Aisla el bacteriófago denominado S6 a partir de una muestra de intestinos de pollo. Se evalúa la estabilidad del bacteriófago sometiéndolo a diferentes temperaturas y pH, también se determina la sensibilidad al cloroformo y las características biológicas como multiplicidad de infección, tasa de adsorción y curva de un paso del bacteriófago aislado. Los resultados indican que el bacteriófago S6 es estable a pH entre 6 - 8 y temperaturas de 80°C hasta 60°C. Además, presenta características líticas solo para serovares de Salmonella como Typhimurium, Bispebjerg, Enteritidis mediante la microscopía electrónica de transmisión se determinó que pertenece al orden Caudovirales y a la familia Siphoviridae. / Tesis

Manifiesta que el cuy es una especie de producción que se ve afectada principalmente por Salmonella Typhimurium, la cual expresa factores de virulencia codificados por diferentes genes, que, en conjunto, cumplen funciones coordinadas para llevar a cabo la patogenia y desarrollar la enfermedad. Por ello, el presente estudio evaluó la presencia de 10 genes codificantes de diversos factores de virulencia de importancia biológica de un total de 100 aislados de Salmonella Typhimurium, compuestos por 90 cepas procedentes de cuyes enfermos y 10 cepas procedentes de cuyes aparentemente sanos, confirmados en estudios previos. El ADN de los aislados fue extraído y analizado mediante la técnica de PCR múltiple, para evaluar la presencia de los genes spvB, spiA, cdtB, sipB, tolC, sitC, lpfC, sifA, sopB y pefA, obteniéndose un patrón genético similar, con frecuencias de detección variables mayores al 60%, tanto en aislados de cuyes sanos como enfermos, excepto el gen cdtB, el cual no fue detectado; concluyéndose que no existe diferencia entre los factores de virulencia presentes en cepas de Salmonella Typhimurium aisladas de cuyes enfermos y cuyes aparentemente sanos; sin embargo, debe tenerse en cuenta el potencial peligro que representan los animales portadores dentro de la producción. / Universidad Nacional Mayor de San Marcos (Lima). Vicerrectorado de Investigación y Posgrado Perú. Ministerio de la Producción. Programa Nacional de Innovación para la Competitividad y Productividad (Innóvate Perú) / Tesis

Orientador: Angelo Berchieri Junior / Coorientador: Hélio José Montassier / Banca: Rosângela Zacarias Machado / Banca: Luiz Felipe Caron / Banca: Raphael Lucio Andreatti Filho / Banca: Marcelo Brocchi / Resumo: Salmonella Enteritidis (SE) causa doença transmitida por alimentos (DTA) em humanos. Carne de frango e ovos frequentemente estão associados a esses casos. O controle da infecção em aves, baseia-se em medidas de biossegurança, incluindo-se a vacinação. Tem sido comum a utilização de vacinas vivas (VV) e inativadas (Bacterinas - BA), porém pouco se sabe sobre os mecanismos imunes desencadeados pelas vacinas contra SE. Neste estudo, utilizaram-se quatroprogramas vacinais (VV; VV+VV; BA; VV+BA) em galinhas leves de variedade branca para postura de ovos de mesa, vacinadas com 5 e/ou 25 dias de vida, e desafiadas aos 45 dias de vida com SE. No dia anterior à infecção (1 DAI) e 1, 6 e 9 dias pós-infecção (DPI), cinco aves/grupo foram sacrificadas para amostragem. A população de linfócitos CD4+ e CD8+ foi avaliada por imuno-histoquímica em tonsilas cecais e fígado; citocinas foram quantificadas por RT-qPCR em tempo real em tonsilas cecais e baço; níveis de IgG e IgM foram mensurados por ELISA no soro e IgA em lavado intestinal. Os níveis de imunoglobulina (IgG, IgM e IgA) estavam significativamente mais altos em aves vacinadas com BA, do 1 DAI ao 9 DPI, em comparação aos grupos vacinados somente com VV. Os níveis de IFN-γ, na tonsila cecal, eram similares em todos os grupos após o desafio. Antes do desafio (1 DAI), IL-10 foi altamente expressa em baço de aves que receberam somente BA (25 dias de vida), sugerindo o desenvolvimento de resposta por linfócitos T CD4+ auxiliar 2 (Ta2), reforçado pelos altos níveis de IgG encontrados neste grupo (p<0.05). Os níveis de TGF-β4 e das citocinas pró-inflamatórias IL-6 e TNFSF15 eram bastante elevados no grupo que recebeu VV+VV. A vacinação por via oral com VV aumentou significativamente o fluxo de linfócitos T CD8+ para as tonsilas cecais após o desafio. Isso poderia... