Thesis (doctoral)--Vrije Universiteit te Amsterdam, 1980. / Summary in Dutch. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 58-62.

Thesis (M.Med.Sc.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 26-32). Also available in print.

Thesis (doctoral)--Vrije Universiteit te Amsterdam, 1980. / Summary in Dutch. Includes bibliographical references.

Made available in DSpace on 2015-06-12T14:01:14Z (GMT). No. of bitstreams: 2 54.pdf: 1028475 bytes, checksum: d2d42ea5ee44212711e7935436caa735 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2011 / Fundação Oswaldo Cruz. Instituto Nacional de Controle de Qualidade em Saúde. Rio de Janeiro, RJ, Brasil. / Nas últimas quatro décadas espécies de Campylobacter spp. têm sido reconhecidas como patógenos emergentes e despontaram como importantes agentes de gastrenterites de origem alimentar em várias partes do mundo. No Brasil, cabe aos órgãos normatizadores e à Vigilância Sanitária assegurar o cumprimento das legislações a fim de garantir a segurança dos alimentos comercializados e preservar a saúde do consumidor. O objetivo deste estudo foi verificar a ocorrência das espécies termofílicas de Campylobacter em 30 amostras de carcaças resfriadas de frango adquiridas no comércio do Município do Rio de Janeiro. A preparação das amostras e o isolamento de colônias suspeitas de Campylobacter spp. foram realizados de acordo com os protocolos descritos no Compendium of Methods for the Microbiological Examination of Foods, APHA. A confirmação de Campylobacter spp. foi feita pelo teste de aglutinação em látex e a diferenciação das espécies foi realizada pela bioquímica convencional e pela abordagem molecular. Foi proposto, neste estudo, a utilização da Duplex PCR para amplificar os genes 16S rRNA e o gene da oxirredutase, para a detecção das espécies do gênero Campylobacter e da espécie C. jejuni respectivamente. O plaqueamento direto das amostras, utilizando meios de cultivo seletivos, foi mais eficiente no isolamento de Campylobacter spp. do que a etapa de enriquecimento seletivo. / During the last four decades, different species of Campylobacter spp. have been recognized as emerging pathogens and important agents of gastroenteritis from food source worldwide. In Brazil, health authorities are responsible for the surveillance of foods in order to preserve the health of the population. The aim of this study was to determine the proportion of thermophilic Campylobacter species among 30 chilled chicken carcasses samples purchased in the Rio de Janeiro City. Sample preparation and isolation of suspected Campylobacter spp. colonies were performed according to the protocols described in the Compendium of Methods for the Microbiological Examination of Foods, APHA. Campylobacter spp. confirmation was performed with the latex agglutination test and species differentiation was carried out through biochemistry tests and molecular approach. A Duplex-PCR approach has been proposed through amplification of 16S rRNA and oxidoreductase genes, for the detection of the genera Campylobacter and C. jejuni respectively. Direct plating of samples using selective culture media, was more efficient for the isolation of Campylobacter spp. then the selective enrichment step. We detected the presence of Campylobacter spp. in 21 samples (70%), six (28,6%) from slaughterhouses, eight (38,1%) from supermarkets and seven (33,3%) from street markets. Two (9,6%) out of 21 isolates were identified as C. coli, 18 (85,7%) as C. jejuni and one isolate showed after 7 days an ambiguous result by biochemical tests. Duplex PCR confirmed the biochemical results for C. coli and detected 19 (90,48%) C. jejuni after 4 hours. Our results suggest that the implementation of rapid and reliable methods for the detection of this food pathogen in poultry may contribute for the improvement of food surveillance systems and public health surveillance.

Campylobacter jejuni is one of the most frequent causes of gastroenteritis in both the developing and the developed world. Understanding C. jejuni biology is paramount to reducing the amount of Campylobacter jejuni in the food chain, however our understanding of the regulatory networks that enable Campylobacter jejuni to successfully colonize various hosts remains incomplete. Campylobacter jejuni has an absolute requirement for iron in order to grow as iron catalyzes a wide range of essential biochemical reactions. In contrast to many Gram negative bacteria, the genome of Campylobacter jejuni contains two iron activated Fur-family transcriptional regulators, Fur and PerR, which are primarily responsible for regulating iron homeostasis and oxidative stress respectively. We have used an integrated approach that combines genome wide technologies (ChIP-chip, RNA-seq) and structural studies to define the role of iron, Fur and PerR in Campylobacter jejuni. These studies have demonstrated that apo-Fur directly regulates gene transcription in Campylobacter jejuni, identified novel ncRNAs that are Fur and/or iron responsive, and revealed that the Fur and PerR regulons are more extensive than previously characterized. These results provide further insight into the surprisingly complex regulatory networks that allow Campylobacter jejuni to be a successful gut pathogen.

Salmonella and Campylobacter are two foodborne pathogens that continue to persist in broiler processing. Various studies have demonstrated that peracetic acid can effectively reduce the prevalence pathogens on broiler meat. However, there are a limited number of studies comparing the effects of peracetic acid on broiler meat from different processing plants. The objective of this study was to determine the prevalence of Salmonella, Campylobacter, and spoilage microbes on broiler meat at different stages of poultry processing in commercial plants that use peracetic acid as the primary antimicrobial. Results indicated that there was a high initial microbial presence on broiler meat at initial stages of processing in all three plants. Peracetic acid effectively reduced the prevalence and microbial load of all microbes analyzed in this study. All microbes were reduced to nondetectable levels in the finishing chiller. However, contamination of all microbes in mechanically deboned meat closely resembled initial carcass contamination. In conclusion, the intervention with the greatest effect on microbial prevalence was peracetic acid in carcass chilling tanks, and, given the level of contamination in mechanically deboned meat, an intervention at this step would be worth investigating.

