Identification of Klebsiella pneumoniae by DNA hybridization and fatty acid analysis.

On the basis of the idea that DNA sequences encoding cell surface-exposed regions of outer membrane proteins are genus or species specific, two oligonucleotide probes which were based on the PhoE protein of Klebsiella pneumoniae were evaluated. In slot blot hybridizations and in polymerase chain reactions, no cross-hybridizations were observed with non-Klebsiella strains. When the probes were tested on 75 different K-antigen reference Klebsiella strains, 16 strains were not recognized although they did produce PhoE protein under phosphate starvation. To determine whether these 16 strains belong to (a) different species, the reference strains were also tested for the ability to produce indole and to grow at 10 degrees C and their whole-cell fatty acid patterns were analyzed by gas chromatography. A strong correlation was observed among (i) reaction with the probes, (ii) the inability to produce indole, (iii) the inability to grow at 10 degrees C, and (iv) the presence of the hydroxylated fatty acid C14:0-2OH. From these results we conclude that the two oligonucleotides are specific for the species K. pneumoniae. Furthermore, analysis of fatty acid patterns appears to be a useful tool to distinguish K. pneumoniae from other Klebsiella species.