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Salmonella Enteritidis (SE) causes foodborne infection in humans. Poultry meat and eggs are frequently associated with these cases. The control of this bacterium is based on sanitary measures and mainly, vaccination of chicken flocks. Vaccine programs are used worldwide to control SE in poultry flocks. Live (LV) and killed vaccines (KV) are often combined, although few studies regarding immune mechanisms developed by SE vaccines are available. In this work, four vaccine programs were studied (LV; LV+LV; KV; LV+KV) in white layer-hens vaccinated at 5 and/or 25 days-old and challenged at 45 days-old with SE. At 1 day before (dbi) and 1, 6 and 9 days post-infection (DPI), five birds/group were sacrificed for sampling. The population of CD4+ and CD8+ T cells was evaluated by immunohistochemistry in caecal tonsils and liver, cytokines were quantified by real time RT-qPCR in caecal tonsils and spleen; IgG, IgM and IgA levels were measured by ELISA in serum and the latter in intestinal washes. The immunoglobulin levels (IgG, IgM and IgA) were significantly higher in birds vaccinated with KV, from 1 dbi to 9 DPI, than in groups that received only LV. In caecal tonsils, IFN-γ levels were similar in all groups after challenge. Before challenge (1 dbi), IL-10 was highly expressed in spleen of birds that received only KV (25 days-old), suggesting the development of the T CD4+ helper 2 (Th2) type of immune response, reinforced by high IgG levels against SE seen in this group (p<0.05). TGF-β4 and the proinflammatory cytokines IL-6 and TNFSF15 were higher in caecal tonsils in the group that received LV+LV. Vaccination by oral route with LV clearly increased the influx of CD8+ T cells in caecal tonsils after challenge. This could be correlated with the better control of SE noticed in groups that received at least one dose of LV, including... (Complete abstract click electronic access below) / Doutor

A total of 842 single patient isolates of Salmonella spp. from the New Territories East Cluster hospitals, Hong Kong, were collected during 2002 and 2004. The most common Salmonella enterica serotype isolated was S. Enteritidis (29.7%, 250 of 842) followed by S. Typhimurium (13.7%, 115 of 842). The remaining 29.6% (249 of 842) belonged to 44 serotypes and 27.1% (228 of 842) were non-typeable. The majority of isolates were from patients aged two years or younger and were isolated during June to October of each of the three years. The susceptibilities to 19 antimicrobial agents of the 834 isolates that survived were tested. Resistant strains were investigated for [1] the mechanisms of resistance to fluoroquinolones and the third generation cephalosporins; [2] the genetic mechanisms of emergence of antibiotic-resistant salmonellae; and [3] their molecular epidemiology. / Less than half (46.9%, 391 of 834) of the isolates were susceptible to all the antimicrobial agents tested and 21.3% (178 of 834) were resistant to three and up to 14 in a total of 75 resistance patterns. Resistance to nalidixic acid increased from 18.9% (53 of 280) in 2002 to 36.6% (94 of 259) in 2004 (p &lt;0.001) while reduced susceptibility and resistance to ciprofloxacin increased from 17.9% (50 of 280) to 39.4% (102 of 259) (p &lt;0.001). All salmonellae remained susceptible to the third generation cephalosporins until 2003 when we isolated the first resistant isolate and two more in 2004. / No mutations in the quinolone resistance-determining region of target genes gyrA, gyrB, parC and parE were detectable in six of the 59 isolates that were resistant to 0.03 mg/l of ciprofloxacin and 14 that were susceptible to 0.03 mg/l of ciprofloxacin, all isolates being obtained in 2002. Forty-two isolates harboured one mutation, and one to eight harboured two to four mutations with those in positions Ser83 and/or Asp87 of the gyrA gene being the most common (89.8%, 53 of 59). No mutation was detected in the gyrB gene. A parC mutation at Ser80 was present only in strains with one or two gyrA mutation(s) while that at Thr57 could be present in strains without any other target gene mutations. A parE mutation (Ser458&rarr;Pro) was detected together with two gyrA and one parC mutations in only one isolate which was resistant to high concentrations of fluoroquinolones. Complementation experiments using a wild-type gyrA gene performed on isolates with gyrA gene mutations showed that mutations in gyrA contributed to fluoroquinolone-resistance. Only two among the 349 isolates that were obtained during 2002-2004 and resistant to 0.03 mg/l of ciprofloxacin harboured the qnr gene. / Of the three isolates that were resistant to the third generation cephalosporins, one, a S. Typhimurium, produced a beta-lactamase, CTX-M-9, of pI 8.1, and two, a S. Typhimurium and a S. Enteritidis, produced CTX-M-14, of pI 7.9. The blaCTX-M-9 gene was located on a class 1 integron on a 62 kb transferable plasmid and the blaCTX-M-14 gene was associated with the insertion sequence ISEcp1 and present on a 70 kb and a 92 kb transferable plasmid, respectively. This is the first report of a CTX-M-9 enzyme in S. Typhimurium in Hong Kong. (Abstract shortened by UMI.) / The MICs of nalidixic acid in the