Midgley J, Desmarchelier P
University of Queensland, St Lucia, Australia.
Lett Appl Microbiol. 2001 May;32(5):307-11. doi: 10.1046/j.1472-765x.2001.00912.x.
The aim of the study was to monitor the shedding and transmission of generic and Shiga toxin-producing Escherichia coli (STEC) in a consignment of cattle during lot feeding.
Faecal and environmental samples were tested for total E. coli and screened with PCR specific for Shiga toxin and O157 rfb. STEC were isolated using colony hybridization and characterized by serology and genotyping. STEC prevalence initially decreased after the diet shift from pasture to grain, although there were intermittent peaks in numbers of cattle shedding STEC and E. coli O157. Water troughs and soil were intermittently contaminated. Common genotypes and serotypes were isolated from animals, water and soil in the feedlot, with additional types introduced at slaughter.
STEC and E. coli O157 are endemic in cattle and intermittent peaks in shedding occur. Prevention of these peaks and/or reduction in transmission is required to reduce the risk of carcass contamination during slaughter.
These findings contribute to the understanding of the ecology of STEC and suggest control points for reducing STEC contamination in feedlot cattle production.
本研究的目的是监测育肥牛群中普通大肠杆菌及产志贺毒素大肠杆菌（STEC）的排泄和传播情况。
对粪便和环境样本进行总大肠杆菌检测，并用志贺毒素和O157 rfb特异性PCR进行筛查。采用菌落杂交法分离STEC，并通过血清学和基因分型进行鉴定。从牧场日粮转换为谷物后，STEC流行率最初有所下降，不过排泄STEC和大肠杆菌O157的牛数量出现了间歇性峰值。水槽和土壤受到间歇性污染。在饲养场的动物、水和土壤中分离出常见的基因型和血清型，屠宰时引入了其他类型。
STEC和大肠杆菌O157在牛群中呈地方性流行，排泄会出现间歇性峰值。需要预防这些峰值和/或减少传播，以降低屠宰过程中胴体污染的风险。
这些发现有助于了解STEC的生态学，并为减少饲养场肉牛生产中STEC污染的控制点提供了建议。
