Abstract
Streptococcus suis (S. suis) is an important swine pathogen and an emerging zoonotic agent worldwide. Serotype 9 is the most prevalent serotype in several European countries but it is relatively rare in China. In this study, through the investigation of the serotypes of 279 S. suis strains isolated from China from 2015 to 2017, it was found that serotype 9 is the second most prevalent serotype (43 out of 279), behind serotype 2 (83 out of 279). Next, the 43 serotype 9 isolates were sequenced and compared with those from the Netherland (28) and the U.K. (eight). For the purpose of comparison, the strain D12 (GCA_000231905), which has completed genome sequences, was also incorporated. Phylogenetic tree analysis showed that the strains from China and the U.K. were heterogeneous. In contrast, all but one from the Netherland belonged to the same clade. The dominant clades of Chinese strains (33) and strains from the Netherland (27) were very similar. Both of them may have originated from the same strain about 70 years ago. Then, the distributions of virulence-associated genes and antibiotic resistance genes among different clades and sources were analyzed. By comparison, strains from the Netherland carried more virulence-associated genes and those from the U.K. had more antibiotic resistance genes. Additionally, some virulence-associated genes (salK and salR) and antibiotic resistance genes (lincomycin and spectinomycin) existed only in several Chinese strains. In conclusion, our data displayed the population characteristics and differences of S. suis serotype 9 between China and Europe, suggesting that they have taken different evolutionary paths.
Highlights
Streptococcus suis, an important emerging zoonotic pathogen, causes significant economic losses in the swine industry and severe systemic infections in humans [1,2]
It was thought that S. suis caused only sporadic human infection cases
The detailed background information of the 279 S. suis isolates is provided in Supplementary Table S1
Summary
Streptococcus suis, an important emerging zoonotic pathogen, causes significant economic losses in the swine industry and severe systemic infections in humans [1,2]. The first human infection case occurred in Denmark in 1968. 1600 S. suis infections in humans worldwide [2,3]. Human S. suis cases have dramatically increased over the past two decades [2]. It was thought that S. suis caused only sporadic human infection cases. Two epidemics in China in 1998 and 2005 provoked considerable public health concerns worldwide [4]. The growing threat of S. suis to humans highlights the critical need to better understand the prevalent characterization of S. suis for the promotion of public health [6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
