MOLECULAR TYPING OF METHICILLIN-RESISTANT STAPHYLOCOCCUS-AUREUS ON THE BASIS OF PROTEIN-A GENE POLYMORPHISM

The polymorphic X-region of the protein A gene (spa) was used for mole cular typing of methicillin-resistant Staphylococcus aureus (MRSA) str ains. The X-region is characterized by a variable number (between 3 an d 15) of small repeats, DNA sequencing of MRSA strains revealed 25 dis tinct repeats, Analysis of MRSA strains grown in vitro and in vivo rev ealed that the X-region was sufficiently stable for epidemiologic typi ng of MRSA strains, Spa typing of MRSA strains was compared to phage t yping and, in general, concordance was found between the two methods, However, spa typing was more sensitive, allowing differentiation of st rains within a particular phage type, Results obtained with spa typing suggest that hospital outbreaks may be caused by two or more MRSA str ains. Spa typing may be an important tool in unravelling the spread of MRSA strains within and between hospitals.