Development of PCR for identifying Streptococcus parasuis, a close relative of Streptococcus suis

Ryoko Yamada, Le Hong Thuy Tien, Sakura Arai, Mari Tohya, Kasumi Ishida-Kuroki, Ryohei Nomoto, Hyunjung Kim, Eriko Suzuki, Ro Osawa, Takayasu Watanabe, Tsutomu Sekizaki

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


Streptococcus parasuis has recently been removed taxonomically from Streptococcus suis, a zoonotic pathogen. S. parasuis has been detected in healthy pigs and in diseased pigs, which suggests that S. parasuis is involved in the normal microbiota of pigs and has potential pathogenicity. However, the pathogenicity of S. parasuis in pigs is unclear because of the lack of appropriate detection methods that discriminate S. parasuis from S. suis. In this study, we developed a PCR method that is specific for S. parasuis. The detection limit of the PCR was 350 CFU per reaction. Bacteria isolated from the saliva of eight pigs were collected and examined by PCR. Sixty-four isolates positive for PCR were obtained from the samples of all pigs. Thirteen of the 64 isolates were genetically confirmed as S. parasuis, and biologically and biochemically had nearly the same features of known S. parasuis strains, which suggested that strains positive for PCR were S. parasuis. Among the 64 isolates, 28 isolates were serotypes 20, 22, or 26 in the S. suis serotyping scheme. The remaining 36 isolates were untypeable, which suggested the presence of novel serotypes or a capsule-negative form. Therefore, the PCR method described in this study is a useful tool for identifying S. parasuis, and can be used in etiological studies on this bacterium.

Original languageEnglish
Pages (from-to)1101-1107
Number of pages7
JournalJournal of Veterinary Medical Science
Issue number7
Publication statusPublished - Jul 2018
Externally publishedYes


  • PCR
  • Pig saliva
  • RecN
  • Streptococcus parasuis
  • Streptococcus suis


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