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Published on: January 27, 2021
Mobile Colistin Resistance Genetic Determinants of Non-Typhoid Salmonella enterica Isolates from Russia
Konstantin V Kuleshov1,2, Anastasia S Pavlova1, Elizaveta D Shedko1
1Central Research Institute of Epidemiology, 111123 Moscow, Russia.
Abstract:
Polymyxin resistance, determined by mcr genes located on plasmid DNA, currently poses a high epidemiological threat. Non-typhoid Salmonella (NTS) are one of the key pathogens causing diarrheal diseases. Here, we report the isolation and whole genome sequencing of multidrug colistin-resistant/susceptible isolates of non-typhoid Salmonella enterica serovars carrying mcr genes. Non-typhoid strains of Salmonella enterica subsp. enterica were isolated during microbiological monitoring of the environment, food, and diarrheal disease patients between 2018 and 2020 in Russia (n = 586). mcr-1 genes were detected using a previously developed qPCR assay, and whole genome sequencing of mcr positive isolates was performed by both short-read (Illumina) and long-read (Oxford Nanopore) approaches. Three colistin-resistant isolates, including two isolates of S. Enteritidis and one isolate of S. Bovismorbificans, carried the mcr-1.1 gene located on IncX4 and IncI2 conjugative plasmids, respectively. The phenotypically colistin-susceptible isolate of S. Typhimurium carried a mcr-9 gene on plasmid IncHI2. In conclusion, we present the first three cases of mcr gene-carrying NTS isolates detected in Russia with both outbreak and sporadic epidemiological backgrounds.
Insights
Polymyxin resistance is a growing threat. This study identified mcr genes in non-typhoid Salmonella (NTS) from Russia, including colistin-resistant and susceptible strains, highlighting plasmid-mediated resistance.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Polymyxin resistance, driven by plasmid-borne mcr genes, presents a significant global health challenge.
- Non-typhoid Salmonella (NTS) are crucial pathogens responsible for diarrheal illnesses.
Purpose of the Study:
- To report the isolation and whole genome sequencing of multidrug-resistant and susceptible non-typhoid Salmonella enterica serovars carrying mcr genes.
- To investigate the presence and genetic context of mcr genes in NTS isolates from Russia.
Main Methods:
- Isolation of NTS from environmental, food, and patient samples (2018-2020).
- Detection of mcr-1 genes via qPCR assay.
- Whole genome sequencing using short-read (Illumina) and long-read (Oxford Nanopore) technologies.
Main Results:
- Three colistin-resistant NTS isolates (S. Enteritidis, S. Bovismorbificans) harbored the mcr-1.1 gene on IncX4 and IncI2 plasmids.
- One colistin-susceptible S. Typhimurium isolate carried the mcr-9 gene on an IncHI2 plasmid.
- This marks the first detection of mcr gene-carrying NTS in Russia across outbreak and sporadic cases.
Conclusions:
- The study identified mcr gene-carrying NTS in Russia, underscoring the need for surveillance.
- Plasmid-mediated polymyxin resistance in NTS is an emerging concern.
- The findings contribute to understanding the epidemiology of antimicrobial resistance in Salmonella.
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