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Mobile genetic elements-driven partitions of mega-plasmids resistome in Salmonella Infantis
Yujie Zhang1, Mackenna Chu1, Yen-Te Liao1
1Produce Safety and Microbiology Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center, Albany, California, USA.
Microbiology Spectrum
|July 23, 2026
Summary
Salmonella Infantis mega-plasmids carry antibiotic-resistant genes (ARGs) via mobile genetic elements (MGEs). Understanding MGEs
Area of Science:
- Genomics and Bioinformatics
- Microbiology
- Public Health
Background:
- Salmonella enterica serovar Infantis (S. Infantis) is a leading cause of foodborne illness in the US, with global spread facilitated by pESI-like plasmids.
- The mechanisms of S. Infantis transmission, especially concerning mobile genetic elements (MGEs) and horizontal gene transfer, are not well understood.
- Antibiotic resistance in S. Infantis is a growing public health concern, with mega-plasmids identified as key reservoirs for antibiotic-resistant genes (ARGs).
Purpose of the Study:
- To investigate the relationship between MGEs, ARGs, and virulence factors (VFs) in S. Infantis.
- To elucidate the role of MGEs in the acquisition and dissemination of ARGs within S. Infantis mega-plasmids.
Main Methods:
- Genomic analysis of 91 high-quality complete S. Infantis genomes.
- Bioinformatic analysis to identify and characterize MGEs, ARGs, and VFs.
- Comparative genomics to assess the distribution and association of genetic elements.
Main Results:
- Most VFs were located on bacterial chromosomes, while ARGs were predominantly found on S. Infantis mega-plasmids, often associated with MGEs.
- Integrons and transposons showed a close association with specific ARGs.
- Prophages within mega-plasmids exhibited a diverse profile of ARGs, suggesting varied contributions to the resistome.
Conclusions:
- MGE-mediated horizontal gene transfer likely facilitates ARG acquisition by mega-plasmids in S. Infantis.
- The findings highlight the role of MGEs in shaping the antibiotic resistome of S. Infantis mega-plasmids.
- This research provides crucial insights for developing targeted strategies to control multidrug-resistant S. Infantis and safeguard public health.
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