摘要
介绍
脆弱拟杆菌多药耐药性的出现，特别是携带碳青霉烯酶基因cfiA的系统发育谱系，对人类健康构成了越来越大的威胁。然而，关于耐多药菌株的多样性和携带抗生素抗性基因（ARGs）的遗传因素的知识仍然有限。
目标
本研究的目的是描述cfiA阳性脆弱双歧杆菌的耐药性。
方法
通过全基因组测序分析了2015-2017年香港不同来源的人类（8株菌血症，15株伤口感染）和动物（2只鸡，2只猪，6只狗，3只猫）中的cfiA阳性脆弱芽孢杆菌。
后果
在36个分离株中，检测到除cfiA之外的13个不同的ARG（总数83，中位数2，每个分离株的范围为0-7）。编码对氨基糖苷类、β-内酰胺类、大环内酯类、磺酰胺类和四环素类抗性的ARGs由CTn341样、CTnHyb样、Tn5220样、Tn 4555样和Tn613样转座子携带，并在不同宿主来源的系统发育多样的分离株中检测到。只有少数编码甲硝唑和四环素耐药性的ARG定位在质粒上。在两个鸡分离株中，发现一种新的转座子（命名为Tn6994）参与多种ARG的传播，介导对多种抗生素的耐药性，包括甲硝唑和利奈唑胺，这对厌氧感染的治疗至关重要。在交配实验中，Tn6994和相关的表型抗性可以转移到诺氏拟杆菌受体。
结论
本研究阐明了转座子在脆弱芽孢杆菌cfiA阳性分裂中ARGs传播的重要性。一种卫生方法对于追踪ARGs的传播是必要的。
Abstract
Introduction
The emergence of multidrug resistance in Bacteroides fragilis, especially the phylogenetic lineage carrying the carbapenemase gene cfiA, represents an increasing threat to human health. However, knowledge on the diversity of the multidrug-resistant strains and the genetic elements carrying the antibiotic resistance genes (ARGs) remains limited.

Aim
The objective of the study was to describe the resistome in cfiA-positive B. fragilis.

Methods
A collection of cfiA-positive B. fragilis from diverse human (8 bacteremias, 15 wound infections) and animal (2 chickens, 2 pigs, 6 dogs, 3 cats) sources in Hong Kong, 2015–2017 was analysed by whole genome sequencing.

Results
In the 36 isolates, 13 distinct ARGs (total number 83, median 2, range 0–7 per isolate) other than cfiA were detected. ARGs encoding resistance to aminoglycosides, β-lactams, macrolides, sulphonamides and tetracyclines were carried by CTn341-like, CTnHyb-like, Tn5220-like, Tn4555-like and Tn613-like transposons and were detected in phylogenetically diverse isolates of different host sources. Only few ARGs encoding resistance to metronidazole and tetracyclines were localized on plasmids. In two chicken isolates, a novel transposon (designated as Tn6994) was found to be involved in the dissemination of multiple ARGs mediating resistance to multiple antibiotics, including metronidazole and linezolid that are critically important for treatment of anaerobic infections. In mating experiments, Tn6994 and the associated phenotypic resistance could be transferred to Bacteroides nordii recipient.

Conclusion
This study illustrates the importance of transposons in the dissemination of ARGs in the cfiA-positive division of B. fragilis. One Health approach is necessary to track the dissemination of ARGs.

https://www.sciencedirect.com/science/article/pii/S1438422122000121