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Published on: November 4, 2016
Mastitis diagnostics: quantitative PCR for Staphylococcus aureus genotype B in bulk tank milk
1Clinic for Ruminants, Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, University of Berne, 3001 Switzerland.
Journal of Dairy Science
|December 25, 2010
Summary
A new real-time PCR test detects Staphylococcus aureus genotype B (GTB) in bulk milk, aiding control of this costly dairy herd pathogen. This assay offers a reliable tool for routine monitoring and reducing Staph. aureus GTB prevalence.
Area of Science:
- Veterinary Microbiology
- Dairy Science
- Molecular Diagnostics
Background:
- Staphylococcus aureus genotype B (GTB) causes significant economic losses in Swiss dairy herds.
- Effective control strategies require reliable detection methods in bulk milk.
- Existing methods may not be suitable for routine bulk tank milk analysis.
Purpose of the Study:
- To develop and validate a novel real-time quantitative PCR (qPCR) assay for detecting Staphylococcus aureus genotype B (GTB) in bulk tank milk.
- To establish the assay's analytical sensitivity and specificity.
- To evaluate the assay's potential for routine use in dairy herd management.
Main Methods:
- Development of a qPCR assay targeting 3 GTB-specific sequences (2 enterotoxin genes, 1 leucotoxin E polymorphism).
- Validation using a panel of mastitis-associated bacteria to determine analytical specificity.
- Determination of analytical sensitivity in milk (colony-forming units per milliliter).
- Correlation analysis between simulated cow prevalence and qPCR results.
- Initial field study on 33 Swiss dairy herds.
Main Results:
- The qPCR assay demonstrated 100% analytical specificity and high repeatability.
- Analytical sensitivity in milk was determined to be 40 cfu/mL.
- An exponential association was observed between simulated cow prevalence and qPCR results.
- An initial field study identified 1 GTB-positive herd out of 33.
Conclusions:
- The developed real-time qPCR assay is a novel and effective tool for detecting Staphylococcus aureus GTB in bulk tank milk.
- The assay is suitable for routine monitoring and contributes to the control of GTB in Swiss dairy herds.
- This method is expected to minimize Staph. aureus GTB prevalence and associated economic losses.
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