Ornithine decarboxylating strains of Klebsiella pneumoniae demonstrated by DNA-DNA hybridization.

Genotypic relatedness was assessed to clarify the taxonomic position of strains phenotypically behaving like K. pneumoniae, but for the ornithine reaction. Using DNA-DNA hybridization it could be shown that 25 non-motile ornithine decarboxylating strains showed high genotypic relatedness to the type strain of K. pneumoniae. Thus, it is proposed that they be considered as ornithine decarboxylating strains of the species K. pneumoniae. The API 20E system was used for phenotypic characterization, but the API code obtained by these strains was not registered in the API Profile Index. However, except for the ornithine reaction the isolates behaved as typical K. pneumoniae. Three ornithine negative strains of E. aerogenes were identified as K. pneumoniae by the API 20E System, but they showed high genotypic relatedness to the type strain of E. aerogenes.