Abstract
A rapid, reproducible, mini-volume assay capable of detecting staphylococcal plasmid DNA in the range of 0.8 to 32 megadaltons has been developed. The assay employs lysostaphin-mediated lysis of cells followed by a short, low-speed centrifugation and does not require treatment with ribonuclease or protease or deproteinization with phenol. A period of only 24 h may be required to detect the presence and size of a plasmid once an organism has been isolated. This method has been used to study the plasmid ecology of Staphylococcus epidermidis and to correlate the presence or absence of plasmids with tetracycline, chloramphenicol, neomycin, penicillin, and cadmium resistances.