Huang Ying-Chi, Chen Feng-Jui, Huang I-Wen, Wu Han-Chieh, Kuo Shu-Chen, Huang Tzu-Wen, Lauderdale Tsai-Ling
National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan.
Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
J Glob Antimicrob Resist. 2024 Dec;39:100-108. doi: 10.1016/j.jgar.2024.06.005. Epub 2024 Jul 10.
The prevalence of vancomycin-resistant Enterococcus faecium (VREfm) has increased significantly in Taiwan. We investigated the molecular epidemiology of clinical VREfm isolates to increase our understanding on their spread and changes in population structure over a 14-year span.
A total of 1113 E. faecium isolates were collected biennially from 2004 to 2018 in Taiwan. MICs were determined by broth microdilution. Whole-genome sequencing (WGS) was performed on 229 VREfm isolates to characterize their genetic environment of vancomycin resistance and wgMLST was used to investigate their clonal relationship.
Among the 229 isolates, ST17 and ST78 predominated, especially during the later years, and their prevalences increased from 14.6% (7/48) and 25.0% (12/48) in 2004-2010 to 47.5% (87/181) and 29.8% (54/181) in 2012-2018, respectively. Four types of vanA-carrying Tn1546 variants were detected, with type 1 and type 2 predominated. Type 1 Tn1546 contained an addition of IS1251, while type 2 resembled type 1 but had an addition of IS1678. wgMLST revealed several distinct clusters of ST17 and ST78 isolates, with type 1 Tn1546-harbouring ST17-Cluster 16 being the largest and most widespread clones throughout the study years. Type 2 Tn1546-carrying ST78 became a predominant clone (Cluster 21) after 2012. Isolates within these clusters are highly similar despite being from different hospitals, regions, and study year.
The increase of VREfm in Taiwan was attributed to horizontal transfer of vanA-carrying Tn1546 variants between different STs and spread of persistent clones. This study highlights the importance of integrating WGS into surveillance to combat antimicrobial resistance.
耐万古霉素屎肠球菌（VREfm）在台湾的流行率显著上升。我们调查了临床VREfm分离株的分子流行病学，以增进我们对其在14年期间的传播及种群结构变化的了解。
2004年至2018年期间，台湾每隔两年收集共1113株屎肠球菌分离株。采用肉汤微量稀释法测定最低抑菌浓度（MIC）。对229株VREfm分离株进行全基因组测序（WGS），以表征其耐万古霉素的遗传环境，并使用全基因组多位点序列分型（wgMLST）研究它们的克隆关系。
在229株分离株中，ST17和ST78占主导地位，尤其是在后期，其流行率分别从2004 - 2010年的14.6%（7/48）和25.0%（12/48）增至2012 - 2018年的47.5%（87/181）和29.8%（54/181）。检测到四种携带vanA的Tn1546变体类型，其中1型和2型占主导。1型Tn1546含有一个额外的IS1251，而2型与1型相似，但含有一个额外的IS1678。wgMLST揭示了ST17和ST78分离株的几个不同聚类，其中携带1型Tn1546的ST17 - 聚类16是整个研究期间最大且分布最广的克隆。携带2型Tn1546的ST78在2012年后成为主要克隆（聚类21）。尽管这些聚类中的分离株来自不同医院、地区和研究年份，但它们高度相似。
台湾VREfm的增加归因于携带vanA的Tn1546变体在不同ST之间的水平转移以及持续克隆的传播。本研究强调了将WGS纳入监测以对抗抗菌药物耐药性的重要性。
