Genomic Characterization of Potential Opportunistic Zoonotic Streptococcus parasuis Isolated in China.

(1)

Background

S. parasuis is a potential opportunistic zoonotic pathogen that can infect pigs, cattle, and humans, composed of former members of S. suis serotypes 20, 22, and 26. In recent years, unclassified serotypes and a serotype 11 S. parasuis have been discovered. (2)

Methods

We characterized two S. parasuis strains (FZ1 and FZ2) isolated from brain samples of paralyzed pigs and examined evolutionary divergence among 22 available S. parasuis and 8 serotype 2 S. suis genomes through whole-genome sequencing and comparative genomic analysis. We compared virulence genes (VGs) and antibiotic resistance genes (ARGs) and analyzed mobile genetic elements (MGEs) in FZ1 and FZ2. (3)

Results

Comparative genomics revealed that srtC, ctpV, and sugC may represent key virulence determinants in S. parasuis, although their pathogenic potential appears attenuated compared to serotype 2 S. suis. In addition, S. parasuis exhibited primary resistance to aminoglycosides, macrolides, tetracyclines, and oxazolidinones, while demonstrating heightened susceptibility to oxazolidinone-class antibiotics. Moreover, we found an important association between MGEs and antibiotic resistance in S. parasuis FZ1 and FZ2. (4)

Conclusions

This study provides new insights into the genomic and evolutionary characteristics of S. parasuis and provides a new basis for the study of bacterial pathogenesis and drug resistance in the future.