Persistent presence of Bacteroides forsythus as a risk factor for attachment loss in a population with low prevalence and severity of adult periodontitis

Background: Previous longitudinal studies investigating the role of microor ganisms in periodontitis have focused on subjects with a high prevalence an d severity of disease. The complex profile of microbial species in severe c ases of periodontitis might not allow us to differentiate which bacterial s pecies initiate disease or which species simply proliferate after disease p rogression. This prospective longitudinal study followed a group of 205 sub jects who showed a low prevalence and severity of adult periodontitis, and thus allowed us to monitor early microbiological changes in the development of periodontitis. Methods: Subgingival plaque was collected from proximal surfaces of a poste rior sextant at 6-month intervals for 2 years. During the monitoring period , 44 subjects had either attachment loss or attachment gain. Using multiple x polymerase chain reaction (PCR), all plaque samples from those 44 subject s were analyzed for the presence of Actinobacillus actinomycetemcomitans, B acteroides forsythus, and Porphyromonas gingivalis. Results: Both subjects with attachment loss and those with attachment gain bad a high prevalence of these 3 periodontal pathogens. The mere presence o f any of the 3 species at a site could not predict future attachment loss a t that specific site. However, subjects with a persistent presence of B. fo rsythus at any site across all visits had 5.3 times higher odds of having a t least one site in their mouth losing attachment compared to subjects with occasional or no presence of B, forsythus. Conclusions: The persistence of B. forsythus identified subjects at higher risk, but not which specific sites in those subjects would lose attachment.