presence of 20 mg/l of Phe-Arg beta-naphthylamide (PAbetaN) for the 73 isolates that were tested for the presence of target gene mutations and S. Typhimurium ATCC 13311 were at least 4-fold lower than those of nalidixic acid in the absence of PAbetaN, indicating presence of an efflux system that could be inhibited by PAbetaN and of which nalidixic acid was a substrate. / Twenty-one isolates with different target gene mutations and fluoroquinolone susceptibilities were selected to investigate the effect of active efflux system, outer membrane permeability and target gene expression on fluoroquinolone-susceptibility. The amount of ciprofloxacin accumulated in the presence of carbonyl cyanide m-chloro-phenylhydrazone (CCCP) was significantly more than that in the absence of CCCP in 15 of these 21 strains, indicating presence of an efflux system that used proton motive force as energy. The amount of ciprofloxacin accumulated in 15 strains was significantly less than that in the standard strain (ATCC 13311) after the addition of CCCP, indicating that these strains were less permeable to ciprofloxacin than the standard strain. Real-time PCR experiments revealed that there were strains with overexpression of target genes as well as the acrB gene that codes for AcrB in the AcrAB-TolC efflux system. No aac(6')-Ib-cr was detected in our strains. / Jin, Yujuan. / "January 2008." / Adviser: M. L. Ling. / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4543. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 195-219). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

by Koo Ching Irene. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 105-118). / Abstract also in Chinese. / Acknowledgments --- p.i / Abstract --- p.ii / Content --- p.iv / List of tables --- p.viii / List of figures --- p.x / Chapter Chapter 1: --- Introduction --- p.1 / Chapter A. --- Classification of salmonellae --- p.1 / Chapter B. --- Salmonellae enterica ser Enteritidis --- p.4 / Chapter C. --- Global increase in the prevalence of S. Enteritidis --- p.6 / Chapter D. --- Susceptibility of S. Enteritidis to antimicrobial agents --- p.13 / Chapter E. --- Methods for the epidemiological typing of S. Enteritidis --- p.17 / Chapter 1. --- Phenotypic methods --- p.17 / Chapter (1) --- Biotyping --- p.17 / Chapter (2) --- Antibiotic resistance pattern --- p.18 / Chapter (3) --- Phage typing --- p.18 / Chapter (4) --- Characterization of plasmids --- p.19 / Chapter a. --- Resistance plasmids --- p.20 / Chapter b. --- Transferability of plasmids --- p.20 / Chapter c. --- Incompatibility --- p.21 / Chapter 2. --- Molecular methods --- p.21 / Chapter (1) --- Plasmid analysis --- p.21 / Chapter a. --- Plasmid profile --- p.22 / Chapter b. --- Plasmid fingerprinting --- p.22 / Chapter (2) --- Chromosomal DNA fingerprinting --- p.24 / Chapter a. --- Restriction fragment length polymorphism (RFLP) of chromosomal DNA --- p.25 / Chapter b. --- Pulsed-field gel electrophoresis (PFGE) --- p.25 / Chapter c. --- Hybridization with specific gene probes --- p.26 / Chapter d. --- Ribotyping --- p.27 / Chapter e. --- Insertion sequence IS200 fingerprinting --- p.29 / Chapter (3) --- Polymerase chain reaction (PCR) --- p.30 / Chapter 3. --- Other --- p.32 / Chapter (1) --- Lipopoly saccharide (LPS) analysis --- p.32 / Chapter (2) --- "Whole cell protein profile analysis, fatty acid profile analysis, multilocus enzyme electrophoresis and Fourier-transform injfrared spectroscopy" --- p.33 / Chapter F. --- Epidemiology of S. Enteritidis in different parts of the world --- p.34 / Chapter G. --- Objectives --- p.35 / Chapter Chapter 2: --- Materials and Methods --- p.36 / Materials --- p.36 / Methods --- p.38 / Chapter A. --- Identification --- p.38 / Chapter 1. --- Biochemical tests --- p.38 / Chapter 2. --- Serotyping --- p.38 / Chapter B. --- Antimicrobial susceptibility testing --- p.39 / Chapter C. --- Characterization of β-lactamases --- p.39 / Chapter 1. --- Extraction of β-lactamases --- p.39 / Chapter 2. --- Determination of isoelectric points (pIs) --- p.41 / Chapter D. --- Characterization ofplasmids --- p.42 / Chapter 1. --- Genetic studies --- p.42 / Chapter (1) --- Transferability of resistance plasmids --- p.42 / Chapter (2) --- Mobilization of resistances --- p.43 / Chapter 2. --- Molecular studies --- p.44 / Chapter (1) --- Plasmid profile analysis --- p.44 / Chapter a. --- Plasmid extraction --- p.44 / Chapter b. --- Agarose gel electrophoresis --- p.45 / Chapter (2) --- Plasmid DNA fingerprinting --- p.45 / Chapter a. --- Preparation of pure plasmid DNA --- p.46 / Chapter b. --- Preparation of individual plasmid from strains harbouring more than one plasmid --- p.46 / Chapter c. --- Restriction endonuclease digestion of plasmid