Work

Prevalence and molecular epidemiology of optrA-positive Enterococcus in herders and yaks from high-altitude Tibet, China

Year: 2025

Type: article

Abstract: OBJECTIVES: Antimicrobial resistance (AMR) in high-altitude environments remains understudied despite its growing global concern. This study investigates the molecular epidemiology of the optrA gene, which confers resistance to oxazolidinones and phenicols, in Enterococcus species isolated from herders and yak faecal samples in Nagqu, Tibet, China. METHODS: A total of 161 faecal samples from herders and 42 from yaks were collected and analysed for the presence of optrA-positive Enterococcus strains. Antimicrobial susceptibility testing (AST) was performed to determine resistance patterns. Whole-genome sequencing (WGS) and phylogenetic analysis were used to assess genetic relationships and the potential for clonal spread and horizontal gene transfer. RESULTS: The optrA gene was detected in 6.2% (10/161) of human samples and 9.5% (4/42) of yak samples, indicating a higher prevalence in yaks. Resistance was highest for tetracycline (100%), erythromycin (92.9%), and linezolid (92.9%). Phylogenetic analysis revealed clonal dissemination, with some isolates exhibiting high genetic homology. Notably, one E. faecalis strain belonged to ST16, a sequence type commonly found in low-altitude cities, suggesting potential transmission between regions. The optrA gene was frequently associated with mobile genetic elements, indicating a risk of horizontal gene transfer and further dissemination of resistance. CONCLUSION: The presence of optrA-positive Enterococcus in both human and animal populations in this high-altitude region underscores the role of human-animal interactions in AMR transmission. The increasing prevalence of resistant strains in yaks, coupled with genetic evidence of clonal expansion, highlights the need for a comprehensive One Health approach to AMR surveillance and mitigation in remote, high-altitude environments.

Source: Journal of Global Antimicrobial Resistance

DOI: 10.1016/j.jgar.2025.10.016

Authors: Hanyu Wang, Xinyue Han, Aoxiao Chen, Zelin Yan, Rong Zhang, Yang Wang

Institutions: Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Second Affiliated Hospital of Zhejiang University, Zhejiang University

Language: English

Topic: Antibiotic Resistance in Bacteria

Subfield: Molecular Medicine

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $1,890