TYPING OF LEGIONELLA-PNEUMOPHILA SEROGROUP-1 ISOLATES BY DEGENERATE (D-)RAPD FINGERPRINTING

A new method to identify clonal strains of pathogenic bacteria has bee n developed recently in this laboratory. The method utilizes degenerat e random amplified polymorphic DNA primers (D-RAPD) to amplify random fragments in crude bacterial lysates, generating reproducible DNA band ing profiles or fingerprints. We use this method to type outbreak and non-outbreak isolates of Legionella pneumophila serogroup 1 from four hospitals near to, and affiliated with the University of Pittsburgh Me dical Center. Patient isolates from a large outbreak, and nearly half of the contemporaneous environmental isolates showed the same DNA prof ile. Other isolates derived from non-outbreak patients showed easily d istinguishable profiles. Other Legionella isolates collected between 1 984 and 1994 were also analysed by this method. Our studies demonstrat e that four strains were common among patient and environmental isolat es at the four hospitals. These strains were also found to be differen t from a limited number of isolates from outside the Pittsburgh area. Because of its speed, simplicity and powerful discriminating ability, we believe that the D-RAPD approach provides epidemiologists and hospi tal infection control teams with a powerful tool in their efforts in a nalysing and terminating infection outbreaks. (C) 1995 Academic Press Limited