DNA --- p.47 / Chapter E. --- Total DNA fingerprinting --- p.47 / Chapter 1. --- Total DNA preparation --- p.48 / Chapter 2. --- Restriction endonuclease digestion of total DNA --- p.48 / Chapter 3. --- Ribotyping --- p.49 / Chapter (1) --- Restriction enzyme digestion of total DNA --- p.49 / Chapter (2) --- Transfer of DNA fragments to solid support --- p.49 / Chapter (3) --- Reverse transcription of rRNA into cDNA and labelling of cDNA --- p.50 / Chapter (4) --- Hybridization --- p.50 / Chapter (5) --- Detection of hybridized fragments --- p.51 / Chapter 4. --- AP-PCR (Arbitrary primed-PCR) --- p.51 / Chapter F. --- Experimental design --- p.52 / Chapter Chapter 3: --- Results --- p.54 / Chapter A. --- Prevalence of S. Enteritidis in the Prince of Wales Hospital --- p.54 / Chapter B. --- Antimicrobial susceptibilities --- p.58 / Chapter C. --- β-lactamases produced by β-lactam-resistant S. Enteritidis --- p.66 / Chapter D. --- Plasmid profile analysis --- p.66 / Chapter E. --- Characterization of resistance plasmids --- p.69 / Chapter F. --- Plasmid fingerprinting --- p.72 / Chapter G. --- Total DNA fingerprinting --- p.76 / Chapter H. --- Ribotyping --- p.82 / Chapter I. --- AP-PCR --- p.85 / Chapter J. --- "Correlation of plasmid analysis, total DNA fingerprinting, ribotyping and AP-PCR results" --- p.88 / Chapter Chapter 4: --- Discussion --- p.91 / Chapter A. --- Prevalence of S. Enteritidis --- p.91 / Chapter B. --- Susceptibilities of S. Enteritidis to antimicrobial agents --- p.92 / Chapter C. --- Evaluation of methods for epidemiological typing of S. Enteritidis --- p.94 / Chapter D. --- Molecular epidemiology of S. Enteritidis in Hong Kong --- p.99 / Chapter E. --- Areas for future research --- p.102 / References --- p.105 / Appendix --- p.119

<i>Salmonella enterica serovar Enteritidis</i> is an important biofilm-forming food-borne pathogen. This study examined the adaptive responses of <i>Salmonella serovar Enteritidis</i> biofilms to different environmental conditions such as flow velocity and benzalkonium chloride (BC) treatment. The influence of a 10-fold difference in nutrient laminar flow velocity on the dynamics of biofilm formation and protein expression profiles was compared. The mode of development and architecture of low-flow and high-flow biofilms were distinct. Exopolymer composition of the two biofilms was also different. However, no major shift in protein expression was seen between the biofilms, nor were there any stress response proteins involved. The biofilms altered their architecture in response to flow, presumably assuming a structure that minimized overall biofilm stress. An empirically-determined shear-inducing flow was applied on high-flow biofilms, fractionating the biofilms into shearable and non-shearable regions. Length:width indices of cells from the two biofilm regions, as well as planktonic cells from biofilm effluent and continuous culture were determined to be 3.2, 2.3, 2.2, and 1.7, respectively. Expression of proteins involved in cold-shock response, adaptation, and broad regulatory functions in the shearable region, and expression of protein involved in heat-shock response and chaperonin function in the non-shearable region indicated that the physiological status of cells in two biofilm regions was also distinct. The development of biofilm adaptive resistance to BC was then examined. Adapted biofilms survived a lethal BC challenge and re-grew, whereas unadapted biofilms did not. Proteins up-regulated following adaptation included those involved in energy metabolism, amino acid and protein biosynthesis, nutrient-transportation, adaptation, detoxification, and 1,2-propanediol degradation. A putative universal stress protein was also up-regulated. Cold-shock response, stress response, and detoxification are suggested to play roles in adaptive resistance to BC. Functional differences in adaptive response and survival of plankonic and biofilm cells adapted to BC were also studied. The proportion of BC-adapted biofilm cells that survived a lethal BC exposure and heat-shock was significantly higher than that of BC-adapted planktonic cells. Enhanced biofilm-specific up-regulation of various proteins, coupled with alterations in cell surface roughness and shift in fatty acid composition are proposed to function in the enhanced survival of BC-adapted biofilm cells, relative to BC-adapted planktonic cells.<p>It is concluded that biofilms adapt to the stress conditions by means of community, cellular, and sub-cellular level responses. These adaptive responses help the biofilms to enhance their ability for survival in the nature, especially those formed in critical environments such as healthcare facilities, the food industry, and households.

