RANDOM AMPLIFICATION OF POLYMORPHIC DNA (RAPD), PULSED-FIELD GEL-ELECTROPHORESIS (PFGE) AND PHAGE-TYPING IN THE ANALYSIS OF A HOSPITAL OUTBREAK OF SALMONELLA-ENTERITIDIS

Isolates of Salmonella Enteritidis from 81 patients from Herlev Hospit al or from Copenhagen County were analysed by random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE) and ph age-typing. Fourteen polymorphic markers from five decamer primers una mbiguously placed all isolates into six RAPD groups: 65 isolates of ph age-type 6 (PFGE type I) were resolved into three RAPD groups constitu ting 86, 12, and 2%, respectively. A fourth RAPD group of 10 isolates was coincident with phage type 8 (PFGE type II) and two isolates, one phage-type 1, the other phage-type 4 (both PFGE type I) formed the fif th group. The sixth group of four isolates was not phage typeable and was PFGE type III. Forty outbreak-related isolates of phage-type 6 wer e resolved into three strains. No diversity of phage-type 6 was found among isolates unrelated to the outbreak. It is concluded that RAPD is useful as a tool in investigations of microbial outbreaks in its own right, or to supplement phage-typing and PFGE of Salmonella Enteritidi s.