Modified multiplex PCR for serotyping and pathotyping of Streptococcus suis

Area of Science:

• Microbiology
• Molecular Biology
• Public Health

Background:

• Streptococcus suis is a zoonotic pathogen causing invasive infections in humans through contact with pigs or pork products.
• Current methods lack universal markers to differentiate pathogenic from non-pathogenic S. suis strains.
• A diagnostic tool is needed for effective surveillance and implementing a One Health approach.

Purpose of the Study:

• To enhance a multiplex PCR assay for identifying all 29 recognized Streptococcus suis serotypes.
• To distinguish pathogenic S. suis strains by targeting capsule and ROK pathogenic marker genes.
• To develop a single assay for simultaneous serotyping and pathotyping.

Main Methods:

• Modification and improvement of four sets of multiplex PCR reactions.
• Utilizing primers targeting capsule genes for serotype identification.
• Employing the ROK gene as a marker for pathogenic pathotypes.

Main Results:

• The multiplex PCR successfully amplified S. suis-specific, serotype-specific, and pathogenic markers simultaneously.
• The ROK gene demonstrated high accuracy (84.7%), sensitivity (96.4%), and specificity (67.6%) for pathotyping.
• Significant statistical indicators (P<0.001, OR 55.1) support the ROK gene's utility as a pathogenic marker.
• No cross-reactions were observed with other bacterial species, confirming assay specificity.

Conclusions:

• The modified multiplex PCR assay effectively differentiates 29 Streptococcus suis serotypes and predicts pathogenic potential in a single reaction.
• This assay is a valuable tool for One Health surveillance of S. suis in both human and pig populations.
• The ROK gene is a reliable marker for identifying pathogenic S. suis strains.