Luo Mengting, Li Qiao, He Fang, Yang Zhengquan
The Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou, Zhejiang, China; Laboratory Medicine Center, Department of Clinical Laboratory, Zhejiang Provincial People's Hospital (Affiliated People's Hospital), Hangzhou Medical College, Hangzhou, Zhejiang, China.
Laboratory Medicine Center, Department of Clinical Laboratory, Zhejiang Provincial People's Hospital (Affiliated People's Hospital), Hangzhou Medical College, Hangzhou, Zhejiang, China.
J Glob Antimicrob Resist. 2025 Jun 20;44:146-148. doi: 10.1016/j.jgar.2025.06.010.
Despite the widespread occurrence of tet(X4)-mediated tigecycline resistance in Escherichia coli from animal and environmental sources, its presence in human clinical isolates remains rare. In this study, we report the first whole-genome sequence of a E. coli isolate harboring tet(X4) and belonging to a novel sequence type, recovered from an infant in China.
The complete genome of E. coli Q65 was sequenced using a combination of Illumina NovaSeq 6000 and Oxford Nanopore MinION sequencing platforms. Functional annotation was conducted using the NCBI Prokaryotic Genome Annotation Pipeline (PGAP), and genomic features were further analyzed with a range of bioinformatics tools.
The genome of E. coli strain Q65 is 5 442 192 bp in length and encodes 5089 proteins. Strain Q65 was classified as sequence type ST17306, a novel member of the ST69 clonal complex, and was assigned the serotype O17:H18. Q65 exhibited multidrug resistance, carrying 14 antimicrobial resistance genes, including tet(X4). The tet(X4) gene was located on a 192 048 bp hybrid plasmid belonging to the IncFIA(HI1)/IncHI1B(R27)/IncHI1A replicon types. A search of the NCBI database revealed similar tet(X4)-carrying hybrid plasmids present in various Enterobacteriaceae species, suggesting that such plasmids may play a key role in mediating the horizontal transfer of tet(X4).
This study presents the first complete genome sequence of a tet(X4)-positive, multidrug-resistant E. coli strain belonging to the novel sequence type ST17306, isolated from a Chinese infant with bronchopneumonia. Continuous global surveillance of the dissemination of tet(X4)-harboring strains is crucial to monitor and control the potential public health threat.
尽管在来自动物和环境源的大肠杆菌中，tet(X4)介导的替加环素耐药性广泛存在，但其在人类临床分离株中的存在仍然罕见。在本研究中，我们报告了从中国一名婴儿分离出的携带tet(X4)且属于一种新型序列类型的大肠杆菌分离株的首个全基因组序列。
使用Illumina NovaSeq 6000和Oxford Nanopore MinION测序平台相结合的方法对大肠杆菌Q65的完整基因组进行测序。使用NCBI原核生物基因组注释管道（PGAP）进行功能注释，并使用一系列生物信息学工具进一步分析基因组特征。
大肠杆菌菌株Q65的基因组长度为5442192 bp，编码5089种蛋白质。菌株Q65被分类为序列类型ST17306，是ST69克隆复合体的一个新成员，并被指定为血清型O17:H18。Q65表现出多重耐药性，携带14个抗菌耐药基因，包括tet(X4)。tet(X4)基因位于一个192048 bp的杂交质粒上，该质粒属于IncFIA(HI1)/IncHI1B(R27)/IncHI1A复制子类型。对NCBI数据库的搜索显示，各种肠杆菌科物种中存在类似的携带tet(X4)的杂交质粒，这表明此类质粒可能在介导tet(X4)的水平转移中起关键作用。
本研究展示了从一名患有支气管肺炎的中国婴儿分离出的属于新型序列类型ST17306的tet(X4)阳性、多重耐药大肠杆菌菌株的首个完整基因组序列。持续对携带tet(X4)菌株的传播进行全球监测对于监测和控制潜在的公共卫生威胁至关重要。
