Abstract：
Due to its increasing occurrence in cattle farms in various countries, leading to significant economic losses in affected livestock, Salmonella enterica subspecies enterica serovar Dublin (S. Dublin) has become a highly investigated pathogen in cattle production. In Austria, there have been occasional human cases of S. Dublin as well as an increase in laboratory-confirmed cases in cattle, indicating the need for a screening programme to determine the current status in Austria. The aims of this study were, firstly, to determine the seroprevalence of S. Dublin in dairy herds through bulk milk screenings in two federal states (Salzburg, Tyrol) of Austria. Secondly, the study aimed to identify the infection status of the herds through individual animal and herd level detection, comparing microbiological, molecular and serological detection methods. The results of the study will allow the development of a sampling strategy for a surveillance programme in Austria. A total of 6973 dairy farms were tested through serological bulk milk screening. The seroprevalence for the federal state of Tyrol was 14.8 % and for Salzburg it was 18.2 %, resulting in an average seroprevalence of 16.5 %. At an individual animal level, 205 (11.3 %) animals tested positive for shedding of S. Dublin in the faeces through microbiological detection, and 268 (17.0 %) animals had positive values (ct value ≤ 38) by qPCR. The association between microbiological and molecular detection was statistically significant (p < 0.001), with a calculated kappa value of 0.65 ± 0.27 (p ≤ 0.001), assuming a substantial level of agreement. In 17 herds, where an individual animal tested positive for shedding of S. Dublin, environmental sampling and testing were carried out. At a herd level 16 (94.1 %) out of the 17 participating herds, tested positive for S. Dublin either microbiologically or by molecular assay in boot swab samples. Bulk milk samples from 14 out of the 17 participating herds were analysed for antibodies to S. Dublin and 12 samples (85.7 %) were positive. In total 111 (18.9 %) out of 587 blood samples tested positive for S. Dublin antibodies, demonstrating a statistically significant correlation (p < 0.001) both with microbiological (κ = 0.32 ± 0.49; p ≤ 0.001) and molecular (κ=0.23 ± 0.06; p ≤ 0.001) findings. It was possible to identify S. Dublin by culture from boot swabs in 14 (82.4 %) out of 17 herds and by molecular assay using qPCR in 15 (88.2 %) out of 17 herds, indicating a suitable sample type for screening on a herd level-basis for acute infections, but not for identifying chronic infections or asymptomatic carriers. Other environmental samples, such as sponge-sticks, are only suitable to a limited extent for the detection of S. Dublin. The results of this study demonstrate a moderate S. Dublin prevalence in dairy herds in the selected Austrian regions, signalling further screening and management programmes for the future.
摘要：
由于其在各个国家的养牛场中的发生率越来越高，导致受影响牲畜的重大经济损失，肠沙门氏菌亚种肠血清型都柏林（S.都柏林）已成为牛生产中备受关注的病原体。在奥地利,偶尔有都柏林的人类病例，以及牛的实验室确诊病例增加，表明需要一个筛查计划来确定奥地利的现状。这项研究的目的是，首先,通过两个联邦州的散装牛奶筛查来确定都柏林在奶牛群中的血清阳性率(萨尔茨堡，奥地利的蒂罗尔）。其次,该研究旨在通过个体动物和畜群水平检测来确定畜群的感染状况，比较微生物，分子和血清学检测方法。研究结果将有助于制定奥地利监测方案的抽样战略。通过血清学散装牛奶筛选对总共6973个奶牛场进行了测试。蒂罗尔州的血清阳性率为14.8％，萨尔茨堡为18.2％，导致平均血清阳性率为16.5%。在动物个体层面,通过微生物检测，205只（11.3％）动物的粪便中都柏林的脱落呈阳性，qPCR检测有268只(17.0%)动物阳性(ct值≤38)。微生物学和分子检测之间的关联具有统计学意义（p<0.001），计算kappa值为0.65±0.27(p≤0.001)，假设有实质性的协议。在17个牛群中，一只动物的都柏林脱落试验呈阳性，进行了环境采样和测试。在17个参与牧群中，牧群水平为16个(94.1%)，在靴子拭子样本中，无论是微生物学还是分子检测，都柏林都呈阳性。分析了来自17个参与牛群中的14个的大量牛奶样品的针对S.Dublin的抗体，并且12个样品（85.7％）为阳性。在587份血液样本中，有111份（18.9%）的都柏林抗体检测呈阳性，与微生物学（κ=0.32±0.49；p≤0.001）和分子（κ=0.23±0.06；p≤0.001）的发现均具有统计学上的显着相关性（p<0.001）。可以通过从17个牧群中的14个（82.4％）的靴子拭子中进行培养，并通过使用qPCR对17个牧群中的15个（88.2％）进行分子测定来鉴定都柏林。表明适合在群体水平基础上筛查急性感染的样本类型，但不能用于识别慢性感染或无症状携带者。其他环境样本,比如海绵棒，仅在有限的程度上适用于都柏林的检测。这项研究的结果表明，在选定的奥地利地区，牛群中都柏林的患病率适中。发出未来进一步筛选和管理计划的信号。
