Long Xiaoqian, Lin Feng, Tang Biao, Miao Fengcheng, Li Zhiyu, Shen Yao, Yang Hua, Ma Jiangang
State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products & Institute of Agro-product Safety and Nutrition, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China; Xianghu Laboratory, Hangzhou, China.
Key Laboratory of Healthy Freshwater Aquaculture, Ministry of Agriculture and Rural Affairs, Key Laboratory of Fish Health and Nutrition of Zhejiang Province, Zhejiang Institute of Freshwater Fisheries, Huzhou, Zhejiang, China.
J Glob Antimicrob Resist. 2025 Mar;41:1-7. doi: 10.1016/j.jgar.2024.12.004. Epub 2024 Dec 17.
Acinetobacter indicus is an important pathogen of nosocomial infection. The purpose of this study was to analyze the resistance and transmission of A. indicus strain AIBD14 isolated from slaughterhouse environment.
A total of 96 environmental samples were collected from slaughterhouse. The antimicrobial susceptibility test was carried out by microbroth dilution method and E-test. Whole genome sequencing and bioinformatics analysis of the AIBD14 were performed, then S1-PFGE and southern blot verified the location of bla and tet(X6).
The AIBD14 is resistant to meropenem but susceptibility to tigecycline, and coharboring bla and tet(X6). The bla is located on the pAIBD14-NDM-1 that cannot be transferred by conjugation. Specifically, bla is located on the transposon Tn125, and bla can be transferred to other species with the help of transposon. The genetic background of bla is "ISAba125-bla-ble-dsbD-cutA-groES-groEL-insE-ISAba125". pAIBD14-NDM-1 is classified into the GR31 plasmid based on the homology of the repB. Meanwhile, there are two XerC/D-like binding sites on the plasmid, which can mediate the transfer of resistance genes. The tet(X6) gene is located on the chromosome of AIBD14, its downstream is accompanied by the neglected macrolide resistance gene estT, and there is a single copy of the insertion element ISCR2 around tet(X6) as the genetic background "ISAba4-IS3-hp-hp-tet(X6)-estT-guaA-ISCR2".
This is the first report of the coexistence of tet(X6) and bla in the A. indicus, and it has the risk of horizontal transfer across multiple species. So strict monitoring the multiple-resistant bacteria in the industrial chain is necessary based on the "One Heath".
印度不动杆菌是医院感染的重要病原菌。本研究旨在分析从屠宰场环境分离出的印度不动杆菌AIBD14菌株的耐药性及传播情况。
从屠宰场共采集96份环境样本。采用微量肉汤稀释法和E-test进行药敏试验。对AIBD14进行全基因组测序和生物信息学分析，然后通过S1-PFGE和Southern印迹验证bla和tet(X6)的位置。
AIBD14对美罗培南耐药，但对替加环素敏感，且同时携带bla和tet(X6)。bla位于不能通过接合转移的pAIBD14-NDM-1上。具体而言，bla位于转座子Tn125上，可借助转座子转移至其他物种。bla的基因背景为“ISAba125-bla-ble-dsbD-cutA-groES-groEL-insE-ISAba125”。基于repB的同源性，pAIBD14-NDM-1被归类为GR31质粒。同时，该质粒上有两个XerC/D样结合位点，可介导耐药基因的转移。tet(X6)基因位于AIBD14的染色体上，其下游伴有被忽视的大环内酯类耐药基因estT，tet(X6)周围有单个插入元件ISCR2作为基因背景“ISAba4-IS3-hp-hp-tet(X6)-estT-guaA-ISCR2”。
这是印度不动杆菌中tet(X6)和bla共存的首次报道，且具有跨多种物种水平转移的风险。因此，基于“同一健康”理念，有必要对产业链中的多重耐药菌进行严格监测。
