Department of Microbiology, Queen Mary Hospital, University of Hong Kong, Hong Kong Special Special Administrative Region of China; Carol Yu Center for Infection, University of Hong Kong, Hong Kong Special Special Administrative Region of China.
Department of Microbiology, Queen Mary Hospital, University of Hong Kong, Hong Kong Special Special Administrative Region of China.
Int J Med Microbiol. 2022 Aug;312(6):151559. doi: 10.1016/j.ijmm.2022.151559. Epub 2022 Aug 8.
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.
The objective of the study was to describe the resistome in cfiA-positive B. fragilis.
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.
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.
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.
脆弱拟杆菌出现多药耐药性，尤其是携带碳青霉烯酶基因 cfiA 的进化谱系，这对人类健康构成了日益严重的威胁。然而，关于多药耐药菌株的多样性以及携带抗生素耐药基因（ARGs）的遗传元件的知识仍然有限。
本研究旨在描述 cfiA 阳性脆弱拟杆菌的耐药组。
2015 年至 2017 年，从香港不同人类（8 例菌血症，15 例伤口感染）和动物（2 只鸡、2 只猪、6 只狗、3 只猫）来源的 cfiA 阳性脆弱拟杆菌收集了一组样本，并通过全基因组测序进行分析。
在 36 株分离株中，除了 cfiA 之外，还检测到 13 种不同的 ARGs（总数 83 个，中位数 2 个，每个分离株 0-7 个）。编码对氨基糖苷类、β-内酰胺类、大环内酯类、磺胺类和四环素类耐药的 ARGs 由 CTn341 样、CTnHyb 样、Tn5220 样、Tn4555 样和 Tn613 样转座子携带，并且在不同宿主来源的具有不同进化关系的分离株中都有检测到。编码对甲硝唑和四环素耐药的少数 ARGs 定位于质粒上。在 2 只鸡分离株中，发现了一种新的转座子（命名为 Tn6994），它参与了多种 ARGs 的传播，这些 ARGs 介导了对多种抗生素的耐药性，包括甲硝唑和利奈唑胺，这些抗生素对治疗厌氧感染至关重要。在交配实验中，Tn6994 及其相关表型耐药性可被转移到拟杆菌 nordii 受体。
本研究说明了转座子在 cfiA 阳性脆弱拟杆菌中 ARGs 传播中的重要性。需要采取“同一健康”方法来跟踪 ARGs 的传播。
