Characterization of motile and acetoin-negative Klebsiella pneumoniae strains by DNA: DNA by hybridization.

Hybridization studies were carried out to determine the extent of divergence between different members of the Enterobacteriaceae and group D, previously described by numerical analysis of phenotypic characters, and comprising strains isolated from surface waters. This group, apparently belonging in or related to the genus Citrobacter on the basis of the IMViC tests differs from this taxon by numerical analysis and DNA base composition. Our work reveals a DNA relatedness of 81-89% between the centrotype strain of this group and the genus Klebsiella. Although strains of group D show positive motility and negative Voges-Proskauer reactions, a comparison of their phenotypic characters leads us to consider that the strains with a high level of hybridization within this group belong to K. pneumoniae. These results suggest a complete revision of the traditional classification scheme of the genus Klebsiella.