Prevalence and molecular characterization of mcr-1-positive foodborne ST34-Salmonella isolates in China

Zhenyu Wang; Zhongyi Jiang; Haiyan Xu; Xinan Jiao; Qiuchun Li

doi:10.1016/j.micres.2023.127441

Prevalence and molecular characterization of mcr-1-positive foodborne ST34-Salmonella isolates in China

Microbiol Res. 2023 Sep:274:127441. doi: 10.1016/j.micres.2023.127441. Epub 2023 Jun 20.

Authors

Zhenyu Wang¹, Zhongyi Jiang¹, Haiyan Xu², Xinan Jiao³, Qiuchun Li⁴

Affiliations

¹ Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, Yangzhou University, China.
² Nantong Center for Disease Control and Prevention, Nantong 226007, China.
³ Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, Yangzhou University, China. Electronic address: jiao@yzu.edu.cn.
⁴ Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, Yangzhou University, China. Electronic address: qcli@yzu.edu.cn.

PMID: 37356255
DOI: 10.1016/j.micres.2023.127441

Abstract

Salmonella enterica serovar Typhimurium (S. Typhimurium) and S. 4,[5],12:i:- have become the most common serovars associated with human salmonellosis worldwide. Moreover, the emergence of mcr-carrying S. Typhimurium and S. 4,[5],12:i:- with multidrug resistance (MDR) patterns has posed a threat to public health. In this study, we retrospectively screened 2009-2022 laboratory-preserved strains for the presence of mcr genes. We obtained 16 mcr-1-positive S. Typhimurium and S. 4,[5],12:i:- strains with MDR that belonged to sequence type 34 (ST34). Whole-genome sequencing analysis revealed that the mcr-1 was located on the IncI2 or IncHI2 plasmids. The ISApl1 element downstream of mcr-1 was present in all pig-derived strains. Conjugation experiments confirmed that nine mcr-1-carrying IncHI2 plasmids could not be transferred to Escherichia coli due to loss of the conjugation region. Finally, core genome single nucleotide polymorphism (cgSNP) analyses of the 16 mcr-1-carrying strains and 77 mcr-carrying ST34-Salmonella genome sequences from the NCBI and ENA databases showed that five out of eight clusters contained strains from pig and pig products, revealing pigs and pig products as key reservoirs of mcr-1-positive ST34-Salmonella strains. The transmission of mcr-carrying ST34 Salmonella strains to humans via the pig food chain is a potential cause for public health concern in controlling human salmonellosis.

Keywords: Core genome single nucleotide polymorphism (cgSNP); Pig; S. 4,[5],12:i:-; Salmonella enterica serovar Typhimurium (S. Typhimurium); mcr-1.

MeSH terms

Animals
Anti-Bacterial Agents
China
Escherichia coli / genetics
Humans
Microbial Sensitivity Tests
Plasmids / genetics
Prevalence
Retrospective Studies
Salmonella Infections*
Salmonella typhimurium* / genetics
Swine

Substances

Anti-Bacterial Agents