Rapid identification of bacteria in blood cultures by using fluorescently labeled oligonucleotide probes

The applicability of whole-cell hybridization for the identification of pat hogenic bacteria in blood from septic patients was examined. Oligonucleotid e probes, fluorescently labeled with fluorescein isothiocyanate, directed a gainst the variable regions of the 16S rRNAs of the following bacterial spe cies and/or genera were used: Streptococcus spp,, Enterococcus faecalis, St aphylococcus aureus, coagulase-negative staphylococci (CoNS), Escherichia c all, Pseudomonas aeruginosa, and the Enterobacteriaceae family. A probe spe cific for the rRNAs of almost all bacteria and its complementary; reversed counterpart was used as positive and negative control, respectively, The pr obes were used in conjunction with a fast and simple-to-use protocol for wh ole-cell hybridization. This protocol yields an identification after 25 to 45 min, depending on whether the bacterium Is gram positive or gram negativ e. A total of 182 blood samples which tested positive in a blood culture ma chine were investigated. All probes except for the ones for S, aureus and t he CoNS shelved sensitivities and specificities of 1.000, It was concluded that whole-cell hybridization is well suited for the fast screening of sept ic bleed containing streptococci and/or enterococci or gram-negative rods.