College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu Province, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu Province, PR China; Institute of Comparative Medicine, Yangzhou University, Yangzhou, Jiangsu Province, PR China.
College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu Province, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu Province, PR China.
Sci Total Environ. 2020 Sep 1;733:139306. doi: 10.1016/j.scitotenv.2020.139306. Epub 2020 May 11.
Emergence of high-level tigecycline resistance tet(X) variants in animal and human Enterobacterales is posing a public health concern. Recently, novel tet(X) variants including tet(X3), tet(X4), tet(X5) and tet(X6) were detected in Enterobacterales and Acinetobacter baumannii. Here, we comprehensively investigated the prevalence of tet(X) variants among different bacterial species in swine farm environment with nanopore sequencing. The tet(X6) gene was found located on both plasmids and ICEs in Proteus, but tet(X4) was in plasmids in E. coli. To our knowledge, this is the first report of the emergence of IncA/C2-type plasmid-mediated tet(X6). The bacterial host adaptation of different tet(X) variants implies they evolved in microbiota separately, but ISCR2 should be the key element facilitating horizontal transfer of various tet(X) variants through circular intermediates. Our findings further expand the knowledge about reservoirs of mobile tigecycline resistance genes and the epidemic characteristics of tet(X) variants in animals and related environments.
高水平替加环素耐药基因 tet(X) 变体在动物和人类肠杆菌科中的出现引起了公众健康关注。最近，肠杆菌科和鲍曼不动杆菌中检测到新型 tet(X) 变体，包括 tet(X3)、tet(X4)、tet(X5) 和 tet(X6)。在这里，我们通过纳米孔测序全面调查了替加环素耐药基因 tet(X) 变体在猪养殖场环境中不同细菌种属中的流行情况。tet(X6)基因被发现位于变形杆菌中的质粒和 ICEs 上，但 tet(X4)位于大肠杆菌中的质粒上。据我们所知，这是首次报道 IncA/C2 型质粒介导的 tet(X6)的出现。不同 tet(X)变体的细菌宿主适应性表明它们是在微生物群中分别进化的，但 ISCR2 应该是通过环状中间体促进各种 tet(X) 变体水平转移的关键因素。我们的研究结果进一步扩展了关于移动替加环素耐药基因库以及动物和相关环境中 tet(X) 变体的流行特征的知识。
