Preliminary study of the genetic variability of fimbriae A (fimA) of Porphyromonas

Abstract

Porphyromonas gingivalis (P. gingivalis) is one of the major causative agents of periodontal disease (PD). Its aggressiveness is evidenced by virulence factors encoded in its genome. Fimbriae provide the bacterium with the ability to adhere to the supporting tissue, to the acquired film, and to coaggregate with other bacterial species. Among the types of fimbriae, we find the fimbriae A (fimA), which has 6 different genotypes (I, Ib, II, III, IV, V). FimA II and FimA IV genotypes are identified in subjects with periodontitis, while FimA I is characteristic of healthy subjects. Knowing the prevalence of P. gingivalis strains in our population would provide information to anticipate the evolution of periodontal treatment. For the moment, we observed that fimA IV was associated with probing depth (PD) and clinical attachment level (CAL) corresponding to periodontitis A and B Grade, stages I and II, whereas fimA II was detected in less severe PD pockets.

In a descriptive, cross-sectional study, we recruited 81 systemically healthy adults of both sexes with a diagnosed PD, with the presence of at least 18 teeth in the mouth, who provided signed consent to participate in the project. Those who had received periodontal treatment and antibiotic medication in the previous 6 months and/or drug use were excluded. We examined 307 diseased sites and took a sample from each to genotype the most frequent types of FimA by molecular biology.

Eighteen percent of the sites detected FimA II, corresponding to a PS of 4mm and a NIC of 3mm. FimA IV was detected in 15% of the sites with PS of 5mm and 4mm NIC. The remaining 68% would correspond to the rest of the genotypes to be investigated.

At the moment, we observed that fimA IV was associated with PS and NIC values corresponding to stage I and II grade A and B periodontitis while fimA II was detected in sites with PD of lesser severity.