Rapid Microprocedure for Extraction of Plasmid DNA from Staphylococcus aureus

A rapid micromethod for extraction of plasmid DNA from Staphylococcus aureus in quantities sufficient for restriction endonuclease analysis was developed. The method of "fingerprinting" is useful for identification of epidemic strains in the clinical setting and is more reliable than frequently used determinations of plasmid molecular weight, particularly when small numbers of plasmids are involved. Restriction endonuclease analysis of plasmid DNA is a valid and important method of typing epidemic strains of Staphylococcus aureus [1]. Since the evolution of multiple antibiotic resistance, much of which is plasmid mediated, the classic phage types have failed to correlate with outbreaks of infection [2]. Previously published methods for extraction of plasmid DNA for analysis frequently are cumbersome, time consuming, or expensive [3, 4]. We have developed a rapid microprocedure for plasmid DNA extraction; the microprocedure is a modification of a method developed for the extraction of small plasmids from Escherichia coli [5].