Role of current typing methods in investigating the genetic diversity of Salmonella strains isolated from different sources and their antibiotic susceptibility

Materials and methods. There were data of a reference center for salmonellosis monitoring on the biological characteristics of 4240 Salmonella strains isolated from humans and animals, foodstuffs and environmental objects in different areas of the country in 2011-2016. Serotyping was performed using Enteroclons monoclonal reagents («SIFIN», Germany). Phage typing of S. enteritidis was carried out applying the collection of type phages, which had been designed by the National Institute of Hygiene (Hungary). Antibiotic susceptibility was determined on the ATBTM G-5 plates («bioMerieux», France), the structure of the strains was ascertained by analysis of a set of total DNA restriction products with pulsed field gel electrophoresis (PFGE). Results. The leading strains in the etiological structure of salmonellosis were S. enteritidis (39.5 to 71.3%), followed by S. typhimurium (2.0 to 6.7%) and S. infantis (4.8 to 9.0%). 85% of the S. enteritidis strains isolated from different sources were shown to belong to phage type 1. 72% of the strains of this serovar were susceptible to all tested antibiotics. The susceptibility to all antibiotics was revealed in S. typhimurium (19%) and S. infantis (32%). The strains resistant to several antibiotics were predominant among S. infantis strains. Molecular genetic typing has shown that Salmonella strains belonging to the same PFGE pattern, leading of which were JEGX 01.0001-JEGA 26.0001 (S. enteritidis), JPXX0 1.0013-JPXA 26.0009 (S. typhimurium), and JFXX 01.0015-JFXA 26.0011 (S. infantis), circulate in different areas of the country. Conclusion. PFGE analysis was attempted to identify Salmonella strains that are difficult to diagnose.

monitoring, salmonellosis, phage typing, antibiotic susceptibility, pulsed field electrophoresis (PFGE), etiological structure