Genomic and pathogenic investigations of Streptococcus suis serotype 7 population derived from a human patient and pigs

Emerg Microbes Infect. 2021 Dec;10(1):1960-1974. doi: 10.1080/22221751.2021.1988725.

Abstract

Streptococcus suis is one of the important emerging zoonotic pathogens. Serotype 2 is most prevalent in patients worldwide. In the present study, we first isolated one S. suis serotype 7 strain GX69 from the blood culture of a patient with septicemia complicated with pneumonia in China. In order to deepen the understanding of S. suis serotype 7 population characteristics, we investigated the phylogenetic structure, genomic features, and virulence of S. suis serotype 7 population, including 35 strains and 79 genomes. Significant diversities were revealed in S. suis serotype 7 population, which were clustered into 22 sequence types (STs), five minimum core genome (MCG) groups, and six lineages. Lineages 1, 3a, and 6 were mainly constituted by genomes from Asia. Genomes of Lineages 2, 3b, and 5a were mainly from Northern America. Most of genomes from Europe (41/48) were clustered into Lineage 5b. In addition to strain GX69, 13 of 21 S. suis serotype 7 representative strains were classified as virulent strains using the C57BL/6 mouse model. Virulence-associated genes preferentially present in highly pathogenic S. suis serotype 2 strains were not suitable as virulence indicators for S. suis serotype 7 strains. Integrative mobilizable elements were widespread and may play a critical role in disseminating antibiotic resistance genes of S. suis serotype 7 strains. Our study confirmed S. suis serotype 7 is a non-negligible pathotype and deepened the understanding of the population structure of S. suis serotype 7, which provided valuable information for the improved surveillance of this serotype.

Keywords: Streptococcus suis serotype 7; integrative mobilizable elements; phylogeny; virulence; zoonotic pathogens.

MeSH terms

  • Aged
  • Animals
  • Anti-Bacterial Agents / pharmacology
  • Bacteremia / microbiology*
  • Bacterial Zoonoses / microbiology
  • China
  • Disease Models, Animal
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Female
  • Genome, Bacterial / genetics*
  • Humans
  • Interspersed Repetitive Sequences / genetics
  • Mice
  • Mice, Inbred C57BL
  • Microbial Sensitivity Tests
  • Multilocus Sequence Typing
  • Phylogeny
  • Pneumonia, Bacterial / microbiology*
  • Polymorphism, Single Nucleotide / genetics
  • Serogroup
  • Streptococcal Infections / microbiology
  • Streptococcus suis / drug effects*
  • Streptococcus suis / genetics*
  • Streptococcus suis / isolation & purification
  • Streptococcus suis / pathogenicity
  • Swine
  • Swine Diseases / microbiology
  • Virulence
  • Virulence Factors / genetics

Substances

  • Anti-Bacterial Agents
  • Virulence Factors

Grants and funding

This work was supported by the National Science and Technology Major Project from the Ministry of Health of the People's Republic of China [grant number 2017ZX10303405-002] and the National Natural Science Foundation of China [grant number 81572044].