BACKGROUND:Clostridium difficile is an important cause of intestinal infections in some animal species and animals might be a reservoir for community associated human infections. Here we describe a collection of animal associated C. difficile strains from 12 countries based on inclusion criteria of one strain (PCR ribotype) per animal species per laboratory.RESULTS:Altogether 112 isolates were collected and distributed into 38 PCR ribotypes with agarose based approach and 50 PCR ribotypes with sequencer based approach. Four PCR ribotypes were most prevalent in terms of number of isolates as well as in terms of number of different host species: 078 (14.3% of isolates / 4 hosts), 014/020 (11.6% / 8 hosts) / 002 (5.4% / 4 hosts) and 012 (5.4% / 5 hosts). Two animal hosts were best represented / cattle with 31 isolates (20 PCR ribotypes / 7 countries) and pigs with 31 isolates (16 PCR ribotypes / 10 countries).CONCLUSIONS:This results show that although PCR ribotype 078 is often reported as the major animal C. difficile type, especially in pigs, the variability of strains in pigs and other animal hosts is substantial. Most common human PCR ribotypes (014/020 and 002) are also among most prevalent animal associated C. difficile strains worldwide. The widespread dissemination of toxigenic C. difficile and the considerable overlap in strain distribution between species furthers concerns about interspecies, including zoonotic, transmission of this critically important pathogen.

The genus Salmonella, comprised of 2400 serotypes, is one of the leading causes of foodborne illnesses in the US and has been used for the deliberate contamination of food. A rapid system for detection, isolation, typing and antibiotic susceptibility profiling is essential for diagnosis and source tracking in natural outbreaks or a bioterrorism event. Pure culture is essential for molecular typing and antibiotic resistance testing. The virulence and the resistance mechanisms of Salmonella are rapidly evolving and many are still unexplained. The first aim of the study was to rapidly detect and isolate Salmonella from intentionally contaminated food. The second aim was to build a DNA fingerprinting database for accurate identification of the subtype. The third objective was to study the antibiotic susceptibility patterns and the underlying mechanisms of resistance. A correlation between the DNA subtypes and antibiograms was hypothesized. An association between the resistance determinants and pathogenicity genes was expected. A total of 114 isolates including environmental and clinical sources were tested. General and selective enrichments and immunomagnetic separation (IMS) were tested for rapid detection and isolation of Salmonella from eight food groups. Isolates were subtyped by pulsed field gel electrophoresis (PFGE) and automated RiboPrinter®. Resistance to 31 drugs was tested by the Sensititre® system and integrons were identified by PCR. The association between virulence and resistance was verified by Southern hybridization. Of the three genes tested, ompF was found to be the most reliable target for identifying Salmonella subspecies I, III and IV. Detection by real time PCR after enrichment in buffered peptone water and isolation by IMS provided the fastest results. Sixty two ribotypes and 74 pulsotypes were observed for the 100 isolates subtyped. Sixty isolates were resistant to one or more antimicrobials and 12 had class-1 integrons. In conclusion, pure culture was achieved in 25 hours by IMS. Ribotyping, a comparatively rapid technique was found to be ideal for initial identification. PFGE, which was more discriminatory, was appropriate for source tracking. Contrary to the original hypothesis, no correlation between subtyping and antibiograms was observed and no association of integrons with the virulence genes tested was demonstrated

