Streptococcus suis is a significant cause of mortality in piglets and growing pigs worldwide. The species contains pathogenic and commensal strains, with pathogenic strains causing meningitis, arthritis, endocarditis, polyserositis, and septicemia. Serotyping and multilocus sequence typing (MLST) are primary methods to differentiate strains, but the information is limited for strains found in the United States. The objective of this study was to characterize the diversity of 208 S. suis isolates collected between 2014 and 2017 across North America (mainly the United States) by serotyping and MLST and to investigate associations between subtype and pathotype classifications (pathogenic, possibly opportunistic, and commensal), based on clinical information and site of isolation. Twenty serotypes were identified, and the predominant serotypes were 1/2 and 7. Fifty-eight sequence types (STs) were identified, and the predominant ST was ST28. Associations among serotypes, STs, and pathotypes were investigated using odds ratio and clustering analyses. Evaluation of serotype and ST with pathotype identified a majority of isolates of serotypes 1, 1/2, 2, 7, 14, and 23 and ST1, ST13, ST25, ST28, ST29, ST94, ST108, ST117, ST225, ST373, ST961, and ST977 as associated with the pathogenic pathotype. Serotypes 21 and 31, ST750, and ST821 were associated with the commensal pathotype, which is composed of isolates from farms with no known history of S. suis-associated disease. Our study demonstrates the use of serotyping and MLST to differentiate pathogenic from commensal isolates and establish links between pathotype and subtype, thus increasing the knowledge about S. suis strains circulating in the United States.
Bibliographical noteFunding Information:
The research project was funded by the Rapid Agricultural Response Fund, established by the Minnesota legislature and administered by the University of Minnesota Agricultural Experiment Station. April A. Estrada’s stipend was funded by the USDA National Needs Fellowship Award, 2016-38420-25288.
We thank the bacteriology sections at UMNVDL and KSVDL for their technical assistance. In addition, we thank Lacey Marshall-Lund (University of Minnesota, St. Paul, MN) and Marta P?rez-Sancho (Universidad Complutense de Madrid, Madrid, Spain) for technical assistance and Richard Gebhart (University of Minnesota, St. Paul, MN) and Laura Bruner (Swine Vet Center) for critical discussion of the manuscript. The research project was funded by the Rapid Agricultural Response Fund, established by the Minnesota legislature and administered by the University of Minnesota Agricultural Experiment Station. April A. Estrada's stipend was funded by the USDA National Needs Fellowship Award, 2016-38420-25288.
Copyright © 2019 American Society for Microbiology. All Rights Reserved.
Copyright 2019 Elsevier B.V., All rights reserved.
- Multilocus sequence typing
- Streptococcus suis