Molecular characterization and resistance mechanisms of linezolid-resistant enterococci clinical isolates and identification of a clinical Enterococcus faecium strain co-harboring optrA, poxtA, and cfr(D) in a tertiary hospital in China.
Ni Suo, Jing Yu, Haijun Li, Nan Yi, Cailin Liu, Wanhai Wang
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引用次数: 0
Abstract
Objectives: The emergence of linezolid-resistant enterococci has become a significant global health concern. This study aimed to investigate the molecular characterization and resistance mechanisms in clinical isolates in a tertiary hospital in China.
Methods: The VITEK®2 Compact system, VITEK® MS, and whole-genome sequencing (WGS) were used to identify 59 linezolid-resistant enterococci isolates. Antimicrobial susceptibilities were assessed by broth microdilution. WGS and bioinformatics tools analyzed resistance mechanisms and molecular characteristics. Plasmid-borne linezolid resistance gene transfer was assessed via conjugation and transformation assays.
Results: We collected 59 linezolid-resistant enterococci isolates, including 54 Enterococcus faecalis and 5 Enterococcus faecium strains. One strain carried the poxtA gene, one isolate carried the G2576T mutation in the 23S rRNA gene, and 56 isolates harbored the optrA gene. Notably, one isolate co-harbored the optrA, poxtA, and cfr(D) genes. Twenty-three sequence types (STs) were identified. ST16 (48.1%, 26/54) predominated in E. faecalis. Multilocus sequence typing (MLST) and evolutionary analysis indicated that E. faecalis strains of the same ST were genetically related. Among the seven strains (two E. faecium and five E. faecalis strains) selected for further investigation, IS1216E was detected on plasmids carrying linezolid resistance genes in all five strains. Additionally, transposon Tn554 was detected on the chromosome of an optrA-carrying strain.
Conclusion: This study describes the molecular characteristics and resistance mechanisms of linezolid-resistant enterococci in our hospital, including a novel E. faecium isolate with optrA, poxtA, and cfr(D), highlighting the need for enhanced surveillance to control the dissemination of resistant strains.
期刊介绍：
The Journal of Global Antimicrobial Resistance (JGAR) is a quarterly online journal run by an international Editorial Board that focuses on the global spread of antibiotic-resistant microbes.
JGAR is a dedicated journal for all professionals working in research, health care, the environment and animal infection control, aiming to track the resistance threat worldwide and provides a single voice devoted to antimicrobial resistance (AMR).
Featuring peer-reviewed and up to date research articles, reviews, short notes and hot topics JGAR covers the key topics related to antibacterial, antiviral, antifungal and antiparasitic resistance.
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