Isolation and characterization of Streptococcus suis strains from swine in Jiangsu province, China

Abstract

Aims The aim of this study is to investigate Streptococcus suis strains present in Jiangsu province, China. Methods and Results In all, 1650 nasal and anal swab samples and 100 tonsils were collected from clinically healthy swine. Culture characteristics, colony morphology and PCR‐based analysis of the glutamate dehydrogenase (gdh) gene were performed for S. suis identification, and eight isolates were confirmed to be S. suis. The isolates serogroups were identified by agglutinating test, including 4, 7, 3, 5 and 8. Gene profiling by PCR showed that the manN, purD, orf2, gdh genes were conserved among the isolates and that 50% of the isolates carried dltA, pgdA, srtA and sspA. Antimicrobial susceptibility test showed the isolates displayed resistance to clindamycin, erythromycin, tetracycline, penicillin G, vancomycin and linezolid; while none was resistant to chloramphenicol, multi‐drug resistance was seen in most of the isolates. Finally, the LD50 (assessed by zebrafish) of isolates RD105 was 2·6431 × 105 and HA24 was 7·1198 × 106, which showed RD105 more virulent and was consistent with the results of virulence factor identification. Conclusions There is a very low proportion of S. suis in the healthy pigs. The virulence factors were related to pathogenicity. Bacteria in Nantong possess greater virulence potential than those in Huaian. Significance and Impact of the Study Systematic investigation of S. suis provided the most basic theoretical support for the prevention and control of swine streptococcosis.

Antimicrobial resistance phenotypes and genotypes of Streptococcus suis isolated from clinically healthy pigs from 2017 to 2019 in Jiangxi Province, China

“…A recent study investigated S. suis isolates from nasal and anal swab samples and tonsils in Jiangsu Province, China, and reported a very low proportion (0·46%, 8/1750) of S. suis in healthy pigs (Huan et al . 2020), indicating that the prevalence of S. suis is indeed geographically variable.…”

Comparative analysis of Streptococcus suis genomes identifies novel candidate virulence-associated genes in North American isolates

“…Our results indicated a lack of correlation between the presence of MGE-associated VAGs and pathotype. The presence of VAGs in a majority of the commensal pathotype provides further evidence that commensal strains may act as gene reservoirs [ 66 , 71 ]. Although the 89 K PAI (a S. suis MGE) was absent in all isolates in this study, the in silico detection of 89 K PAI sequences (CH1/CH2 and CH5/CH6) and the presence of PAI VAGs suggest some genetic similarity between North American isolates and the virulent S. suis strain 05ZYH33 [ 45 ].…”

Novel Multiplex PCR Assay and Its Application in Detecting Prevalence and Antibiotic Susceptibility of Porcine Respiratory Bacterial Pathogens in Guangxi, China

“…In addition, S. suis and P. multocida have the potential to infect humans and threaten human health. PRDC has become a serious problem which urgently needs to be solved in large-scale Chinese pig farms ( 17 – 21 ). However, the prevalence of PRBPs in Guangxi Province, where several large-scale pig farms are located, remains largely unknown.…”