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Molecular typing of methicillin-resistant Staphylococcus aureus on the basis of protein A gene polymorphism
H M Frénay1, A E Bunschoten, L M Schouls
1Molecular Microbiology Unit, National Institute of Public Health and Environmental Protection, Bilthoven, The Netherlands.
Abstract:
The polymorphic X-region of the protein A gene (spa) was used for molecular typing of methicillin-resistant Staphylococcus aureus (MRSA) strains. The X-region is characterized by a variable number (between 3 and 15) of small repeats. DNA sequencing of MRSA strains revealed 25 distinct repeats. Analysis of MRSA strains grown in vitro and in vivo revealed that the X-region was sufficiently stable for epidemiologic typing of MRSA strains. Spa typing of MRSA strains was compared to phage typing and, in general, concordance was found between the two methods. However, spa typing was more sensitive, allowing differentiation of strains within a particular phage type. Results obtained with spa typing suggest that hospital outbreaks may be caused by two or more MRSA strains. Spa typing may be an important tool in unravelling the spread of MRSA strains within and between hospitals.
Insights
Spa typing, using the protein A gene's X-region, effectively identifies methicillin-resistant Staphylococcus aureus (MRSA) strains. This molecular method offers greater sensitivity than traditional phage typing for tracking MRSA outbreaks in hospitals.
Area of Science:
- Microbiology
- Molecular Biology
- Epidemiology
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant threat in healthcare settings.
- Accurate molecular typing is crucial for understanding and controlling MRSA transmission.
Purpose of the Study:
- To evaluate the utility of the polymorphic X-region of the protein A gene (spa) for molecular typing of MRSA strains.
- To compare the efficacy of spa typing with conventional phage typing.
Main Methods:
- DNA sequencing of the spa gene's X-region in MRSA strains.
- Analysis of X-region stability in vitro and in vivo.
- Comparison of spa typing results with established phage typing data.
Main Results:
- The spa gene's X-region exhibits a variable number of repeats (3-15), with 25 distinct repeats identified.
- The X-region demonstrated sufficient stability for reliable epidemiologic typing.
- Spa typing showed concordance with phage typing but offered enhanced sensitivity, differentiating strains within phage types.
- Spa typing suggested that hospital MRSA outbreaks may involve multiple strains.
Conclusions:
- Spa typing is a stable and sensitive molecular tool for MRSA strain characterization.
- This method can improve the identification of MRSA strains during hospital outbreaks.
- Spa typing holds promise for elucidating MRSA dissemination within and between healthcare facilities.