Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 41-49). Also available via the Internet.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 107-118). Also available in electronic version.

O leite é um alimento muito importante na alimentação humana, mas, quando contaminado com resíduos de antibióticos, pode ser considerado adulterado e constituir risco à saúde pública. Desta forma, é importante que este alimento apresente condições sanitárias adequadas e risco à saúde minimizado ou inexistente. O presente estudo teve como objetivos identificar os resíduos de antibióticos comumente encontrados em leite cru produzido em propriedades rurais no Rio Grande do Sul (RS), avaliar a presença de resíduos de antibióticos nas amostras analisadas quanto ao limite máximo de resíduos (LMR) descrito no Programa Nacional de Controle de Resíduos e Contaminantes (PNCRC), averiguar o conhecimento dos responsáveis pela ordenha do leite quanto aos medicamentos utilizados em seu rebanho, bem como, identificar os resíduos de antibióticos comumente avaliados, na rotina, e a motivação para a escolha destes, em plataformas de recebimento de leite cru em estabelecimentos industriais, inspecionados pelo serviço oficial do RS. Para tanto, foram realizados dois estudos exploratório-descritivos. No primeiro, em 2013, foi realizada coleta de dados a campo, mediante aplicação de questionário referente à administração de medicamentos veterinários, bem como, da análise, no Laboratório Nacional Agropecuário, de 388 amostras de leite cru, oriundas de propriedades rurais distribuídas no Estado. No segundo estudo, que ocorreu de 2014 a 2015, foi aplicado questionário referente aos testes de detecção de resíduos de antibióticos em 36 estabelecimentos industriais, sob inspeção estadual. Os resultados do primeiro estudo demonstraram que 96 (24,7%) amostras apresentaram algum resíduo de antibiótico dos 45 analitos pesquisados. Destas, 91 (23,5%) estavam conformes, segundo a legislação vigente e, apenas, 5 (1,3%) foram suspeitas de violação do LMR descrito no PNCRC. Dos resíduos de antibióticos identificados, os da classe dos macrolídeos (n=51; 13,1%), seguidos das quinolonas (n=49; 12,6%) e das tetraciclinas (n=18; 4,6%) foram os comumente encontrados em leite cru produzido no RS. Quanto ao conhecimento dos responsáveis pela ordenha, infere-se que 22,6% não registraram ou controlaram a administração de medicamentos ao rebanho leiteiro, embora, 87,4% (n=339) tenha assegurado descartar o leite durante o período residual. Ainda, apenas 3,4% (n=13) dos entrevistados consideraram a bula do medicamento ou a orientação de veterinário (n=12; 3,1%), para o descarte do leite, guiando-se, principalmente, pela indicação da cooperativa a qual estiverem associados (55,9%; n=217). No segundo estudo, dos 36 estabelecimentos participantes, 83% foram classificados como fábrica de laticínios, sendo os antibióticos dos grupos dos betalactâmicos (100%) e das tetraciclinas (69%) os comumente pesquisados. Quanto à escolha do teste para a pesquisa de resíduos de antibióticos, esta foi influenciada pela praticidade e rapidez na execução do mesmo (67%) e não no conhecimento, especificamente, dos antibióticos utilizados pelos fornecedores de leite à indústria (22%). Conclui-se que o leite consumido no RS, quanto à presença de resíduos de antibióticos, no período da coleta, apresentou resultados compatíveis com aqueles identificados no PNCRC, oferecendo baixo risco à saúde pública. Mesmo assim, esforços devem ser direcionados quanto à melhoria das boas práticas agropecuárias nas propriedades rurais e às empresas quanto aos critérios de escolha dos testes de detecção de resíduos de antibióticos. / Milk is an important food for human consumption, but when contaminated with antibiotic residues may be considered adulterated and risk to public health. Thus, it is important that this food presents sanitary conditions and minimized or zero risk to the public health. This study aimed to identify the commonly antibiotic residues found in raw milk produced in rural properties in Rio Grande do Sul (RS), to evaluate the conformity of samples regarding the maximum residue limit (MRL) established by the National Plan for Control of Residues and Contaminants in Animal in milk (PNCRC), to verify the knowledge level of people responsible for the milking process, in regard to the medications used in the herd and the withdrawal period, as well to identify the antibiotic residues commonly screened during the dairy processing routine, and the reasons for selecting them, at raw milk receiving points in the dairy plant, inspected by official services in the RS. Therefore, it held two exploratory and descriptive studies. In the first one, the milk samples collection occurred in 2013. At the moment of collection, a questionnaire was employed in order to evaluate the use of veterinary medicines by people responsible for milking. The 388 samples of raw milk, from rural properties distributed along the state were analyzed at the National Agricultural Laboratory. The second one, was from 2014 to 2015, which was administered questionnaire regarding the testing of antibiotic residues in 36 industrial establishments under state inspection. In the first study, 388 samples were analyzed in which 96 (24.7%) contained some antibiotic residue from the 45 analytes searched; 91 of these samples (23.5%), were in conformance with the current legislation. Only a total of five samples (1.3%) were suspected of violating the MRL described in the PNCRC. The antibiotic residues commonly found in the raw milk produced in RS were the macrolides (n=51; 13.1%), followed by quinolones (n=49; 12.6%) and the tetracyclines (n=18; 4.6%). The analysis of degree of knowledge of those responsible for