Abstract: 【Objective】A uniplex polymerase chain reaction(PCR) assay was developed for direct detection of Staphylococcus aureus without enrichment in dairy products. 【Method】A solvent extraction procedure was successfully modified for extraction of Staphylococcus aureus DNA from artifically contaminated whole milk, skim milk and cheese. Primer targeting the thermostable nuclease gene (nuc) was used in the uniplex PCR. A DNA fragment of 279 bp was amplified. PCR product was confirmed by DNA sequencing. In this study, the uniplex PCR, GB 4789.10-94, Perifilm RSA. Count Plate, and Baird-parker + RPF Agar were compared. 【Result】The detection limit of the uniplex PCR is 10 CFU/ml of whole milk, skim milk and 55 CFU/g cheese. The developed methodology allows detection of Staphylococcus aureus in dairy products in less than 6 h, the time of this developed PCR assay is 12-24 h less than the time of general PCR assay with enrichment method, and the coincidence rates of PCR is 94.3%, the sensitivity of PCR is 100%.【Conclusion】The solvent extraction procedure is an effective method for PCR assay of Staphylococcus aureus in milk and milk products.

Key words: PCR, Detection, Dairy products, Staphylococcus aureus