The study of the prevalence of class I integrons and virulence plasmid in clinical strains of Salmonella Typhimurium

Certain serovars of Salmonella, belonging to subspecies I of Salmonella enterica, carry virulence plasmid of spv operon carrier. This operon along with other genes has a major role in creating virulence and drug resistance. Considering the importance of the issue, this study examines the prevalence of class I integrons and virulence plasmid in clinical strains of Salmonella Typhimurium. 663 stool samples were collected from hospitals in Tehran. After performing biochemical tests on the samples, 37 genuses of salmonella were isolated. Then using specific primers ST11,ST15 and Fli15,Typ04 to identify genus and species respectively, 12 isolates from the total of 37 salmonella, were confirmed as salmonella Typhimurium. Finally in order to investigate the presence of class I integrons and virulence plasmid, Multiplex PCR test was performed, using Int and Vir primers. The results showed that from the total of 12 isolates, 4 isolates (33.3%) had the genes related to class I integron and 5 isolates 41.7%) had the virulence plasmid. The presence of virulence plasmid genes and class I integrons among Typhimurium strains isolated in this study shows that, considering the horizontal transfer of these genes, these strains can cause serious problems in public health, community health and treatment.