Rice D H, McMenamin K M, Pritchett L C, Hancock D D, Besser T E
Department of Veterinary Clinical Sciences, Washington State University, Pullman 99164-7060, USA.
Epidemiol Infect. 1999 Jun;122(3):479-84. doi: 10.1017/s0950268899002496.
Escherichia coli O157 (n = 376) from 41 cattle farms were subtyped using pulsed field gel electrophoresis of endonuclease cleaved chromosomal DNA. Cleavage with XbaI resulted in 81 subtypes. Fifty-one isolates from subtypes found in more than one herd, or in herds on multiple sample collection dates were compared using the endonuclease NotI, resulting in 23 additional subtypes. Up to 11 XbaI subtypes were found per farm with up to 7 subtypes/farm identified from a single date. Indistinguishable subtypes (both XbaI and NotI) were found to persist on 4 farms for 6-24 months. Five subtypes were found on more than one farm separated by up to 640 km. Dairy farms where cattle had moved onto the farm had a similar number of subtypes as farms with no movement of cattle, and feedlots had more subtypes than dairy farms. These data indicate that there is a mechanism for multiple herd exposure to specific subtypes, there are multiple sources of exposure for cattle on farms, and on-farm reservoirs other than cattle may exist.
来自41个养牛场的376株大肠杆菌O157，采用对经核酸内切酶切割的染色体DNA进行脉冲场凝胶电泳的方法进行亚型分型。用XbaI酶切产生了81种亚型。对来自不止一个牛群或在多个采样日期的牛群中发现的亚型的51株分离株，使用核酸内切酶NotI进行比较，又产生了23种亚型。每个农场发现多达11种XbaI亚型，在单个日期最多可鉴定出7种亚型/农场。在4个农场发现难以区分的亚型（XbaI和NotI）持续存在6至24个月。在相距达640公里的多个农场发现了5种亚型。有牛迁入的奶牛场的亚型数量与没有牛迁移的农场相似，饲养场的亚型比奶牛场更多。这些数据表明，存在一种使多个牛群接触特定亚型的机制，农场中的牛有多种接触源，并且可能存在除牛以外的农场内储存宿主。
