kojima je koža uzorkovana brisevima: ukupne mikroflore (TVC) za 6,6 log (&gt;1000 puta vi&scaron;e u odnosu na 2,9 log redukcije kod tretmana samo etanolom), generičke Escherichia coli za najmanje 2,9 i Enterobacteriaceae za najmanje 4,8 log. Ove redukcije sve tri grupe mikroorganizama su bile značajno vi&scaron;e u odnosu na redukcije postignute tretmanom kože kombinacijom ispiranja sanitajzerom i vakumiranja. Značajno vi&scaron;e redukcije prenosa TVC sa kože na sunđerske briseve su postignute kori&scaron;ćenjem vi&scaron;ih koncentracija &scaron;elaka (23% i 30%) u odnosu na niže (4,8-16,7%) i u slučajevima kada je temperatura rastvora &scaron;elaka bila 20, 30 ili 40oC u odnosu na 50oC i 60oC. Takođe, tretman kože &scaron;elakom je značajno (3,7 puta) redukovao prevalencu E. coli O157 na prirodno kontaminiranoj, neinokulisanoj koži, kao i broj E. coli O157 na ve&scaron;tački inokulisanim kožama (redukcija od 2,1 log), u odnosu na odgovarajuće netretirane kontrole.<br />U uslovima laboratorijskog modela direktnog kontakta kože i mesa, tretman kože (različitih kategorija čistoće) 23% rastvorom &scaron;elaka je značajno smanjio prenos mikroorganizama sa tretirane kože na sterilno goveđe meso: do 3,6 log cfu/cm2 redukcije ukupnog broja bakterija (TVC), do 2,5 log cfu/cm2 Enterobacteriaceae (EC) i do 1,7 log cfu/cm2 generičke E. coli (GEC). Redukcija prenosa TVC je bila značajno vi&scaron;a, a redukcije EC i GEC slične, u odnosu na redukcije nakon tretiranja kože kombinacijom ispiranja-vakumiranja sanitajzerom.<br />U uslovima male komercijalne klanice sa nezadovoljavajućom procesnom praksom (klanje prljavih goveda i neadekvatna higijena procesa klanja i obrade), tretman koža zaklanih goveda 23% rastvorom &scaron;elaka je rezultirao značajnom mikrobnom redukcijom na mesu trupova goveda nakon skidanja kože: 1,7 log cfu/cm2 TVC, 1,4 log cfu/cm2 EC i 1,3 log cfu/cm2 GEC. Redukcija TVC na mesu trupova je bila značajno vi&scaron;a, a redukcije EC i GEC slične, u odnosu na redukcije nakon tretiranja kože ispiranjem-vakumiranjem sanitajzerom.<br />Ova istraživanja su po prvi put pružila naučne dokaze da se tretman kože goveda u cilju imobilizacije mikroflore na dlaci može uspe&scaron;no koristiti u cilju smanjenja kontaminacije mesa trupova tokom procesa skidanja kože, unapređenja finalnog mikrobiolo&scaron;kog statusa mesa i bezbednosti goveđeg mesa uop&scaron;te. Da bi se ostvario puni potencijal ovog novog tretmana u praksi, neophodna su dalja istraživanja u cilju njegove tehničke optimizacije u uslovima industrije mesa.</p> / <p> In this research, a new approach to cattle hide treatments, based on using a natural, food-grade resin, Shellac, to reduce microbial cross-contamination from the hides onto carcass meat, was developed and evaluated. The basis of this treatment is immobilisation of microorganisms on cattle hide&rsquo;s hair and subsequent reduction of their transmissibility from the hair onto carcass meat during dressing of slaughtered cattle.<br /> Under in vitro conditions, treatment of samples of visually clean and dry hides with 23% Shellac-in-ethanol solution reduced sponge-swabbing recoveries of general microflora (TVC) by a factor of 6.6 logs (&gt;1000-fold greater than the 2.9 log reduction observed by ethanol alone), and of generic E. coli (GEC) and Enterobacteriaceae (EC) by factors of at least 2.9 and 4.8 logs, respectively. The reductions of these three groups of microorganisms were superior to those achieved by a sanitizer rinse-vacuum hide treatment. Significantly greater reductions of TVC recoveries from hides were achieved when using higher Shellac concentrations (23.0% and 30.0% rather than 4.8-16.7%) and when Shellac solution temperatures were 20-40&deg;C rather than 50-60&deg;C. Furthermore, the Shellac-based treatment also markedly reduced the E. coli O157 prevalence (3.7-fold reduction) on natural, uninoculated hides, as well as the counts of E. coli O157 on artificially inoculated hides (2.1 log reduction) when compared to corresponding untreated controls.<br /> Under the conditions of a hide-to-meat direct contact laboratory-based model, treatment of hides (of varying visual cleanliness) with the 23% Shellac solution produced significant reductions of microbial transfer from treated hide onto sterile beef: up to 3.6 log10 CFU/cm2 of TVC, up to 2.5 log10 CFU/cm2 of EC and up to 1.7 log10 CFU/cm2 of GEC. TVC reductions of microbial transfer from treated hide onto beef achieved by the Shellac hide treatment were superior to those achieved by the comparative sanitizer rinse-vacuum hide treatment, but reductions of EC and GEC did not differ between the two hide treatments.<br /> In a small commercial abattoir with unsatisfactory process practices (slaughtering dirty cattle, inadequate process hygiene), treatment of hides with Shellac produced significant microbial reductions on skinned beef carcasses: 1.7 log10 CFU/cm2, 1.4 log10 CFU/cm2 and 1.3 log10 CFU/cm2 of TVC, EC and GEC, respectively. TVC reductions on skinned beef carcasses achieved by the Shellac hide treatment were superior to those achieved by the comparative sanitizer rinse-vacuum hide treatment, but reductions of EC and GEC did not differ significantly between the two hide treatments.<br /> These investigations produced the first scientific evidence that treatment of cattle hides with aim of immobilising microflora on the hair can be very successfully used to reduce carcass meat contamination during the skinning operation, thus improving the microbiological status of the final beef carcasses as well as the beef safety in general. To achieve the full potential of this new treatment in practice, further research aimed at its further technical optimization under real-life meat industry conditions is necessary.</p>