milking demonstrates that 22.6% do not record or control the drug administration to the dairy herd. However, 87.4% (n=339) of the producers ensured to perform the discharge of the milk during the residual period, although, only 3.4% (n=13) of them consider the instructions present in the medicine bottle or the veterinary instructions (n=12; 3.1%) for this procedure, being guided by the cooperative in which they are associated (n=217; 55.9%). In the second study, the results showed that from the 36 participating facilities, 83% were classified as dairy plants, in which it was observed that the most commonly screened antibiotics were those belonging to the beta lactam group (100%) and tetracyclines (69%), whereas the selection of which antibiotic residues to screen, at the milk receiving point of the plant, was influenced by the practicality and quickness in performing the screening (67%) rather than by specific knowledge on which antibiotics were used by milk suppliers (22%). It was concluded that the milk consumed in RS was in accordance with the previously results obtained by the PNCRC in terms of the presence of antibiotic residues during the collection period, offering negligible health risk. However, efforts should be directed to farmers on good agricultural practices and to industries in regard to criteria for choice of tests for antibiotic residue detection.

Thesis (MApSc(MedicalLaboratorySce))--University of South Australia, 2003.

Thesis (MAppSc)--University of South Australia, 2001.

The advent of new methods to detect animal drug residues has resulted in a need to independently validate them. The effects of processing milk on the performance of these methods was evaluated. Antibiotic-free milk samples were spiked with sulfamethazine, penicillin G, and chlortetracycline at levels of 10, 10 and 30 ppb, respectively. Spiked milk and negative control milk was heat-treated, homogenized or heat-treated and homogenized. The procedures evaluated for penicillin detection were Bacillus stearothermophilus disk assay, a HPLC described by Barker et al., Charm II microbial receptor assay, and CITE Probe and LacTek enzyme immunoassays. The procedures evaluated for sulfonamide detection were an HPLC method described by Long et al., Charm II microbial receptor assay, CITE Probe, LacTek and Signal enzyme immunoassays. The methods evaluated for tetracycline detection were a HPLC method described by Long et al., Charm II microbial receptor assay, and LacTek and CITE Probe enzyme immunoassays. The results indicate that the commercial tests and the disk assay were not adversely affected by processing treatments. Significant treatment differences were found when testing raw Charm II data by analysis of variance but these differences did not effect the overall results of the test. Results of the HPLC method were inconclusive for the three drugs tested. / Master of Science

Thesis (M. Tech. ) - Central University of Technology, Free State, 2006 / Antibiotics have been used on animals since the Second World War for therapeutic purposes. The risks associated with the use of antibiotics in food animals are enormous, due to the possibility of resistance of organisms caused by the usage of low levels of antibiotics. The goals of this study were to determine the prevalence of antibiotic residues in C grade milk cows, and to determine the practices and knowledge of producers regarding the use of antibiotics as well as the knowledge and habits of consumers. In the study the presence of antibiotic residues was tested by means of microbiological inhibition testing. Fifteen percent of all tested samples tested positive for the presence of antibiotic residues. Eleven samples that tested positive on the microbiological inhibition test were sent to the Onderstepoort Veterinary Institute for confirmation. The knowledge of the consumer as well as that of the producer was tested by means of a questionnaire and then processed statistically. Producers were, in general, fairly ignorant regarding the withdrawal period of antibiotic residues. Age and the combination of age and reproduction were the common reasons for the selling of milk cows. Both the sampling and the questionnaires proved that the presence of antibiotic residues is higher than that stated in literature. The selling of the animals was mostly by auction or directly to the abattoirs. Consumer practices regarding the antibiotic residues were mostly in order, although consumers did not have knowledge regarding antibiotic residues. High temperatures, for example in the frying or grilling of meat, will reduce the presence of antibiotic residues because these effects have an influence on the presence of antibiotic residues (Rose et al., 1995). Almost 75% of consumers describe antibiotics in a positive manner. Milk and meat are regarded as posing the greatest risk for the origin of antibiotic residues. A lack of general knowledge regarding antibiotic residues was noteworthy, especially from the consumers of Thaba ’Nchu and Heidedal. The wrong usage of antibiotics by medical practitioners and consumers will certainly have consequences. Most of the consumers (112/227 respondents) indicated that they always completed a course of antibiotics. Forty-nine respondents indicated that they had already used antibiotics and that the therapy was unsuccessful. Antibiotic residues are still present so the risk to the consumer is still viable. Improved sampling and monitoring at abattoirs both for local and export abattoirs is necessary. The “farm to fork” concept and financial incentives by way of subsidies for residue-free products is a positive step. South African consumers are not quality conscious and further studies are necessary to improve the quality and safety of meat.

