Genotyping of Salmonella enterica serovar Enteritidis, isolated from human and animal by REP-PCR

* Corresponding author: Taghi Zahraei Salehi E-mail: tsalehi@ut.ac.ir Background: Salmonellosis is a zoonotic disease of human and animals. One of the most important serovars in human, livestock and poultry is Salmonella enteritidis, which is a worldwide common foodborne pathogen. Conventional culture, biochemical and serological methods has been shown to have limited value as molecular analysis tool with low discriminatory power but molecular typing methods such as REP-PCR produced DNA profiles for differentiation and characterization of Salmonella strains. The aim of this study was differentiation of isolates of Salmonella enteritidis by molecular fingerprinting method based on repeated sequences (rep-PCR). Materials and Methods: In a cross-sectional study, 64 isolates of Salmonella Enteritidis from various sources (cows, poultry and humans) were studied by rep-PCR method and REP1R and REP2I primers. The molecular patterns were determined on the basis of the existence or absence of DNA fragments were separated according to their size by agarose gel electrophoresis. By using a computer program NTSYS, dendrogram were drawn. Results: The number of 5-14 bands with the approximate size ranging from 100 to 3,000 base pairs with a common fragment (400 bp) were observed. The number of molecular profiles obtained by REP1R and REP2I primers for 64 isolates of Salmonella Enteritidis was 38 profiles. The similarities between avian and human isolates based on cluster analysis were more than bovine isolates and about 72% to 81%. However, a bovine strain known as B13 was found with 82% similarity to human strains. Conclusion: In this study, rep-PCR demonstrated a high discriminatory power in analyzing Salmonella Enteritidis isolates. High heterogeneity (92.8%) was measured in a population of 64 different isolates of Salmonella enteritidis by Shannon-Wiener index. Meanwhile, according to the results, Salmonella enteritidis strains isolated from poultry and human have more similarities together (almost 72-81%) than bovine strains (48% similarity). Therefore, it suggests that epidemiologically risk of human infections caused by Salmonella enteritidis strains, which originates from poultry and its products is higher.