title: "Reverse" DNA hybridization method for the rapid identification of subgingival microorganisms.
abstract: A "reverse" hybridization method is described, in which whole chromosomal DNA was extracted from 10-20 colonies of "unknown" strains in pure culture and labelled with digoxigenin by a random primer technique. DNA probes were prepared from a total of 23 strains and hybridized with targets containing 100 ng purified, denatured DNA from 38 reference strains fixed to nitrocellulose. 21/23 digoxigenin-labelled DNA probes successfully detected all members of the homologous species present on filters. Probes to Fusobacterium nucleatum strains 364 and MG detected 3/4 and 1/4 members of this species, respectively; 13/23 probes were 100% specific, but cross reactions between 10 probes and DNA targets from closely related, heterologous species occurred in 15/834 possible instances. False-positive reactions that occurred between closely related species were, however, easily distinguished and did not prevent the accurate identification of probe strains. Digoxigenin-labelled probes were capable of detecting 100 pg of homologous DNA. The reverse hybridization procedure allows identification or grouping of a large number of isolates within 3 days and provides a more economical means of characterizing subgingival isolates than predominant cultivable techniques and conventional phenotypic testing. This method could be adapted for the direct identification of microorganisms in subgingival plaque samples.
authors.forename: G L
authors.initials: GL
authors.lastname: Smith
authors.forename: S S
authors.initials: SS
authors.lastname: Socransky
authors.forename: C
authors.initials: C
authors.lastname: Sansone
mesh_terms: D001419:Bacteria / Q000235:genetics*; D015342:DNA Probes; D005881:Gingiva / Q000382:microbiology*; D006824:Hybridization, Genetic; D008722:Methods
chemical_list: D015342:DNA Probes