Abstract

Foodborne diseases are common problems worldwide. Staphylococcus aureus is one of the most important food-borne pathogens. Listeria monocytogenes is widely found in contaminated foods, especially in refrigerated and ready-to-eat foods. Rapid detection and identification are needed to prevent and control the food contamination by these infectious microorganisms. For the objective of the research, multiplex PCR technique has been developed for rapid detection of S. aureus and L. monocytogenes in ready-to-eat foods. In this study, two-pair of primers were designed within conserved regions of the virulence genes, coa gene of S. aureus and prfA gene of L. monocytogenes and then were used for detection of those bacteria. The results showed that this multiplex PCR could detect at least 1 ng of S. aureus DNA and 150 pg of L. monocytogenes DNA. Investigation into the artificially contaminated foods, this multiplex PCR was able to detect less than 10⁴ cells/g of S. aureus and 1 cell/g of L. monocytogenes in foods. In addition, there were no amplifications of nucleic acids from other food related-pathogens, indicating the specificity of this test. Detections in thirty ready-to-eat food samples from local markets in Chonburi province, Thailand, showed that none of them were contaminated with S. aureus and L. monocytogenes. Therefore, this finding indicated good hygiene in production of ready-to-eat foods in these areas. Consequently, this multiplex PCR can be further developed and employed for monitoring of S. aureus and L. monocytogenes in contaminated foods.

Keywords: Multiplex PCR, Ready-to-eat Foods, Staphylococcus aureus, Listeria monocytogenes