Abstract

A rapid and sensitive multiplex polymerase chain reaction (MPCR) based assay was developed for the detection of Salmonella enterica serovars such as Typhi (ATCC 122235), Paratyphi A (MTCC 735), Typhimurium (MTCC 98), Enteritidis (ATCC 13065), Weltevreden (MTCC 1169) Bovismorbificians (MTCC 1162), Brunei (MTCC 1168), Arizonae (MTCC 660) and Infantis (MTCC 1167) in shrimps within 4 h of pre-enrichment. The Salmonella genus specific gene of himA gene was selected and 16S-23S internal transcribed spacer region was used as an internal amplification control (IAC). The genomic DNA was extracted by using boiling and centrifugation method. Sensitivity of the assay was tested by artificially inoculating the shrimp homogenate with viable cells of Salmonella. The MPCR assay could detect up to 5 cells within 4 h of pre-enrichment. Amplification of DNA extracted from other bacterial pathogens viz. Vibrio cholerae (NICED 16582), Escherichia coli (ATCC 9637) andStaphylococcus aureus (ATCC 12598) yielded negative results. This MPCR assay provides specific, rapid and reliable results and allows for the cost effective detection of serovars of S. enterica in one reaction tube in mixed bacterial communities that are prevalent in shrimp products.

Key words: Multiplex polymerase chain reaction (MPCR), Salmonella enteric, himA,16S-23S spacer region, 4 h assay.