optrA-ermB引起猪链球菌对酰胺醇类-噁唑烷酮类-大环内酯类-林可胺类-链阳菌素类（PhO-MLS）抗菌药物的耐药现象已突显，但有关该基因组合在猪链球菌中的共转移机制及演化特点尚不清楚，有待深入研究。本项目以此为切入点，基于前期基础，采用生物信息学方法及多种分子生物学实验技术，拟系统分析和阐明猪链球菌中optrA-ermB的流行情况、以整合性和结合性基因元件（ICE）为载体的共转移机制以及其在猪链球菌中的演化特点。上述关键科学问题的解决有利于我们认识和控制猪链球菌耐药性的水平传播，并为兽用抗菌药的风险评估提供可靠依据，故具有深远的理论和实践意义。

optrA/ermB could conceivably have played a role in the rising incidence of Phenicols-Oxazolidinone-Microlides-Lincomycin-Streptogramins (PhO-MLS) resistance in Streptococcus suis. It will be seriously jeopardized by the rapid emergence and spread of antimicrobial-resistant bacteria induced by ICEs if we don’t take precautions against it. However, to date, our understanding on the mechanisms of optrA/ermB cotransfer and evolution in Streptococcus suis is still restricted to few reports, thus consequently understanding of optrA/ermB coevolution is only beginning to be unraveled. Based on our preliminary data we generated the hypothesis that ICE is the emerging mobile genetic elements which harbor optrA/ermB and mobilize horizontal transmission of optrA/ermB among gram positive population. Thus, in this study, we will focus on investigating the following scientific issues by using a series of molecular biological methods. 1) Analyzing the temporal and spatial characteristics and change trend of PhO-MLS resistant Streptococcus suis; 2) Studying the cotransmission mechanism of optrA and ermB in PhO-MLS resistant Streptococcus suis; 3) Preliminarily clarifying the evolution mechanism of optrA-ermB in Streptococcus suis. Solving the above key scientific problems will help us to understand and control the spread of Streptococcus suis resistance level, and provide a reliable basis for the risk assessment of animal-label used antibiotics, which has a far-reaching significance of high practical relevance and theory point of the view.