Vibrio parahaemolyticus is a leading cause of seafood-borne illness with a newly emerged pandemic strain. Previous studies compared the pandemic and non-pandemic strains to understand the evolution of the pandemic strain but no definitive explanation for its emergence has been discovered. This study investigated the molecular characteristics of the pandemic strain and growth characteristics at different temperatures. The hypothesis tested was that pandemic strains of V. parahaemolyticus have modifications to their proteome that give a selective advantage over the other V. parahaemolyticus strains at temperatures normally encountered in the environment. Molecular typing techniques; automated ribotyping, pandemic specific PCR and multilocus sequence typing (MLST), were compared to determine the best method for pandemic strain determination. MLST was the best method because it was the most informative and accurate. Furthermore, nine Florida outbreak strains were identified as pandemic. Using representatives of both strains, growth curves were produced at four temperatures. The five pandemic strains had a significantly faster growth rate at 12°C than five non-pandemic strains. Temperature specific proteomic comparisons were completed using liquid chromatography followed by tandem mass spectroscopy. The proteome differences between these two groups at 12°C included three proteins (DnaA, DnaJ-related protein and DnaK-related protein) with functions related to cold stress. DnaA was expressed in the non-pandemic strain and not the pandemic strain, while the reverse was true for DnaJ-related and DnaK-related proteins. Western blot analysis and LC-MS/MS analysis on additional strains did not support the initial LC-MS/MS results. Growth studies using expression recombinants were employed to investigate these proteins on growth at 12°C. The overexpression of DnaA and DnaJ-related proteins did not significantly alter the growth rates compared to the control strain, but the overexpression recombinant strains DnaK-5 has a significantly slower growth rate than the control strain, the opposite direction as expected. The pandemic strain grows faster at lower temperatures, but the reason has not been determined. A theory is offered in which the pandemic growth advantage related to regulation of cold stress, leading to a shorter lag phase and faster growth rate after acclimation to the lower temperatures. Further experiments to investigate this theory are discussed.

Orientador: Edir Nepomuceno da Silva / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-05T01:10:55Z (GMT). No. of bitstreams: 1 Botelho_Lidiane_D.pdf: 2674428 bytes, checksum: 87e73a9d73408a767f62587a3afcade5 (MD5) Previous issue date: 2005 / Resumo: No período de março a maio de 2001, várias culturas lácticas foram isoladas de 11 marcas de produtos contendo microrganismos vivos, comercializados na região de Campinas (SP). A amostragem incluiu 3 iogurtes, 5 leites fermentados, 2 bebidas lácteas e 1 mistura simbiótica em pó. As culturas foram identificadas por características fenotípicas e genotípicas. Foram também submetidas a testes para verificação do cumprimento dos pré-requisitos mínimos exigidos para culturas probióticas, que são resistência ao pH, resistência à bile e a produção de bacteriocinas. Os resultados da identificação por características fenotípicas (36 culturas), feita utilizando-se o Kit de identificação API 50CHL (BioMérieux), mostraram as seguintes espécies: 1o) Lactobacillus paracasei subsp. paracasei ¿ isolado de 6 produtos, 2o) Streptococcus thermophilus ¿ isolado de 4 produtos, 3o) Leuconostoc mesenteroides subsp.cremoris ¿ isolados de 3 produtos, 4o) Lactobacillus rhamnosus, Lactobacillus acidophilus e Lactococcus lactis subsp.lactis ¿ isolados de 2 produtos cada, 5o) Lactobacillus delbrueckii subsp.bulgaricus, Lactobacillus delbrueckii subsp. lactis, Leuconostoc lactis e Lactobacillus curvatus subsp. curvatus ¿ isolados de 1 produto cada. Os resultados da identificação por características genotípicas (41 culturas, 36 de produtos e 5 padrão de coleção de culturas), feita utilizando a técnica de ribotipagem automática Riboprinter (Dupont/Qualicon), mostraram os seguintes resultados: duas culturas não se mostraram tipáveis pelo Riboprinter (Leuconostoc mesenteroides subsp. cremoris pelo API 50CHL). Cinco foram tipadas mas não identificadas pelo Riboprinter (Leuconostoc mesenteroides subsp. cremoris e Lactobacillus acidophilus pelo API 50CHL). Três foram identificadas como Lactobacillus apenas até o nível de gênero (Lactobacillus delbrueckii subsp. lactis e Lactobacillus acidophilus pelo API 50CHL). As demais