Identification of the genus Salmonella and S. Typhi by multiplex PCR

Salmonella are regarded as the predominant cause of food borne as well as septicaemic illness in humans which has increased substantially during the last decade in developed as well as developing nations. We, in present study, intend to develop a multiplex PCR based assay for the early and rapid detection of Salmonella spp. including S. typhi from specimens such as food, faeces, domestic water and patient’s sample. Standardization of multiplex PCR using two different sets of primers specific to flagellin gene sequences from consewed regions I and VIII (Salmonella specific) and VI and VIII (specific to S. typhi) are reported here. Initially the amplification of respective target sequences using individual pairs of specific primers was standardized and susequent evaluation of sensitivity and specific of the assay was achieved. 10 pg of DNA could be picked up easily and was highly specific to Salmonella spp. Coamplification by both primer pairs either gave a Salmonella spp. specific single 1530 bp amplication product or this was accompanied by another amplicon of 486 bp, suggestive of presence of S. typhi also in the test specimen. In a multiplex PCR, multiple primer pairs specific for different targets are included in the same amplification reaction (single tube PCR) so that cost effective panel of tests for multiple pathogens from a single specimen could be developed, which in our case proves to be more promising approach than nested-PCR.