Increase in probing depth is correlated with a higher number of Prevotella intermedia genotypes.
BACKGROUND
The aims of this study were to determine the genotypic diversity of Prevotella intermedia in subgingival plaque samples by using two techniques, arbitrarily primed polymerase chain reaction (AP-PCR) and heteroduplex analysis, and to assess the relationship of this diversity with increase in probing depth.


METHODS
The subgingival plaque samples were obtained from 12 patients using paper points inserted into periodontal pockets (diseased sites) and healthy gingival sulci (healthy sites) of the same subjects. After isolation and identification, AP-PCR was performed for genotypic characterization of P. intermedia (80 isolates). The clinical samples with a positive result for P. intermedia were amplified by 16S rRNA-based PCR method, and the amplicons were subjected to heteroduplex analysis.


RESULTS
The agreement between the two methods was very high; the AP-PCR and heteroduplex analysis showed that subjects harbored between one and five distinct genotypes of P. intermedia, with a positive association between numbers of genotypes by AP-PCR (P = 0.0042) or heteroduplex (P = 0.0099) and increase in probing depth. No matching of P. intermedia genotypes was observed between healthy and diseased sites of the same individual. Interindividual analyses demonstrated absence of identical clones and indicated a high level of genetic diversity in the species.


CONCLUSIONS
A clear relationship was observed between a higher number of genotypes and increase in probing depth; these results suggest that environmental challenges in the periodontal pockets may modulate the microbiota by selecting genotypes best able to exploit the environment.
Oral Microbiology and Immunology Laboratory, Dentistry School of Piracicaba, State University of Campinas, São Paulo, Brazil.
Ana Cláudia B A
AC
Alves
Marcelo H
MH
Napimoga
Marlise I
MI
Klein
Jose F
JF
Hofling
Reginaldo B
RB
Gonçalves
D000328:Adult; D000368:Aged; D015169:Colony Count, Microbial; D003773:Dental Plaque / Q000382:microbiology; D005260:Female; D014644:Genetic Variation / Q000235:genetics; D005838:Genotype; D005881:Gingiva / Q000382:microbiology; D005884:Gingival Hemorrhage / Q000382:microbiology; D020180:Heteroduplex Analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010514:Periodontal Pocket / Q000382:microbiology*; D010518:Periodontitis / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods; D018713:Prevotella intermedia / Q000145:classification* / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000032:analysis
D012336:RNA, Ribosomal, 16S