foram identificadas até o nível de espécie, 63% com o mesmo resultado do API 50CHL e 37% com resultados discordantes. A discordância concentrou-se nas culturas identificadas pelo API 50CHL como Leuconostoc mesenteroides (subsp. cremoris e lactis), Streptococcus thermophilus, Lactobacillus acidophilus e Lactobacillus delbrueckii subsp. bulgaricus. As culturas com resultados concordantes concentraram-se naquelas identificadas pelo API 50CHL como Lactobacillus rhamnosus e Lactobacillus paracasei subsp. paracasei., enquanto os discordantes concentraram-se naquelas identificadas pelo API 50CHL como Leuconostoc, Streptococcus thermophilus, Lactobacillus acidophilus e Lactobacillus delbrueckii subsp. lactis. Uma cepa de Bifidobacterium bifidum (KCTC 3440) foi corretamente identificada pelo Riboprinter e 1 cepa de Bifidobacterium subtile (ATCC 27537) foi erroneamente identificada como Enterococcus faecium. Na avaliação da resistência ao pH, 36 culturas foram avaliadas e a maioria apresentou completa perda da viabilidade após 1 a 3 hora em pH 1,0 (25 culturas ou seja 69,4%) ou 2,0 (16 culturas ou seja 44,4%). Em pH 3,0 a taxa de sobrevivência foi maior. Dois critérios foram utilizados para a conclusão. De acordo com o primeiro, são consideradas como potencialmente probióticas as culturas que apresentam 80% de sobrevivência (menos de 0,1 reduções) após 3 horas de permanência em pH 3 ou 1% de bile. De acordo com esse critério, nenhuma das culturas isoladas pode ser considerada probiótica. De acordo com o segundo critério, a resistência em pH 3 por 90 minutos e na presença de 0,1% de bile (24h), sem redução na contagem de viáveis, indica culturas potencialmente probióticas. De acordo com esse critério, duas culturas se mostraram potencialmente probióticas, uma de Lactobacillus rhamnosus e uma de Lactobacillus acidophilus. Na avaliação da resistência à bile, 29 culturas foram avaliadas e dois critérios utilizados para a conclusão. De acordo com o primeiro, culturas que apresentam taxa de 80% de sobrevivência (redução menor do que 0,1 log) na presença de 1,0% w/v de bile e pH 3,0 por 3 horas são resistentes. Segundo esse critério, nenhuma das 29 culturas isoladas de produtos mostrou resistência à bile. De acordo com o segundo, culturas que apresentem crescimento em presença de 1% de Oxgall, igual ou superior a 20% daquele obtido no controle, é considerada resistente (redução menor do que 0,7 log). Segundo esse critério, 24% ou seja, 7 das 29 culturas isoladas de produtos mostraram-se resistentes: uma cepa de L.acidophilus, uma de L.rhamnosus, uma de L.paracasei subsp. paracasei, uma de Streptococcus thermophilus, uma de Lactococcus lactis subsp. lactis e duas de Leuconostoc mesenteroides subsp cremoris. Na avaliação da produção de bacteriocinas, 32 culturas foram testadas, todas com resultados negativos. Na avaliação do antagonismo contra algumas espécies de bactérias patogênicas Gram negativas e Gram positivas, uma cepa de L.rhamnosus promoveu a inibição de Listeria e outra cepa de L.rhamnosus promoveu a inibição de Listeria e S. aureus. Não se observou inibição das bactérias Gram-negativas (E. coli e Salmonella) / Abstract: In the period between March and May 2001, a series of lactic cultures were isolated from 11 different brand products purchased from regular retail outlets located in Campinas (SP, Brazil). The sample types collected included 3 yogurts, 5 fermented milks, 2 dairy beverages and 1 symbiotic dry mix. The strains were identified by phenotypic and genotypic characteristics, in addition to being submitted to tests to investigate whether they fulfill the minimum prerequisites for microorganisms to be considered probiotic, i.e. resistance to pH, resistance to bile and bacteriocin production. Phenotypic identification (36 strains) using the API 50CHL Identification Kit (BioMérieux) evidenced the presence of the following species: 1o) Lactobacillus paracasei subsp. paracasei - isolated from 6 products, 2o) Streptococcus thermophilus - isolated from 4 products, 3o) Leuconostoc mesenteroides subsp.cremoris - isolated from 3 products, 4o) Lactobacillus rhamnosus, Lactobacillus acidophilus and Lactococcus lactis subsp.lactis - isolated from 2 products each, 5o) Lactobacillus delbrueckii subsp.bulgaricus, Lactobacillus