Characterization of members of the Legionellaceae family by automated ribotyping.

In order to implement a new and reliable method for characterizing different species of Legionella, a genetic fingerprinting study with an automated ribotyping system (RiboPrinter) was completed with members of this genus which were deposited at the American Type Culture Collection. The RiboPrinter examined the different patterns of EcoRI digestion fragments from the rRNA operons of 110 strains, representing 48 of the 49 described Legionella species as well as 70 serogroups of those species. Distinctive and consistent patterns were obtained for the type strains of the 48 species investigated. Legionella pneumophila subsp. fraseri and L. pneumophila subsp. pascullei each generated a specific pattern, whereas L. pneumophila subsp. pneumophila produced six different fingerprint patterns. No correlation seemed to exist between the ribotypes obtained and the 15 serotypes of L. pneumophila. For the other species, those with two known serogroups presented two distinctive patterns with the RiboPrinter with the exception of L. hackeliae and L. quinlivanii, which yielded only one pattern. We also encountered ribotypes for strains which were not identified to the species level. The ribotypes generated for these strains with the RiboPrinter did not match those generated for known type strains, suggesting the putative description of new serogroups or species. Although the automated system did not have sufficient discriminatory ability to serve as an epidemiological tool in a clinical setting, it appeared to be a powerful tool for general genomic analysis of the Legionella isolates (e.g., determination of new species) and assessment of the interrelationship among Legionella strains through the RiboPrinter database connection.