2021 Volume 74 Issue 9 Pages 576-581
We investigated the relationship between S. Rissen strains isolated from pigs in Niigata prefecture (26 strains) and strains from pigs in other regions (5 strains), strains from humans (10 strains), and a strain from a feed ingredient (1 strain). With respect to the S. Rissen from pigs, the strains in Niigata Prefecture and the strains in other regions are genetically closely related, and it is considered that clones of S. Rissen established in pig farms in other regions subsequently invaded pig farms in Niigata Prefecture. Two groups of S. Rissen from humans were considered to have different origins, one of which was genetically closely related to the strains from pigs and showed an antimicrobial resistance pattern consistent with that of the strains from pigs, suggesting that one of the sources of S. Rissen infection in humans was pork contaminated with S. Rissen from carrier pigs. The strain from the feed ingredient examined in this study was different from the strains from pigs in both PFGE type and antimicrobial resistance pattern, and it is considered that soybean oil residue was unrelated to S. Rissen infections in the tested pigs.
