Distribution ofPorphyromonas gingivalis fimAandmfa1fimbrial genotypes in subgingival plaques

Abstract

BackgroundStrains of periodontal disease-associated bacteriumPorphyromonas gingivalishave different pathogenicity, which can be attributed to clonal genetic diversity.P. gingivalistypically expresses two types of fimbriae, FimA and Mfa1, which comprise six (I, Ib, II, III, IV, and V) and two (mfa53andmfa70) genotypes, respectively. This study was conducted to investigate the distribution of the two fimbrial genotypes ofP. gingivalisin clinical specimens.MethodsSubgingival plaques were collected from 100 participants during periodontal maintenance therapy and examined forP. gingivalisfimbrial genotypes by direct polymerase chain reaction and/or DNA sequencing. We also analyzed the relationship between fimbrial genotypes and clinical parameters of periodontitis recorded at the first medical examination.ResultsBoth fimbrial types could be detected in 63 out of 100 samples; among them,fimAgenotype II was found in 33 samples (52.4%), in which themfa70genotype was 1.75 times more prevalent thanmfa53. The total detection rate offimAgenotypes I and Ib was 38.1%; in these samples, the twomfa1genotypes were observed at a comparable frequency. In two samples positive forfimAIII (3.2%), onlymfa53was detected, whereas in four samples positive forfimAIV (6.3%), the twomfa1genotypes were equally represented, and none offimAV-positive samples defined themfa1genotype. No associations were found between clinical parameters and fimbrial subtype combinations.DiscussionBothP. gingivalisfimbrial types were detected at various ratios in subgingival plaques, and a tendency forfimAandmfa1genotype combinations was observed. However, there was no association betweenP. gingivalisfimbrial genotypes and periodontitis severity.