Purpose: The aim of this study was to compare the method for the detection of S. aureus in a range of foods with a standard cultural method, AOAC Official Method 975.55.
Methods: In total, 1200 food samples were analyzed, representing 20 food types at 3 levels of contamination. Both naturally and artificially contaminated samples were included. In addition, an inclusivity and exclusivity study was performed.
Results: Of the 1200 samples tested, 699 were confirmed positive by the method while the Reference Method confirmed 332 positive. Fractional recovery was achieved for all food types at the low level inoculums (< 5 cells/g). Overall, the results of this study show that the test gave an increased proportion of positive results when compared to the Reference Method in its recovery of S. aureus from foods inoculated at the low level. Chi-square analysis at the 5% level shows that there was significant improvement in recovery of S. aureus contamination from these samples compared to the Reference Method. For uninoculated and high-level samples (10-50 cells/g), the two methods were statistically equivalent.
Significance: The test method provides simple and sensitive presumptive detection of S. aureus within 27 hours.