Distribution of Porphyromonas gingivalis fimA and mfa1 fimbrial genotypes in subgingival plaques

Strains of periodontal disease-associated bacterium have different pathogenicity, which can be attributed to clonal genetic diversity. typically expresses two types of fimbriae, FimA and Mfa1, which comprise six (I, Ib, II, III, IV, and V) and two ( and ) genotypes, respectively. This study was conducted to investigate the distribution of the two fimbrial genotypes of in clinical specimens. Subgingival plaques were collected from 100 participants during periodontal maintenance therapy and examined for fimbrial 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. Both fimbrial types could be detected in 63 out of 100 samples; among them, genotype II was found in 33 samples (52.4%), in which the genotype was 1.75 times more prevalent than . The total detection rate of genotypes I and Ib was 38.1%; in these samples, the two genotypes were observed at a comparable frequency. In two samples positive for III (3.2%), only was detected, whereas in four samples positive for IV (6.3%), the two genotypes were equally represented, and none of V-positive samples defined the genotype. No associations were found between clinical parameters and fimbrial subtype combinations. Both fimbrial types were detected at various ratios in subgingival plaques, and a tendency for and genotype combinations was observed. However, there was no association between fimbrial genotypes and periodontitis severity.