delbrueckii subsp. lactis, Leuconostoc lactis and Lactobacillus curvatus subsp. curvatus - isolated from 1 product each. Identification on the basis of genotypic characteristics (41 strains, 36 of which isolated from products and 5 standard strains from a culture collection) using an automated ribotyping method RiboPrinter® microbial characterization system, (Dupont/Qualicon) produced the following results: two strains could not be typed by the Riboprinter method (identified as Leuconostoc mesenteroides subsp. cremoris by API 50CHL). Five strains were typed but not identified by the Riboprinter system (identified as Leuconostoc mesenteroides subsp. cremoris and Lactobacillus acidophilus by API 50CHL). Three strains were identified as Lactobacillus only to the genus level (identified as Lactobacillus delbrueckii subsp. lactis and Lactobacillus acidophilus by API 50CHL). The remaining strains were identified to the species level, 63% with the same results as those obtained with API 50CHL and 37% with discordant results. Most of the discordant results between the two identification methods were generated by the strains identified by API 50CHL as Leuconostoc mesenteroides (subsp. cremoris and lactis), Streptococcus thermophilus, Lactobacillus acidophilus and Lactobacillus delbrueckii subsp. bulgaricus. The strains with concordant results were predominantly those identified by API 50CHL as Lactobacillus rhamnosus and Lactobacillus paracasei subsp. paracasei, while the strains producing discordant results were mainly those identified by API 50CHL as Leuconostoc, Streptococcus thermophilus, Lactobacillus acidophilus and Lactobacillus delbrueckii subsp. lactis. One strain of Bifidobacterium bifidum (KCTC 3440) was correctly identified by the Riboprinter system, whereas 1 strain of Bifidobacterium subtile (ATCC 27537) was incorrectly identified as Enterococcus faecium. Most of the 36 strains evaluated for resistance to pH showed complete loss of viability after 1 to 3 hours at pH 1,0 or 2,0. At pH 3,0 the survival rate was considerably greater. Two criteria were used for drawing conclusions relative to the probiotic potential of the strains. According to the first criterion, strains exhibiting an 80% survival rate (reduction factor smaller than 0.1 log) after exposure for 3 hours to pH 3 or 1% bile. Based on this criterion, none of the strains isolated could be considered probiotic. According to the second criterion, resistance to pH 3 for 90 minutes and in the presence of 0,1% bile (24h), without reduction in viable counts, indicates potentially probiotic strains. Based on this latter criterion, two strains were found to exhibit probiotic potential, one strain of Lactobacillus rhamnosus and another of Lactobacillus acidophilus. A total of 29 strains were evaluated for bile resistance and the conclusions of the test results produced were based on two different criteria. According to the first, strains presenting an 80% survival rate (reduction factor smaller than 0,1 log) after 3 hours exposure to 1,0% w/v bile and pH 3,0 are considered resistant. Based on this criterion, none of the 29 strains isolated was found to be resistant to bile. According to the second criterion, cultures presenting growth in the presence of 1% Oxgall, equal or greater than 20% of that produced by the control, are considered resistant (reduction factor smaller than 0,7 log). Based on this criterion, 7 (24%) of the 29 strains isolated from products were found to be resistant: one strain of L.acidophilus, one of L.rhamnosus, one of L.paracasei subsp. paracasei, one of Streptococcus thermophilus, one of Lactococcus lactis subsp. lactis and two strains of Leuconostoc mesenteroides subsp cremoris. Thirty-two strains were tested for bacteriocin production, all of which gave negative results. The results of the test performed to evaluate antagonism against some species of Gram-negative and Gram-positive pathogenic bacteria showed that one strain of L.rhamnosus inhibited Listeria, while another strain of L.rhamnosus inhibited both Listeria and S. aureus. No inhibition of Gram-negative bacteria (E. coli e Salmonella) was found / Doutorado / Tecnologia de Alimentos / Doutor em Tecnologia de Alimentos

No description available.

