Thesis (M.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 174-185). Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 128-42). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 128-42). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 77-86). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 77-86). Also available on the Internet.

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

Thesis (MSc Food Sc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Listeria monocytogenes is a foodborne pathogen that has been isolated from a variety of food sources. It is the cause of the food-borne disease, listeriosis that shows symptoms such as meningitis, encephalitis and abortion. Different strains of L. monocytogenes exist and not all are thought to be pathogenic to humans. The aim of this study was to evaluate and compare conventional methods, culturing on selective (Oxford agar) and chromogenic (RAPID’L.mono agar) media, as well as speciesspecific and multiplex polymerase chain reaction (PCR) methods for the detection and identification of 94 L. monocytogenes isolates from various areas in an avocado processing facility, as well as the final product. To achieve a better understanding of the genetic diversity of the confirmed L. monocytogenes strains isolated from the avocado facility, two subtyping techniques, PCR-restriction fragment length polymorphism (PCR-RFLP) and pulsed-field gel electrophoresis (PFGE), were employed. All of the isolates were identified as Listeria species on both Oxford and RAPID’L.mono agar. On the RAPID’L.mono agar, 76 of the 94 isolates produced colonies typical of L. monocytogenes, with the remaining 18 showing colonies typical of L. innocua (n=13) and L. ivanovii (n=5). The species-specific PCR successfully amplified a 730 base pairs region of the hly gene of 80 of the 94 isolates. For the same 80 isolates the multiplex PCR successfully amplified 800, 517 and 238 base pair (bp) fragments of the inlA, inlC and inlJ genes, respectively. The remaining 14 isolates included the 13 isolates identified as L. innocua, as well as an isolate identified as L. monocytogenes on RAPID’L.mono. The results obtained on the Oxford agar showed a 100 % positive correlation when compared to the PCR results in identifying Listeria species, while the RAPID’L.mono had a 4 % false negative result in identifying L. monocytogenes compared to the PCR results. Sixty-four of the confirmed L. monocytogenes isolates were subtyped using PCRRFLP and PFGE. For the PCR-RFLP analysis, a 733 bp fragment of the inlA gene was successfully amplified for all of the isolates, followed by digestion with the restriction enzymes, AluI and Tsp509I. AluI produced three different banding patterns and Tsp509I produced two different banding patterns. Subtyping of the isolates using PFGE was carried out by macrorestriction of the genomic DNA with ApaI and AscI. The restriction fragments were resolved by PFGE and the fingerprints were classified into four clusters. In the combined analyses, cluster I contained forty-eight isolates (n=48), cluster II 1 isolate (n=1), cluster III fifteen isolates (n=15) and cluster IV 1 isolate (n=1). The PCR-RFLP results had a 98 % correlation with the PFGE results. The results of this study indicated inconsistencies between the results obtained by conventional and molecular detection methods for the identification of L. monocytogenes. Species-specific and multiplex PCR, however, proved useful to accurately detect and identify L. monocytogenes in a shorter period of time and could replace the use of conventional agar during identification. Both PCR-RFLP and PFGE proved useful in the subtyping of L. monocytogenes isolates with the PCR-RFLP being less expensive and results obtainable in a shorter period of time. / AFRIKAANSE OPSOMMING: Listeria monocytogenes is ‘n patogeen afkomstig van voedsel wat uit ‘n verskeidenheid voedselbronne geisoleer kan word. Dit is die oorsaak van die voedsel afkomstigde siekte, listeriosis met simptome soos harsingvliesontsteking, ensefalitis en aborsie. ‘n Verskeidenheid L. monocytogenes stamme bestaan, maar nie almal word as patogenies beskou nie. Die doel van hierdie studie was om konvensionele metodes, naamlik mikrobiologiese kweking op selektiewe (Oxford agar) en chromatografiese (RAPID’L.mono agar) media, sowel as spesies-spesifieke en multipleks polimerase ketting reaksie (PKR) metodes te evalueer en vergelyk vir die deteksie en identifikasie van 94 L. monocytogenes isolate geisoleer vanuit verskeie areas in ‘n avokado prosesseringsfasiliteit sowel as die finale produk. Om ‘n beter begrip van die genetiese diversiteit van die isolate wat as L. monocytogenes bevestig is te verkry, is twee subtiperingstegnieke, PKR-restriksiefragmentlengte polimorfisme (PKR-RFLP) en pulsveld jel-elektroforese (PVJE) toegepas. Beide Oxford en RAPID’L.mono agar het al die isolate as Listeria spesies geidentifiseer. Op die RAPID’L.mono agar het 76 van die 94 isolate kolonies tipies van L. monocytogenes gevorm, 13 kolonies was tipies van L. innocua (n=13) en vyf kolonies tipies van L. ivanovii (n=5). Die spesies-spesifieke PKR het ‘n 730 basis paar (bp) streek van die hly geen suksesvol geamplifiseer vir 80 van die 94 isolate. Die multipleks PKR het 800, 517 en 238 bp fragmente van die inlA, inlC and inlJ gene onderskeidelik, vir dieselfde 80 isolate suksesvol geamplifiseer. Die oorblywende 14 isolate het die 13 isolate wat as L. innocua geïdentifiseer is en die een isolaat wat as L. monocytogenes op RAPID’L.mono geïdentifiseer is ingesluit. Resultate verkry met die Oxford agar het 100 % ooreengestem met die PKR resultate vir die identifikasie van Listeria spesies. Die RAPID’L.mono het ‘n 4 % vals negatiewe resultaat gelewer in vergelyking met die PKR resultate. Vier-en-sestig van die bevestigde L. monocytogenes isolate is gesubtipeer deur PKR-RFLP en PVJE. Tydens die PKR-RFLP analise is ‘n 733 bp fragment van die inlA geen suksesvol geamplifiseer, gevolg deur vertering met die restriksie-ensieme, AluI and Tsp509I. AluI het drie verskillende bandpatrone opgelewer en Tsp509I twee verskillende bandpatrone. Subtipering deur PVJE is uitgevoer deur makro-restriksie van die genomiese DNA met ApaI en AscI. Die restriksie fragmente is geskei deur PVJE en die vingerafdrukke is in vier groepe geklassifiseer. Groep I het 48 isolate (n=48), groep II 1 isolaat (n=1), groep III 15 isolate (n=15) en groep IV 1 isolaat (n=1) gehad tydens die gekombineerde analise. Die PKR-RFLP resultate het 98 % ooreengestem met die van die PVJE. Die resultate van hierdie studie het teenstrydighede tussen die resultate van konvensionele en molekulêre deteksie metodes opgelewer vir die identifikasie van L. monocytogenes. Die spesies-spesifieke en multipleks PKR het egter beide goed te pas gekom vir die akkurate deteksie en identifikasie van L. monocytogenes en kan heel moontlik die gebruik van konvensionele agar tydens identifikasie vervang. Beide PKRRFLP en PVJE was nuttig vir die subtipering van L. monocytogenes isolate. PKR-RFLP is egter ‘n goedkoper tegniek en die resultate is in ‘n korter tydsperiode beskikbaar.

