Escherichia coli O157:H7 infection of calves:: infectious dose and direct contact transmission
Escherichia coli O157:H7 infection of calves:: infectious dose and direct contact transmission
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DOI：
10.1017/s095026880100615x
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发表时间：
2001-12-01
影响因子：
4.2
通讯作者：
Hancock, DD
中科院分区：
文献类型：
--
作者：
Besser, TE;Richards, BL;Hancock, DD
牛被认为是大肠杆菌O 157：H7的储存宿主，而受污染的牛源性食物是人类感染的重要媒介。本研究测定了犊牛对实验性大肠杆菌的易感性。大肠杆菌O 157：H7感染。17头小牛中有2头接触极低浓度（< 300 c.f.u.）暴露于低剂量（< 10000 c.f.u.）剂量，随后在其粪便中排泄攻毒株。所有小牛（n = 12）共享隔离室与小牛排泄的挑战菌株在他们的粪便中同样开始粪便排泄相同的菌株在21天或更短的时间内。之间的挑战菌株和小牛粪便排泄的菌株的身份进行了确认，限制性消化电泳模式，使用脉冲场凝胶电泳。犊牛舍E.大肠杆菌O 157：H7在其粪便中非常低的剂量暴露后，浓度范围为< 30 to >10（7）c.f.u./ g，持续时间与先前报告的较大剂量攻毒小牛的值相似。小牛在极低的接触或直接接触受感染小牛后对感染的敏感性对该病原体的收获前控制方案具有重要意义。
Cattle are considered to be a reservoir host of Escherichia coli O157:H7 and contaminated foods of bovine origin are important vehicles of human infection. In this study, the susceptibility of calves to experimental E. coli O157:H7 infection following low oral exposures was determined. Two of 17 calves exposed to very low (< 300 c.f.u.) doses, and 3 of 4 calves exposed to low (< 10000 c.f.u.) doses, subsequently excreted the challenge strains in their faeces. All calves (n = 12) sharing isolation rooms with calves that excreted the challenge strain in their faeces similarly began faecal excretion of the same strains within 21 days or less. The identity between the challenge strains and the strains excreted in calf faeces was confirmed by restriction digestion electrophoretic patterns using pulsed field gel electrophoresis. Calves shed E. coli O157:H7 in their faeces after very low dose exposures at concentrations ranging from < 30 to > 10(7) c.f.u./g, and for durations similar to the values previously reported for calves challenged by larger doses. The susceptibility of calves to infection following very low exposures or direct contact with infected calves has important implications for programmes for pre-harvest control of this agent.