Goswami Priti S, Gyles Carlton L, Friendship Robert M, Poppe Cornelis, Kozak Gosia K, Boerlin Patrick
Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Vet Microbiol. 2008 Oct 15;131(3-4):400-5. doi: 10.1016/j.vetmic.2008.04.007. Epub 2008 May 23.
A particularly virulent O149:H10 enterotoxigenic Escherichia coli clone harbours a newly characterized plasmid pTENT2 carrying the tetracycline-resistance tetA and the virulence genes estA, paa, and sepA that were not present in less virulent clones. The objectives of this study were to assess whether the additional genes on pTENT2 played a role in the increased severity of post-weaning diarrhoea and if they provided any potential advantage for the emergence of the highly virulent clone. Groups of pigs were dosed orally with isogenic pTENT2-positive and pTENT2-negative ETEC strains, and the clinical and pathological changes were compared between the groups. Two additional groups were given the pTENT2-positive strains and maintained on feed with or without chlortetracycline to assess the effect of subtherapeutic levels of tetracycline on the short-term persistence of the ETEC O149:H10 clone. The severity of diarrhoea within the first few hours post-inoculation was significantly increased (p=0.0408) in animals receiving pTENT2-positive strains as compared to animals receiving pTENT2-negative strains. There were no consistent or significant histopathological differences between any of the groups and no significant difference in the persistence of ETEC between groups.
一种毒性特别强的O149:H10产肠毒素大肠杆菌克隆株携带一种新鉴定的质粒pTENT2，该质粒带有四环素抗性基因tetA以及毒性基因estA、paa和sepA，而这些基因在毒性较弱的克隆株中不存在。本研究的目的是评估pTENT2上的额外基因是否在断奶后腹泻严重程度增加中起作用，以及它们是否为高毒力克隆株的出现提供了任何潜在优势。给猪群口服等基因的pTENT2阳性和pTENT2阴性肠毒素大肠杆菌菌株，并比较两组之间的临床和病理变化。另外两组给予pTENT2阳性菌株，并分别饲喂含或不含金霉素的饲料，以评估亚治疗水平的四环素对肠毒素大肠杆菌O149:H10克隆株短期持续性的影响。与接受pTENT2阴性菌株的动物相比，接受pTENT2阳性菌株的动物在接种后最初几小时内腹泻的严重程度显著增加（p = 0.0408）。各组之间没有一致或显著的组织病理学差异，各组之间肠毒素大肠杆菌的持续性也没有显著差异。