The microbiological testing of foods is a well-established science. Due to the severity of foodborne pathogen illnesses, the widespread use and implementation of rapid detection methods in food testing labs is increasingly important. The first step for successful testing is sampling. Surfactants have been highly used in food microbiology, but there is not much, if any, published research about the use of fatty alcohols and chemical dispersants as aids in microbial separation. The microbial extraction efficiency of Escherichia coli K12 and Listeria innocua from hot dogs, spinach, and milk was measured using chemical additives (surfactants, fatty alcohols, and a chemical dispersant) in a buffer solution. Dry matter content was calculated using the oven method to determine how clean the sample was at the end of processing. Tween 80 at 0.01% was found to be the most effective additive for microbial recovery for each food matrix examined. The addition of fatty alcohols to surfactants also showed much promise in aiding separation as well as in minimizing dry matter in the final solution. However, the use of Buffered Peptone Water as the diluting agent resulted in very high recovery percentages without the need for additives.

Epidemiology of the incidence of foodborne disease in the Czech Republic In my thesis I focused on the incidence of foodborne disease in the Czech Republic and their prevention. Group of foodborne disease, which is dominated by the fecal-oral transmission, is strongly influenced by the human factor. Foodborne disease easier occurs in communities of large group of people and in particular there where are problems with compliance with basic hygiene. Presented work is an abbreviated synthesized look at existing development and current severity of foodborne illnesses. The aim is not a detailed data analysis of individual foodborne illness, but their global assessment of occurrence in the Czech Republic. This is specifically focused only on selected infectious diseases where is possible to show long-term changes. A separate chapter is devoted to detailed incidence of viral hepatitis A, which is currently a very hot topic. Furthermore, I also present information on the recent epidemic of HAV in the Czech Republic in 2008. In the first section of presented thesis I describe process of collection and completion of related data in Czech Republic, also programs which are currently used for collection of data and their evaluation. I have also indicated external factors influencing disease emergence. In the second part, I compiled information on selected diseases and processed those into a graphs and maps of occurrence. Based on knowledge of the occurrence of these trends, it could be used for recommendation of effective infection control measures affecting the spread of the disease. The outcome of my thesis shows that in the Czech Republic are primarily important acute diarrheal diseases of bacterial and viral origin. For number of foodborne illnesses the trend of occurrence in Czech Republic is at very low level and the problem is with their import from developing countries with endemic occurrence. Certain foodborne diseases are eliminated, as we have in place specific immuno-prevention for long time. Good example is elimination of polio disease in the Czech Republic. Due to positive influence on certain diseases even more comes to the forefront diseases of infectious origin and importance of their actual and relative increase. As example are certain bacterial and viral diseases. Most significant are salmonellosis, campylobacteriosis and viral hepatitis. This development can be worldwide observed. In economically highly developed countries all this is associated with the growth of the food industry. The incidence of the campylobacteriosis disease in the Czech Republic yearly exceeds 20 thousand cases, which is the most common human zoonosis. Given the importance of this issue the aim of my thesis is not proposing solution. The aim is only to map and point out the current epidemiological situation of occurrence of selected foodborne diseases in the Czech Republic.

