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Abstract

Salmonella species have been frequently implicated in foodborne illnesses. These organisms can be transmitted via ingestion of a wide variety of contaminated food items and polluted drinking water. The detection of Salmonella in such commodities relies mainly on some laborious, and time-consuming conventional methods. This warrants for development and/or adoption of other nonconventional, user-friendly and rapid methods.

In view of the above-mentioned facts, studies have been conducted to develop a simple, cost-effective and rapid polymerase chain reaction (PCR)-based method for the detection of Salmonella in food samples using the primers for invA gene sequence. The method developed, based on PCR, has been compared with the conventional method for Salmonella detection. Experiments were performed with different inoculum sizes and time intervals to determine the sensitivity of the method. Optimization studies were also conducted using rice sample with different inoculum size and time interval combinations. Initially, the method developed was tested for its efficacy on different artificially contaminated samples, and later on, in commercially available products in comparison with the conventional method. The method developed is also free of any involvement of kit-based proprietary instruments.

Practical Applications

Food products are being scrutinized intensively for Salmonella contamination, especially during export or marketing across the boundaries. Consequently, the food industry is facing economic problems like rejection of consignments, recall of the product, loss of product, marred product prestige, etc. Usually, 4 to 6 days are required for Salmonella detection. The manufacturers have either to ship the product without the laboratory clearance or to keep the product in storage until laboratory report is obtained. Both alternatives are not economically appealing. The product might be recalled or rejected as microbiological safety can be violated or additional handling and storage expenditures could be involved. These considerations demand for a rapid test for Salmonella detection that is at least as sensitive and accurate as the tests used currently. The PCR test described here fulfills these criteria and can be used for rapid detection of Salmonella in food testing laboratories.