Campylobacter spp. are the second leading bacterial cause of food borne illness in the U.S.  New antimicrobials that prevent bacterial attachment may be effective for reducing Campylobacter.  Delmopinol hydrochloride (delmopinol) is a cationic surfactant that is effective for treating and preventing gingivitis and periodontitis.  This study evaluated the effectiveness of delmopinol for reducing attachment of Campylobacter jejuni to chicken, stainless steel and high-density polyethylene. Chicken pieces, steel and HDPE coupons were spot-inoculated with 0.1 mL of a Campylobacter jejuni culture.  After 10 min, samples were sprayed with 0.5% or 1.0% delmopinol, 0.01% sodium hypochlorite, or distilled water.  Contact times were 1, 10, or 20 min prior to rinsing with buffered peptone water. Rinses were serially diluted onto Campy Cefex Agar for enumeration.  For additional samples, solutions were applied first, followed by inoculation with C. jejuni after 10 min.  Cultures remained undisturbed for 1, 10, or 20 min.  Then samples were rinsed and plated as above. When C. jejuni was inoculated before treatments, 1% delmopinol application led to mean log reductions of 1.26, 3.70, and 3.72 log CFU/mL, greater than distilled water, for chicken, steel and HDPE respectively. When C. jejuni was inoculated after spray treatments, 1% delmopinol reduced C. jejuni by 2.72, 3.20, and 3.99 mean log CFU/mL more than distilled water for chicken, steel and HDPE respectively.  Application of 1% delmopinol, either before or after bacteria inoculation, resulted in a significantly (p<0.05) greater log reduction than 0.01% sodium hypochlorite or distilled water. Delmopinol may be a promising antimicrobial treatment. / Master of Science in Life Sciences

C. pylori have been shown to be associated with gastritis and peptic ulceration, but the mechanism of their pathogenicity is unknown. Since a number of virulence factors are known to be plasmid mediated, it was decided to study the plasmids of C. pylori. A variety of techniques were used to establish the best method of plasmid extraction from C. pylori. The method of alkaline lysis as described by Birnboim and Doly was shown to give the most consistent results and the greatest plasmid yield. Plasmid DNA was found in 54% (26 out of 48) of the isolates examined and the plasmids varied in size from 3,4kb to greater than 137kb. The majority (21 out of 26) of isolates had unique plasmid profiles, but 5 isolates showed common ones. Three of these 5 isolates were studied in more detail. The evidence presented here suggests that all 3 plasmid bands visible in these three isolates were different conformations of the same plasmid which has a molecular weight of 6, 2 kilo bases. The plasmids appeared labile and covalently closed circular DNA was rarely isolated. Restriction enzyme digestion was done with a variety of enzymes, but only 3 of the enzymes used digested the DNA. EcoRI and HindIII partially digested the DNA, while Sau3A digested the plasmids completely, generating 2 fragments of 2,2kb and 2,4kb, and a number of smaller fragments. The DNA was shown to be methylated and the fragments generated by Sau3A digestion suggest that the plasmids may contain a repetitive element. Chromosomal DNA was also isolated and digested with a variety of enzymes. The chromosomal DNA restriction pattern was shown to be affected by methylation, which may be important when using restriction enzyme patterns to differentiate between strains. Plasmid restriction fragments were end-labelled to detect bands which were poorly visible by ethidium bromide staining. This technique was shown to be more sensitive than ethidium bromide staining of DNA, but the inability to obtain complete digestion of C. pylori DNA made it impossible to construct a restriction enzyme map of the plasmids. Hybridization experiments showed the plasmids of C. pylori to be related and was also used to detect bands which were not easily visible after ethidium bromide staining. Attempts were made to clone C. pylori DNA into pUC18 and pUC19, but no recombinant plasmids containing C. pylori DNA were obtained.

Campylobacter jejuni is one of the most common causes of foodborne diarrheal illness in the U.S. and worldwide. (1-2). C. jejuni infection in humans is most often attributed to undercooked poultry (3-6). However, since 2001, the Centers for Disease Control (CDC) has confirmed 9 outbreaks of campylobacteriosis linked to consumption of beef and beef products, resulting in 297 illnesses and 10 hospitalizations, and cattle isolates have been linked to other human infections (7-10). Because Campylobacter infection is generally sporadic, and not all cases are linked to poultry, other animal reservoirs such as beef likely exist. Because beef is not commonly considered a significant source of Campylobacter, interventions regarding beef cattle are generally geared toward other pathogens, such as E. coli O157:H7. Interventions to prevent Campylobacter spread in poultry houses include reducing flock colonization and bacterial loads, (11), as well as interventions directly targeting consumer behavior. Despite these efforts, many countries have not been able to reduce the prevalence of Campylobacter in poultry. The goals of this research were to 1) determine Campylobacter loads in broilers at poultry farms and processing houses through the 3-tube MPN method, and determine baseline data for poultry production systems, 2) describe temporal relationships and prevalence of Campylobacter strains in a potentially underrepresented host/environment (cattle feedlot environment), and 3) test the efficacy of natural, plant derived compounds against C. jejuni on meat. Our results show that there is a significant positive association between pre-harvest and post-harvest Campylobacter loads in poultry, with Campylobacter levels during the final step of processing remaining at infectious levels. Beef cattle represent another potential and not well-described source of campylobacteriosis, as beef cattle and their environment become rapidly contaminated with Campylobacter from weaning through processing, and cross-contamination of carcasses is possible. This research also determined that natural plant extracts of cinnamon and oregano essential oils, when added to edible films, reduced surface contamination of retail poultry meat with C. jejuni, and thus may be a useful post-harvest intervention for future use in packaging of retail meat with a high risk of Campylobacter contamination.