Application of Polymerase Chain Reaction (PCR) for the Specific Detection of Enterotoxigenic Staphylococcus aureus in Various Food Samples

HAU-YANG TSEN, *TONG-RONG CHEN AND GEE-KAITE YU

Department of Food Science, National Chung-Hsing University, Taichung, Taiwan, R.O.C.
*Department of Food Technology, National Chia-Yi Institute of Agriculture, Chia-Yi, Taiwan, R.O.C.

ABSTRACT

   In this study, PCR primers specific for Staphylococcus aureus enterotoxin genes were used for the detection of enterotoxigenic S.aureus in foods. Neither the naturally occuring microflora in the food samples nor the food components would interfere with the detection. Study on the detection sensitivity showed that when PCR cycles were 35, DNA from < 10 CFU per ml of target bacterium in culture broth or < 100 CFU per gram of food sample could be detected. However, when the PCR cycles were reduced to 25, the cell numbers required for positive reaction were > 1000 CFU per ml of culture broth. Therefore, a short enrichment of target cells followed by suitable dilution and PCR using a suitable number of cycles could detect viable bacteria. Non-viable cells which could not grow would be diluted out and not be detected by PCR.

Key Words : Polymerase chain reaction, Enterotoxins, S.aureus.