Van Kessel Jo Ann S, Karns Jeffrey S, Wolfgang David R, Hovingh Ernest
Environmental Microbial and Food Safety Laboratory, Beltsville Agricultual Research Center, U.S. Department of Agriculture-Agricultural Research Service, Beltsville, Maryland 20705, USA.
Foodborne Pathog Dis. 2013 May;10(5):448-52. doi: 10.1089/fpd.2012.1380. Epub 2013 Mar 28.
Salmonella enterica is a zoonotic pathogen that is often associated with dairy farms. The organism can cause disease in cows but is also frequently shed in large numbers by dairy cows that are asymptomatic. Long-term asymptomatic infections with serotypes Cerro and Kentucky were previously identified in cows on a 100-head dairy farm in Pennsylvania, United States (focal dairy). Milk filters were collected from farms within 30 miles of the focal dairy to determine whether the infections by Cerro and Kentucky were limited to the focal dairy or whether the infection might be more regional in nature. Analysis of milk filters showed that Cerro and Kentucky were widespread in the surrounding region with 16 of 39 farms (41%) positive for one or both serotypes. Pulsed-field gel electrophoresis showed that the milk filter Kentucky strains shared >90% similarity with strains from the focal dairy and from local streams. Although there was more variation between Cerro strains (>80% similarity), most milk filter Cerro isolates from most milk filters were highly similar (>90%) to strains isolated from the focal dairy and local streams. In this intensely dairy-farmed region, Salmonella infection of dairy cows appears to be regional in nature, a fact that will impact efforts to control these pathogens.
肠炎沙门氏菌是一种人畜共患病原体，常与奶牛场有关。该病原体可导致奶牛发病，但无症状的奶牛也经常大量排出该病原体。此前在美国宾夕法尼亚州一个拥有100头奶牛的奶牛场（重点奶牛场）的奶牛中发现了Cerro和肯塔基血清型的长期无症状感染。从重点奶牛场30英里范围内的农场收集牛奶过滤器，以确定Cerro和肯塔基血清型的感染是否仅限于重点奶牛场，或者这种感染在本质上是否更具区域性。对牛奶过滤器的分析表明，Cerro和肯塔基血清型在周边地区广泛存在，39个农场中有16个（41%）一种或两种血清型呈阳性。脉冲场凝胶电泳显示，牛奶过滤器中的肯塔基菌株与重点奶牛场和当地溪流中的菌株相似度>90%。尽管Cerro菌株之间的差异更大（相似度>80%），但大多数牛奶过滤器中的Cerro分离株与从重点奶牛场和当地溪流中分离的菌株高度相似（>90%）。在这个奶牛养殖密集的地区，奶牛的沙门氏菌感染在本质上似乎具有区域性，这一事实将影响控制这些病原体的努力。
