Detection of Staphylococcus aureus in Dairy Products by Polymerase Chain Reaction Assay

A polymerase chain reaction (PCR) assay was employed for direct detection of Staphylococcus aureus without enrichment in dairy products. A solvent extraction procedure was successfully modified for the extraction of Staphylococcus aureus DNA from artificially contaminated whole milk, skim milk, and cheese. A primer targeting the thermostable nuclease gene (nuc) was used in the PCR. A DNA fragment of 279 bp was amplified. The PCR product was confirmed by DNA sequencing. In this study, the PCR, GB-4789.10–94, Perifilm RSA. Count Plate, and Baird-Parker + RPF Agar were compared. The sensitivity of the PCR was 10 CFU mL−1 of whole milk, skim milk, and 55 CFU g−1 of cheese. The developed methodology allowed for detection of Staphylococcus aureus in dairy products in less than 6 h. The time taken for the development of this PCR assay was 12–24 h, less than the time taken by the general PCR assay using the enrichment method, and the coincidence rate of this developed PCR was 94.3%, the sensitivity was 100%. It was a rapid, sensitive, and effective method for PCR to detect Staphylococcus aureus in milk and milk products.