<i>Salmonella enterica serovar Enteritidis</i> is an important biofilm-forming food-borne pathogen. This study examined the adaptive responses of <i>Salmonella serovar Enteritidis</i> biofilms to different environmental conditions such as flow velocity and benzalkonium chloride (BC) treatment. The influence of a 10-fold difference in nutrient laminar flow velocity on the dynamics of biofilm formation and protein expression profiles was compared. The mode of development and architecture of low-flow and high-flow biofilms were distinct. Exopolymer composition of the two biofilms was also different. However, no major shift in protein expression was seen between the biofilms, nor were there any stress response proteins involved. The biofilms altered their architecture in response to flow, presumably assuming a structure that minimized overall biofilm stress. An empirically-determined shear-inducing flow was applied on high-flow biofilms, fractionating the biofilms into shearable and non-shearable regions. Length:width indices of cells from the two biofilm regions, as well as planktonic cells from biofilm effluent and continuous culture were determined to be 3.2, 2.3, 2.2, and 1.7, respectively. Expression of proteins involved in cold-shock response, adaptation, and broad regulatory functions in the shearable region, and expression of protein involved in heat-shock response and chaperonin function in the non-shearable region indicated that the physiological status of cells in two biofilm regions was also distinct. The development of biofilm adaptive resistance to BC was then examined. Adapted biofilms survived a lethal BC challenge and re-grew, whereas unadapted biofilms did not. Proteins up-regulated following adaptation included those involved in energy metabolism, amino acid and protein biosynthesis, nutrient-transportation, adaptation, detoxification, and 1,2-propanediol degradation. A putative universal stress protein was also up-regulated. Cold-shock response, stress response, and detoxification are suggested to play roles in adaptive resistance to BC. Functional differences in adaptive response and survival of plankonic and biofilm cells adapted to BC were also studied. The proportion of BC-adapted biofilm cells that survived a lethal BC exposure and heat-shock was significantly higher than that of BC-adapted planktonic cells. Enhanced biofilm-specific up-regulation of various proteins, coupled with alterations in cell surface roughness and shift in fatty acid composition are proposed to function in the enhanced survival of BC-adapted biofilm cells, relative to BC-adapted planktonic cells.<p>It is concluded that biofilms adapt to the stress conditions by means of community, cellular, and sub-cellular level responses. These adaptive responses help the biofilms to enhance their ability for survival in the nature, especially those formed in critical environments such as healthcare facilities, the food industry, and households.

Zusammenfassung Untersuchungen zur Beeinflussung von experimentellen Salmonella Enteritidis PT4 Infektionen bei Küken durch den probiotischen Stamm Escherichia coli Nissle 1917 Imad Azmi Awadein Mohamed Institut für Bakteriologie und Mykologie, Veterinärmedizinische Fakultät, Universität Leipzig und Institut für Geflügelkrankheiten, Veterinärmedizinische Fakultät, Freie Universität Berlin Eingereicht im Januar, 2004 Schlüsselworte: (E. coli Stamm Nissle 1917, Küken, S. Enteritidis, Probiotika, Bdellovibrionen) (94 Seiten, 48 Abbildungen, 16 Tabellen und 150 Referenzen) 1- Untersucht wurden die Auswirkungen der oralen Applikation von E. coli Stamm Nissle 1917 und Bdellovibrio bacteriovorus auf die Reduktion der Ansiedlung von S. Enteritidis PT4, auf die Reduktion der Mortalitätsrate, auf die Gesamtzahl aerober und Gram-negativer Bakterien, auf die Anzahl von Bdellovibrionen und auf das Körpergewicht von SPF-Hühnern. Im Vergleich zur positiven Kontrollgruppe konnten bei der Ansiedlung von S. Enteritidis PT4 im Caecum der Testgruppen an den Tagen 14, 21 und 28 signifikante Unterschiede festgestellt werden. Im Vergleich zur positiven Kontrollgruppe, die eine Mortalitätsrate von 10% aufweist, war die Mortalitätsrate der Testgruppen deutlich reduziert. Ebenso waren in den Testgruppen die aerobe und Gram-negative Gesamtkeimzahl am Tag 28 im Vergleich zur positiven Kontrollgruppe deutlich verringert. Signifikanten Anstieg der Bdellovibrionen Anzahl zeigten die Testgruppen sowohl im Vergleich zur positiven als auch negativen Kontrollgruppe. Beim Vergleich zwischen dem Gesamtkörpergewicht der Testgruppen zu dem der negativen und den überlebenden Tieren der positiven Kontrollgruppe gab es keine signifikanten Unterschiede. 2- Untersucht wurden die Auswirkungen der oralen Applikation von E. coli Stamm Nissle 1917 und Bdellovibrio bacteriovorus auf die Reisolation von S. Enteritidis PT4 aus verschiedenen Teilen des Intestinaltrakts und diverser Organe von SPF-Hühnern. In Kropf, Proventrikel, Herzblut, Lunge, Leber und Milz der Testgruppen konnte im Vergleich zur positiven Kontrollgruppe eine Reduktion ermittelt werden, die Reisolation von S. Enteritidis aus dem Caecum der Testgruppen zeigte keinen Unterschied im Vergleich zur positiven Kontrollgruppe. 