DISTRIBUTION AND GENETIC-ANALYSIS OF ORAL PREVOTELLA-INTERMEDIA AND PREVOTELLA-NIGRESCENS

A total of 344 Prevotella intermedia and nigrescens group isolates fro m 59 subjects were identified by hybridization with nonradioactively l abeled species-specific oligonucleotide probes. Identification of 20 P . intermedia and 46 P. nigrescens isolates was confirmed by analyzing the electrophoretic mobilities of malate and glutamate dehydrogenase e nzymes. A total of 111 isolates (32%) were identified as P. intermedia and 233 isolates (68%) as P. nigrescens. Identification performed wit h oligonucleotide probes and with malate and glutamate dehydrogenase e lectrophoresis matched perfectly. The distribution of oral P. intermed ia and P. nigrescens in various periodontal status groups was investig ated in periodontally healthy or diseased individuals. To reveal intra - and interindividual genetic diversity and possible intrafamilial tra nsmission, P. intermedia and P. nigrescens isolates from 16 to 59 subj ects, representing 8 married couples, were ribotyped, ;The stability o f colonization was examined in 12 of the 59 subjects, of whom 6 receiv ed periodontal treatment and 6 were untreated. All children and period ontally healthy adults and most subjects with initial periodontitis (1 3/21) harbored only P. nigrescens. Of the 20 subjects with advanced pe riodontitis, 7 harbored both P. intermedia and P. nigrescens, 7 only P . intermedia and 6 only P. nigrescens. One or two ribotypes of P. inte rmedia and/or P. nigrescens were found intraindividually. The spouses in 5 of the 8 married couples shared an identical ribotype of P. inter media or P. nigrescens, whereas ribotypes from unrelated subjects were mostly unique. Colonization was stable, since the same ribotypes were found 1-6 months apart in both periodontally treated and untreated su bjects. In conclusion, the study indicates that P. intermedia and P. n igrescens may occur simultaneously in the oral cavity, the colonizatio n is stable and P. intermedia is associated with periodontal diseases. Ribotyping revealed considerable genetic heterogeneity in unrelated s ubjects, whereas isolates obtained from spouses could represent the sa me ribotype, which suggests transmission of these species.