Genetic environment of the transferable oxazolidinone/phenicol resistance gene optrA in Enterococcus faecalis isolates of human and animal origin
Genetic environment of the transferable oxazolidinone/phenicol resistance gene optrA in Enterococcus faecalis isolates of human and animal origin
复制标题
人源和动物源粪肠球菌分离株中可转移恶唑烷酮/苯尼考抗性基因 optrA 的遗传环境
DOI：
10.1093/jac/dkw016
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发表时间：
2016-06-01
影响因子：
5.2
通讯作者：
Wang, Yang
中科院分区：
文献类型：
--
作者：
He, Tao;Shen, Yingbo;Wang, Yang
目的：本研究的目的是分析 17 个人类和动物来源的非相关粪肠球菌分离株中新型恶唑烷酮/苯酚抗性基因 optrA 的遗传环境。方法：通过全基因组测序和从头组装来分析 17 个粪肠球菌分离株中 optrA 基因的侧翼序列。当 optrA 位于质粒上时，进行接合试验以检查质粒是否接合并确认与这些质粒相关的抗性表型。结果：所有 9 个携带 optrA 的质粒均接合到粪肠球菌 JH2-2 中，并且转接合子表现出 optrA 相关表型。在这些质粒中，在 optrA 基因的上游和/或下游检测到 IS1216E 元件。在 8 个质粒中，在 optrA 上游发现了苯尼考尔输出基因 fexA，在 6 个质粒中，在 optrA 下游检测到了一种新的 erm(A) 相关大环内酯-林可酰胺-链霉素 B 抗性基因。当位于染色体 DNA 中时，在四个分离株中发现 optrA 基因位于转录调节基因 araC 的下游，或在另外四个分离株中位于 fexA 基因的下游。在两个分离株中观察到 optrA 区域整合到位于染色体 radC 基因中的 Tn558-Tn554 杂合体中。结论：本研究的结果扩展了目前关于 optrA 遗传环境的知识，并表明 IS1216E 元件在 optrA 在不同类型肠球菌质粒之间的传播中发挥着重要作用。 optrA 整合到染色体 DNA 中的机制需要进一步研究。
Objectives: Aim of this study was to analyse 17 non-related Enterococcus faecalis isolates of human and animal origin for the genetic environment of the novel oxazolidinone/phenicol resistance gene optrA.Methods: WGS and de novo assembly were conducted to analyse the flanking sequences of the optrA gene in the 17 E. faecalis isolates. When optrA was located on a plasmid, conjugation assays were performed to check whether the plasmids are conjugative and to confirm the resistance phenotype associated with these plasmids.Results: All nine optrA-carrying plasmids were conjugated into E. faecalis JH2-2 and the transconjugants exhibited the optrA-associated phenotype. In these plasmids, an IS1216E element was detected either upstream and/or downstream of the optrA gene. In eight plasmids, the phenicol exporter gene fexA was found upstream of optrA and in six plasmids, a novel erm(A)-related gene for macrolide-lincosamide-streptogramin B resistance was detected downstream of optrA. When located in the chromosomal DNA, the optrA gene was found downstream of the transcriptional regulator gene araC in four isolates, or downstream of the fexA gene in another four isolates. Integration of the optrA region into a Tn558-Tn554 hybrid, located in the chromosomal radC gene, was seen in two isolates.Conclusions: The findings of the present study extend the current knowledge about the genetic environment of optrA and suggest that IS1216E elements play an important role in the dissemination of optrA among different types of enterococcal plasmids. The mechanism underlying the integration of optrA into the chromosomal DNA requires further investigation.