Fluorescent whole-cell hybridization with 16S r-RNA-targeted oligonucleotide probes to identify Brucella spp. by flow cytometry

A whole-cell hybridization assay with fluorescent oligonucleotide probes de rived from the 16S rRNA sequence of Brucella abortus in combination with fl ow cytometry has been developed. With the three fluorescent probes selected , a positive signal was observed with all the representative strains of the species and biovars of Brucella and with a total of nine different Brucell a clinical isolates. Using the B9 probe in the hybridization assay, it was possible to discriminate between Brucella suis biovars 2, 3, 4, and 5 and a lmost all the other Brucella spp. On the basis of differences in fluorescen ce intensities, no discrimination was established between Brucella spp. and other phylogenetically related microorganisms, No positive fluorescence si gnals were detected with any of the bacteria showing serological cross-reac tions with Brucella spp. and with a total of 17 clinical isolates not belon ging to the genus Brucella, These results suggest that the 16S rRNA whole c ell hybridization technique could be a valuable diagnostic tool for the det ection and identification of Brucella spp.