No description available.

Tesis por compendio / [ES] Los residuos de antibióticos en la leche constituyen un aspecto de gran importancia para la salud pública y pueden tener un efecto negativo en la industria láctea. Para proteger al consumidor se han establecido los Límites Máximos de Residuos (LMR) para diferentes antibióticos en la leche cruda. Sin embargo, la transferencia de estas sustancias de la leche al queso ha sido poco estudiada y, por lo tanto, se desconoce el impacto de la presencia de antibióticos sobre el proceso de elaboración y la seguridad del queso. El objetivo de la tesis ha sido evaluar la transferencia de los antibióticos más empleados en el ganado caprino lechero, desde la leche a quesos curados y frescos, así como estudiar el efecto sobre el proceso de fabricación y la calidad de los quesos durante la maduración. Para alcanzar el objetivo se han realizado elaboraciones de quesos curados (60 días) a partir de leche en presencia de diversos antibióticos (amoxicilina, bencilpenicilina, cloxacilina, eritromicina, ciprofloxacina, enrofloxacina y oxitetraciclina) a niveles admisibles (LMR) y fabricaciones de leche libre de antibiótico como referencia. Los resultados obtenidos sugieren que la mayor parte de los antibióticos en la leche no afectaron al proceso de fabricación del queso. Solamente la eritromicina y oxitetraciclina incrementaron el tiempo requerido en el proceso de elaboración. Respecto a las características del queso evaluadas a diferentes tiempos de maduración (0, 30 y 60 días), las pocas diferencias encontradas se refirieron a la concentración de ácidos grasos libres, el color y las propiedades de textura, pero en su mayoría no fueron detectadas en la evaluación sensorial. Sin embargo, cantidades variables de antibióticos, se transfirieron de la leche al queso (entre 7,4 y 68%). Las quinolonas y oxitetraciclina presentaron las más elevadas tasas de retención, así como persistencia a lo largo de la maduración, con altas concentraciones de quinolonas (enrofloxacina: 148±12 µg/kg; ciprofloxacina: 253±24 µg/kg) y de oxitetraciclina (20±5,7 µg/kg) después de los 60 días de curado. En el estudio de quesos frescos, se evaluó la presencia de residuos de medicamentos en la leche pasteurizada y en los quesos frescos a partir de leche de cabra con antibióticos (amoxicilina, bencilpenicilina, cloxacilina, neomicina, eritromicina, ciprofloxacina, enrofloxacina y oxitetraciclina) a niveles de seguridad (LMR). Los resultados mostraron que altas cantidades de antibióticos, entre el 71 y el 100% de la concentración inicial en la leche cruda, permanecieron en la leche pasteurizada y que fueron transferidas al queso en gran medida, con porcentajes de retención que oscilaron entre 37,5 y 75%. Con respecto a los márgenes de seguridad de estos productos, se calcularon teniendo en cuenta diferentes grupos de edades (niños, adolescentes y adultos), y los efectos negativos de estos antibióticos sobre la salud. Los resultados indicaron que el mínimo margen de seguridad en la leche pasteurizada lo presentaron la ciprofloxacina, enrofloxacina, y eritromicina para el grupo de niños. En relación al queso fresco, se obtuvo un elevado margen de seguridad para todos los antibióticos y grupos de edad considerados, lo que sugiere que este producto probablemente no tenga efectos negativos en la salud del consumidor. Es importante enfatizar que concentraciones relativamente altas de antibióticos podrían permanecer en la leche de cabra pasteurizada y productos relacionados, como los quesos frescos y de corta maduración. La presencia de estos antibióticos podría contribuir al desarrollo y propagación de la resistencia a los antimicrobianos que actualmente constituye un grave problema a nivel mundial. Los resultados de este trabajo podrían servir a las autoridades de salud pública para evaluar si los sistemas actuales de control de antibióticos en la leche y los productos lácteos son adecuados o deberían ser revisados. / [CA] Els residus d'antibiòtics en la llet animal constitueixen un aspecte de gran importància per a la salut pública, i poden tindre un efecte negatiu en la indústria làctia. Per a protegir al consumidor s'han establit els Límits Màxims de Residus (LMR) per a diferents medicaments veterinaris en la llet crua. No obstant això, la transferència d'estes substàncies de la llet al formatge ha sigut poc estudiada i, per tant, es desconeix el