p. 1-38 / Submitted by Santiago Fabio (fabio.ssantiago@hotmail.com) on 2013-04-22T18:31:53Z No. of bitstreams: 1 2222.pdf: 561666 bytes, checksum: ebfdba1c6ab3fc6216c180b8b833b776 (MD5) / Approved for entry into archive by Maria Creuza Silva(mariakreuza@yahoo.com.br) on 2013-05-04T17:28:47Z (GMT) No. of bitstreams: 1 2222.pdf: 561666 bytes, checksum: ebfdba1c6ab3fc6216c180b8b833b776 (MD5) / Made available in DSpace on 2013-05-04T17:28:47Z (GMT). No. of bitstreams: 1 2222.pdf: 561666 bytes, checksum: ebfdba1c6ab3fc6216c180b8b833b776 (MD5) Previous issue date: 2008 / Introdução: No Brasil, a vigilância epidemiológica das doenças transmitidas por alimentos (VE-DTA) iniciou-se em 1999. O objetivo desse estudo é descrever a epidemiologia dos surtos de DTA no Brasil para desenvolver estratégias para prevenir futuros surtos. Material e métodos: Foi desenvolvido um estudo ecológico dos surtos de DTA ocorridos no Brasil e notificados à Secretaria de Vigilância em Saúde (SVS) do Ministério da Saúde (MS), entre 1999 a 2006. Os dados foram analisados utilizando-se o pacote estatístico EpiInfo versão 6.04d e SPSS versão 13.0. Resultados: De 1999 a 2006, a VE-DTA recebeu notificação de 5.370 surtos, com 1.587.920 expostos, 108.793 doentes e 60 óbitos. A mediana de doentes foi sete (intervalo: 1 – 2.723), da incidência entre expostos foi de 71,4% (intervalo: 0,1 – 100,0) e do coeficiente de letalidade de 0% (intervalo: 0 – 75,0). As notificações foram recebidas de 24 UF e a região Sul notificou 50,9% dos surtos. Nos surtos com etiologia conhecida (50,2% - 2695/5370), 83,5% foram causados por bactérias, 14,1% por vírus, 1,4% por produtos químicos e 1% por parasitas. Os agentes etiológicos mais freqüentes foram: Salmonella spp em 42,1% (1134/2695) e Staphylococcus spp em 20,4%. Alimentos contendo ovos crus ou mal cozidos foram o principal veículo de transmissão, sendo a causa de 818 (22,4%) surtos, seguidos por alimentos mistos (17,5%), receitas com carnes vermelhas (11,8%), sobremesas (11,1%), água (8,7%), múltiplos alimentos (7,1%) e leite e derivados (6,9%). Dos 4.126 com local conhecido, a maior parte ocorreu nas residências (45,5%); restaurantes (19,1%) e instituições de ensino (11,0%). Surtos na comunidade apresentaram a maior razão de casos por local (144,2 – 17.753/124), seguidos por instituições com internação (64,3), eventos (45,7) e festas (40,5). Nas residências ocorreram as maiores proporções de óbitos (49,3% - 25/57). Conclusões: No período estudado houve aumento do número de surtos notificados e uma melhoria na qualidade da informação, à medida que as UF implantaram e utilizaram o sistema da VE-DTA. Neste sentido, recomenda-se aperfeiçoar as estratégias de segurança alimentar para que a população consuma produtos saudáveis, isentos de contaminação; implantar a VE-DTA nos demais municípios e aprimora qualidade das investigações dos surtos,para que de forma mais sensível, rápida e contínua, as equipes sejam capazes de identificar, controlar e prevenir a ocorrência de surtos. / Salvador