Related Experiment Video
Updated: Dec 24, 2025
An Allelotyping PCR for Identifying Salmonella enterica serovars Enteritidis, Hadar, Heidelberg, and Typhimurium
Published on: July 22, 2011
Carriage of Distinct mcr-1-Harboring Plasmids by Unusual Serotypes of Salmonella
Biao Tang1, Jiang Chang1,2, Ling Zhang2
1Institute of Quality and Standard for Agro-Products & State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, 310021, China.
Abstract:
Colistin acts as a last-resort antibiotic against lethal infections by carbapenem-resistant Enterobacterial pathogens. Enterobacteriaceae carrying mobile colistin resistance (MCR) genes are rapidly emerging and threatening human health and food safety. Despite mcr-1 being prevalent in Escherichia coli, its dissemination in Salmonella is not well characterized. Herein, two unusual serotypes of colistin-resistant Salmonella isolates are reported first, namely serotype Ngor (ST5399) and Goldcoast (ST2529). Using whole genome sequencing, it is shown that mcr-1 is located on the IncHI2-like plasmid pTB501 (188,527 bp) of strain SSDFZ54 and the IncX4-type plasmid pTB602 (33,303 bp) in strain SSDFZ69, respectively. Furthermore, the backbone, tra- and antimicrobial resistance genes relative variable regions in the mcr-1-bearing IncHI2 plasmids are systematically characterized. Phylogenetic analysis shows that all IncHI2-type plasmids from non-Chinese regions are clustered together, suggesting a possible Chinese origin. Taken together, these findings extend the understanding of Salmonella as a vehicle of mcr-1 carriage and distribution.
Insights
Mobile colistin resistance (MCR) genes in Salmonella are a growing threat. This study identifies novel MCR-1 carrying Salmonella serotypes and plasmids, highlighting their potential for wider dissemination.
Area of Science:
- Microbiology
- Genetics
- Public Health
Background:
- Colistin is a critical antibiotic for treating carbapenem-resistant Enterobacterial infections.
- The emergence of mobile colistin resistance (MCR) genes, particularly mcr-1, poses a significant threat to human health and food safety.
- The prevalence and characteristics of mcr-1 dissemination in Salmonella species are not fully understood.
Purpose of the Study:
- To characterize the presence and genetic context of the mcr-1 gene in previously unreported colistin-resistant Salmonella serotypes.
- To investigate the plasmid types and genomic features associated with mcr-1 in Salmonella.
- To explore the potential origin and dissemination patterns of mcr-1-bearing plasmids in Salmonella.
Main Methods:
- Whole genome sequencing of colistin-resistant Salmonella isolates.
- Plasmid analysis, including size, type, and gene content.
- Phylogenetic analysis of IncHI2-type plasmids.
Main Results:
- Identification of two novel colistin-resistant Salmonella serotypes, Ngor (ST5399) and Goldcoast (ST2529), carrying the mcr-1 gene.
- mcr-1 was located on an IncHI2-like plasmid (pTB501) in one isolate and an IncX4 plasmid (pTB602) in another.
- Systematic characterization of mcr-1-bearing IncHI2 plasmids revealed conserved backbone structures and variable regions.
- Phylogenetic analysis suggested a possible Chinese origin for IncHI2-type plasmids found in non-Chinese regions.
Conclusions:
- Salmonella can act as a significant vehicle for the carriage and distribution of the mcr-1 gene.
- The findings expand the understanding of mcr-1 epidemiology in Salmonella.
- Continued surveillance is crucial to monitor the spread of mobile colistin resistance in foodborne pathogens.
Related Concept Videos
01:28Plasmids
01:19Mechanism of Conjugation
01:19Conjugation