impacte de la presència de antibiòtics sobre el procés d'elaboració i la seguretat del formatge. L'objectiu de la tesi ha sigut avaluar la transferència dels antibiòtics més empleats en el bestiar caprí lleter, des de la llet a formatges curats i frescos, així com l'efecte sobre el procés de fabricació i la qualitat dels formatges durant la maduració. Per a aconseguir l'objectiu s'han realitzat elaboracions de formatges curats (60 dies) a partir de llet en presència de diversos antibiòtics (amoxicilina, bencilpenicilina, cloxacilina, eritromicina, ciprofloxacina, enrofloxacina i oxitetraciclina) a nivells admissibles (LMR) i fabricacions de llet lliure d'antibiòtic (control) com a referència. Els resultats obtinguts suggerixen que la major part dels antibiòtics en la llet no van afectar el procés de fabricació del formatge. Només l'eritromicina i l'oxitetraciclina van incrementar el temps requerit en el procés d'elaboració del formatge. Respecte a les característiques del formatge avaluades a diferents temps de maduració (0, 30 i 60 dies), les poques diferències trobades es van referir a la concentració d'àcids greixos lliures, el color i les propietats de textura, però majoritàriament no van ser detectades en l'avaluació sensorial. No obstant això, quantitats variables d'antibiòtics, es van transferir de la llet al formatge (entre 7,4 i 68%). Les quinolones i l'oxitetraciclina van presentar les més elevades taxes de retenció, així com persistència al llarg de la maduració, amb altes concentracions de quinolones (enrofloxacina: 148±12 µg/kg; ciprofloxacina: 253±24 µg/kg) i d'oxitetraciclina (20±5,7 µg / kg) després dels 60 dies de curació. En l'estudi de formatges frescos, es va avaluar la presència de residus de medicaments en la llet pasteuritzada i en els formatges frescos a partir de llet de cabra amb antibiòtics (amoxicilina, bencilpenicilina, cloxacilina, neomicina, eritromicina, ciprofloxacina, enrofloxacina i oxitetraciclina) a nivells de seguretat (LMR). Els resultats van mostrar que altes quantitats d'antibiòtics, entre el 71 i el 100% de la concentració inicial en la llet crua, van romandre en la llet pasteuritzada i que van ser transferides al formatge en gran manera, amb percentatges de retenció que van oscil·lar entre 37,5 i 75%. Respecte als marges de seguretat d'estos productes, es van calcular tenint en compte diferent grups d'edats (xiquets, adolescents i adults), i els efectes negatius d'estos antibiòtics sobre la salut. Els resultats van indicar que el mínim marge en la llet pasteuritzada ho van presentar la ciprofloxacina, la enrofloxacina, i l'eritromicina per al grup de xiquets. En relació al formatge fresc, es va obtindre un elevat marge de seguretat per a tots els antibiòtics i grups d'edat considerats, la qual cosa suggereix que este producte probablement no tinga efectes negatius en la salut del consumidor. És important emfatitzar que concentracions relativament altes d'antibiòtics podrien romandre en la llet de cabra pasteuritzada i productes relacionats, com els formatges frescos i de curta maduració. La presència d'estos antibiòtics podria contribuir al desenrotllament i propagació de la resistència als antimicrobians que actualment constitueix un greu problema a nivell mundial. Els resultats d'este treball podrien servir les autoritats de salut pública per a avaluar si els sistemes actuals de control d'antibiòtics en la llet i els productes lactis són adequats o haurien de ser revisats. / [EN] Antibiotic residues in milk are a great concern for public health, and they have negative implications for the dairy industry. To guarantee the safety of milk and derivates, Maximum Residues Limits (MRL) for different veterinary drugs in raw milk have been established. However, the transfer of these substances from milk to cheese, has been poorly studied and, therefore, the impact of the use of raw milk containing antibiotics on the cheese-making and the cheese safety is thus far unknown. The aim of this thesis was to evaluate the transfer of the most widely used antibiotics used in dairy goats, from milk to matured and fresh cheese, as well as their effect on the cheese-making process and the quality characteristics of the cheeses during ripening. To this end, antibiotic-free milk was spiked individually with seven veterinary drugs (amoxicillin, benzylpenicillin, cloxacillin, erythromycin, ciprofloxacin, enrofloxacin and