DETECTION OF SALMONELLAE IN CHICKEN AND FISH SAMPLES USING DNA-PROBE

The use of DNA probes for rapid identification of foodborne pathogens is an emerging field. We have standardized a method for the detection of Salmonella in food samples by using a specific insertion sequence ( IS-200) of Salmonella chromosomal DNA as the probe. The procedure for colony hybridization, and washing conditions for the stringency were e stablished. All the ten Salmonella strains, belonging to various serot ypes tested were positive while 18 other bacterial cultures, mainly be longing to the family Enterobacteriaceae such as E. coli Shigella, Pro teus etc., were negative in colony hybridization. The sensitivity of t he detection was found to be 10(5) cfu using P-32-labeled probe. We su rveyed 16 chicken and 6 fish samples from local market using IS-200 pr obe after preenrichment and selective enrichment. All the samples test ed were found positive with DNA probe. The major strains of Salmonella isolared from these samples were S. gallinarum, S. typhimurium, S. en teritidis, S. choleraesuis and S. paratyphi A. These results were conf irmed by standard Salmonella identification method.