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.
Highlights
All isolates were subjected to antibiotic susceptibility testing, as well as screened for the presence of mcr1-type by a specific qPCR
The presence of an mcr-9 gene in its genome was discovered during a whole genome sequencing study of Salmonella isolates circulating in Russia, which were characterized as a multidrug-resistant phenotype
The novelty of our study is the detection and description of four Russian Non-typhoid strains of Salmonella enterica (NTS) isolates at a genomic level, revealing details about plasmids carrying mcr genes
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Non-typhoid strains of Salmonella enterica (NTS) contribute significantly to the incidence of intestinal infections worldwide [1]. There are more than 90 million cases of Salmonella gastroenteritis each year, resulting in 155,000 deaths [2]. Despite a trend towards a decrease in salmonellosis, it is still the most frequently recorded foodborne zoonosis in Russia. The annual incidence rate of salmonellosis in Russia decreased from. ND food (chicken meat) SLR1_8245 Russia:El’ban Outbreak human SLR1_7627
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