rapid and specific detection of salmonella typhimurium by pcr-elisa

objectives: salmonella typhimurium is important food-borne pathogen responsible for gastroenteritis. in this work a polymerase chain reaction based enzyme linked immunosorbent assay (pcr-elisa) was developed to identify salmonella typhimurium. materials and methods: the rfb gene which is responsible for biosynthesis of the salmonella o-antigenic lipopolysaccharide was selected as the target sequence. the selected primers amplified fragment size of 882bp of s. typhimurium. food samples contaminated with salmonella typhimurium as well as clinical and standard samples were used in this investigation. the pcr products randomly labeled with dig-11-dutp were transformed to a plate coated with streptoavidin and tested with anti digoxigenin. an internal biotin-labeled probe was used to confirm the amplified pcr product. results: the specificity of the assay toward s.typhimurium samples was confirmed by testing 20 salmonella and 6 non salmonella strains. elisa increased the sensitivity of the conventional pcr method by approximately 1000 fold. conclusion: the method presented here is a rapid and specific alternative for the traditional time consuming culture methods for the detection of s. typhimurium in food and clinical samples. due to its high specificity and sensitivity, our method finds its place as an alternative to pcr in large scale screenings, for detection of s. typhimurium.