Complete Genome Sequence of Salmonella enterica subsp. enterica Serovar Paratyphi B Sequence Type 28 Harboring mcr-1

Area of Science:

• Microbiology
• Genomics
• Antimicrobial Resistance

Background:

• Plasmid-mediated colistin resistance emerged in 2015 due to the mobilized phosphoethanolamine transferase gene (mcr-1) in Enterobacteriaceae.
• Colistin is a critical last-resort antibiotic for treating multidrug-resistant Gram-negative infections.

Purpose of the Study:

• To announce the complete genome sequence of the earliest known d-tartrate-fermenting Salmonella Paratyphi B isolate harboring the mcr-1 gene.
• To characterize the genetic context of early mcr-1 acquisition in Salmonella.

Main Methods:

• Whole-genome sequencing of a Salmonella Paratyphi B isolate.
• Bioinformatic analysis to identify the mcr-1 gene and its surrounding genetic elements.
• Phylogenetic analysis to determine the isolate's relationship to other Salmonella strains.

Main Results:

• The complete genome sequence of a d-tartrate-fermenting Salmonella Paratyphi B isolate from Germany was determined.
• This isolate represents the earliest documented instance of mcr-1 carriage in this specific Salmonella serovar.
• The mcr-1 gene was found on a plasmid, providing insights into its mobilization.

Conclusions:

• The findings highlight the early presence and potential for plasmid-mediated spread of colistin resistance in Salmonella.
• This genomic data is vital for understanding the evolution and dissemination of antimicrobial resistance globally.
• Surveillance and characterization of such early resistant strains are crucial for public health interventions.