Study of integrons class 1, 2, and 3 frequencies in Salmonella Typhimurium isolated from clinical samples using polymerase chain reaction

  Presence of integrons class 1, 2, and 3 in Salmonella typhimurium with multidrug resistance have been raised concerns about the integrons’ frequencies in clinic. Regarding different drug resistant genes are located in integrons and on the other hand, integrons are able to spread rapidly, so that identification of isolates carrying integrons could provide useful information about the degree of resistance. The gaim of this study was the molecular analysis of integrons class 1, 2 and 3 as important integron classes in Salmonella typhimurium strains which are isolated from patients by using multiplex PCR. In this study, 891 samples are collected from patients with acute gastroenteritis and then Salmonella typhimurium strains were detected by using standard biochemical test and PCR in culture method. Antimicrobial susceptibility test was done on Müller-Hinton agar media according to the Clinical and laboratory standards institute (CLSI) guidelines. After DNA extraction, the presence of integrons class 1, 2, and 3 were analyzed by multiplex PCR. Out of 891 samples, 48 strains detected as a Salmonella typhimurium. Out of these 48 strains, 46 strains (95.8%) had the intI gene, 2 strains (4.1%) had the intII gene, and 18 strains (37.5%) had the intIII gene. Antimicrobial susceptibility test showed that the most antibiotic resistance pattern was observed to cefotaxime. Strians with integrin genes had resistance to Gentamicin, Ampicillin,Tetracycline,Co-amoxiclave and Trimethoprim antibiotics. In this study, we observed the high incidence of integrons class 1, 2, and 3 in comparison to previous studies which were presumably due to differences in hygiene and also overuse of antibiotics.
Carrying out appropriate methods for controlling infection and treatment in studied health centers are essential for preventing the further spread of multi drug resistant Salmonella typhimurium.