Edrington T S, Hume M E, Looper M L, Schultz C L, Fitzgerald A C, Callaway T R, Genovese K J, Bischoff K M, McReynolds J L, Anderson R C, Nisbet D J
Food and Feed Safety Research Unit, Southern Plains Agricultural Research Center, USDA, ARS, College Station, TX 77845, USA.
Lett Appl Microbiol. 2004;38(5):366-72. doi: 10.1111/j.1472-765X.2004.01495.x.
To examine the variability in faecal shedding of Salmonella and Escherichia coli O157:H7 in healthy lactating dairy cattle and to evaluate the genetic relatedness of Salmonella isolates.
Faecal samples were obtained from lactating Holstein dairy cattle on four commercial farms in the southwestern US. All farms were within an 8-km radius and were sampled in August 2001, January 2002 and August 2002 (60 cows per farm per sampling; n = 720 total samples). Samples were cultured for E. coli O157:H7 and Salmonella and a portion of the recovered Salmonella isolates were examined for genetic relatedness using pulsed-field gel electrophoresis (PFGE).
Faecal shedding of E. coli O157:H7 and Salmonella varied considerably between farms and at the different sampling times. Large fluctuations in the percentage of positive animals were observed from summer to summer for both of these pathogens. Similarly, Salmonella serotype and serotype prevalence varied from farm to farm and within farm from one sampling time to another. Multiple Salmonella genotypes were detected for a number of serotypes and identical genotypes were found on different farms with one genotype of Salmonella Senftenberg identified on three of the four farms.
This study demonstrated the wide variability in pathogen shedding within and among dairy farms all located in a small geographical region and highlights the complexity of pathogen control at the farm level.
检测健康泌乳奶牛粪便中沙门氏菌和大肠杆菌O157:H7的排泄变异性，并评估沙门氏菌分离株的遗传相关性。
从美国西南部四个商业农场的泌乳荷斯坦奶牛采集粪便样本。所有农场都在半径8公里范围内，并于2001年8月、2002年1月和2002年8月进行采样（每个农场每次采样60头奶牛；共720个样本）。对样本进行大肠杆菌O157:H7和沙门氏菌培养，并使用脉冲场凝胶电泳（PFGE）对部分回收的沙门氏菌分离株进行遗传相关性检测。
大肠杆菌O157:H7和沙门氏菌的粪便排泄量在不同农场和不同采样时间差异很大。这两种病原体在夏季到夏季之间阳性动物的百分比都有很大波动。同样，沙门氏菌血清型和血清型流行率在不同农场之间以及农场内部不同采样时间之间也有所不同。检测到多种血清型的多个沙门氏菌基因型，并且在不同农场发现了相同的基因型，在四个农场中的三个农场发现了一种森夫滕贝格沙门氏菌基因型。
本研究表明，位于小地理区域内的奶牛场内部和之间病原体排泄存在广泛变异性，并突出了农场层面病原体控制的复杂性。