oxytetracycline) and used to make mature Tronchón cheeses, which were analyzed at different ripening times (0, 30, and 60 days) to determine antibiotic residues, pH, chemical composition, proteolytic and lipolytic activities, color, and textural properties. The cheese-making process was unaffected by the presence of most antibiotics in milk. Only erythromycin and oxytetracycline significantly increased the time required for cheese production. Regarding cheese characteristics, the few differences found were related to the free fatty acid concentration, color and textural properties, which remained mostly undetected by the sensory analysis panelists. However, variable amounts of antibiotics, ranging from 7.4 to 68 %, were transferred from milk spiked with antibiotics, to cheese. Oxytetracycline and quinolones presented the highest retention rates as well as persistence along maturation, with high concentrations of quinolones (enrofloxacin: 148±12 µg/kg, ciprofloxacin: 253±24 µg/kg) and oxytetracycline residues (20±5.7 µg/kg) in cheeses after 60 days of ripening. In the study of fresh cheeses was evaluated the presence of drug residues in pasteurized fluid milk and fresh cheeses obtained from goat milk containing antibiotics (amoxicillin, benzylpenicillin, cloxacillin, neomycin, erythromycin, ciprofloxacin, enrofloxacin and oxytetracycline) at safety levels (MRLs). The safety margin of these dairy products for consumers was also evaluated. Results showed that high amounts of antibiotics, between 71-100% of the initial concentration in raw milk, remained in pasteurized goat milk and were transferred to cheese to a high extent, with retention percentages ranging from 37.5 to 75%. Regarding the safety margin of goat milk products, calculated taking into account different age groups (children, teenagers and adults), and the published negative effects of such antibiotics on consumer health, results indicate that the minimum safety margin of pasteurized milk was obtained for ciprofloxacin, enrofloxacin and erythromycin in the group of children. Regarding fresh cheese, an elevated safety margin was obtained for all antibiotics and age groups considered. It is important to emphasize that relatively high concentrations of antibiotics could remain in pasteurized fluid goat milk and related products such as fresh cheese and cheeses of a short ripening period. The presence of these antibiotics in dairy products might contribute to the development and spread of antimicrobial resistance, which is considered an important public health concern worldwide. The result of this research could serve the public health authorities to assess if current control systems of antibiotics in milk and dairy products are adequate or have to be revised. / Por último, quiero dar las gracias a la educación pública que permite que la economía no sea una barrera para la formación y al “Programa de ayudas a la investigación” (FPI-2014) de la Universitat Politècnica de Valencia, que me concedió la oportunidad de realizar está investigación durante los 4 años de trabajo. / Quintanilla Vázquez, PG. (2019). Effect of antibiotics in goat milk on the manufacture and characteristics of cheese [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/125701 / Compendio

The novel hypothesis that antimicrobial growth promoters (AGP) function by modulating the mammalian immune system was tested. Sampling methods to characterize the mucosa-associated microbiota of the murine intestine by terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that direct plug extraction was superior to wash methods. Using T-RFLP analysis, non-therapeutic administration of chlortetracycline (CTC) and sulfamethazine to beef cattle did not affect the composition of bacterial communities associated with intestinal mucosa and in digesta, with exception of those associated with mucosa of the proximal jejunum. Similarly, oral administration of non-therapeutic concentrations of CTC did not affect the mucosa-associated microbiota of the murine intestine. Oral administration of nontherapeutic concentrations of CTC prevented weight loss, reduced pathologic changes, modulated transcription levels of inflammatory cytokines in C. rodentium-infected mice, and did not consistently affect the colonic microbiota. These findings support the hypothesis that AGP primarily function by modulating the intestinal immune system. / xiv, 160 leaves ; 29 cm