Genetic Profiling of Salmonella enteritidis Strains Isolated in the Stavropol Region in 2016–2019

Abstract

Introduction: Salmonella enteritidis is the most common etiologic agent of salmonellosis in humans in the Stavropol Region, which is in line with the global trend. In this regard, the definition of a serovar provides little information in the course of an epidemiological investigation and necessitates subspecific typing of S. enteritidis isolates. Objective: MLVA typing of S. enteritidis strains isolated in the Stavropol Region in 2016–2019 and the analysis of the genetic structure of the local Salmonella population. Materials and methods: We studied 122 strains of S. enteritidis isolated in 2016–2019 from stool samples of patients with acute intestinal infections in the city of Stavropol and the Caucasian Mineral Waters (CMW) of the Stavropol Region. Multi Locus Variable Number Tandem Repeat (MLVA) typing was performed based on five variable loci. The size of amplified loci was determined by capillary electrophoresis. Results: The studied strains were distinguished by high genetic heterogeneity and belonged to 25 MLVA genotypes. S. enteritidis strains belonging to 24 MLVA types were identified on the territory of Stavropol. The dominant genetic variant in the city was 3-10-5-4-1, which included 40 Salmonella strains (44.4%) isolated in 2016–2019. In some years, the proportion of other genetic variants increased. In the CMW area, strains belonging to seven MLVA genotypes were isolated, most of which belonged to the profile 3-10-5-4-1, while a change in the dominant variant of S. Enteritidis was registered annually. Prevalent regional MLVA types are widespread in the world and have a significant epidemic potential. Conclusions: We obtained new data on S. enteritidis MLVA genotypes in the Stavropol Region, established dominant genetic variants, and noted differences in the ratio of circulating MLVA genotypes of S. enteritidis in 2016–2019. Our findings necessitate constant molecular genetic monitoring to assess real-time dynamic changes in the genetic structure of the Salmonella population. They can also be used in investigations of possible cases (outbreaks) of salmonellosis to determine their source and routes of transmission.