Prevalence of the oral pathogen Filifactor alocis and its FtxA toxin related to clinical parameters and presence of Aggregatibacter actinomycetemcomitans

The Gram-positive organism <i>Filifactor alocis</i> is implicated in multiple oral diseases including periodontitis, and approximately 50% of known strains encode and produce a recently identified repeat-in-toxin (RTX) protein, FtxA, partly homologous to the <i>Aggregatibacter actinomycetemcomitans</i> leukotoxin. By assessing a longitudinal Ghanaian study population of adolescents, we recently identified a possible correlation between <i>F. alocis</i> levels, <i>ftxA</i> gene carriage, and progression of clinical attachment loss (CAL). To extend knowledge on the possible significance of <i>F. alocis</i> and its FtxA in periodontal disease, we have in the present work analyzed saliva samples in an independent cohort of periodontitis (n=156), collected at two private periodontal specialist practices in Perth, Western Australia. The present results corroborate that high loads of <i>F. alocis</i> and the presence of its <i>ftxA</i> gene together are associated with parameters of periodontal tissue destruction and severity. Moreover, among the individuals carrying <i>A. actinomycetemcomitans</i>, a majority also exhibited an <i>ftxA</i>-positive <i>F. alocis</i>, supporting the notion of the synergistic behavior of these two species. This emphasizes that <i>F. alocis</i> and its <i>ftxA</i> are involved in the pathogenesis of periodontitis and may have ecological roles, with diagnostic and prognostic implications for the disease.