Detection of a new tet(X6)-encoding plasmid in Acinetobacter towneri

文献类型： 外文期刊

第一作者： Cheng, Yingying

作者： Cheng, Yingying;Chen, Yong;Liu, Yang;Song, Jingjie;Zhou, Kai;Cheng, Yingying;Chen, Yong;Liu, Yang;Song, Jingjie;Zhou, Kai;Chen, Yunbo;Xiao, Yonghong;Shan, Tongling

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关键词： Plasmid-borne; Novel plasmid; tet(X6); Tigecycline resistance; Acinetobacter towneri

期刊名称：JOURNAL OF GLOBAL ANTIMICROBIAL RESISTANCE （ 影响因子：4.035； 五年影响因子：3.611 ）

ISSN： 2213-7165

年卷期： 2021 年 25 卷

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收录情况： SCI

摘要： Objectives: The aim of this study was to characterise a novel tet(X6)-carrying plasmid detected in a livestock-associated Acinetobacter towneri isolate. Methods: PCR screening was performed to detect tet(X) variants in livestock-associated Acinetobacter spp. isolates. The tet(X6)-positive isolate was analysed by whole-genome sequencing. Functional cloning was performed to detect the activity of Tet(X6). Antibiotic susceptibility was determined by broth dilution and microbiological degradation assays. Site-directed mutagenesis was performed to identify the role of 23-Ala residue of Tet(X6) in tigecycline resistance. Results: The tet(X6) gene was detected on a 159-kb plasmid (pAT205) carried by a tigecycline-susceptible A. towneri isolate recovered from a swine faecal sample. The genetic context of tet(X6) [Delta ISVsa3-tet(X6)-abh-guaA-ISVsa3] is highly similar to that of the reported plasmid-borne tet(X) variants, suggesting that it may represent a common structure mediating the dissemination of plasmid-borne tet(X) genes. Additional resistance genes detected on pAT205 were carried by a Tn6205-like region and a disrupted class 2 integron. Gene expression and microbiological degradation assays consistently suggested that the activity of tet(X6) is weaker than that of tet(X3) and tet(X4). The 23-Ala residue of the first FAD-binding site conferred higher activity to Tet(X6) than the Gly reside conserved in the other plasmid-borne tet(X) variants, indicating that the site might be under selection. Conclusion: This study alerts to the silent dissemination possibility of tigecycline resistance mediated by a novel plasmid. Continuous monitoring of plasmid-borne tet(X) is imperative for tackling its dissemination. (C) 2021 The Author(s). Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy.

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