Use of Real-Time PCR and High-Resolution Melting Analysis for Detection and Discrimination of Salmonella typhimurium and Salmonella enteritidis in Contaminated Raw-Egg Samples

In order to evaluate the efficacy of high-resolution melting (HRM) analysis in the detection and discrimination of S. typhimurium and S. enteritidis, this study was conducted on 30 samples of raw eggs, where 14 treatments were employed: 4 groups of samples contaminated with Salmonella typhimurium, 4 with S. enteritidis, 4 with a mixture of both, as well as 2 control groups. DNA was extracted from the contaminated samples and used for preparation of a target DNA sequence using an invA gene-specific primer pair. RT-PCR identified and detected Salmonella in the contaminated egg samples within less than 24 hours, and HRM analysis proved that this method is suitable for the discrimination of the S. enteritidis and S. typhimurium species. The sensitivity of this method was equal to 200 Salmonella cells per microliter, and HRM analysis could distinguish S. enteritidis and S. typhimurium and their combination with high consistency (R2 > 0.993).