Serratia marcescens strains commonly cause hospital outbreaks. A random amp
lified polymorphic DNA (RAPD) assay was applied to the epidemiology of Ser.
marcescens using formaldehyde fixation and boiling of bacterial cells for
DNA extraction. The method preserved bacterial DNA and gave optimal results
of RAPD-fingerprinting, facilitating the investigation of hospital infecti
ons caused by Ser. marcescens.