Genetic-molecular Sources of Multidrug Resistance of Salmonella Isolated from Eggs

Background: Bacteria can be transmitted to consumers around the world due to the movement of animals, and food products. The current study's goal is to look into the genetic and molecular causes of Salmonella isolated from eggs' multidrug resistance. Methods: ۵۰۰ egg samples from ۳۷ Iranian brands were extracted from Salmonella yolk and shell source and after confirmation by differential phenotypic methods and resistance test for tetracycline, cellophanamide and nitrofurantoin-furazolidone antibiotics were performed. DNA of strains was extracted and using PCR with specific primers, the presence of tetA, tetB, tetC, tetD, tetG, tetE, tetE, tetH, sul (I), sul (II), sul (III), nfsA, nfsB were examined according to control DNA (ATCC۱۴۰۲۸). Results: Among the genes of teta, tetb.tetc, tetd, tete, tetf, tetg and teth, the presence of tetc was seen in ۸۱% of the samples and not in ۱۹% of them. Other tetracycline resistance genes were not found in the samples. Tracing of genes related to sulfonamide resistance by PCR showed that among the Sul۱, Sul۲, and Sul۳ genes, sulfonamide resistance of Sul۲ was observed in ۹۵.۵% of the samples. Nitrofurantoin resistance genes in the samples showed that ۹.۱% of the samples contained nfsa gene and ۴.۵% contained nfsb gene. Other samples did not have any nitrofurantoin resistance gene. Conclusion: Improper use of antibiotics has caused multidrug resistance to Salmonella, so the study of genes and resistance mechanisms in Salmonella strains isolated from produced eggs in Iran is vital.