3- Untersucht wurden die Auswirkungen der oralen Applikation von E. coli Stamm Nissle 1917 und Bdellovibrio bacteriovorus an Konzentrationen von Serum-Avidin, IgY gegen S. Enteritidis und IgY gegen E. coli Nissle 1917 bei experimentell mit S. Enteritidis-infizierten SPF-Hühnern. Die Untersuchungen ergaben eine signifikante Senkung der Serum-Avidin-Konzentration im Vergleich zur positiven Kontrollgruppe, vor allem sieben Tage post infectionem mit S. Enteritidis. Ein signifikanter Anstieg der Konzentration von IgY gegen S. Enteritidis konnte bei den Testgruppen im Vergleich zur positiven Kontrollgruppe vor allem an den Tagen sieben verzeichnet werden. Ein signifikanter Anstieg der Konzentration von IgY gegen E. coli Nissle 1917 konnte in allen Testgruppen im Vergleich zur positiven Kontrollgruppe festgestellt werden. 4- Untersucht wurden die Auswirkungen der oralen Applikation von E. coli Nissle 1917 mit und ohne Plasmid auf die Reduktion der Ansiedelung von S. Enteritidis PT4, auf die Reduktion der Mortalitätsrate, die aerobe und Gram-negative Gesamtkeimzahl, die Bdellovibrionen-Gesamtkeimzahl, Keimzahlen von Lactobacillus, Bifidobacterium und C. perfringens und das Körpergewicht von SPF-Hühnern. Im Vergleich zur positiven Kontrollgruppe konnte im Caecum der Testgruppen ein signifikanter Rückgang der Ansiedelung von S. Enteritidis an den Tagen 7, 21 und 28 verzeichnet werden, außerdem konnte bei den Testgruppen kein Todesfall festgestellt werden, wohingegen die Sterblichkeitsrate der positiven Kontrollgruppe bei 15% lag. Ein signifikantes Absinken in der totalen Gesamtkeimzahl und der Gram-negativen Gesamtkeimzahl konnte für die Testgruppen im Vergleich zur positiven Kontrollgruppe an den Tagen 21 beziehungsweise 28 verzeichnet werden. Die Isolation von Bdellovibrionen aus den Testgruppen ergab keinen Unterschied zu den Kontrollgruppen. Die Lactobacillus-Bifidobacterium-Keimzahl war in den Testgruppen im Vergleich zur positiven Kontrollgruppe signifikant erhöht, vor allem am Tag sieben. Die C. perfringens-Keimzahl war in der positiven Kontrollgruppe gegenüber den Testgruppen am Tag 7 und 14 signifikant erhöht. Die Vergleiche des Körpergewichts der Testgruppen, negativer und überlebender Tiere der positiven Kontrollgruppe zeigten keinen signifikanten Unterschied. 5- Untersucht wurden die Auswirkungen der oralen Applikation von E. coli Stamm Nissle 1917 mit und ohne Plasmid auf die Reisolation von S. Enteritidis aus unterschiedlichen Teilen des Intestinaltraktes und aus Organen von SPF-Hühnern. Im Kropf, Proventrikel, Duodenum, Herzblut, Lunge, Leber und Milz konnte bei den Testgruppen im Vergleich zur positiven Kontrollgruppe eine Senkung der Reisolationsrate festgestellt werden, wohingegen sich keine Unterschied beim Vergleich der Caeca von positiver Kontrollgruppe und von den Testgruppen zeigte. 6- Untersucht wurden die Auswirkungen der oralen Applikation von E. coli Stamm Nissle 1917 mit und ohne Plasmid auf die Konzentrationen von Serum-Avidin, IgY gegen S. Enteritidis und IgY gegen E. coli Nissle 1917 bei experimentell mit S. Enteritidis-infizierten SPF-Hühnern. Bei der Serum-Avidin-Konzentration konnte kein Unterschied zwischen Testgruppen und positiver Kontrollgruppe festgestellt werden. Die Testgruppen zeigten ihrerseits im Vergleich zur positiven Kontrollgruppe eine signifikante Erhöhung der Konzentration von IgY gegen S. Enteritidis, vor allem an den Tagen 21 und 28. Ein signifikanter Anstieg der Konzentration von IgY gegen E. coli Nissle 1917 konnte in allen Testgruppen im Vergleich zur positiven Kontrollgruppe, vor allem an den Tagen sieben und vierzehn festgestellt werden. 7- Aus den Resultaten des ersten und des zweiten Versuchs schließen wir, dass der probiotische Stamm E. coli Nissle 1917 das Caecum von 7 bis 28 Tage alten Hühnern erfolgreich kolonialisieren kann. Orale Applikation des Stammes kann die Ansiedlung von S. Enteritidis, aerobe und Gram-negative Gesamtkeimzahl, Mortalitätsrate, Reisolationsrate von S. Enteritidis in Organen und im Intestinaltrakt (mit Ausnahme des Caecums im ersten Versuch) deutlich reduzieren. Die Kombination von E. coli Nissle 1917 und Bdellovibrio bacteriovorus hatte nicht den gewünschten Effekt, der auch von mehreren Autoren in-vitro beobachtet wurde. Bdellovibrionen waren in den Testgruppen des ersten Versuchs im Vergleich zu denen im zweiten deutlich erhöht. Beim durchschnittlichen Körpergewicht konnte kein signifikanter Unterschied zwischen beiden Versuchen festgestellt werden. Der Serum-Avidin-Spiegel war im ersten Versuch in der Testgruppe deutlich reduziert, im zweiten dagegen nicht. Dies ist möglicherweise auf den Effekt von Bdellovibrionen zurückzuführen, bedarf allerdings noch der weiteren Bestätigung. Im Allgemeinen konnten wir eine signifikante Verbesserung des Immunsystems der Vögel als Resultat der oralen Applikation von E. coli Nissle 1917 feststellen. 