High Prevalence and Overexpression of Fosfomycin-Resistant Gene fos X in Enterococcus faecium From China

Ling Xin; Xiaogang Xu; Qingyu Shi; Renru Han; Jue Wang; Yan Guo; Fupin Hu

doi:10.3389/fmicb.2022.900185

High Prevalence and Overexpression of Fosfomycin-Resistant Gene fos X in Enterococcus faecium From China

Front Microbiol. 2022 Jul 8:13:900185. doi: 10.3389/fmicb.2022.900185. eCollection 2022.

Authors

Ling Xin^{1

2}, Xiaogang Xu^{1

2}, Qingyu Shi^{1

2}, Renru Han^{1

2}, Jue Wang^{1

2}, Yan Guo^{1

2}, Fupin Hu^{1

2}

Affiliations

¹ Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China.
² Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China.

Abstract

Enterococci are one of the main causes of gastrointestinal tract infections in the healthcare system and can develop resistance to fosfomycin through plasmid or chromosomally encoded fosfomycin resistance genes. To investigate the mechanisms of fosfomycin resistance, a total of 4,414 clinical isolates of non-replicated clinical enterococci collected from 62 hospitals in 26 provinces or cities in China were tested. Antibiotic susceptibility testing, detection of fosfomycin resistance genes, and cloning of the fosX gene were done. The PFGE, MLST, qRT-PCR, and next genome sequencing were carried out. The results revealed that the fosfomycin-resistant rate of enterococci was 3.5% (153/4,414), and the major resistance mechanism was fosX (101/153) and fosB (52/153) genes. The fosX gene could increase 4- fold fosfomycin MIC in Enterococcus faecium BM4105RF transformants, and the results of PFGE showed the 101 E. faecium carrying fosX were grouped into 48 pulse types. The multilocus sequence typing identified ST555 as the vast majority of STs, mostly distributed in Shanghai, China. Furthermore, the fosX gene expression was strongly related to the fosfomycin-resistant levels of enterococci. The present study was the first to describe the high prevalence presence of the fosX gene in E. faecium from China.

Keywords: Enterococci; fosX; fosfomycin; prevalence; resistance.