Salmonella enterica serovar Dublin is a cattle-adapted S. enterica serovar causing both intestinal and systemic infection in its bovine host, and it is also a serious threat to human health. The present study aimed to determine the population structure of S. Dublin isolates obtained from Danish cattle herds and to investigate how cattle isolates relate to Danish human isolates, as well as to non-Danish human and bovine isolates. Phylogenetic analysis of 197 Danish cattle isolates from 1996 to 2016 identified three major clades corresponding to distinct geographical regions of cattle herds. Persistence of closely related isolates within the same herd and their circulation between epidemiologically linked herds for a period of more than 20 years were demonstrated. These findings suggest that a lack of internal biosecurity and, to some extent, also a lack of external biosecurity in the herds have played an important role in the long-term persistence of S. Dublin in Danish cattle herds in the period investigated. Global population analysis revealed that Danish cattle isolates clustered separately from bovine isolates from other countries, whereas human isolates were geographically spread. Resistance genes were not commonly demonstrated in Danish bovine isolates; only the isolates within one Danish clade were found to often harbor two plasmids of IncFII/IncFIB and IncN types, the latter plasmid carrying bla_TEM-1, tetA, strA, and strB antibiotic resistance genes.

IMPORTANCE S. Dublin causes economic losses in cattle production, and the bacterium is a public health concern. A surveillance and control program has been in place in Denmark since 2002 with the ultimate goal to eradicate S. Dublin from Danish cattle herds; however, a small proportion of herds have remained positive for many years. In this study, we demonstrate that herds with persistent infection often were infected with the same strain for many years, indicating that internal biosecurity has to be improved to curb the infection. Further, domestic cases of S. Dublin infection in humans were found to be caused both by Danish cattle isolates and by isolates acquired abroad. This study shows the strength of whole-genome sequencing to obtain detailed information on epidemiology of S. Dublin and allows us to suggest internal biosecurity as a main way to control this bacterium in Danish cattle herds.

肠炎沙门氏菌都柏林是一种适应牛的肠炎沙门氏菌，在其牛寄主中引起肠道和全身感染，对人类健康也构成了严重威胁。针对本研究确定的人口结构小号。从丹麦牛群获得的都柏林分离株，并研究牛分离株与丹麦人类分离株以及非丹麦人类和牛分离株之间的关系。从1996年到2016年对197例丹麦牛分离株进行系统进化分析，确定了三个主要进化枝，分别对应于不同的牛群地理区域。证明了同一群内密切相关的分离株的持续存在及其在流行病学相关的群之间的传播超过20年。这些结果表明，一个缺乏内部生物安全的，并在一定程度上，也缺乏在牛群外部生物安全已经在长期的持续性发挥了重要作用小号。在都柏林对丹麦牛群的调查期间。全球人口分析显示，丹麦的牛分离株与其他国家的牛分离株分开聚集，而人类分离株在地理上分布。丹麦牛分离株中未普遍显示出抗性基因。仅发现一个丹麦进化枝中的分离物经常带有两个IncFII / IncFIB和IncN型质粒，后一个质粒带有bla _TEM-1，tetA，strA和strB抗生素抗性基因。

重要性 š。都柏林给牛只生产造成经济损失，这种细菌是公共卫生问题。一种监视和控制方案已经到位，丹麦自2002年以来，其最终目标，以消除小号。来自丹麦牛群的都柏林；然而，多年来，一小部分牛群仍然保持积极状态。在这项研究中，我们证明了持续感染的畜群经常被同一株感染多年，这表明必须改善内部生物安全性以遏制感染。此外，国内的S病例。发现人类的都柏林感染是由丹麦牛分离株和在国外获得的分离株引起的。这项研究显示了全基因组测序的优势，可以获取有关S流行病学的详细信息。都柏林，并允许我们提出内部生物安全性作为控制丹麦牛群中这种细菌的主要方法。