Zhang Junkai, Yang Yingying, Sun Huarun, Luo Xingwei, Cui Xiaodie, Miao Qingqing, He Dandan, Zhao Jinfeng, Yan Fengbin, Pan Yushan, Zhai Yajun, Hu Gongzheng
Department of Pharmacology and Toxicology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China.
National Reference Laboratory of Veterinary Drug Residues (HZAU), Huazhong Agricultural University, Wuhan, China.
Res Microbiol. 2023 Sep-Oct;174(7):104078. doi: 10.1016/j.resmic.2023.104078. Epub 2023 May 4.
Aim of this study was to investigate the prevalence and genetic environment of the oxazolidinone resistance gene optrA in Streptococcus suis (S. suis) isolates from diseased pigs in China. A total of 178 S. suis isolates were screened for the optrA gene by PCR. The phenotypes and genotypes of optrA-positive isolates were investigated by antimicrobial susceptibility testing, core genome Multilocus Sequence Typing (cgMLST), capsular serotypes determination and whole-genome sequencing (WGS). Fifty-one (28.7%) S. suis isolates were positive for optrA. Phylogenetic analysis indicated that the spread of the optrA among S. suis isolates was primarily due to horizontal transfer. Analysis of S. suis serotypes from diseased pigs revealed substantial diversity. The genetic environment of optrA was complex and diverse and could be divided into 12 different types. Interestingly, we identified a novel integrative and conjugative element ICESsu988S, carrying optrA and erm(T) genes. This is to the best of our knowledge the first report of the optrA and erm(T) co-located on an ICE in S. suis. Our results showed a high prevalence of optrA gene in S. suis isolates in China. Further research is needed to evaluate the importance of ICEs, as they horizontally propagate important clinical resistance genes.
本研究旨在调查中国患病猪源猪链球菌（S. suis）分离株中恶唑烷酮耐药基因optrA的流行情况及其遗传环境。通过PCR对178株猪链球菌分离株进行optrA基因筛查。通过药敏试验、核心基因组多位点序列分型（cgMLST）、荚膜血清型测定和全基因组测序（WGS）对optrA阳性分离株的表型和基因型进行研究。51株（28.7%）猪链球菌分离株optrA呈阳性。系统发育分析表明，optrA在猪链球菌分离株中的传播主要是由于水平转移。对患病猪的猪链球菌血清型分析显示出很大的多样性。optrA的遗传环境复杂多样，可分为12种不同类型。有趣的是，我们鉴定出一种新型的整合和接合元件ICESsu988S，它携带optrA和erm(T)基因。据我们所知，这是optrA和erm(T)在猪链球菌的一个ICE上共定位的首次报道。我们的结果显示optrA基因在中国猪链球菌分离株中具有较高的流行率。由于ICEs水平传播重要的临床耐药基因，因此需要进一步研究以评估其重要性。
