Genomic and phenotypic evaluation of Salmonella typhimurium and Salmonella enteritidis in Iran

Genomic and phenotypic evaluation of Salmonella typhimurium and Salmonella enteritidis by two simple, fast, and applicable methods of random amplified polymorphic DNA (RAPD) polymerase chain reaction (PCR) and antibiotic susceptibility for employment in epidemiologic surveillance screening systems in Iran was the objective in this study. We selected 60 (30 S. typhimurium and 30 S. enteritidis) isolates from different animal sources and different times and places among 1975–2006 in Iran. Serotyping with traditional method and reliable antisera was done and then confirmed with multiplex PCR (with four and three pair of primers, respectively). All of S. typhimurium and S. enteritidis isolates have virulence genes of invA and spv, respectively. Then, from nine primers, two primers that have enough discriminatory power were selected for RAPD analysis. We set up the quality and quantity of DNA template, primers, MgCl₂, Taq DNA polymerase, and deoxyribonucleotide triphosphates concentration for RAPD analysis. We also examined the strains with disk diffusion standard antibiotic susceptibility test. With the application of primer P1254; we saw four and seven and primer 23L, six and three profiles in RAPD analysis and 13 and six profiles of R-type in susceptibility test of S. typhimurium and S. enteritidis, respectively. Combination of two methods differentiated these 30 strains to 20 and 16 different profiles, respectively. The finding of this study indicated that clonality of S. enteritidis is more than S. typhimurium in Iran and RAPD-PCR in combination with antibiotic susceptibility test were fast, easy, relatively reliable, and discriminatory molecular and phenotypic methods in the differentiation of S. typhimurium and S. enteritidis for epidemiologic purposes in Iran.