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Published on: May 8, 2013
Real-time PCR method for quantification of Staphylococcus aureus in milk
M Goto1, H Takahashi, Y Segawa
1Division of Microbiology, National Institute of Health Sciences, Setagaya, Tokyo 158-8501, Japan.
Journal of Food Protection
|February 3, 2007
Summary
A new real-time PCR method accurately quantifies Staphylococcus aureus in milk. This sensitive and specific technique can detect bacterial contamination even after certain heat treatments, aiding milk safety monitoring.
Area of Science:
- Microbiology
- Food Science
- Molecular Biology
Background:
- Staphylococcus aureus is a pathogen that can contaminate milk.
- Accurate quantification methods are needed for milk safety.
Purpose of the Study:
- To develop a reproducible real-time PCR method for quantifying S. aureus in milk.
- To assess the method's specificity, sensitivity, and performance under pasteurization conditions.
Main Methods:
- Designed specific primers and probes targeting a transcriptional regulator gene of S. aureus.
- Validated specificity against S. aureus and other bacterial strains.
- Performed real-time PCR on purified DNA, pure cultures, and milk samples, including heat-treated samples.
Main Results:
- Achieved high correlation coefficients (r2 = 0.99) for standard curves with purified DNA and pure cultures.
- Successfully quantified S. aureus in milk samples within a broad range (10^7 to 10^1 CFU/ml).
- The method detected S. aureus DNA after low-temperature long-time (63°C for 30 min) but not high-temperature short-time (72°C for 15 s) pasteurization.
Conclusions:
- The developed real-time PCR method is effective for monitoring S. aureus contamination in milk.
- The assay demonstrates high specificity and sensitivity.
- The method's performance is influenced by milk heat treatment, providing insights into pasteurization efficacy.
