Epidemiological and genomic characteristics of linezolid-resistant Enterococci iso-lated from livestock farms in Changsha
10.16303/j.cnki.1005-4545.2025.05.13
- VernacularTitle:长沙地区养殖场利奈唑胺耐药肠球菌的流行及基因组特征
- Author:
Jianqin LIU
1
;
Jianchao ZHANG
;
Zhi CHEN
;
Hui YANG
;
Honggang ZHU
;
Liang QI
;
Xiao-jun CHEN
Author Information
1. 湖南农业大学 动物医学院湖南省兽药工程技术研究中心,湖南 长沙 410000
- Publication Type:Journal Article
- Keywords:
Enterococcus;
oxazolidinone;
drug resistance;
WGS
- From:
Chinese Journal of Veterinary Science
2025;45(5):978-986
- CountryChina
- Language:Chinese
-
Abstract:
To investigate the antimicrobial resistance of Enterococci isolated from 596 anal swabs,feces and environmental samples were collected from pig,cattle,chicken and quail farms in Chang-sha,Hunan Province,Enterococci were isolated and identified by mass spectrometry.The minimum inhibitory concentrations(MICs)of 10 antimicrobial agents were determined by AGAR diffusion method.Whole genome sequencing(WGS)was used to detect the distribution of multilocus se-quence typing(ST),drug resistance genes and virulence genes.A total of 272 strains of Enterococ-cus were isolated(45.6％).The isolates were resistant to cefoxitin(68.9％)and cefotiofur(58.5％),followed by trimethoprim/sulfamethoxazole(52.2％),vancomycin(4.4％),and linezolid(13.6％).In this study,six linezolid highly resistant Enterococci isolates were analyzed by whole genome sequencing to explore the transmission mechanism of linezolid resistance because linezolid is forbidden to be used in aquaculture.ST403(4/6),ST16(1/6)and ST476(1/6)were the most common ST types,which all originated from the same farm.Three oxazolidinone resistance genes(cfr,poxtA and optrA)were found in all 21 strains.One strain(Ecc60)carried all three oxazo-lidinone resistance genes,but none of them were located on the plasmid.tet(M),aph(3')-Ⅲ,and lsa(A)were found in all six Enterococcus isolates.Interestingly,the present study is the first to i-dentify enterococci carrying the optrA gene in quail fecal samples.The analysis of the genetic envi-ronment of oxazolidinone resistance genes showed that the genetic environment of cfr(D),poxtA and optrA of isolates from the same farm was similar.A total of 19 virulence genes were detected in 6 isolates,of which 12 genes(ElrA,SrtA,ace,agg,cCF10,cOB1,cad,camE,ebpA,ebpC,efaAfs,tpx)were carried by all 6 isolates,and the types of virulence genes in strains from the same farm were extremely similar.The results showed that the drug resistance of Enterococci iso-lated from the fish farms in Changsha was serious,and the resistance rate to linezolid,which was prohibited in the fish farms,was high.The oxazolidinone resistance gene loci were accompanied by other resistance genes,especially the florfenicol resistance gene(FexA),which may be related to the abuse of florfenicol in the fish farms.
