Cloned randomchromosomal sequences as probes to identify Salmonella species

We have developed and evaluated a new technique- chromosomal probe fingerprinting- to differentiate between strains of Salmonella species by using sequences of cloned chro-mosomal DNA as probes to highlight restriction site heterogeneity. Chromosomal probe fingerprint patterns were compared with other strain-typing methods and epidemiologi-cal data. Seventeen isolates of Salmonella typhimurium recovered from 11 outbreaks had six unique chromosomal probe fingerprint patterns. Most strains of Salmonella dublin, including some that had identical plasmid profiles and restriction endonuclease analysis patterns, could be distinguished by this method. On the other hand, eight of nine isolates of Salmonella enteritidis had a common chromosomal probe fingerprint pattern, although there were differences in plasmid profiles and the isolates had been collected over a lengthy time interval from widely disparate geographic locations. These results suggest clonal dis-semination of some Salmonella serovars. The identification of an "epidemic strain " is often critical to the success of epidemiological investiga-tons. Plasmid fingerprinting has been an especiall