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

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.

Genomic comparison of two Streptococcus suis serotype 1 strains recovered from porcine and human disease cases

“…Using a novel multiplex PCR test 13 , we first retyped the 46 strains in our collection previously identified using multiplex PCR 14 as serotype 1 or 14. Among them, 2 strains were confirmed as serotype 1 by the new multiplex PCR 13 , PCR–RFLP of the cpsK locus 15 and SNP at position 483 of cpsK 16 (Fig. 1 ).…”

“…We used a recently described improved multiplex PCR, capable of discriminating between serotypes 1 and 14 13 , to re-type a total of 46 S. suis strains present in our collection; these had been assigned to serotype 14 or 1. In total, two serotype 1 strains were identified from these 46 strains.…”

Investigation and analysis of etiology associated with porcine respiratory disease complex in China from 2017 to 2021

“…In this study, we only focused on serotypes 1 to 10 and used the first multiplex PCR (mPCR) assay (serotypes 1 to 10, 1/2, and 14) developed by Liu ( 23 ). To further identify serotypes 1 and 14, 2, and 1/2, the PCR assay developed by Thu was used ( 24 ). G. parasuis can be classified into 15 serotypes according to the differences in its capsular loci.…”

Human Streptococcus suis Infections in Thailand: Epidemiology, Clinical Features, Genotypes, and Susceptibility

“…Overall, this campaign led to a marked decrease in the annualized incidence of human S. suis disease, from 6.4/100,000 persons in 2010 (before the campaign implementation) to 2.7/100,000 persons in 2011, then to 2.0/100,000 persons in 2012, and finally to 3.5/100,000 persons in 2013 [42]. Finally, early diagnostics in S. suis suspected patients using rapid alternative methods rather than traditional culture (a gold standard but slower) could facilitate prompt treatment and reduce the mortality rate, as well as prompt epidemiological investigation [84][85][86][87].…”