Development of PCR for identifying <i>Streptococcus parasuis</i>, a close relative of <i>Streptococcus suis</i>

Abstract

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.

Characterization of pig saliva as the major natural habitat of Streptococcus suis by analyzing oral, fecal, vaginal, and environmental microbiota

“…orisratti , and 1 S . ruminantium strains [23]; and (iv) 16S rRNA gene sequences of 4,596 streptococcal strains in the RDP (last accessed in January 2016). These sequences were dereplicated using Cluster Database at High Identity with Tolerance (CD-HIT) program [24] with the sequence identity threshold of 1.0, and were finally clustered into 909 groups.…”

Investigation of the Genomic and Pathogenic Features of the Potentially Zoonotic Streptococcus parasuis

“…The two strains were confirmed as not belonging to S. suis by amplifying a nearly complete 16S rRNA gene using primer 27F(5′-AGAGTTTGATCMTGGCTCAG-3″) and 1492R (5′-TACGGYTACCTTGTTACGACTT-3′) and S. suis –specific recN and gdh genes [ 31 , 32 , 33 , 34 ]. Data of 16S rRNA sequencing and the PCR method detecting recN gene specific to S. parasuis [ 6 ] indicated that the two strains belonged to the S. parasuis species.…”

“…S. suis serotypes 32 and 34 have been reclassified as Streptococcus orisratti [4]. Recently, S. suis reference strains of serotypes 20, 22, 26 were proposed as Streptococcus parasuis [5] and serotype 33 was reclassified as Streptococcus ruminantium [6]. The presence of S. parasuis in diseased pigs and calves with pneumonia or systemic infection (meningitis, arthritis, endocarditis, or septicemia) indicated that S. parasuis may be pathogenic to pigs and/or calves [7][8][9][10].…”

Draft Genome Sequence of Streptococcus parasuis 4253, the First Available for the Species

“…It is closely related to S. suis but can be distinguished from it based on genetic content and biochemical features, such as the absence of both β-galactosidase activity and arginine hydrolyses (1, 2). Strains can easily be classified as S. parasuis based on a positive PCR targeting a 679-bp fragment near the recN gene (2).…”

“…Until now it was unclear whether S. parasuis is a pathogen, like its close relative S. suis, or whether it is a member of the commensal microbiota of pigs (2).…”