Although Streptococcus suis has attracted public attention as a major swine and human pathogen, this bacterium has also been isolated from other animals, including ruminants. However, recent taxonomic studies revealed the existence of other species that were previously identified as S. suis, and some of these isolates were reclassified as the novel species Streptococcus ruminantium. In Japan, biochemically identified S. suis is frequently isolated from diseased ruminants; however, such isolates have not yet been identified accurately, and their aetiological importance in ruminants is unclear. Therefore, to understand the importance of S. suis and S. suis-like bacteria in ruminants, we reclassified S. suis isolates from ruminants according to the updated classification and investigated their genetic diversity. Although both S. suis and S. ruminantium were isolated from healthy and diseased ruminants, most of the isolates from diseased animals were S. ruminantium, implying that S. ruminantium is more likely to be associated with ruminant disease than S. suis. However, the ruminant S. suis and S. ruminantium isolates from diseased animals were classified into diverse genotypes rather than belonging to certain clonal groups. Genome sequence analysis of 20 S. ruminantium isolates provided information about the antibiotic resistance, potential virulence, and serological diversity of this species. We further developed an S. ruminantium-specific PCR assay to aid in the identification of this bacterium. The information obtained and the method established in this study will contribute to the accurate diagnosis of ruminant streptococcal infections.

中文翻译：

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反刍动物中猪链球菌和类猪链球菌反刍动物链球菌的基因型多样性。

尽管猪链球菌作为主要的猪和人类病原体已经引起了公众的注意，但这种细菌也已从包括反刍动物在内的其他动物中分离出来。但是，最近的分类学研究揭示了以前鉴定为猪链球菌的其他物种的存在，其中一些分离株被重新分类为反刍动物链球菌。在日本，经过生化鉴定的猪链球菌通常是从患病的反刍动物中分离出来的。但是，这种分离物尚未得到准确鉴定，其在反刍动物中的病因学重要性尚不清楚。因此，为了解猪链球菌和猪链球菌样细菌在反刍动物中的重要性，我们根据更新的分类对反刍动物的猪链球菌分离株进行了重新分类，并调查了它们的遗传多样性。尽管猪链球菌和猪链球菌 反刍动物是从健康和患病的反刍动物中分离出来的，大多数来自患病动物的分离株是反刍动物，这表明反刍动物比反义链球菌更可能与反刍动物疾病有关。但是，将来自患病动物的反刍动物猪链球菌和反刍动物沙门氏菌分离物分为多种基因型，而不是属于某些克隆组。对20株反刍动物分离株的基因组序列分析提供了有关该物种的抗生素抗性，潜在毒力和血清学多样性的信息。我们进一步开发了一种反刍动物反刍动物特异性PCR检测方法，以帮助鉴定该细菌。这项研究中获得的信息和建立的方法将有助于反刍类链球菌感染的准确诊断。