Plasmid Analysis of 26 Staphylococcal Species by a Rapid Microscale Technique

Objective:Evaluate a plasmid typing technique for a diverse group of staphylococci.Design:In vitro testing on known isolates.Setting:University hospital.Intervention:The plasmid content of 195 isolates representing 26 staphylococcal species was analyzed by agarose gel electrophoresis following lysostaphin-alkaline-SDS lysis, with and without acetone treatment.Results:Isolates yielded plasmid profiles with 0 to 7 extra-chromosomal bands (median, 1; 1.5); 171 (88%) had a profile with at least 1 band. Species with more than one isolate available for testing showed considerable diversity of plasmid profiles, except forStaphylococcus haemolyticus.Conclusions:The ease of the procedure and the diversity of plasmid profiles within each species examined suggests that plasmid profiling is an accessible and useful epidemiologic tool applicable to most staphylococcal species by epidemiologic units or clinical laboratories.