8- Untersucht wurden die antagonistischen Effekte von E. coli Stamm Nissle 1917 mit und ohne Plasmid auf die in-vitro-Wachstumsrate von S. Enteritidis PT4. Wir konnten feststellen, dass E. coli Nissle 1917 sowohl mit als auch ohne Plasmid die Wachstumsrate von S. Enteritidis erfolgreich reduzieren konnte. / Summary Influence of the probiotic strain Escherichia coli Nissle 1917 on experimental infections with Salmonella Enteritidis PT4 in chickens Imad Azmi Awadein Mohamed Institute of Bacteriology and Mycology, Faculty of Veterinary Medicine, University of Leipzig and Institute of Poultry Diseases, Faculty of Veterinary Medicine, Free University Berlin Submitted in January, 2004 Keywords: (E. coli strain Nissle 1917, chickens, S. Enteritidis, Probiotics, Bdellovibrios) (94 pages, 48 figures, 16 tables and 150 references) 1- The effect of oral application of E. coli strain Nissle 1917 with Bdellovibrio bacteriovorus on the colonization of S. Enteritidis PT4, reduction of the mortality rate, total aerobic bacterial counts, Gram negative bacterial counts, bdellovibrio bacterial counts and body weight of Specific Pathogen Free chickens were investigated. A significant reduction in the colonization of S. Enteritidis PT4 in the caecum of trial groups at 14, 21 and 28 days old in comparison to the positive control group was observed. A reduction in mortality rate in the trial groups was seen in comparison to the positive control group which had 10 %. The total aerobic and Gram negative bacterial counts were significantly decreased in the trial groups at 28 days old in comparison to the positive control group. Bdellovibrio bacterial counts were significantly increased in the trial groups in comparison to the control groups. No significant difference was seen in the mean body weight of the trial groups in comparison to control groups. 2- The effect of oral application of E. coli strain Nissle 1917 with Bdellovibrio bacteriovorus on reisolation rate of S. Enteritidis from different parts of the intestinal tract and organs of SPF chickens was investigated. A reduction in the S. Enteritidis reisolation rate was seen from crop, proventriculus, duodenum, heart blood, lungs, livers and spleens of the trial groups in comparison to the positive control group but not from the caecum. 3- The effect of oral application of E. coli strain Nissle 1917 and Bdellovibrio bacteriovorus on the serum avidin levels, IgY against S. Enteritidis and IgY against E. coli strain Nissle 1917 levels of SPF chickens experimentally infected with S. Enteritidis was investigated. A significant reduction in the serum avidin levels was observed in the trial groups at 7 days old in comparison to the positive control group. The antibody levels against S. Enteritidis was significantly increased in the trial group at 7 days old in comparison to the positive control group. A significant increase at day 7 in the antibody levels against E. coli strain Nissle 1917 was seen in the trial group in comparison to the positive control group. 4- The effect of oral application E. coli Nissle 1917 with and without plasmid on reduction on the colonization of S. Enteritidis PT4, reduction of the mortality rate, total aerobic bacterial counts, Gram negative bacterial counts, bdellovibrio bacterial counts, Lactobacillus-Bifidobacterium counts, C. perfringens bacterial counts and body weight of SPF chickens were investigated. A significant reduction in the colonization of S. Enteritidis PT4 in the caecum of trial groups at 7, 21 and 28 days old in comparison to the positive control group was observed. No mortalities were seen in the both trial groups in comparison to the positive control group which had 15 % mortalities. The total aerobic and Gram negative bacterial counts were significantly decreased in the trial groups at 21 and 28 days respectively old in comparison to the positive control group. No significant difference was observed in bdellovibrio isolation from the trial groups in comparison to the control group. Lactobacillus-Bifidobacterium bacterial counts were significantly increased in the trial groups at 7, 14 and 21 days old in comparison to the positive control group. A significant reduction in C. perfringens bacterial counts were seen in the trial groups at 7 and 14 days old in comparison to positive control group. No significant difference was observed in the mean body weight of the trial groups in comparison to control groups. 5- The effect of oral application E. coli Nissle 1917 with and without plasmid on the reisolation of S. Enteritidis from different parts of intestinal tract and organs of SPF chickens was investigated. A reduction in the S. Enteritidis reisolation rate was seen from crop, proventriculus, duodenum, caecum, heart blood, lungs, livers and spleens of the trial groups in comparison to the positive control group. 