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首页> 外文学位 >An evaluation of diarrheagenic Escherichia colisurvival after ingestion by Tetrahymena sp. and Helicobacter pylori's fate after ingestion by Tetrahymena sp. and Acanthamoeba polyphaga.
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An evaluation of diarrheagenic Escherichia colisurvival after ingestion by Tetrahymena sp. and Helicobacter pylori's fate after ingestion by Tetrahymena sp. and Acanthamoeba polyphaga.

机译：评估四膜虫（Tetrahymena sp。）摄入后的腹泻性大肠埃希菌存活率。和四膜虫（Tetrahymena sp。）摄入后的幽门螺杆菌（Helicobacter pylori）命运。和棘阿米巴polyphaga。

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摘要

Diarrheagenic pathotypes of Escherichia coli are responsible for a substantial number of childhood deaths each year, and Helicobacter pylori causes gastric diseases in both children and adults worldwide. Free-living protozoa have been implicated in the survival and transport of pathogens in the environment, but the relationship between non-Shiga toxin-producing E. coli or H. pylori and free-living ciliated protozoa has not been characterized. Likewise, there is a paucity of research regarding the ability of these pathogenic bacteria to survive phagocytosis by amoebae.;A literature review revealed two articles demonstrating survival of E. coli O157:H7 or an environmental isolate of E. coli in Acanthamoeba and one article reporting survival of H. pylori in Acanthamoeba. There have been several reports of E. coli O157:H7 or genetically modified laboratory strains surviving digestion by the ciliate, Tetrahymena, and no investigations on the resistance of H. pylori to digestion by this protozoan.;Therefore, for the present study, six diarrheagenic serotypes of E. coli and an isolate of H. pylori were evaluated for their susceptibility to digestion by Tetrahymena. Escherichia coli and H. pylori were fed separately to Tetrahymena strain MB125, and the ciliate's egested products were examined for viable pathogens. Viability was assessed by the BacLight(TM) LIVE/DEAD(TM) assay, by a cell elongation method, and by colony counts. Three H. pylori strains were used: one expressing the green fluorescent protein, an ATCC strain originating from a clinical isolate, and a fresh clinical isolate of H. pylori, and each was fed separately to Acanthamoeba polyphaga. Viability of H. pylori in Acanthamoeba was assessed with: the BacLight(TM) LIVE/DEAD(TM) assay, fluorescent in situ hybridization, and quantification of amplified gene products unique to H. pylori over time, determined by a real time polymerase chain reaction test.;All six pathogenic E. coli serotypes survived digestion by Tetrahymena and emerged as viable cells in fecal pellets, whereas H. pylori was digested. Growth of E. coli on agar plates indicated that the bacteria were able to replicate after passage through the ciliate. Transmission electron micrographs of E. coli cells as intact rods versus degraded H. pylori cells corroborated these results. Scanning electron microscopy revealed a net-like matrix around intact E. coli cells in fecal pellets. Helicobacter pylori did not survive phagocytosis by Acanthamoeba..;These results suggest a possible role for Tetrahymena and its egested fecal pellets in the survival and dissemination of diarrheagenic E. coli in the environment. This bacterial-protozoan association may increase opportunities for transmission of these bacterial pathogens to mammalian hosts including humans.
机译：大肠埃希氏菌的致病性致病原因每年导致大量儿童死亡，幽门螺杆菌在全世界的儿童和成人中均引起胃部疾病。自由生活的原生动物与环境中病原体的存活和运输有关，但是尚未鉴定非志贺毒素生产大肠杆菌或幽门螺杆菌与自由生活的纤毛原生动物之间的关系。同样，关于这些致病细菌在变形虫吞噬作用下生存能力的研究还很少。一篇文献综述揭示了两篇证明大肠杆菌O157：H7或大肠杆菌在大肠杆菌中在棘阿米巴中生存的文章，其中一篇报告幽门螺杆菌在棘阿米巴中的存活。有几篇关于大肠杆菌O157：H7或转基因实验室菌株在纤毛虫，四膜虫的消化中存活的报道，并且没有关于幽门螺杆菌对这种原生动物消化的抵抗力的研究；因此，在本研究中，有六种评估了大肠杆菌的腹泻致病血清型和幽门螺杆菌的分离物对四膜虫消化的敏感性。将大肠杆菌和幽门螺杆菌分别喂食四膜虫MB125菌株，并检查纤毛虫的巢状产品中是否存在活菌。通过BacLight TM LIVE / DEAD TM测定法，细胞伸长方法和菌落计数评估生存力。使用了三种幽门螺杆菌菌株：一种表达绿色荧光蛋白，一种源于临床分离株的ATCC菌株，和新鲜的幽门螺杆菌临床分离株，每一种都分别喂入多头棘阿米巴。通过以下方法评估幽门螺杆菌在棘阿米巴中的生存力：BacLight™LIVE / DEAD™测定，荧光原位杂交以及随时间推移幽门螺杆菌特有的扩增基因产物的定量，通过实时聚合酶链测定反应测试。;所有六种致病性大肠杆菌血清型均经四膜虫消化后存活，并在粪便颗粒中以活细胞形式出现，而幽门螺杆菌被消化。大肠杆菌在琼脂平板上的生长表明，细菌在通过纤毛体后能够复制。完整棒状大肠杆菌细胞与降解的幽门螺杆菌细胞的透射电子显微照片证实了这些结果。扫描电子显微镜显示粪便颗粒中完整的大肠杆菌细胞周围有网状基质。幽门螺杆菌不能通过棘阿米巴的吞噬作用幸免于难；这些结果表明四膜虫及其粪便在环境中的腹泻性大肠杆菌的生存和传播中可能发挥作用。这种细菌-原生动物的联系可能会增加这些细菌病原体向包括人在内的哺乳动物宿主传播的机会。

著录项

  • 作者

    Smith, Charlotte Dery.;

  • 作者单位

    University of California, Berkeley.;

  • 授予单位 University of California, Berkeley.;
  • 学科 Microbiology.;Public health.;Environmental science.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 65 p.
  • 总页数 65
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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