Neste estudo 60 cepas de Aeromonas, 15 A. hydrophila, 15 A. caviae, 15 A. sobria e 15 A. jandaei, isoladas de 5 diferentes pontos do reservatório de Guarapiranga, São Paulo, e previamente testada quanto à produção de fatores de virulência, acúmulo de fluído em alça ligada e hemólise em ágar sangue, foram submetidas a ribotipagem e a análise do perfil plasmidial. Cada cepa apresentou um perfil de ribotipagem diferente tendo-se observado para as espécies A. hydrophila e A. caviae a diferenciação em 3 agrupamentos, e A. sobria e A. jandaei dois agrupamentos cada. A análise do perfil plasmidial demonstrou que 13,4 por cento das A. hydrophila apresentaram um ou no máximo 2 plasmídios, enquanto 33,3 por cento das A. sobria e 53,3 por cento das A. jandaei apresentaram de 1 a 6 plasmídios para cada espécie; A. caviae não apresentou cepas contendo plasmídios. Não foi observada correlação entre a presença de plasmídios e a produção de fatores de virulência pelas cepas estudadas. A ribotipagem demonstrou haver um polimorfismo genômico dentro de uma mesma espécie de Aeromollas e, ainda, diferenciou cepas isoladas de um mesmo ponto de amostragem. Estas metodologias, ribotipagem e análise do perfil plasmidial, apresentam em geral características que são complementares, demonstrando ser ferramentas importantes a serem empregadas, tanto em estudos epidemiológicos como ecológicos. / In this work 60 Aeromonas strains, 15 A. hydrophila, 15 A. caviae, 15 A. sobria and 15 A. jandaei isolated from 5 different points of Guarapiranga Dam, São Paulo, and previously tested for virulence factors production (ileal loop assay and hemolysis on blood agar) were submitted to ribotyping and plasmidial profiles analysis. Each strain showed a different ribopattern and there were observed that for A. hydrophila and A. caviae each specie were grouped in 3 ribotypes, A. sobria and A. jandaei in 2 ribotype each. Plasmidial profiles analysis demonstrated that 13,4 per cent af A. hydrophila had at least one but no more than 2 plasmids, 33,3 per cent of A. sobria and 53,3 per cent af A. jandaei had from one to 6 plasmids each, and A. caviae didn\'t show to have any plasmids. There were not observed correlation between presence of plasmids and virulence factor production. Ribotyping showed that there are genomic polymorphism within the same Aeromonas specie and differentiate strains that were isolated from the same sample point, indicating that those methodologies have in general characteristics that are complementary and are important tools to be used either in epidemiological or ecological studies.

