Direct Detection of Streptococcus suis from Cerebrospinal Fluid, Positive Hemoculture, and Simultaneous Differentiation of Serotypes 1, 1/2, 2, and 14 within Single Reaction.

Ingyin Shun Lae Thu,Khajornsak Tragoolpua,Chayada Sitthidet Tharinjaroen,Phadungkiat Khamnoi,Sorasak Intorasoot,Anusak Kerdsin,Usanee Anukool

doi:10.3390/pathogens10080996

Abstract

Streptococcus suis is an emerging zoonotic bacterium causing septicemia and meningitis in humans. Due to rapid disease progression, high mortality rate, and many underdiagnosed cases by time-consuming routine identification methods, alternative diagnostic testing is essential. Among 29 broadly accepted S. suis serotypes, serotypes 2 and 14 are high prevalent; however, many PCR assays showed an inability to differentiate serotype 2 from 1/2, and 1 from 14. In this study, we developed and validated a new multiplex PCR assay that facilitates the identification of only the 29 true serotypes of S. suis and simultaneously differentiates serotypes 1, 1/2, 2, and 14 within a single reaction. Importantly, the multiplex PCR could detect S. suis directly from positive hemocultures and CSF. The results revealed high sensitivity, specificity, and 100% accuracy with almost perfect agreement (κ = 1.0) compared to culture and serotyping methods. Direct detection enables a decrease in overall diagnosis time, rapid and efficient treatment, reduced fatality rates, and proficient disease control. This multiplex PCR offers a rapid, easy, and cost-effective method that can be applied in a routine laboratory. Furthermore, it is promising for developing point-of-care testing (POCT) for S. suis detection in the future.

Highlights

Streptococcus suis, a Gram-positive cocci bacterium, is one of the leading causative agents of massive economic losses in the pig industry
We reported a simple, cheap, high accuracy multiplex PCR assay for differentiating among serotypes 1, 1/2, 2, and 14 based on the targeted cpsJ gene, the single nucleotide polymorphism (SNP)
Two new pairs of primers were designed in this study; one pair primer was based on the recN gene to identify S. suis with the expected product size at

Summary

Introduction

Streptococcus suis, a Gram-positive cocci bacterium, is one of the leading causative agents of massive economic losses in the pig industry. It is an emerging zoonotic infectious organism that has been receiving growing concern around the world [1,2]. S. suis naturally colonizes in the upper respiratory tract of pigs, in tonsils and nasal cavities. It is responsible for meningitis, arthritis, pericarditis, polyserositis, septicemia, and sudden death of weaning piglets, as well as growing pigs [3]. Humans can be infected when in close contact with diseased pigs or consuming S. suis contaminated raw pork or pork-derived products [1]. Various symptoms, including fever, headache, septicemia, deafness to severe septic shock syndrome, and fatality, are found

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Conclusion