title: Population Structure and Antimicrobial Resistance Profiles of Streptococcus suis Serotype 2 Sequence Type 25 Strains.
abstract: Strains of serotype 2 Streptococcus suis are responsible for swine and human infections. Different serotype 2 genetic backgrounds have been defined using multilocus sequence typing (MLST). However, little is known about the genetic diversity within each MLST sequence type (ST). Here, we used whole-genome sequencing to test the hypothesis that S. suis serotype 2 strains of the ST25 lineage are genetically heterogeneous. We evaluated 51 serotype 2 ST25 S. suis strains isolated from diseased pigs and humans in Canada, the United States of America, and Thailand. Whole-genome sequencing revealed numerous large-scale rearrangements in the ST25 genome, compared to the genomes of ST1 and ST28 S. suis strains, which result, among other changes, in disruption of a pilus island locus. We report that recombination and lateral gene transfer contribute to ST25 genetic diversity. Phylogenetic analysis identified two main and distinct Thai and North American clades grouping most strains investigated. These clades also possessed distinct patterns of antimicrobial resistance genes, which correlated with acquisition of different integrative and conjugative elements (ICEs). Some of these ICEs were found to be integrated at a recombination hot spot, previously identified as the site of integration of the 89K pathogenicity island in serotype 2 ST7 S. suis strains. Our results highlight the limitations of MLST for phylogenetic analysis of S. suis, and the importance of lateral gene transfer and recombination as drivers of diversity in this swine pathogen and zoonotic agent.
authors.affiliation: Public Health Ontario, Toronto, ON, Canada.
authors.forename: Taryn B T
authors.initials: TB
authors.lastname: Athey
authors.affiliation: Public Health Ontario, Toronto, ON, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Teatero
authors.affiliation: Bacterial and Parasitic Diseases Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan.|The United Graduate School of Veterinary Science, Gifu University, Gifu, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Takamatsu
authors.affiliation: Department of Human Genetics, McGill University and Génome Québec Innovation Centre, Montreal, QC, Canada.
authors.forename: Jessica
authors.initials: J
authors.lastname: Wasserscheid
authors.affiliation: Department of Human Genetics, McGill University and Génome Québec Innovation Centre, Montreal, QC, Canada.
authors.forename: Ken
authors.initials: K
authors.lastname: Dewar
authors.affiliation: Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, QC, Canada.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Gottschalk
authors.affiliation: Public Health Ontario, Toronto, ON, Canada.|Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
authors.forename: Nahuel
authors.initials: N
authors.lastname: Fittipaldi
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004251:DNA Transposable Elements; D024881:Drug Resistance, Bacterial; D023061:Gene Order; D016680:Genome, Bacterial; D059014:High-Throughput Nucleotide Sequencing; D008826:Microbial Sensitivity Tests; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide; D011995:Recombination, Genetic; D065288:Serogroup; D017011:Streptococcus suis / Q000145:classification / Q000187:drug effects* / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements