Abstract
Nine isolates of methicillin-resistant Staphylococcus aureus were cultured over a six-month period from patients in a hospital burn unit. A comparison of plasmid profiles suggested that the isolates could comprise three different groups of organisms. Analysis of plasmid EcoRI restriction fragments by conventional electrophoresis, and SmaI chromosomal fragments by field inversion gel electrophoresis, revealed that all nine isolates were clonally derived.