Molecular profile and epidemiological traits of Streptococcus suis isolated from diseased pigs in western Canada reveal multiple-serotype infection: Implications for disease control.

OBJECTIVE: Streptococcus suis is a major agent of disease in modern swine operations, linked to increased mortality, treatment costs, and secondary infections. Although it is ubiquitous in swine, only a fraction of pigs develop clinical disease. The goals of this study were to profile isolates obtained from diseased pigs in western Canada and to investigate potential associations with disease severity.

PROCEDURE: Isolates of S. suis ( n = 128) from 75 diagnostic submission and 63 premises were paired with epidemiological surveys completed by submitting practitioners ( n = 22). Whole-genome sequencing was used to type isolates.

RESULTS: The most prevalent serotypes identified were 1/2 (7.8%, 10/128), 2 (9.3%, 12/128), 3 (9.3%, 12/128), and 7 (7.8%, 10/128); and sequence types 28 (17%, 23/128) and 839 (14%, 19/128). There was no association between serotype or sequence type and organ source or barn location. Approximately 74% (14/19) of the premises had diseased animals colonized by > 1 S. suis serotype, but only 1 pig was simultaneously infected with multiple serotypes and sequence types. Serotype distribution from diseased pigs in western Canada differed from that of those in other geographic regions.

CONCLUSION: Infection of diseased pigs by multiple serotypes should be considered when disease control strategies are implemented. No association between S. suis type and isolation organ was identified.