Comparamos os resultados obtidos por meio de sorotipagem com o painel de mAbs acrescido dos mAbs para os sorotipos 7 e 10 , produzidos pelo Instituto Adolfo Lutz com os resultados obtidos pela ribotipagem. O estudo incluiu 95 cepas pertencentes ao sorogrupo B que expressaram o sorotipo 4, representados pelos fenótipos B:4; B;4,1; B:4,7; B:4,10 e B:4,21. A ribotipagem utilizando a endonuclease de restrição C/a\\ dividiu as cepas em dez ribotipos e a endonuclease EcoRV em outros cinco padrões. Quando os padrões de bandas foram combinados, formaram-se 12 ribotipos (Rb A-L). Ribotipos com 85% de similaridade entre as bandas foram combinados em grupos, Rb-1, incluindo os ribotipos C e D (sorotipo B:4,10) e Rb-2, incluindo os ribotipos A, B, E, F e I (sorotipo B:4,7). O Rb-H (sorotipo B:4,1) e Rb-G (sorotipo B:4,21) representaram distintos ribotipos diferindo dos dois primeiros grupos por mais de 25% de diferença entre as bandas. Nossos resultados sugerem que a caracterização de múltiplos epítopos de sorotipo podem melhorar a correlação entre o método fenotípico e genotípico para cepas de meningococo sorogrupo B. / The purpose of this study was to assess the correlation between phenotypic- and genotypic- methods for typing Neisseria meningitidis. We compare the results obtained by serotyping of PorB epitopes using an expanded panel of monoclonal antibodies (MAb) including MAb 7 and MAb 10, with results obtained by RFLP of rRNA genes (ribotyping). The study included a total of 95 serogroup B strains that express epitope 4 representing the phenotypes B:4; B:4,1; B:4,7; B:4, 10, and B:4,21. The ribotypes obtained using C/ai or EcoRV endonucleases divided the strains into ten and five different patterns, respectively. When banding patterns for the two enzymes were combined, twelve unique ribotypes were obtained (Rb A-L). Particular ribotypes with ≥ 85% identical bands were combined into groups, RbGroup1, including Rbs C and D (B:4,10 strains), and RbGroup-2 including Rbs A, B, E, F, and I (B:4,7 strains). The Rb-H (B:4,1 strains) and Rb-G (B:4,21 strains) represent distinct ribotypes differing from the first two groups by more than 25% of band mismatches. The phenotypic characterization of more than one PorB VR epitope on the same PorB protein was able to divide our collection of B:4 strains in groups of strains genetic related. This additional characterization of PorB epitopes improved the correlation between these two methods of typing N.meningitidis.

Neste estudo 60 cepas de Aeromonas, 15 A. hydrophila, 15 A. caviae, 15 A. sobria e 15 A. jandaei, isoladas de 5 diferentes pontos do reservatório de Guarapiranga, São Paulo, e previamente testada quanto à produção de fatores de virulência, acúmulo de fluído em alça ligada e hemólise em ágar sangue, foram submetidas a ribotipagem e a análise do perfil plasmidial. Cada cepa apresentou um perfil de ribotipagem diferente tendo-se observado para as espécies A. hydrophila e A. caviae a diferenciação em 3 agrupamentos, e A. sobria e A. jandaei dois agrupamentos cada. A análise do perfil plasmidial demonstrou que 13,4 por cento das A. hydrophila apresentaram um ou no máximo 2 plasmídios, enquanto 33,3 por cento das A. sobria e 53,3 por cento das A. jandaei apresentaram de 1 a 6 plasmídios para cada espécie; A. caviae não apresentou cepas contendo plasmídios. Não foi observada correlação entre a presença de plasmídios e a produção de fatores de virulência pelas cepas estudadas. A ribotipagem demonstrou haver um polimorfismo genômico dentro de uma mesma espécie de Aeromollas e, ainda, diferenciou cepas isoladas de um mesmo ponto de amostragem. Estas metodologias, ribotipagem e análise do perfil plasmidial, apresentam em geral características que são complementares, demonstrando ser ferramentas importantes a serem empregadas, tanto em estudos epidemiológicos como ecológicos. / In this work 60 Aeromonas strains, 15 A. hydrophila, 15 A. caviae, 15 A. sobria and 15 A. jandaei isolated from 5 different points of Guarapiranga Dam, São Paulo, and previously tested for virulence factors production (ileal loop assay and hemolysis on blood agar) were submitted to ribotyping and plasmidial profiles analysis. Each strain showed a different ribopattern and there were observed that for A. hydrophila and A. caviae each specie were grouped in 3 ribotypes, A. sobria and A. jandaei in 2 ribotype each. Plasmidial profiles analysis demonstrated that 13,4 per cent af A. hydrophila had at least one but no more than 2 plasmids, 33,3 per cent of A. sobria and 53,3 per cent af A. jandaei had from one to 6 plasmids each, and A. caviae didn\'t show to have any plasmids. There were not observed correlation between presence of plasmids and virulence factor production. Ribotyping showed that there are genomic polymorphism within the same Aeromonas specie and differentiate strains that were isolated from the same sample point, indicating that those methodologies have in general characteristics that are complementary and are important tools to be used either in epidemiological or ecological studies.

