Group B   Streptococcus   (GBS;   Streptococcus agalactiae  ) is a major neonatal and opportunistic bacterial pathogen of humans and an important cause of mastitis in dairy cattle with significant impacts on food security. Following the introduction of mastitis control programmes in the 1950s, GBS was nearly eradicated from the dairy industry in northern Europe, followed by re-emergence in the 21st century. Here, we sought to explain this re-emergence based on short and long read sequencing of historical (1953–1978; n=44) and contemporary (1997–2012; n=76) bovine GBS isolates. Our data show that a globally distributed bovine-associated lineage of GBS was commonly detected among historical isolates but never among contemporary isolates. By contrast, tetracycline resistance, which is present in all major GBS clones adapted to humans, was commonly and uniquely detected in contemporary bovine isolates. These observations provide evidence for strain replacement and suggest a human origin of newly emerged strains. Three novel GBS plasmids were identified, including two showing >98 % sequence similarity with plasmids from   Streptococcus pyogenes   and   Streptococcus dysgalactiae   subsp.   equisimilis  , which co-exist with GBS in the human oropharynx. Our findings support introduction of GBS into the dairy population due to human-to-cattle jumps on multiple occasions and demonstrate that reverse zoonotic transmission can erase successes of animal disease control campaigns.

中文翻译：

---

奶牛中 B 群链球菌的兴衰：由于人对牛宿主跳跃而重新引入？

B组 链球菌 （GBS； 无乳链球菌 ）是人类主要的新生儿和机会性细菌病原体，是奶牛乳腺炎的重要原因，对粮食安全有重大影响。在 1950 年代引入乳腺炎控制计划之后，GBS 在北欧的乳制品行业几乎被根除，随后在 21 世纪重新出现。在这里，我们试图根据历史（1953-1978；n = 44）和当代（1997-2012；n    =76) 牛 GBS 分离物。我们的数据显示，在历史分离株中通常检测到全球分布的与牛相关的 GBS 谱系，但在当代分离株中从未检测到。相比之下，在适应人类的所有主要 GBS 克隆中都存在四环素耐药性，在当代牛分离物中普遍且独特地检测到。这些观察结果为菌株替代提供了证据，并表明新出现的菌株起源于人类。 鉴定了三个新的 GBS 质粒，其中两个与化脓性链球菌 和停乳 链球菌 亚种的质粒显示 >98% 的序列相似性。 平等的       , 在人类口咽中与 GBS 共存。我们的研究结果支持将 GBS 引入奶牛群是由于人与牛之间的多次跳跃，并证明人畜共患病的反向传播可以抹杀动物疾病控制活动的成功。