Huaiyin Normal University, College of Life Sciences, Huaian, Jiangsu, China.
Yangzhou University, College of Veterinary Medicine, Yangzhou, Jiangsu, China.
J Appl Microbiol. 2020 Jun;128(6):1606-1612. doi: 10.1111/jam.14591. Epub 2020 Feb 5.
The aim of this study is to investigate Streptococcus suis strains present in Jiangsu province, China.
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 LD (assessed by zebrafish) of isolates RD105 was 2·6431 × 10 and HA24 was 7·1198 × 10 , which showed RD105 more virulent and was consistent with the results of virulence factor identification.
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.
Systematic investigation of S. suis provided the most basic theoretical support for the prevention and control of swine streptococcosis.
本研究旨在调查中国江苏省的猪链球菌（Streptococcus suis）菌株。
共采集 1650 份鼻拭子和肛拭子样本以及 100 份扁桃体样本，来自临床健康猪。通过培养特性、菌落形态和基于聚合酶链反应（PCR）的谷氨酸脱氢酶（gdh）基因分析进行 S. suis 鉴定，8 株分离株被确认为 S. suis。通过凝集试验鉴定分离株血清群，包括 4、7、3、5 和 8。通过 PCR 基因谱分析显示，这些分离株的 manN、purD、orf2、gdh 基因是保守的，50%的分离株携带 dltA、pgdA、srtA 和 sspA。药敏试验显示，分离株对克林霉素、红霉素、四环素、青霉素 G、万古霉素和利奈唑胺耐药；而对氯霉素均无耐药性，大多数分离株呈多药耐药。最后，RD105 株和 HA24 株的 LD（通过斑马鱼评估）分别为 2.6431×10 和 7.1198×10 ，表明 RD105 株的毒力更强，与毒力因子鉴定结果一致。
健康猪中 S. suis 的比例非常低。毒力因子与致病性有关。南通分离株比淮安分离株具有更大的毒力潜力。
对 S. suis 的系统调查为猪链球菌病的防控提供了最基本的理论支持。
