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Staphylococcus aureus protein A: quantitation by microhemagglutination
Archivos De Investigacion Medica
|January 1, 1980
Summary
This study presents a new method to semiquantitatively measure bacterial surface Protein A in Staphylococcus aureus. The method accurately quantifies Protein A levels, aiding in the analysis of its distribution and identification of new producing strains.
Area of Science:
- Microbiology
- Immunochemistry
- Bacterial surface proteins
Background:
- Protein A is a surface protein of Staphylococcus aureus with high affinity for immunoglobulins.
- Its use as an immunochemical reagent is growing due to its broad applicability across animal species.
Purpose of the Study:
- To develop and validate a semiquantitative method for determining bacterial surface Protein A.
- To assess Protein A content in certified and clinical Staphylococcus aureus strains.
Main Methods:
- A microassay utilizing standardized bacterial suspensions and sensitized ram erythrocytes for hemagglutination was employed.
- Protein A titers were determined as the inverse of dilutions causing endpoint agglutination.
Main Results:
- The method demonstrated reproducibility using certified strains (Protein A+ Cowan I, Protein A- Wood 46).
- Relative hemagglutinating potency was consistent and strain-specific across 15 new S. aureus isolations.
- Quantified Protein A titers ranged from undetectable to a maximum of 256.
Conclusions:
- The developed microassay provides a reliable method for semiquantitative determination of bacterial surface Protein A.
- This technique allows for the analysis of Protein A distribution in Staphylococcus aureus populations.
- The method can aid in the discovery and characterization of novel Protein A-producing strains.