Bacterial source tracking (BST) methods often involve the use of phenotypic or genotypic fingerprinting techniques to compare indicator bacteria such as Escherichia coli isolated from unknown sources against a library of fingerprints from indicator bacteria found in the feces of various known source animals. The predictive capability of a library is based in part on how well the library isolates reflect the true population diversity of indicator bacteria that can potentially impact a water body. The purpose of this study was to compare the behavior of E. coli population structures in the feces of humans, beef cattle and horses across different parameters. Ribotyping and antibiotic resistance analysis were used to "fingerprint", or subtype E. coli isolates. Significantly greater diversity was observed in the E. coli population of horses compared to the human or beef cattle sampled. Subtype sharing between individuals from all host categories was infrequent, therefore the majority of E. coli subtypes were sampled from a single individual. The dominant E. coli populations of nine individuals (three per host source category) were monitored over time, which demonstrated that E. coli subtypes within a host individual vary on a monthly time frame, and an increase in the frequency of subtype sharing was noted between individuals within the same source group over time. The E. coli population of a single human that had just finished antibiotic treatment was studied on a daily basis for one month. The loss of an E. coli subtype with high antibiotic resistance was observed over time, however there was a single dominant E. coli subtype that was present at every sampling event during the entire month. Geographic distinctiveness of E. coli populations was investigated by sampling four herds located in different geographical regions. We observed that E. coli populations are not geographically distinct, but are somewhat individual-specific, as most E. coli isolates had a subtype that was found in a single individual. This study defines factors that should be considered when constructing a successful BST library, and suggests that E. coli may not be the appropriate indicator organism for BST.

Title from PDF of title page. / Document formatted into pages; contains 117 pages. / Thesis (M.S.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Bacterial source tracking (BST) methods often involve the use of phenotypic or genotypic fingerprinting techniques to compare indicator bacteria such as Escherichia coli isolated from unknown sources against a library of fingerprints from indicator bacteria found in the feces of various known source animals. The predictive capability of a library is based in part on how well the library isolates reflect the true population diversity of indicator bacteria that can potentially impact a water body. The purpose of this study was to compare the behavior of E. coli population structures in the feces of humans, beef cattle and horses across different parameters. Ribotyping and antibiotic resistance analysis were used to "fingerprint", or subtype E. coli isolates. Significantly greater diversity was observed in the E. coli population of horses compared to the human or beef cattle sampled. / ABSTRACT: Subtype sharing between individuals from all host categories was infrequent, therefore the majority of E. coli subtypes were sampled from a single individual. The dominant E. coli populations of nine individuals (three per host source category) were monitored over time, which demonstrated that E. coli subtypes within a host individual vary on a monthly time frame, and an increase in the frequency of subtype sharing was noted between individuals within the same source group over time. The E. coli population of a single human that had just finished antibiotic treatment was studied on a daily basis for one month. The loss of an E. coli subtype with high antibiotic resistance was observed over time, however there was a single dominant E. coli subtype that was present at every sampling event during the entire month. Geographic distinctiveness of E. coli populations was investigated by sampling four herds located in different geographical regions. We observed that E. / ABSTRACT: coli populations are not geographically distinct, but are somewhat individual-specific, as most E. coli isolates had a subtype that was found in a single individual. This study defines factors that should be considered when constructing a successful BST library, and suggests that E. coli may not be the appropriate indicator organism for BST. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.