가공식품과 비가공식품에서의 황색포도상구균 검출을 위한 배지법과 Real-time PCR법의 비교

Staphylococcus aureus is one of the major pathogens that can cause staphylococcal infection and food poisoning. In this study, we compared conventional culture methods and real-time PCR for detection of S. aureus in artificially inoculated milk, sausage, raw pork, and vegetable salad. The performance of a coagulase test for confirming S. aureus was also compared with a colony PCR test. Bulk food samples (500g each) were artificially inoculated with S. aureus and divided into 20 samples (25g or mL each). All samples were added to tryptic soy broth (225 mL/sample) with 10% NaCl and incubated at 37℃ for 24 h. After the enrichment, broth cultures were streaked onto Baird-Parker (BP) agar with egg yolk tellulite, and incubated at 37℃ for 24 h. In addition, 1 mL of broth cultures was collected to perform real-time PCR. Two suspicious colonies from the BP agar were picked up and plated on nutrient agar and incubated at 37℃ for 24 h followed, by a coagulase confirmation test and a colony PCR analysis. There were no statistical differences between culture methods and real-time PCR in food samples with low background microflora, such as milk and sausage. However, a significant statistical difference was found between the culture methods and real-time PCR for raw pork and vegetable salad. Furthermore, the colony PCR test of the presumptive colonies on BP agar for confirming S. aureus is more accurate and efficient than the coagulase test for unprocessed foods.