6- The effect of oral application E. coli Nissle 1917 with and without plasmid on the serum avidin levels, IgY against S. Enteritidis and IgY against E. coli strain Nissle 1917 levels of SPF chickens experimentally infected with S. Enteritidis were investigated. No significant reduction in the serum avidin levels were seen in the trial groups in comparison to the positive control group. The antibody levels against S. Enteritidis were significantly increased in the trial groups at 21 and 28 days old in comparison to the positive control group. A significant increase in the antibody levels against E. coli strain Nissle 1917 were seen in the trial groups in comparison to the positive control group. 7- From the results observed in the first and second experiments we concluded that probiotic strain E. coli Nissle 1917 can successfully colonize the caecum of SPF chickens from 7 to 28 days old. Oral appliction of probiotic strain E. coli Nissle 1917 has significantly reduced the S. Enteritidis colonization, total and Gram negative bacterial counts, mortality rate, reisolation rate of S. Enteritidis in organs and the intestinal tract except the caecum in first experiment in the trial groups in comparison to positive control. The combination between E. coli strain Nissle 1917 and B. bacteriovorus had not achieved the desirable effects in the first experiment which observed by many authors in vitro. Bdellovibrio was significantly increased in the trial groups of the first experiment in comparison to the second experiment. This may be a possible effect of Bdellovibrio which is yet to be confirmed. No significant difference was observed in the mean body weight in both experiment. A significant reduction of serum avidin levels were observed in the trial groups of the first experiment but not in the second experiment. We have observed a significant improvement in the immune system of the birds as a results of oral application of E. coli strain Nissle 1917. 8- Antagonistic effect of E. coli Nissle 1917 with and without plasmid on the growth rate of the S. Enteritidis PT4 in vitro was investigated. We concluded that E. coli Nissle 1917 with and without plasmid successfully reduced the growth rate of S. Enteritidis in comparison to the control one.

Salmonella enteritidis has recently emerged as a potential pathogen in poultry products. The growth of S. enteritidis in poultry is affected by several factors such as storage temperature, pH, water activity, modified atmosphere and the presence of preservatives. All of these factors may act alone or in combination with each other resulting in a synergistic, antimicrobial effect. / In this research, initial storage studies were done to determine the effect of various atmospheres (air, vacuum, oxygen absorbent and gas packaging) on the microbial changes of packaged chicken thighs followed by challenge studies with a strain of S. enteritidis$ sp{ rm{NAST}}$. Chicken thighs were packaged in Cryovac bags and stored at 4 and 12$ sp circ$C for up to 28d. Changes in headspace gas composition, pH, drip loss, color and odor were monitored at each sampling day. / The effect of various packaging treatments, dipping solutions (chitosan (0.2%w/v) and potassium sorbate (0.2%w/v)) and low dose irradiation (1.5 & 3.0 kGy) on the growth of S. enteritidis$ sp{ rm NAST}$ and on the shelf-life of chicken thighs stored at 4 and 12$ sp circ$C was also investigated. (Abstract shortened by UMI.)

Les salmonelles, responsables de fièvres typhoïdes et gastro-entérites, sont un problème majeur de santé publique. Les systèmes de sécrétion de type III (TTSS) sont des facteurs de virulence cruciaux de Salmonella. Nos travaux ont montré que délétion du cadre ouvert de lecture yfgL conduit à une faible transcription des gènes codant les 3 TTSS conduisant à une baisse importante de la virulence de Salmonella Enteritidis. Or, la délétion de ce gène, dont la protéine chez E.coli est en complexe avec les protéines YaeT, YfiO, NlpB et SmpA, conduit à une altération de la membrane externe. Chez S. Enteritidis, nous avons montré que le rôle du complexe « YaeT » dans l’assemblage des protéines de membrane externe est conservé. Or, seule l’inactivation d’yfiO, conduit une diminution de l’expression des TTSS. Nos travaux ont toutefois suggéré que le défaut d’assemblage des protéines de membrane externe n’est pas la cause de ce défaut d’expression des TTSS observés chez les mutants yfgL et yfiO. / Salmonella, responsible for typhoid fever and gastroenteritis, is a worldwide health problem. Type three secretion system (TTSS) are crucial virulence factors in Salmonella. Our work showed that deletion of the open reading frame yfgL led to a transcriptional down-regulation of the genes encoding the proteins involved in the biosynthesis of the 3 TTSS in Salmonella Enteritidis. It was shown that inactivation of yfgL whose encoded protein is in complex with YaeT, YfiO, NlpB and SmpA in E. coli, causes an outer membrane alteration. In S. Enteritidis, we observed that the role of the “YaeT” complex in outer membrane protein assembly is conserved in S. Enteritidis. In addition, only yfiO inactivation resulted in a down-expression of the TTSS. However, we presented elements suggesting that the outer membrane protein targeting defect was not responsible for the TTSS down-expression observed in the yfgL and yfiO mutants.