反刍动物是众所周知的单核细胞增生李斯特菌的储库。除了病原体的无症状携带,反刍动物也可以获得李斯特菌病并以神经系统或胎儿感染的形式发展临床表现,类似于人类中发生的事情。欧洲反刍动物李斯特菌病病例的基因组特征已经确定了与感染相关的谱系1和2菌株,以及通常从人类李斯特菌病病例中分离出的克隆复合物(CC);然而,在美国,关于反刍动物李斯特菌病中单核细胞增生李斯特菌多样性的信息很少。在这项研究中,我们鉴定并比较了从2015年至2020年收集的来自中西部和上平原的反刍动物李斯特菌病病例中的73株单核细胞增生李斯特菌。利用全基因组序列数据,我们对分离株进行了分类,并确定了关键的毒力因子,应激相关基因,和我们数据集中的可移动遗传元素。我们的分离株属于三个不同的谱系:谱系1占31%,谱系2占53%,谱系3占15%。谱系1和3分离株与神经系统感染有关,而谱系2显示胎儿感染的频率更高。此外,移动元素的存在,毒力相关基因,并对应激和抗菌素抗性基因进行了评估。这些遗传元件负责大多数亚组特异性特征,并且可能在高毒力克隆的传播中起关键作用,包括通常与人类疾病相关的高毒力CC1克隆的传播,并可以解释该地区某些克隆的频率增加。重要性单核细胞增生李斯特菌影响人类和动物,引起脑炎,败血症,堕胎,在其他临床结果中。像牛这样的反刍动物,山羊,和绵羊是在农场环境中维持和传播这种病原体的主要载体。来自农场的食物产品的污染是令人担忧的,不仅因为发现存在的许多单核细胞增生李斯特菌基因型与人李斯特菌病有关,而且作为当牲畜和食物产品受到影响时的重大经济损失的原因。反刍动物李斯特菌病在欧洲得到了广泛的表征;然而,在美国,关于这些病例的遗传多样性的信息有限。鉴定具有更大传播能力的亚组可能有助于李斯特菌病的监测和管理,并有助于更好地了解该病原体的基因组多样性。提供对该地区反刍动物李斯特菌病分子流行病学的见解。
Ruminants are a well-known reservoir for Listeria monocytogenes. In addition to asymptomatic carriage of the pathogen, ruminants can also acquire listeriosis and develop clinical manifestations in the form of neurologic or fetal infections, similar to those occurring in humans. Genomic characterization of ruminant listeriosis cases in Europe have identified lineage 1 and 2 strains associated with infection, as well as clonal complexes (CCs) that are commonly isolated from human cases of listeriosis; however, there is little information on the diversity of L. monocytogenes from ruminant listeriosis in the United States. In this study, we characterized and compared 73 L. monocytogenes isolates from ruminant listeriosis cases from the Midwest and the Upper Great Plains collected from 2015 to 2020. Using whole-genome sequence data, we classified the isolates and identified key virulence factors, stress-associated genes, and mobile genetic elements within our data set. Our isolates belonged to three different lineages: 31% to lineage 1, 53% to lineage 2, and 15% to lineage 3. Lineage 1 and 3 isolates were associated with neurologic infections, while lineage 2 showed a greater frequency of fetal infections. Additionally, the presence of mobile elements, virulence-associated genes, and stress and antimicrobial resistance genes was evaluated. These genetic elements are responsible for most of the subgroup-specific features and may play a key role in the spread of hypervirulent clones, including the spread of hypervirulent CC1 clone commonly associated with disease in humans, and may explain the increased frequency of certain clones in the area. IMPORTANCE Listeria monocytogenes affects humans and animals, causing encephalitis, septicemia, and abortions, among other clinical outcomes. Ruminants such as cattle, goats, and sheep are the main carriers contributing to the maintenance and dispersal of this pathogen in the farm environment. Contamination of food products from farms is of concern not only because many L. monocytogenes genotypes found there are associated with human listeriosis but also as a cause of significant economic losses when livestock and food products are affected. Ruminant listeriosis has been characterized extensively in Europe; however, there is limited information about the genetic diversity of these cases in the United States. Identification of subgroups with a greater ability to spread may facilitate surveillance and management of listeriosis and contribute to a better understanding of the genome diversity of this pathogen, providing insights into the molecular epidemiology of ruminant listeriosis in the region.